Remove the old console input code; use qio

[akaros.git] / kern / src / syscall.c

/* See COPYRIGHT for copyright information. */

//#define DEBUG
#include <ros/common.h>
#include <ros/limits.h>
#include <arch/types.h>
#include <arch/arch.h>
#include <arch/mmu.h>
#include <arch/console.h>
#include <time.h>
#include <error.h>

#include <elf.h>
#include <string.h>
#include <assert.h>
#include <process.h>
#include <schedule.h>
#include <pmap.h>
#include <umem.h>
#include <mm.h>
#include <trap.h>
#include <syscall.h>
#include <kmalloc.h>
#include <profiler.h>
#include <stdio.h>
#include <frontend.h>
#include <colored_caches.h>
#include <hashtable.h>
#include <bitmask.h>
#include <vfs.h>
#include <devfs.h>
#include <smp.h>
#include <arsc_server.h>
#include <event.h>
#include <kprof.h>
#include <termios.h>
#include <manager.h>
#include <ros/procinfo.h>

static int execargs_stringer(struct proc *p, char *d, size_t slen,
                             char *path, size_t path_l,
                             char *argenv, size_t argenv_l);

/* Global, used by the kernel monitor for syscall debugging. */
bool systrace_loud = FALSE;

/* Helper, given the trace record, pretty-print the trace's contents into the
 * trace's pretty buf.  'entry' says whether we're an entry record or not
 * (exit).  Returns the number of bytes put into the pretty_buf. */
static size_t systrace_fill_pretty_buf(struct systrace_record *trace,
                                       bool entry)
{
        size_t len = 0;
        struct timespec ts_start = tsc2timespec(trace->start_timestamp);
        struct timespec ts_end = tsc2timespec(trace->end_timestamp);

        /* Slightly different formats between entry and exit.  Entry has retval set
         * to ---, and begins with E.  Exit begins with X. */
        if (entry) {
                len = snprintf(trace->pretty_buf, SYSTR_PRETTY_BUF_SZ - len,
                      "E [%7d.%09d]-[%7d.%09d] Syscall %3d (%12s):(0x%llx, 0x%llx, "
                      "0x%llx, 0x%llx, 0x%llx, 0x%llx) ret: --- proc: %d core: %d "
                      "vcore: %d data: ",
                               ts_start.tv_sec,
                               ts_start.tv_nsec,
                               ts_end.tv_sec,
                               ts_end.tv_nsec,
                               trace->syscallno,
                               syscall_table[trace->syscallno].name,
                               trace->arg0,
                               trace->arg1,
                               trace->arg2,
                               trace->arg3,
                               trace->arg4,
                               trace->arg5,
                               trace->pid,
                               trace->coreid,
                               trace->vcoreid);
        } else {
                len = snprintf(trace->pretty_buf, SYSTR_PRETTY_BUF_SZ - len,
                      "X [%7d.%09d]-[%7d.%09d] Syscall %3d (%12s):(0x%llx, 0x%llx, "
                      "0x%llx, 0x%llx, 0x%llx, 0x%llx) ret: 0x%llx proc: %d core: %d "
                      "vcore: %d data: ",
                               ts_start.tv_sec,
                               ts_start.tv_nsec,
                               ts_end.tv_sec,
                               ts_end.tv_nsec,
                               trace->syscallno,
                               syscall_table[trace->syscallno].name,
                               trace->arg0,
                               trace->arg1,
                               trace->arg2,
                               trace->arg3,
                               trace->arg4,
                               trace->arg5,
                               trace->retval,
                               trace->pid,
                               trace->coreid,
                               trace->vcoreid);
        }
        len += printdump(trace->pretty_buf + len, trace->datalen,
                         SYSTR_PRETTY_BUF_SZ - len - 1,
                         trace->data);
        len += snprintf(trace->pretty_buf + len, SYSTR_PRETTY_BUF_SZ - len, "\n");
        return len;
}

/* Helper: spits out our trace to the various sinks. */
static void systrace_output(struct systrace_record *trace,
                            struct strace *strace, bool entry)
{
        size_t pretty_len;

        pretty_len = systrace_fill_pretty_buf(trace, entry);
        if (strace)
                qiwrite(strace->q, trace->pretty_buf, pretty_len);
        if (systrace_loud)
                printk("%s", trace->pretty_buf);
}

/* Starts a trace for p running sysc, attaching it to kthread.  Pairs with
 * systrace_finish_trace(). */
static void systrace_start_trace(struct kthread *kthread, struct syscall *sysc)
{
        struct proc *p = current;
        struct systrace_record *trace;
        uintreg_t data_arg;
        size_t data_len = 0;

        kthread->strace = 0;
        if (!p->strace_on && !systrace_loud)
                return;
        trace = kmalloc(SYSTR_BUF_SZ, MEM_ATOMIC);
        if (p->strace) {
                /* We're using qiwrite below, which has no flow control.  We'll do it
                 * manually.  TODO: consider a block_alloc and qpass, though note that
                 * we actually write the same trace in twice (entry and exit).
                 * Alternatively, we can add another qio method that has flow control
                 * and non blocking. */
                if (qfull(p->strace->q)) {
                        atomic_inc(&p->strace->nr_drops);
                        kfree(trace);
                        return;
                }
                if (!trace)
                        atomic_inc(&p->strace->nr_drops);
                /* Avoiding the atomic op.  We sacrifice accuracy for less overhead. */
                p->strace->appx_nr_sysc++;
        }
        if (!trace)
                return;
        /* if you ever need to debug just one strace function, this is
         * handy way to do it: just bail out if it's not the one you
         * want.
         * if (sysc->num != SYS_exec)
         * return; */
        trace->start_timestamp = read_tsc();
        trace->end_timestamp = 0;
        trace->syscallno = sysc->num;
        trace->arg0 = sysc->arg0;
        trace->arg1 = sysc->arg1;
        trace->arg2 = sysc->arg2;
        trace->arg3 = sysc->arg3;
        trace->arg4 = sysc->arg4;
        trace->arg5 = sysc->arg5;
        trace->retval = 0;
        trace->pid = p->pid;
        trace->coreid = core_id();
        trace->vcoreid = proc_get_vcoreid(p);
        trace->pretty_buf = (char*)trace + sizeof(struct systrace_record);
        trace->datalen = 0;
        trace->data[0] = 0;

        switch (sysc->num) {
        case SYS_write:
                data_arg = sysc->arg1;
                data_len = sysc->arg2;
                break;
        case SYS_openat:
                data_arg = sysc->arg1;
                data_len = sysc->arg2;
                break;
        case SYS_exec:
                trace->datalen = execargs_stringer(current,
                                                   (char *)trace->data,
                                                   sizeof(trace->data),
                                                   (char *)sysc->arg0,
                                                   sysc->arg1,
                                                   (char *)sysc->arg2,
                                                   sysc->arg3);
                break;
        case SYS_proc_create:
                trace->datalen = execargs_stringer(current,
                                                   (char *)trace->data,
                                                   sizeof(trace->data),
                                                   (char *)sysc->arg0,
                                                   sysc->arg1,
                                                   (char *)sysc->arg2,
                                                   sysc->arg3);
                break;
        }
        if (data_len) {
                trace->datalen = MIN(sizeof(trace->data), data_len);
                copy_from_user(trace->data, (void*)data_arg, trace->datalen);
        }

        systrace_output(trace, p->strace, TRUE);

        kthread->strace = trace;
}

/* Finishes the trace on kthread for p, with retval being the return from the
 * syscall we're tracing.  Pairs with systrace_start_trace(). */
static void systrace_finish_trace(struct kthread *kthread, long retval)
{
        struct proc *p = current;
        struct systrace_record *trace;
        long data_arg;
        size_t data_len = 0;

        if (!kthread->strace)
                return;
        trace = kthread->strace;
        trace->end_timestamp = read_tsc();
        trace->retval = retval;

        /* Only try to do the trace data if we didn't do it on entry */
        if (!trace->datalen) {
                switch (trace->syscallno) {
                case SYS_read:
                        data_arg = trace->arg1;
                        data_len = retval < 0 ? 0 : retval;
                        break;
                }
                trace->datalen = MIN(sizeof(trace->data), data_len);
                if (trace->datalen)
                        copy_from_user(trace->data, (void*)data_arg, trace->datalen);
        }

        systrace_output(trace, p->strace, FALSE);
        kfree(kthread->strace);
        kthread->strace = 0;
}

#ifdef CONFIG_SYSCALL_STRING_SAVING

static void alloc_sysc_str(struct kthread *kth)
{
        kth->name = kmalloc(SYSCALL_STRLEN, MEM_WAIT);
        kth->name[0] = 0;
}

static void free_sysc_str(struct kthread *kth)
{
        char *str = kth->name;
        kth->name = 0;
        kfree(str);
}

#define sysc_save_str(...)                                                     \
{                                                                              \
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];                     \
        snprintf(pcpui->cur_kthread->name, SYSCALL_STRLEN, __VA_ARGS__);           \
}

#else

static void alloc_sysc_str(struct kthread *kth)
{
}

static void free_sysc_str(struct kthread *kth)
{
}

#define sysc_save_str(...)

#endif /* CONFIG_SYSCALL_STRING_SAVING */

/* Helper to finish a syscall, signalling if appropriate */
static void finish_sysc(struct syscall *sysc, struct proc *p)
{
        /* Atomically turn on the LOCK and SC_DONE flag.  The lock tells userspace
         * we're messing with the flags and to not proceed.  We use it instead of
         * CASing with userspace.  We need the atomics since we're racing with
         * userspace for the event_queue registration.  The 'lock' tells userspace
         * to not muck with the flags while we're signalling. */
        atomic_or(&sysc->flags, SC_K_LOCK | SC_DONE);
        __signal_syscall(sysc, p);
        atomic_and(&sysc->flags, ~SC_K_LOCK);
}

/* Helper that "finishes" the current async syscall.  This should be used with
 * care when we are not using the normal syscall completion path.
 *
 * Do *NOT* complete the same syscall twice.  This is catastrophic for _Ms, and
 * a bad idea for _S.
 *
 * It is possible for another user thread to see the syscall being done early -
 * they just need to be careful with the weird proc management calls (as in,
 * don't trust an async fork).
 *
 * *sysc is in user memory, and should be pinned (TODO: UMEM).  There may be
 * issues with unpinning this if we never return. */
static void finish_current_sysc(int retval)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        assert(pcpui->cur_kthread->sysc);
        pcpui->cur_kthread->sysc->retval = retval;
        finish_sysc(pcpui->cur_kthread->sysc, pcpui->cur_proc);
}

/* Callable by any function while executing a syscall (or otherwise, actually).
 */
void set_errno(int errno)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        if (pcpui->cur_kthread && pcpui->cur_kthread->sysc)
                pcpui->cur_kthread->sysc->err = errno;
}

/* Callable by any function while executing a syscall (or otherwise, actually).
 */
int get_errno(void)
{
        /* if there's no errno to get, that's not an error I guess. */
        int errno = 0;
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        if (pcpui->cur_kthread && pcpui->cur_kthread->sysc)
                errno = pcpui->cur_kthread->sysc->err;
        return errno;
}

void unset_errno(void)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        if (!pcpui->cur_kthread || !pcpui->cur_kthread->sysc)
                return;
        pcpui->cur_kthread->sysc->err = 0;
        pcpui->cur_kthread->sysc->errstr[0] = '\0';
}

void vset_errstr(const char *fmt, va_list ap)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];

        if (!pcpui->cur_kthread || !pcpui->cur_kthread->sysc)
                return;

        vsnprintf(pcpui->cur_kthread->sysc->errstr, MAX_ERRSTR_LEN, fmt, ap);

        /* TODO: likely not needed */
        pcpui->cur_kthread->sysc->errstr[MAX_ERRSTR_LEN - 1] = '\0';
}

void set_errstr(const char *fmt, ...)
{
        va_list ap;

        assert(fmt);
        va_start(ap, fmt);
        vset_errstr(fmt, ap);
        va_end(ap);
}

char *current_errstr(void)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        if (!pcpui->cur_kthread || !pcpui->cur_kthread->sysc)
                return "no errstr";
        return pcpui->cur_kthread->sysc->errstr;
}

void set_error(int error, const char *fmt, ...)
{
        va_list ap;

        set_errno(error);

        assert(fmt);
        va_start(ap, fmt);
        vset_errstr(fmt, ap);
        va_end(ap);
}

struct errbuf *get_cur_errbuf(void)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        return pcpui->cur_kthread->errbuf;
}

void set_cur_errbuf(struct errbuf *ebuf)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        pcpui->cur_kthread->errbuf = ebuf;
}

char *get_cur_genbuf(void)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        assert(pcpui->cur_kthread);
        return pcpui->cur_kthread->generic_buf;
}

/* Helper, looks up proc* for pid and ensures p controls that proc. 0 o/w */
static struct proc *get_controllable_proc(struct proc *p, pid_t pid)
{
        struct proc *target = pid2proc(pid);
        if (!target) {
                set_errno(ESRCH);
                return 0;
        }
        if (!proc_controls(p, target)) {
                set_errno(EPERM);
                proc_decref(target);
                return 0;
        }
        return target;
}

static int unpack_argenv(struct argenv *argenv, size_t argenv_l,
                         int *argc_p, char ***argv_p,
                         int *envc_p, char ***envp_p)
{
        int argc = argenv->argc;
        int envc = argenv->envc;
        char **argv = (char**)argenv->buf;
        char **envp = argv + argc;
        char *argbuf = (char*)(envp + envc);
        uintptr_t argbuf_offset = (uintptr_t)(argbuf - (char*)(argenv));

        if (((char*)argv - (char*)argenv) > argenv_l)
                return -1;
        if (((char*)argv + (argc * sizeof(char**)) - (char*)argenv) > argenv_l)
                return -1;
        if (((char*)envp - (char*)argenv) > argenv_l)
                return -1;
        if (((char*)envp + (envc * sizeof(char**)) - (char*)argenv) > argenv_l)
                return -1;
        if (((char*)argbuf - (char*)argenv) > argenv_l)
                return -1;
        for (int i = 0; i < argc; i++) {
                if ((uintptr_t)(argv[i] + argbuf_offset) > argenv_l)
                        return -1;
                argv[i] += (uintptr_t)argbuf;
        }
        for (int i = 0; i < envc; i++) {
                if ((uintptr_t)(envp[i] + argbuf_offset) > argenv_l)
                        return -1;
                envp[i] += (uintptr_t)argbuf;
        }
        *argc_p = argc;
        *argv_p = argv;
        *envc_p = envc;
        *envp_p = envp;
        return 0;
}

/************** Utility Syscalls **************/

static int sys_null(void)
{
        return 0;
}

/* Diagnostic function: blocks the kthread/syscall, to help userspace test its
 * async I/O handling. */
static int sys_block(struct proc *p, unsigned long usec)
{
        sysc_save_str("block for %lu usec", usec);
        kthread_usleep(usec);
        return 0;
}

/* Pause execution for a number of nanoseconds.
 * The current implementation rounds up to the nearest microsecond. If the
 * syscall is aborted, we return the remaining time the call would have ran
 * in the 'rem' parameter.  */
static int sys_nanosleep(struct proc *p,
                         const struct timespec *req,
                         struct timespec *rem)
{
        ERRSTACK(1);
        uint64_t usec;
        struct timespec kreq, krem = {0, 0};
        uint64_t tsc = read_tsc();

        /* Check the input arguments. */
        if (memcpy_from_user(p, &kreq, req, sizeof(struct timespec))) {
                set_errno(EFAULT);
                return -1;
        }
        if (rem && memcpy_to_user(p, rem, &krem, sizeof(struct timespec))) {
                set_errno(EFAULT);
                return -1;
        }
        if (kreq.tv_sec < 0) {
                set_errno(EINVAL);
                return -1;
        }
        if ((kreq.tv_nsec < 0) || (kreq.tv_nsec > 999999999)) {
                set_errno(EINVAL);
                return -1;
        }

        /* Convert timespec to usec. Ignore overflow on the tv_sec field. */
        usec = kreq.tv_sec * 1000000;
        usec += DIV_ROUND_UP(kreq.tv_nsec, 1000);

        /* Attempt to sleep. If we get aborted, copy the remaining time into
         * 'rem' and return. We assume the tsc is sufficient to tell how much
         * time is remaining (i.e. it only overflows on the order of hundreds of
         * years, which should be sufficiently long enough to ensure we don't
         * overflow). */
        if (waserror()) {
                krem = tsc2timespec(read_tsc() - tsc);
                if (rem && memcpy_to_user(p, rem, &krem, sizeof(struct timespec)))
                        set_errno(EFAULT);
                poperror();
                return -1;
        }
        sysc_save_str("nanosleep for %d usec", usec);
        kthread_usleep(usec);
        poperror();
        return 0;
}

// Writes 'val' to 'num_writes' entries of the well-known array in the kernel
// address space.  It's just #defined to be some random 4MB chunk (which ought
// to be boot_alloced or something).  Meant to grab exclusive access to cache
// lines, to simulate doing something useful.
static int sys_cache_buster(struct proc *p, uint32_t num_writes,
                             uint32_t num_pages, uint32_t flags)
{
        #define BUSTER_ADDR             0xd0000000L  // around 512 MB deep
        #define MAX_WRITES              1048576*8
        #define MAX_PAGES               32
        #define INSERT_ADDR     (UINFO + 2*PGSIZE) // should be free for these tests
        uint32_t* buster = (uint32_t*)BUSTER_ADDR;
        static spinlock_t buster_lock = SPINLOCK_INITIALIZER;
        uint64_t ticks = -1;
        page_t* a_page[MAX_PAGES];

        /* Strided Accesses or Not (adjust to step by cachelines) */
        uint32_t stride = 1;
        if (flags & BUSTER_STRIDED) {
                stride = 16;
                num_writes *= 16;
        }

        /* Shared Accesses or Not (adjust to use per-core regions)
         * Careful, since this gives 8MB to each core, starting around 512MB.
         * Also, doesn't separate memory for core 0 if it's an async call.
         */
        if (!(flags & BUSTER_SHARED))
                buster = (uint32_t*)(BUSTER_ADDR + core_id() * 0x00800000);

        /* Start the timer, if we're asked to print this info*/
        if (flags & BUSTER_PRINT_TICKS)
                ticks = start_timing();

        /* Allocate num_pages (up to MAX_PAGES), to simulate doing some more
         * realistic work.  Note we don't write to these pages, even if we pick
         * unshared.  Mostly due to the inconvenience of having to match up the
         * number of pages with the number of writes.  And it's unnecessary.
         */
        if (num_pages) {
                spin_lock(&buster_lock);
                for (int i = 0; i < MIN(num_pages, MAX_PAGES); i++) {
                        upage_alloc(p, &a_page[i],1);
                        page_insert(p->env_pgdir, a_page[i], (void*)INSERT_ADDR + PGSIZE*i,
                                    PTE_USER_RW);
                        page_decref(a_page[i]);
                }
                spin_unlock(&buster_lock);
        }

        if (flags & BUSTER_LOCKED)
                spin_lock(&buster_lock);
        for (int i = 0; i < MIN(num_writes, MAX_WRITES); i=i+stride)
                buster[i] = 0xdeadbeef;
        if (flags & BUSTER_LOCKED)
                spin_unlock(&buster_lock);

        if (num_pages) {
                spin_lock(&buster_lock);
                for (int i = 0; i < MIN(num_pages, MAX_PAGES); i++) {
                        page_remove(p->env_pgdir, (void*)(INSERT_ADDR + PGSIZE * i));
                        page_decref(a_page[i]);
                }
                spin_unlock(&buster_lock);
        }

        /* Print info */
        if (flags & BUSTER_PRINT_TICKS) {
                ticks = stop_timing(ticks);
                printk("%llu,", ticks);
        }
        return 0;
}

static int sys_cache_invalidate(void)
{
        #ifdef CONFIG_X86
                wbinvd();
        #endif
        return 0;
}

/* sys_reboot(): called directly from dispatch table. */

/* Returns the id of the physical core this syscall is executed on. */
static uint32_t sys_getpcoreid(void)
{
        return core_id();
}

// TODO: Temporary hack until thread-local storage is implemented on i386 and
// this is removed from the user interface
static size_t sys_getvcoreid(struct proc *p)
{
        return proc_get_vcoreid(p);
}

/************** Process management syscalls **************/

/* Helper for proc_create and fork */
static void inherit_strace(struct proc *parent, struct proc *child)
{
        if (parent->strace && parent->strace_inherit) {
                /* Refcnt on both, put in the child's ->strace. */
                kref_get(&parent->strace->users, 1);
                kref_get(&parent->strace->procs, 1);
                child->strace = parent->strace;
                child->strace_on = TRUE;
                child->strace_inherit = TRUE;
        }
}

/* Creates a process from the file 'path'.  The process is not runnable by
 * default, so it needs it's status to be changed so that the next call to
 * schedule() will try to run it. */
static int sys_proc_create(struct proc *p, char *path, size_t path_l,
                           char *argenv, size_t argenv_l, int flags)
{
        int pid = 0;
        char *t_path;
        struct file *program;
        struct proc *new_p;
        int argc, envc;
        char **argv, **envp;
        struct argenv *kargenv;

        t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        /* TODO: 9ns support */
        program = do_file_open(t_path, O_READ, 0);
        if (!program)
                goto error_with_path;
        if (!is_valid_elf(program)) {
                set_errno(ENOEXEC);
                goto error_with_file;
        }
        /* Check the size of the argenv array, error out if too large. */
        if ((argenv_l < sizeof(struct argenv)) || (argenv_l > ARG_MAX)) {
                set_error(EINVAL, "The argenv array has an invalid size: %lu\n",
                                  argenv_l);
                goto error_with_file;
        }
        /* Copy the argenv array into a kernel buffer. Delay processing of the
         * array to load_elf(). */
        kargenv = user_memdup_errno(p, argenv, argenv_l);
        if (!kargenv) {
                set_error(EINVAL, "Failed to copy in the args");
                goto error_with_file;
        }
        /* Unpack the argenv array into more usable variables. Integrity checking
         * done along side this as well. */
        if (unpack_argenv(kargenv, argenv_l, &argc, &argv, &envc, &envp)) {
                set_error(EINVAL, "Failed to unpack the args");
                goto error_with_kargenv;
        }
        /* TODO: need to split the proc creation, since you must load after setting
         * args/env, since auxp gets set up there. */
        //new_p = proc_create(program, 0, 0);
        if (proc_alloc(&new_p, current, flags)) {
                set_error(ENOMEM, "Failed to alloc new proc");
                goto error_with_kargenv;
        }
        inherit_strace(p, new_p);
        /* close the CLOEXEC ones, even though this isn't really an exec */
        close_fdt(&new_p->open_files, TRUE);
        /* Load the elf. */
        if (load_elf(new_p, program, argc, argv, envc, envp)) {
                set_error(EINVAL, "Failed to load elf");
                goto error_with_proc;
        }
        /* progname is argv0, which accounts for symlinks */
        proc_set_progname(new_p, argc ? argv[0] : NULL);
        proc_replace_binary_path(new_p, t_path);
        kref_put(&program->f_kref);
        user_memdup_free(p, kargenv);
        __proc_ready(new_p);
        pid = new_p->pid;
        profiler_notify_new_process(new_p);
        proc_decref(new_p);     /* give up the reference created in proc_create() */
        return pid;
error_with_proc:
        /* proc_destroy will decref once, which is for the ref created in
         * proc_create().  We don't decref again (the usual "+1 for existing"),
         * since the scheduler, which usually handles that, hasn't heard about the
         * process (via __proc_ready()). */
        proc_destroy(new_p);
error_with_kargenv:
        user_memdup_free(p, kargenv);
error_with_file:
        kref_put(&program->f_kref);
error_with_path:
        free_path(p, t_path);
        return -1;
}

/* Makes process PID runnable.  Consider moving the functionality to process.c */
static error_t sys_proc_run(struct proc *p, unsigned pid)
{
        error_t retval = 0;
        struct proc *target = get_controllable_proc(p, pid);
        if (!target)
                return -1;
        if (target->state != PROC_CREATED) {
                set_errno(EINVAL);
                proc_decref(target);
                return -1;
        }
        /* Note a proc can spam this for someone it controls.  Seems safe - if it
         * isn't we can change it. */
        proc_wakeup(target);
        proc_decref(target);
        return 0;
}

/* Destroy proc pid.  If this is called by the dying process, it will never
 * return.  o/w it will return 0 on success, or an error.  Errors include:
 * - ESRCH: if there is no such process with pid
 * - EPERM: if caller does not control pid */
static error_t sys_proc_destroy(struct proc *p, pid_t pid, int exitcode)
{
        error_t r;
        struct proc *p_to_die = get_controllable_proc(p, pid);
        if (!p_to_die)
                return -1;
        if (p_to_die == p) {
                p->exitcode = exitcode;
                printd("[PID %d] proc exiting gracefully (code %d)\n", p->pid,exitcode);
        } else {
                p_to_die->exitcode = exitcode;  /* so its parent has some clue */
                printd("[%d] destroying proc %d\n", p->pid, p_to_die->pid);
        }
        proc_destroy(p_to_die);
        /* we only get here if we weren't the one to die */
        proc_decref(p_to_die);
        return 0;
}

static int sys_proc_yield(struct proc *p, bool being_nice)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        /* proc_yield() often doesn't return - we need to set the syscall retval
         * early.  If it doesn't return, it expects to eat our reference (for now).
         */
        free_sysc_str(pcpui->cur_kthread);
        systrace_finish_trace(pcpui->cur_kthread, 0);
        finish_sysc(pcpui->cur_kthread->sysc, pcpui->cur_proc);
        pcpui->cur_kthread->sysc = 0;   /* don't touch sysc again */
        proc_incref(p, 1);
        proc_yield(p, being_nice);
        proc_decref(p);
        /* Shouldn't return, to prevent the chance of mucking with cur_sysc. */
        smp_idle();
        assert(0);
}

static int sys_change_vcore(struct proc *p, uint32_t vcoreid,
                             bool enable_my_notif)
{
        /* Note retvals can be negative, but we don't mess with errno in case
         * callers use this in low-level code and want to extract the 'errno'. */
        return proc_change_to_vcore(p, vcoreid, enable_my_notif);
}

static ssize_t sys_fork(env_t* e)
{
        uintptr_t temp;
        int ret;

        // TODO: right now we only support fork for single-core processes
        if (e->state != PROC_RUNNING_S) {
                set_errno(EINVAL);
                return -1;
        }
        env_t* env;
        ret = proc_alloc(&env, current, PROC_DUP_FGRP);
        assert(!ret);
        assert(env != NULL);
        proc_set_progname(env, e->progname);

        /* Can't really fork if we don't have a current_ctx to fork */
        if (!current_ctx) {
                proc_destroy(env);
                proc_decref(env);
                set_errno(EINVAL);
                return -1;
        }
        copy_current_ctx_to(&env->scp_ctx);

        env->cache_colors_map = cache_colors_map_alloc();
        for (int i = 0; i < llc_cache->num_colors; i++)
                if (GET_BITMASK_BIT(e->cache_colors_map,i))
                        cache_color_alloc(llc_cache, env->cache_colors_map);

        /* Make the new process have the same VMRs as the older.  This will copy the
         * contents of non MAP_SHARED pages to the new VMRs. */
        if (duplicate_vmrs(e, env)) {
                proc_destroy(env);      /* this is prob what you want, not decref by 2 */
                proc_decref(env);
                set_errno(ENOMEM);
                return -1;
        }
        /* Switch to the new proc's address space and finish the syscall.  We'll
         * never naturally finish this syscall for the new proc, since its memory
         * is cloned before we return for the original process.  If we ever do CoW
         * for forked memory, this will be the first place that gets CoW'd. */
        temp = switch_to(env);
        finish_current_sysc(0);
        switch_back(env, temp);

        /* Copy some state from the original proc into the new proc. */
        env->heap_top = e->heap_top;
        env->env_flags = e->env_flags;

        inherit_strace(e, env);

        /* In general, a forked process should be a fresh process, and we copy over
         * whatever stuff is needed between procinfo/procdata. */
        *env->procdata = *e->procdata;
        env->procinfo->heap_bottom = e->procinfo->heap_bottom;

        /* FYI: once we call ready, the proc is open for concurrent usage */
        __proc_ready(env);
        proc_wakeup(env);

        // don't decref the new process.
        // that will happen when the parent waits for it.
        // TODO: if the parent doesn't wait, we need to change the child's parent
        // when the parent dies, or at least decref it

        printd("[PID %d] fork PID %d\n", e->pid, env->pid);
        ret = env->pid;
        profiler_notify_new_process(env);
        proc_decref(env);       /* give up the reference created in proc_alloc() */
        return ret;
}

/* string for sys_exec arguments. Assumes that d is pointing to zero'd
 * storage or storage that does not require null termination or
 * provides the null. */
static int execargs_stringer(struct proc *p, char *d, size_t slen,
                             char *path, size_t path_l,
                             char *argenv, size_t argenv_l)
{
        int argc, envc, i;
        char **argv, **envp;
        struct argenv *kargenv;
        int amt;
        char *s = d;
        char *e = d + slen;

        if (path_l > slen)
                path_l = slen;
        if (memcpy_from_user(p, d, path, path_l)) {
                s = seprintf(s, e, "Invalid exec path");
                return s - d;
        }
        s += path_l;

        /* yes, this code is cloned from below. I wrote a helper but
         * Barret and I concluded after talking about it that the
         * helper was not really helper-ful, as it has almost 10
         * arguments. Please, don't suggest a cpp macro. Thank you. */
        /* Check the size of the argenv array, error out if too large. */
        if ((argenv_l < sizeof(struct argenv)) || (argenv_l > ARG_MAX)) {
                s = seprintf(s, e, "The argenv array has an invalid size: %lu\n",
                                  argenv_l);
                return s - d;
        }
        /* Copy the argenv array into a kernel buffer. */
        kargenv = user_memdup_errno(p, argenv, argenv_l);
        if (!kargenv) {
                s = seprintf(s, e, "Failed to copy in the args and environment");
                return s - d;
        }
        /* Unpack the argenv array into more usable variables. Integrity checking
         * done along side this as well. */
        if (unpack_argenv(kargenv, argenv_l, &argc, &argv, &envc, &envp)) {
                s = seprintf(s, e, "Failed to unpack the args");
                user_memdup_free(p, kargenv);
                return s - d;
        }
        s = seprintf(s, e, "[%d]{", argc);
        for (i = 0; i < argc; i++)
                s = seprintf(s, e, "%s, ", argv[i]);
        s = seprintf(s, e, "}");

        user_memdup_free(p, kargenv);
        return s - d;
}

/* Load the binary "path" into the current process, and start executing it.
 * argv and envp are magically bundled in procinfo for now.  Keep in sync with
 * glibc's sysdeps/ros/execve.c.  Once past a certain point, this function won't
 * return.  It assumes (and checks) that it is current.  Don't give it an extra
 * refcnt'd *p (syscall won't do that).
 * Note: if someone batched syscalls with this call, they could clobber their
 * old memory (and will likely PF and die).  Don't do it... */
static int sys_exec(struct proc *p, char *path, size_t path_l,
                    char *argenv, size_t argenv_l)
{
        int ret = -1;
        char *t_path = NULL;
        struct file *program;
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        int argc, envc;
        char **argv, **envp;
        struct argenv *kargenv;

        /* We probably want it to never be allowed to exec if it ever was _M */
        if (p->state != PROC_RUNNING_S) {
                set_errno(EINVAL);
                return -1;
        }
        if (p != pcpui->cur_proc) {
                set_errno(EINVAL);
                return -1;
        }

        /* Can't exec if we don't have a current_ctx to restart (if we fail).  This
         * isn't 100% true, but I'm okay with it. */
        if (!pcpui->cur_ctx) {
                set_errno(EINVAL);
                return -1;
        }
        /* Preemptively copy out the cur_ctx, in case we fail later (easier on
         * cur_ctx if we do this now) */
        copy_current_ctx_to(&p->scp_ctx);
        /* Check the size of the argenv array, error out if too large. */
        if ((argenv_l < sizeof(struct argenv)) || (argenv_l > ARG_MAX)) {
                set_error(EINVAL, "The argenv array has an invalid size: %lu\n",
                                  argenv_l);
                return -1;
        }
        /* Copy the argenv array into a kernel buffer. */
        kargenv = user_memdup_errno(p, argenv, argenv_l);
        if (!kargenv) {
                set_errstr("Failed to copy in the args and environment");
                return -1;
        }
        /* Unpack the argenv array into more usable variables. Integrity checking
         * done along side this as well. */
        if (unpack_argenv(kargenv, argenv_l, &argc, &argv, &envc, &envp)) {
                user_memdup_free(p, kargenv);
                set_error(EINVAL, "Failed to unpack the args");
                return -1;
        }
        t_path = copy_in_path(p, path, path_l);
        if (!t_path) {
                user_memdup_free(p, kargenv);
                return -1;
        }
        /* This could block: */
        /* TODO: 9ns support */
        program = do_file_open(t_path, O_READ, 0);
        /* Clear the current_ctx.  We won't be returning the 'normal' way.  Even if
         * we want to return with an error, we need to go back differently in case
         * we succeed.  This needs to be done before we could possibly block, but
         * unfortunately happens before the point of no return.
         *
         * Note that we will 'hard block' if we block at all.  We can't return to
         * userspace and then asynchronously finish the exec later. */
        clear_owning_proc(core_id());
        if (!program)
                goto early_error;
        if (!is_valid_elf(program)) {
                set_errno(ENOEXEC);
                goto mid_error;
        }
        /* This is the point of no return for the process. */
        /* progname is argv0, which accounts for symlinks */
        proc_replace_binary_path(p, t_path);
        proc_set_progname(p, argc ? argv[0] : NULL);
        proc_init_procdata(p);
        p->procinfo->heap_bottom = 0;
        /* When we destroy our memory regions, accessing cur_sysc would PF */
        pcpui->cur_kthread->sysc = 0;
        unmap_and_destroy_vmrs(p);
        /* close the CLOEXEC ones */
        close_fdt(&p->open_files, TRUE);
        env_user_mem_free(p, 0, UMAPTOP);
        if (load_elf(p, program, argc, argv, envc, envp)) {
                kref_put(&program->f_kref);
                user_memdup_free(p, kargenv);
                /* Note this is an inedible reference, but proc_destroy now returns */
                proc_destroy(p);
                /* We don't want to do anything else - we just need to not accidentally
                 * return to the user (hence the all_out) */
                goto all_out;
        }
        printd("[PID %d] exec %s\n", p->pid, file_name(program));
        kref_put(&program->f_kref);
        systrace_finish_trace(pcpui->cur_kthread, 0);
        goto success;
        /* These error and out paths are so we can handle the async interface, both
         * for when we want to error/return to the proc, as well as when we succeed
         * and want to start the newly exec'd _S */
mid_error:
        /* These two error paths are for when we want to restart the process with an
         * error value (errno is already set). */
        kref_put(&program->f_kref);
early_error:
        free_path(p, t_path);
        finish_current_sysc(-1);
        systrace_finish_trace(pcpui->cur_kthread, -1);
success:
        user_memdup_free(p, kargenv);
        free_sysc_str(pcpui->cur_kthread);
        /* Here's how we restart the new (on success) or old (on failure) proc: */
        spin_lock(&p->proc_lock);
        __seq_start_write(&p->procinfo->coremap_seqctr);
        __unmap_vcore(p, 0);
        __seq_end_write(&p->procinfo->coremap_seqctr);
        __proc_set_state(p, PROC_WAITING);      /* fake a yield */
        spin_unlock(&p->proc_lock);
        proc_wakeup(p);
all_out:
        /* we can't return, since we'd write retvals to the old location of the
         * syscall struct (which has been freed and is in the old userspace) (or has
         * already been written to).*/
        disable_irq();                  /* abandon_core/clear_own wants irqs disabled */
        abandon_core();
        smp_idle();                             /* will reenable interrupts */
}

/* Helper, will attempt a particular wait on a proc.  Returns the pid of the
 * process if we waited on it successfully, and the status will be passed back
 * in ret_status (kernel memory).  Returns 0 if the wait failed and we should
 * try again.  Returns -1 if we should abort.  Only handles DYING.  Callers
 * need to lock to protect the children tailq and reaping bits. */
static pid_t try_wait(struct proc *parent, struct proc *child, int *ret_status,
                      int options)
{
        if (proc_is_dying(child)) {
                /* Disown returns -1 if it's already been disowned or we should o/w
                 * abort.  This can happen if we have concurrent waiters, both with
                 * pointers to the child (only one should reap).  Note that if we don't
                 * do this, we could go to sleep and never receive a cv_signal. */
                if (__proc_disown_child(parent, child))
                        return -1;
                /* despite disowning, the child won't be freed til we drop this ref
                 * held by this function, so it is safe to access the memory.
                 *
                 * Note the exit code one byte in the 0xff00 spot.  Check out glibc's
                 * posix/sys/wait.h and bits/waitstatus.h for more info.  If we ever
                 * deal with signalling and stopping, we'll need to do some more work
                 * here.*/
                *ret_status = (child->exitcode & 0xff) << 8;
                return child->pid;
        }
        return 0;
}

/* Helper, like try_wait, but attempts a wait on any of the children, returning
 * the specific PID we waited on, 0 to try again (a waitable exists), and -1 to
 * abort (no children/waitables exist).  Callers need to lock to protect the
 * children tailq and reaping bits.*/
static pid_t try_wait_any(struct proc *parent, int *ret_status, int options)
{
        struct proc *i, *temp;
        pid_t retval;
        if (TAILQ_EMPTY(&parent->children))
                return -1;
        /* Could have concurrent waiters mucking with the tailq, caller must lock */
        TAILQ_FOREACH_SAFE(i, &parent->children, sibling_link, temp) {
                retval = try_wait(parent, i, ret_status, options);
                /* This catches a thread causing a wait to fail but not taking the
                 * child off the list before unlocking.  Should never happen. */
                assert(retval != -1);
                /* Succeeded, return the pid of the child we waited on */
                if (retval)
                        return retval;
        }
        assert(retval == 0);
        return 0;
}

/* Waits on a particular child, returns the pid of the child waited on, and
 * puts the ret status in *ret_status.  Returns the pid if we succeeded, 0 if
 * the child was not waitable and WNOHANG, and -1 on error. */
static pid_t wait_one(struct proc *parent, struct proc *child, int *ret_status,
                      int options)
{
        pid_t retval;
        cv_lock(&parent->child_wait);
        /* retval == 0 means we should block */
        retval = try_wait(parent, child, ret_status, options);
        if ((retval == 0) && (options & WNOHANG))
                goto out_unlock;
        while (!retval) {
                cpu_relax();
                cv_wait(&parent->child_wait);
                /* If we're dying, then we don't need to worry about waiting.  We don't
                 * do this yet, but we'll need this outlet when we deal with orphaned
                 * children and having init inherit them. */
                if (proc_is_dying(parent))
                        goto out_unlock;
                /* Any child can wake us up, but we check for the particular child we
                 * care about */
                retval = try_wait(parent, child, ret_status, options);
        }
        if (retval == -1) {
                /* Child was already waited on by a concurrent syscall. */
                set_errno(ECHILD);
        }
        /* Fallthrough */
out_unlock:
        cv_unlock(&parent->child_wait);
        return retval;
}

/* Waits on any child, returns the pid of the child waited on, and puts the ret
 * status in *ret_status.  Is basically a waitpid(-1, ... );  See wait_one for
 * more details.  Returns -1 if there are no children to wait on, and returns 0
 * if there are children and we need to block but WNOHANG was set. */
static pid_t wait_any(struct proc *parent, int *ret_status, int options)
{
        pid_t retval;
        cv_lock(&parent->child_wait);
        retval = try_wait_any(parent, ret_status, options);
        if ((retval == 0) && (options & WNOHANG))
                goto out_unlock;
        while (!retval) {
                cpu_relax();
                cv_wait(&parent->child_wait);
                if (proc_is_dying(parent))
                        goto out_unlock;
                /* Any child can wake us up from the CV.  This is a linear try_wait
                 * scan.  If we have a lot of children, we could optimize this. */
                retval = try_wait_any(parent, ret_status, options);
        }
        if (retval == -1)
                assert(TAILQ_EMPTY(&parent->children));
        /* Fallthrough */
out_unlock:
        cv_unlock(&parent->child_wait);
        return retval;
}

/* Note: we only allow waiting on children (no such thing as threads, for
 * instance).  Right now we only allow waiting on termination (not signals),
 * and we don't have a way for parents to disown their children (such as
 * ignoring SIGCHLD, see man 2 waitpid's Notes).
 *
 * We don't bother with stop/start signals here, though we can probably build
 * it in the helper above.
 *
 * Returns the pid of who we waited on, or -1 on error, or 0 if we couldn't
 * wait (WNOHANG). */
static pid_t sys_waitpid(struct proc *parent, pid_t pid, int *status,
                         int options)
{
        struct proc *child;
        pid_t retval = 0;
        int ret_status = 0;

        sysc_save_str("waitpid on %d", pid);
        /* -1 is the signal for 'any child' */
        if (pid == -1) {
                retval = wait_any(parent, &ret_status, options);
                goto out;
        }
        child = pid2proc(pid);
        if (!child) {
                set_errno(ECHILD);      /* ECHILD also used for no proc */
                retval = -1;
                goto out;
        }
        if (!(parent->pid == child->ppid)) {
                set_errno(ECHILD);
                retval = -1;
                goto out_decref;
        }
        retval = wait_one(parent, child, &ret_status, options);
        /* fall-through */
out_decref:
        proc_decref(child);
out:
        /* ignoring / don't care about memcpy's retval here. */
        if (status)
                memcpy_to_user(parent, status, &ret_status, sizeof(ret_status));
        printd("[PID %d] waited for PID %d, got retval %d (status 0x%x)\n",
               parent->pid, pid, retval, ret_status);
        return retval;
}

/************** Memory Management Syscalls **************/

static void *sys_mmap(struct proc *p, uintptr_t addr, size_t len, int prot,
                      int flags, int fd, off_t offset)
{
        return mmap(p, addr, len, prot, flags, fd, offset);
}

static intreg_t sys_mprotect(struct proc *p, void *addr, size_t len, int prot)
{
        return mprotect(p, (uintptr_t)addr, len, prot);
}

static intreg_t sys_munmap(struct proc *p, void *addr, size_t len)
{
        return munmap(p, (uintptr_t)addr, len);
}

static ssize_t sys_shared_page_alloc(env_t* p1,
                                     void **_addr, pid_t p2_id,
                                     int p1_flags, int p2_flags
                                    )
{
        printk("[kernel] shared page alloc is deprecated/unimplemented.\n");
        return -1;
}

static int sys_shared_page_free(env_t* p1, void *addr, pid_t p2)
{
        return -1;
}

/* Helper, to do the actual provisioning of a resource to a proc */
static int prov_resource(struct proc *target, unsigned int res_type,
                         long res_val)
{
        switch (res_type) {
                case (RES_CORES):
                        /* in the off chance we have a kernel scheduler that can't
                         * provision, we'll need to change this. */
                        return provision_core(target, res_val);
                default:
                        printk("[kernel] received provisioning for unknown resource %d\n",
                               res_type);
                        set_errno(ENOENT);      /* or EINVAL? */
                        return -1;
        }
}

/* Rough syscall to provision res_val of type res_type to target_pid */
static int sys_provision(struct proc *p, int target_pid,
                         unsigned int res_type, long res_val)
{
        struct proc *target = pid2proc(target_pid);
        int retval;
        if (!target) {
                if (target_pid == 0)
                        return prov_resource(0, res_type, res_val);
                /* debugging interface */
                if (target_pid == -1)
                        print_coreprov_map();
                set_errno(ESRCH);
                return -1;
        }
        retval = prov_resource(target, res_type, res_val);
        proc_decref(target);
        return retval;
}

/* Untested.  Will notify the target on the given vcore, if the caller controls
 * the target.  Will honor the target's wanted/vcoreid.  u_ne can be NULL. */
static int sys_notify(struct proc *p, int target_pid, unsigned int ev_type,
                      struct event_msg *u_msg)
{
        struct event_msg local_msg = {0};
        struct proc *target = get_controllable_proc(p, target_pid);
        if (!target)
                return -1;
        /* if the user provided an ev_msg, copy it in and use that */
        if (u_msg) {
                if (memcpy_from_user(p, &local_msg, u_msg, sizeof(struct event_msg))) {
                        proc_decref(target);
                        set_errno(EINVAL);
                        return -1;
                }
        } else {
                local_msg.ev_type = ev_type;
        }
        send_kernel_event(target, &local_msg, 0);
        proc_decref(target);
        return 0;
}

/* Will notify the calling process on the given vcore, independently of WANTED
 * or advertised vcoreid.  If you change the parameters, change pop_user_ctx().
 */
static int sys_self_notify(struct proc *p, uint32_t vcoreid,
                           unsigned int ev_type, struct event_msg *u_msg,
                           bool priv)
{
        struct event_msg local_msg = {0};
        /* if the user provided an ev_msg, copy it in and use that */
        if (u_msg) {
                if (memcpy_from_user(p, &local_msg, u_msg, sizeof(struct event_msg))) {
                        set_errno(EINVAL);
                        return -1;
                }
        } else {
                local_msg.ev_type = ev_type;
        }
        if (local_msg.ev_type >= MAX_NR_EVENT) {
                printk("[kernel] received self-notify for vcoreid %d, ev_type %d, "
                       "u_msg %p, u_msg->type %d\n", vcoreid, ev_type, u_msg,
                       u_msg ? u_msg->ev_type : 0);
                return -1;
        }
        /* this will post a message and IPI, regardless of wants/needs/debutantes.*/
        post_vcore_event(p, &local_msg, vcoreid, priv ? EVENT_VCORE_PRIVATE : 0);
        proc_notify(p, vcoreid);
        return 0;
}

/* Puts the calling core into vcore context, if it wasn't already, via a
 * self-IPI / active notification.  Barring any weird unmappings, we just send
 * ourselves a __notify. */
static int sys_vc_entry(struct proc *p)
{
        send_kernel_message(core_id(), __notify, (long)p, 0, 0, KMSG_ROUTINE);
        return 0;
}

/* This will halt the core, waking on an IRQ.  These could be kernel IRQs for
 * things like timers or devices, or they could be IPIs for RKMs (__notify for
 * an evq with IPIs for a syscall completion, etc).
 *
 * We don't need to finish the syscall early (worried about the syscall struct,
 * on the vcore's stack).  The syscall will finish before any __preempt RKM
 * executes, so the vcore will not restart somewhere else before the syscall
 * completes (unlike with yield, where the syscall itself adjusts the vcore
 * structures).
 *
 * In the future, RKM code might avoid sending IPIs if the core is already in
 * the kernel.  That code will need to check the CPU's state in some manner, and
 * send if the core is halted/idle.
 *
 * The core must wake up for RKMs, including RKMs that arrive while the kernel
 * is trying to halt.  The core need not abort the halt for notif_pending for
 * the vcore, only for a __notify or other RKM.  Anyone setting notif_pending
 * should then attempt to __notify (o/w it's probably a bug). */
static int sys_halt_core(struct proc *p, unsigned long usec)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        struct preempt_data *vcpd;
        /* The user can only halt CG cores!  (ones it owns) */
        if (management_core())
                return -1;
        disable_irq();
        /* both for accounting and possible RKM optimizations */
        __set_cpu_state(pcpui, CPU_STATE_IDLE);
        wrmb();
        if (has_routine_kmsg()) {
                __set_cpu_state(pcpui, CPU_STATE_KERNEL);
                enable_irq();
                return 0;
        }
        /* This situation possible, though the check is not necessary.  We can't
         * assert notif_pending isn't set, since another core may be in the
         * proc_notify.  Thus we can't tell if this check here caught a bug, or just
         * aborted early. */
        vcpd = &p->procdata->vcore_preempt_data[pcpui->owning_vcoreid];
        if (vcpd->notif_pending) {
                __set_cpu_state(pcpui, CPU_STATE_KERNEL);
                enable_irq();
                return 0;
        }
        /* CPU_STATE is reset to KERNEL by the IRQ handler that wakes us */
        cpu_halt();
        return 0;
}

/* Changes a process into _M mode, or -EINVAL if it already is an mcp.
 * __proc_change_to_m() returns and we'll eventually finish the sysc later.  The
 * original context may restart on a remote core before we return and finish,
 * but that's fine thanks to the async kernel interface. */
static int sys_change_to_m(struct proc *p)
{
        int retval = proc_change_to_m(p);
        /* convert the kernel error code into (-1, errno) */
        if (retval) {
                set_errno(-retval);
                retval = -1;
        }
        return retval;
}

/* Assists the user/2LS by atomically running *ctx and leaving vcore context.
 * Normally, the user can do this themselves, but x86 VM contexts need kernel
 * support.  The caller ought to be in vcore context, and if a notif is pending,
 * then the calling vcore will restart in a fresh VC ctx (as if it was notified
 * or did a sys_vc_entry).
 *
 * Note that this will set the TLS too, which is part of the context.  Parlib's
 * pop_user_ctx currently does *not* do this, since the TLS is managed
 * separately.  If you want to use this syscall for testing, you'll need to 0
 * out fsbase and conditionally write_msr in proc_pop_ctx(). */
static int sys_pop_ctx(struct proc *p, struct user_context *ctx)
{
        int pcoreid = core_id();
        struct per_cpu_info *pcpui = &per_cpu_info[pcoreid];
        int vcoreid = pcpui->owning_vcoreid;
        struct preempt_data *vcpd = &p->procdata->vcore_preempt_data[vcoreid];

        /* With change_to, there's a bunch of concerns about changing the vcore map,
         * since the kernel may have already locked and sent preempts, deaths, etc.
         *
         * In this case, we don't care as much.  Other than notif_pending and
         * notif_disabled, it's more like we're just changing a few registers in
         * cur_ctx.  We can safely order-after any kernel messages or other changes,
         * as if the user had done all of the changes we'll make and then did a
         * no-op syscall.
         *
         * Since we are mucking with current_ctx, it is important that we don't
         * block before or during this syscall. */
        arch_finalize_ctx(pcpui->cur_ctx);
        if (copy_from_user(pcpui->cur_ctx, ctx, sizeof(struct user_context))) {
                /* The 2LS isn't really in a position to handle errors.  At the very
                 * least, we can print something and give them a fresh vc ctx. */
                printk("[kernel] unable to copy user_ctx, 2LS bug\n");
                memset(pcpui->cur_ctx, 0, sizeof(struct user_context));
                proc_init_ctx(pcpui->cur_ctx, vcoreid, vcpd->vcore_entry,
                              vcpd->vcore_stack, vcpd->vcore_tls_desc);
                return -1;
        }
        proc_secure_ctx(pcpui->cur_ctx);
        /* The caller leaves vcore context no matter what.  We'll put them back in
         * if they missed a message. */
        vcpd->notif_disabled = FALSE;
        wrmb(); /* order disabled write before pending read */
        if (vcpd->notif_pending)
                send_kernel_message(pcoreid, __notify, (long)p, 0, 0, KMSG_ROUTINE);
        return 0;
}

/* Initializes a process to run virtual machine contexts, returning the number
 * initialized, optionally setting errno */
static int sys_vmm_setup(struct proc *p, unsigned int nr_guest_pcores,
                         struct vmm_gpcore_init *gpcis, int flags)
{
        int ret;
        ERRSTACK(1);

        if (waserror()) {
                poperror();
                return -1;
        }
        ret = vmm_struct_init(p, nr_guest_pcores, gpcis, flags);
        poperror();
        return ret;
}

static int sys_vmm_poke_guest(struct proc *p, int guest_pcoreid)
{
        return vmm_poke_guest(p, guest_pcoreid);
}

/* Pokes the ksched for the given resource for target_pid.  If the target pid
 * == 0, we just poke for the calling process.  The common case is poking for
 * self, so we avoid the lookup.
 *
 * Not sure if you could harm someone via asking the kernel to look at them, so
 * we'll do a 'controls' check for now.  In the future, we might have something
 * in the ksched that limits or penalizes excessive pokes. */
static int sys_poke_ksched(struct proc *p, int target_pid,
                           unsigned int res_type)
{
        struct proc *target;
        int retval = 0;
        if (!target_pid) {
                poke_ksched(p, res_type);
                return 0;
        }
        target = pid2proc(target_pid);
        if (!target) {
                set_errno(ESRCH);
                return -1;
        }
        if (!proc_controls(p, target)) {
                set_errno(EPERM);
                retval = -1;
                goto out;
        }
        poke_ksched(target, res_type);
out:
        proc_decref(target);
        return retval;
}

static int sys_abort_sysc(struct proc *p, struct syscall *sysc)
{
        return abort_sysc(p, sysc);
}

static int sys_abort_sysc_fd(struct proc *p, int fd)
{
        /* Consider checking for a bad fd.  Doesn't matter now, since we only look
         * for actual syscalls blocked that had used fd. */
        return abort_all_sysc_fd(p, fd);
}

static unsigned long sys_populate_va(struct proc *p, uintptr_t va,
                                     unsigned long nr_pgs)
{
        return populate_va(p, ROUNDDOWN(va, PGSIZE), nr_pgs);
}

static intreg_t sys_read(struct proc *p, int fd, void *buf, size_t len)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        ssize_t ret;
        struct file *file = get_file_from_fd(&p->open_files, fd);
        sysc_save_str("read on fd %d", fd);
        /* VFS */
        if (file) {
                if (!file->f_op->read) {
                        kref_put(&file->f_kref);
                        set_errno(EINVAL);
                        return -1;
                }
                /* TODO: (UMEM) currently, read() handles user memcpy
                 * issues, but we probably should user_mem_check and
                 * pin the region here, so read doesn't worry about
                 * it */
                ret = file->f_op->read(file, buf, len, &file->f_pos);
                kref_put(&file->f_kref);
        } else {
                /* plan9, should also handle errors (EBADF) */
                ret = sysread(fd, buf, len);
        }
        return ret;
}

static intreg_t sys_write(struct proc *p, int fd, const void *buf, size_t len)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        ssize_t ret;
        struct file *file = get_file_from_fd(&p->open_files, fd);

        sysc_save_str("write on fd %d", fd);
        /* VFS */
        if (file) {
                if (!file->f_op->write) {
                        kref_put(&file->f_kref);
                        set_errno(EINVAL);
                        return -1;
                }
                /* TODO: (UMEM) */
                ret = file->f_op->write(file, buf, len, &file->f_pos);
                kref_put(&file->f_kref);
        } else {
                /* plan9, should also handle errors */
                ret = syswrite(fd, (void*)buf, len);
        }
        return ret;
}

/* Checks args/reads in the path, opens the file (relative to fromfd if the path
 * is not absolute), and inserts it into the process's open file list. */
static intreg_t sys_openat(struct proc *p, int fromfd, const char *path,
                           size_t path_l, int oflag, int mode)
{
        int fd = -1;
        struct file *file = 0;
        char *t_path;

        printd("File %s Open attempt oflag %x mode %x\n", path, oflag, mode);
        if ((oflag & O_PATH) && (oflag & O_ACCMODE)) {
                set_error(EINVAL, "Cannot open O_PATH with any I/O perms (O%o)", oflag);
                return -1;
        }
        t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        sysc_save_str("open %s at fd %d", t_path, fromfd);
        mode &= ~p->fs_env.umask;
        /* Only check the VFS for legacy opens.  It doesn't support openat.  Actual
         * openats won't check here, and file == 0. */
#define REMOVE_BEFORE_FLIGHT 1
#if REMOVE_BEFORE_FLIGHT
        /*
         * HACK. This is another stopgap until we move away from the
         * vfs. People need to see /dev. This is written in such a way
         * as to fail quickly, be easily removed, and still do what we
         * want.
         */
        if ((fromfd == AT_FDCWD) && (path_l == 4) && (t_path[0] == '/')
                && (t_path[1] == 'd') && (t_path[2] == 'e') && (t_path[3] == 'v')) {
                set_errno(ENOENT);
        } else {
#endif
        if ((t_path[0] == '/') || (fromfd == AT_FDCWD))
                file = do_file_open(t_path, oflag, mode);
        else
                set_errno(ENOENT);      /* was not in the VFS. */
        }
        if (file) {
                /* VFS lookup succeeded */
                /* stores the ref to file */
                fd = insert_file(&p->open_files, file, 0, FALSE, oflag & O_CLOEXEC);
                kref_put(&file->f_kref);        /* drop our ref */
                if (fd < 0)
                        warn("File insertion failed");
        } else if (get_errno() == ENOENT) {
                /* VFS failed due to ENOENT.  Other errors don't fall back to 9ns */
                unset_errno();  /* Go can't handle extra errnos */
                fd = sysopenat(fromfd, t_path, oflag);
                /* successful lookup with CREATE and EXCL is an error */
                if (fd != -1) {
                        if ((oflag & O_CREATE) && (oflag & O_EXCL)) {
                                set_errno(EEXIST);
                                sysclose(fd);
                                free_path(p, t_path);
                                return -1;
                        }
                } else {
                        if (oflag & O_CREATE) {
                                mode &= S_PMASK;
                                fd = syscreate(t_path, oflag, mode);
                        }
                }
        }
        free_path(p, t_path);
        printd("File %s Open, fd=%d\n", path, fd);
        return fd;
}

static intreg_t sys_close(struct proc *p, int fd)
{
        struct file *file = get_file_from_fd(&p->open_files, fd);
        int retval = 0;
        printd("sys_close %d\n", fd);
        /* VFS */
        if (file) {
                put_file_from_fd(&p->open_files, fd);
                kref_put(&file->f_kref);        /* Drop the ref from get_file */
                return 0;
        }
        /* 9ns, should also handle errors (bad FD, etc) */
        retval = sysclose(fd);
        return retval;
}

/* kept around til we remove the last ufe */
#define ufe(which,a0,a1,a2,a3) \
        frontend_syscall_errno(p,APPSERVER_SYSCALL_##which,\
                           (int)(a0),(int)(a1),(int)(a2),(int)(a3))

static intreg_t sys_fstat(struct proc *p, int fd, struct kstat *u_stat)
{
        struct kstat *kbuf;
        struct file *file;
        kbuf = kmalloc(sizeof(struct kstat), 0);
        if (!kbuf) {
                set_errno(ENOMEM);
                return -1;
        }
        file = get_file_from_fd(&p->open_files, fd);
        /* VFS */
        if (file) {
                stat_inode(file->f_dentry->d_inode, kbuf);
                kref_put(&file->f_kref);
        } else {
                unset_errno();  /* Go can't handle extra errnos */
            if (sysfstatakaros(fd, (struct kstat *)kbuf) < 0) {
                        kfree(kbuf);
                        return -1;
                }
        }
        /* TODO: UMEM: pin the memory, copy directly, and skip the kernel buffer */
        if (memcpy_to_user_errno(p, u_stat, kbuf, sizeof(struct kstat))) {
                kfree(kbuf);
                return -1;
        }
        kfree(kbuf);
        return 0;
}

/* sys_stat() and sys_lstat() do nearly the same thing, differing in how they
 * treat a symlink for the final item, which (probably) will be controlled by
 * the lookup flags */
static intreg_t stat_helper(struct proc *p, const char *path, size_t path_l,
                            struct kstat *u_stat, int flags)
{
        struct kstat *kbuf;
        struct dentry *path_d;
        char *t_path = copy_in_path(p, path, path_l);
        int retval = 0;
        if (!t_path)
                return -1;
        kbuf = kmalloc(sizeof(struct kstat), 0);
        if (!kbuf) {
                set_errno(ENOMEM);
                retval = -1;
                goto out_with_path;
        }
        /* Check VFS for path */
        path_d = lookup_dentry(t_path, flags);
        if (path_d) {
                stat_inode(path_d->d_inode, kbuf);
                kref_put(&path_d->d_kref);
        } else {
                /* VFS failed, checking 9ns */
                unset_errno();  /* Go can't handle extra errnos */
                retval = sysstatakaros(t_path, (struct stat *)kbuf);
                printd("sysstat returns %d\n", retval);
                /* both VFS and 9ns failed, bail out */
                if (retval < 0)
                        goto out_with_kbuf;
        }
        /* TODO: UMEM: pin the memory, copy directly, and skip the kernel buffer */
        if (memcpy_to_user_errno(p, u_stat, kbuf, sizeof(struct kstat)))
                retval = -1;
        /* Fall-through */
out_with_kbuf:
        kfree(kbuf);
out_with_path:
        free_path(p, t_path);
        return retval;
}

/* Follow a final symlink */
static intreg_t sys_stat(struct proc *p, const char *path, size_t path_l,
                         struct kstat *u_stat)
{
        return stat_helper(p, path, path_l, u_stat, LOOKUP_FOLLOW);
}

/* Don't follow a final symlink */
static intreg_t sys_lstat(struct proc *p, const char *path, size_t path_l,
                          struct kstat *u_stat)
{
        return stat_helper(p, path, path_l, u_stat, 0);
}

intreg_t sys_fcntl(struct proc *p, int fd, int cmd, unsigned long arg1,
                   unsigned long arg2, unsigned long arg3, unsigned long arg4)
{
        int retval = 0;
        int newfd;
        struct file *file = get_file_from_fd(&p->open_files, fd);

        if (!file) {
                /* 9ns hack */
                switch (cmd) {
                        case (F_DUPFD):
                                return sysdup(fd);
                        case (F_GETFD):
                        case (F_SETFD):
                        case (F_SYNC):
                        case (F_ADVISE):
                                /* TODO: 9ns versions */
                                return 0;
                        case (F_GETFL):
                                return fd_getfl(fd);
                        case (F_SETFL):
                                return fd_setfl(fd, arg1);
                        default:
                                warn("Unsupported fcntl cmd %d\n", cmd);
                }
                /* not really ever calling this, even for badf, due to the switch */
                set_errno(EBADF);
                return -1;
        }

        /* TODO: these are racy */
        switch (cmd) {
                case (F_DUPFD):
                        retval = insert_file(&p->open_files, file, arg1, FALSE, FALSE);
                        if (retval < 0) {
                                set_errno(-retval);
                                retval = -1;
                        }
                        break;
                case (F_GETFD):
                        retval = p->open_files.fd[fd].fd_flags;
                        break;
                case (F_SETFD):
                        /* I'm considering not supporting this at all.  They must do it at
                         * open time or fix their buggy/racy code. */
                        spin_lock(&p->open_files.lock);
                        if (arg1 & FD_CLOEXEC)
                                p->open_files.fd[fd].fd_flags |= FD_CLOEXEC;
                        retval = p->open_files.fd[fd].fd_flags;
                        spin_unlock(&p->open_files.lock);
                        break;
                case (F_GETFL):
                        retval = file->f_flags;
                        break;
                case (F_SETFL):
                        /* only allowed to set certain flags. */
                        arg1 &= O_FCNTL_SET_FLAGS;
                        file->f_flags = (file->f_flags & ~O_FCNTL_SET_FLAGS) | arg1;
                        break;
                case (F_SYNC):
                        /* TODO (if we keep the VFS) */
                        retval = 0;
                        break;
                case (F_ADVISE):
                        /* TODO  (if we keep the VFS)*/
                        retval = 0;
                        break;
                default:
                        warn("Unsupported fcntl cmd %d\n", cmd);
        }
        kref_put(&file->f_kref);
        return retval;
}

static intreg_t sys_access(struct proc *p, const char *path, size_t path_l,
                           int mode)
{
        int retval;
        char *t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        /* TODO: 9ns support */
        retval = do_access(t_path, mode);
        free_path(p, t_path);
        printd("Access for path: %s retval: %d\n", path, retval);
        if (retval < 0) {
                set_errno(-retval);
                return -1;
        }
        return retval;
}

intreg_t sys_umask(struct proc *p, int mask)
{
        int old_mask = p->fs_env.umask;
        p->fs_env.umask = mask & S_PMASK;
        return old_mask;
}

/* 64 bit seek, with the off64_t passed in via two (potentially 32 bit) off_ts.
 * We're supporting both 32 and 64 bit kernels/userspaces, but both use the
 * llseek syscall with 64 bit parameters. */
static intreg_t sys_llseek(struct proc *p, int fd, off_t offset_hi,
                           off_t offset_lo, off64_t *result, int whence)
{
        off64_t retoff = 0;
        off64_t tempoff = 0;
        int ret = 0;
        struct file *file;
        tempoff = offset_hi;
        tempoff <<= 32;
        tempoff |= offset_lo;
        file = get_file_from_fd(&p->open_files, fd);
        if (file) {
                ret = file->f_op->llseek(file, tempoff, &retoff, whence);
                kref_put(&file->f_kref);
        } else {
                retoff = sysseek(fd, tempoff, whence);
                ret = (retoff < 0);
        }

        if (ret)
                return -1;
        if (memcpy_to_user_errno(p, result, &retoff, sizeof(off64_t)))
                return -1;
        return 0;
}

intreg_t sys_link(struct proc *p, char *old_path, size_t old_l,
                  char *new_path, size_t new_l)
{
        int ret;
        char *t_oldpath = copy_in_path(p, old_path, old_l);
        if (t_oldpath == NULL)
                return -1;
        char *t_newpath = copy_in_path(p, new_path, new_l);
        if (t_newpath == NULL) {
                free_path(p, t_oldpath);
                return -1;
        }
        ret = do_link(t_oldpath, t_newpath);
        free_path(p, t_oldpath);
        free_path(p, t_newpath);
        return ret;
}

intreg_t sys_unlink(struct proc *p, const char *path, size_t path_l)
{
        int retval;
        char *t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        retval = do_unlink(t_path);
        if (retval && (get_errno() == ENOENT)) {
                unset_errno();
                retval = sysremove(t_path);
        }
        free_path(p, t_path);
        return retval;
}

intreg_t sys_symlink(struct proc *p, char *old_path, size_t old_l,
                     char *new_path, size_t new_l)
{
        int ret;
        char *t_oldpath = copy_in_path(p, old_path, old_l);
        if (t_oldpath == NULL)
                return -1;
        char *t_newpath = copy_in_path(p, new_path, new_l);
        if (t_newpath == NULL) {
                free_path(p, t_oldpath);
                return -1;
        }
        ret = do_symlink(t_newpath, t_oldpath, S_IRWXU | S_IRWXG | S_IRWXO);
        free_path(p, t_oldpath);
        free_path(p, t_newpath);
        return ret;
}

intreg_t sys_readlink(struct proc *p, char *path, size_t path_l,
                      char *u_buf, size_t buf_l)
{
        char *symname = NULL;
        uint8_t *buf = NULL;
        ssize_t copy_amt;
        int ret = -1;
        struct dentry *path_d;
        char *t_path = copy_in_path(p, path, path_l);
        if (t_path == NULL)
                return -1;
        /* TODO: 9ns support */
        path_d = lookup_dentry(t_path, 0);
        if (!path_d){
                int n = 2048;
                buf = kmalloc(n*2, MEM_WAIT);
                struct dir *d = (void *)&buf[n];
                /* try 9ns. */
                if (sysstat(t_path, buf, n) > 0) {
                        printk("sysstat t_path %s\n", t_path);
                        convM2D(buf, n, d, (char *)&d[1]);
                        /* will be NULL if things did not work out */
                        symname = d->muid;
                }
        } else
                symname = path_d->d_inode->i_op->readlink(path_d);

        free_path(p, t_path);

        if (symname){
                copy_amt = strnlen(symname, buf_l - 1) + 1;
                if (!memcpy_to_user_errno(p, u_buf, symname, copy_amt))
                        ret = copy_amt - 1;
        }
        if (path_d)
                kref_put(&path_d->d_kref);
        if (buf)
                kfree(buf);
        printd("READLINK returning %s\n", u_buf);
        return ret;
}

static intreg_t sys_chdir(struct proc *p, pid_t pid, const char *path,
                          size_t path_l)
{
        int retval;
        char *t_path;
        struct proc *target = get_controllable_proc(p, pid);
        if (!target)
                return -1;
        t_path = copy_in_path(p, path, path_l);
        if (!t_path) {
                proc_decref(target);
                return -1;
        }
        /* TODO: 9ns support */
        retval = do_chdir(&target->fs_env, t_path);
        free_path(p, t_path);
        proc_decref(target);
        return retval;
}

static intreg_t sys_fchdir(struct proc *p, pid_t pid, int fd)
{
        struct file *file;
        int retval;
        struct proc *target = get_controllable_proc(p, pid);
        if (!target)
                return -1;
        file = get_file_from_fd(&p->open_files, fd);
        if (!file) {
                /* TODO: 9ns */
                set_errno(EBADF);
                proc_decref(target);
                return -1;
        }
        retval = do_fchdir(&target->fs_env, file);
        kref_put(&file->f_kref);
        proc_decref(target);
        return retval;
}

/* Note cwd_l is not a strlen, it's an absolute size */
intreg_t sys_getcwd(struct proc *p, char *u_cwd, size_t cwd_l)
{
        int retval = 0;
        char *kfree_this;
        char *k_cwd;
        k_cwd = do_getcwd(&p->fs_env, &kfree_this, cwd_l);
        if (!k_cwd)
                return -1;              /* errno set by do_getcwd */
        if (strlen(k_cwd) + 1 > cwd_l) {
                set_error(ERANGE, "getcwd buf too small, needed %d", strlen(k_cwd) + 1);
                retval = -1;
                goto out;
        }
        if (memcpy_to_user_errno(p, u_cwd, k_cwd, strlen(k_cwd) + 1))
                retval = -1;
out:
        kfree(kfree_this);
        return retval;
}

intreg_t sys_mkdir(struct proc *p, const char *path, size_t path_l, int mode)
{
        int retval;
        char *t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        mode &= S_PMASK;
        mode &= ~p->fs_env.umask;
        retval = do_mkdir(t_path, mode);
        if (retval && (get_errno() == ENOENT)) {
                unset_errno();
                /* mixing plan9 and glibc here, make sure DMDIR doesn't overlap with any
                 * permissions */
                static_assert(!(S_PMASK & DMDIR));
                retval = syscreate(t_path, O_RDWR, DMDIR | mode);
        }
        free_path(p, t_path);
        return retval;
}

intreg_t sys_rmdir(struct proc *p, const char *path, size_t path_l)
{
        int retval;
        char *t_path = copy_in_path(p, path, path_l);
        if (!t_path)
                return -1;
        /* TODO: 9ns support */
        retval = do_rmdir(t_path);
        free_path(p, t_path);
        return retval;
}

intreg_t sys_tcgetattr(struct proc *p, int fd, void *termios_p)
{
        int retval = 0;
        /* TODO: actually support this call on tty FDs.  Right now, we just fake
         * what my linux box reports for a bash pty. */
        struct termios *kbuf = kmalloc(sizeof(struct termios), 0);
        kbuf->c_iflag = 0x2d02;
        kbuf->c_oflag = 0x0005;
        kbuf->c_cflag = 0x04bf;
        kbuf->c_lflag = 0x8a3b;
        kbuf->c_line = 0x0;
        kbuf->c_ispeed = 0xf;
        kbuf->c_ospeed = 0xf;
        kbuf->c_cc[0] = 0x03;
        kbuf->c_cc[1] = 0x1c;
        kbuf->c_cc[2] = 0x7f;
        kbuf->c_cc[3] = 0x15;
        kbuf->c_cc[4] = 0x04;
        kbuf->c_cc[5] = 0x00;
        kbuf->c_cc[6] = 0x01;
        kbuf->c_cc[7] = 0xff;
        kbuf->c_cc[8] = 0x11;
        kbuf->c_cc[9] = 0x13;
        kbuf->c_cc[10] = 0x1a;
        kbuf->c_cc[11] = 0xff;
        kbuf->c_cc[12] = 0x12;
        kbuf->c_cc[13] = 0x0f;
        kbuf->c_cc[14] = 0x17;
        kbuf->c_cc[15] = 0x16;
        kbuf->c_cc[16] = 0xff;
        kbuf->c_cc[17] = 0x00;
        kbuf->c_cc[18] = 0x00;
        kbuf->c_cc[19] = 0x00;
        kbuf->c_cc[20] = 0x00;
        kbuf->c_cc[21] = 0x00;
        kbuf->c_cc[22] = 0x00;
        kbuf->c_cc[23] = 0x00;
        kbuf->c_cc[24] = 0x00;
        kbuf->c_cc[25] = 0x00;
        kbuf->c_cc[26] = 0x00;
        kbuf->c_cc[27] = 0x00;
        kbuf->c_cc[28] = 0x00;
        kbuf->c_cc[29] = 0x00;
        kbuf->c_cc[30] = 0x00;
        kbuf->c_cc[31] = 0x00;

        if (memcpy_to_user_errno(p, termios_p, kbuf, sizeof(struct termios)))
                retval = -1;
        kfree(kbuf);
        return retval;
}

intreg_t sys_tcsetattr(struct proc *p, int fd, int optional_actions,
                       const void *termios_p)
{
        /* TODO: do this properly too.  For now, we just say 'it worked' */
        return 0;
}

/* TODO: we don't have any notion of UIDs or GIDs yet, but don't let that stop a
 * process from thinking it can do these.  The other alternative is to have
 * glibc return 0 right away, though someone might want to do something with
 * these calls.  Someday. */
intreg_t sys_setuid(struct proc *p, uid_t uid)
{
        return 0;
}

intreg_t sys_setgid(struct proc *p, gid_t gid)
{
        return 0;
}

/* long bind(char* src_path, char* onto_path, int flag);
 *
 * The naming for the args in bind is messy historically.  We do:
 *              bind src_path onto_path
 * plan9 says bind NEW OLD, where new is *src*, and old is *onto*.
 * Linux says mount --bind OLD NEW, where OLD is *src* and NEW is *onto*. */
intreg_t sys_nbind(struct proc *p,
                   char *src_path, size_t src_l,
                   char *onto_path, size_t onto_l,
                   unsigned int flag)

{
        int ret;
        char *t_srcpath = copy_in_path(p, src_path, src_l);
        if (t_srcpath == NULL) {
                printd("srcpath dup failed ptr %p size %d\n", src_path, src_l);
                return -1;
        }
        char *t_ontopath = copy_in_path(p, onto_path, onto_l);
        if (t_ontopath == NULL) {
                free_path(p, t_srcpath);
                printd("ontopath dup failed ptr %p size %d\n", onto_path, onto_l);
                return -1;
        }
        printd("sys_nbind: %s -> %s flag %d\n", t_srcpath, t_ontopath, flag);
        ret = sysbind(t_srcpath, t_ontopath, flag);
        free_path(p, t_srcpath);
        free_path(p, t_ontopath);
        return ret;
}

/* int mount(int fd, int afd, char* onto_path, int flag, char* aname); */
intreg_t sys_nmount(struct proc *p,
                    int fd,
                    char *onto_path, size_t onto_l,
                    unsigned int flag
                        /* we ignore these */
                        /* no easy way to pass this many args anyway. *
                    int afd,
                    char *auth, size_t auth_l*/)
{
        int ret;
        int afd;

        afd = -1;
        char *t_ontopath = copy_in_path(p, onto_path, onto_l);
        if (t_ontopath == NULL)
                return -1;
        ret = sysmount(fd, afd, t_ontopath, flag, /* spec or auth */"/");
        free_path(p, t_ontopath);
        return ret;
}

/* Unmount undoes the operation of a bind or mount.  Check out
 * http://plan9.bell-labs.com/magic/man2html/1/bind .  Though our mount takes an
 * FD, not servename (aka src_path), so it's not quite the same.
 *
 * To translate between Plan 9 and Akaros, old -> onto_path.  new -> src_path.
 *
 * For unmount, src_path / new is optional.  If set, we only unmount the
 * bindmount that came from src_path. */
intreg_t sys_nunmount(struct proc *p, char *src_path, int src_l,
                      char *onto_path, int onto_l)
{
        int ret;
        char *t_ontopath, *t_srcpath;
        t_ontopath = copy_in_path(p, onto_path, onto_l);
        if (t_ontopath == NULL)
                return -1;
        if (src_path) {
                t_srcpath = copy_in_path(p, src_path, src_l);
                if (t_srcpath == NULL) {
                        free_path(p, t_ontopath);
                        return -1;
                }
        } else {
                t_srcpath = 0;
        }
        ret = sysunmount(t_srcpath, t_ontopath);
        free_path(p, t_ontopath);
        free_path(p, t_srcpath);        /* you can free a null path */
        return ret;
}

intreg_t sys_fd2path(struct proc *p, int fd, void *u_buf, size_t len)
{
        int ret = 0;
        struct chan *ch;
        ERRSTACK(1);
        /* UMEM: Check the range, can PF later and kill if the page isn't present */
        if (!is_user_rwaddr(u_buf, len)) {
                printk("[kernel] bad user addr %p (+%p) in %s (user bug)\n", u_buf,
                       len, __FUNCTION__);
                return -1;
        }
        /* fdtochan throws */
        if (waserror()) {
                poperror();
                return -1;
        }
        ch = fdtochan(&current->open_files, fd, -1, FALSE, TRUE);
        if (snprintf(u_buf, len, "%s", channame(ch)) >= len) {
                set_error(ERANGE, "fd2path buf too small, needed %d", ret);
                ret = -1;
        }
        cclose(ch);
        poperror();
        return ret;
}

/* Helper, interprets the wstat and performs the VFS action.  Returns stat_sz on
 * success for all ops, -1 or 0 o/w.  If one op fails, it'll skip the remaining
 * ones. */
static int vfs_wstat(struct file *file, uint8_t *stat_m, size_t stat_sz,
                     int flags)
{
        struct dir *dir;
        int m_sz;
        int retval = 0;

        dir = kzmalloc(sizeof(struct dir) + stat_sz, MEM_WAIT);
        m_sz = convM2D(stat_m, stat_sz, &dir[0], (char*)&dir[1]);
        if (m_sz != stat_sz) {
                set_error(EINVAL, ERROR_FIXME);
                kfree(dir);
                return -1;
        }
        if (flags & WSTAT_MODE) {
                retval = do_file_chmod(file, dir->mode);
                if (retval < 0)
                        goto out;
        }
        if (flags & WSTAT_LENGTH) {
                retval = do_truncate(file->f_dentry->d_inode, dir->length);
                if (retval < 0)
                        goto out;
        }
        if (flags & WSTAT_ATIME) {
                /* wstat only gives us seconds */
                file->f_dentry->d_inode->i_atime.tv_sec = dir->atime;
                file->f_dentry->d_inode->i_atime.tv_nsec = 0;
        }
        if (flags & WSTAT_MTIME) {
                file->f_dentry->d_inode->i_mtime.tv_sec = dir->mtime;
                file->f_dentry->d_inode->i_mtime.tv_nsec = 0;
        }

out:
        kfree(dir);
        /* convert vfs retval to wstat retval */
        if (retval >= 0)
                retval = stat_sz;
        return retval;
}

intreg_t sys_wstat(struct proc *p, char *path, size_t path_l,
                   uint8_t *stat_m, size_t stat_sz, int flags)
{
        int retval = 0;
        char *t_path = copy_in_path(p, path, path_l);
        struct file *file;

        if (!t_path)
                return -1;
        retval = syswstat(t_path, stat_m, stat_sz);
        if (retval == stat_sz) {
                free_path(p, t_path);
                return stat_sz;
        }
        /* 9ns failed, we'll need to check the VFS */
        file = do_file_open(t_path, O_READ, 0);
        free_path(p, t_path);
        if (!file)
                return -1;
        retval = vfs_wstat(file, stat_m, stat_sz, flags);
        kref_put(&file->f_kref);
        return retval;
}

intreg_t sys_fwstat(struct proc *p, int fd, uint8_t *stat_m, size_t stat_sz,
                    int flags)
{
        int retval = 0;
        struct file *file;

        retval = sysfwstat(fd, stat_m, stat_sz);
        if (retval == stat_sz)
                return stat_sz;
        /* 9ns failed, we'll need to check the VFS */
        file = get_file_from_fd(&p->open_files, fd);
        if (!file)
                return -1;
        retval = vfs_wstat(file, stat_m, stat_sz, flags);
        kref_put(&file->f_kref);
        return retval;
}

intreg_t sys_rename(struct proc *p, char *old_path, size_t old_path_l,
                    char *new_path, size_t new_path_l)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        ERRSTACK(1);
        int mountpointlen = 0;
        char *from_path = copy_in_path(p, old_path, old_path_l);
        char *to_path = copy_in_path(p, new_path, new_path_l);
        struct chan *oldchan = 0, *newchan = NULL;
        int retval = -1;

        if ((!from_path) || (!to_path))
                return -1;
        printd("sys_rename :%s: to :%s: : ", from_path, to_path);

        /* we need a fid for the wstat. */
        /* TODO: maybe wrap the 9ns stuff better.  sysrename maybe? */

        /* discard namec error */
        if (!waserror()) {
                oldchan = namec(from_path, Aaccess, 0, 0);
        }
        poperror();
        if (!oldchan) {
                retval = do_rename(from_path, to_path);
                free_path(p, from_path);
                free_path(p, to_path);
                return retval;
        }

        printd("Oldchan: %C\n", oldchan);
        printd("Oldchan: mchan %C\n", oldchan->mchan);

        /* If walked through a mountpoint, we need to take that
         * into account for the Twstat.
         */
        if (oldchan->mountpoint) {
                printd("mountpoint: %C\n", oldchan->mountpoint);
                if (oldchan->mountpoint->name)
                        mountpointlen = oldchan->mountpoint->name->len;
        }

        /* This test makes sense even when mountpointlen is 0 */
        if (strlen(to_path) < mountpointlen) {
                set_errno(EINVAL);
                goto done;
        }

        /* the omode and perm are of no importance. */
        newchan = namec(to_path, Acreatechan, 0, 0);
        if (newchan == NULL) {
                printd("sys_rename %s to %s found no chan\n", from_path, to_path);
                set_errno(EPERM);
                goto done;
        }
        printd("Newchan: %C\n", newchan);
        printd("Newchan: mchan %C\n", newchan->mchan);

        if ((newchan->dev != oldchan->dev) ||
                (newchan->type != oldchan->type)) {
                printd("Old chan and new chan do not match\n");
                set_errno(ENODEV);
                goto done;
        }

        struct dir dir;
        size_t mlen;
        uint8_t mbuf[STATFIXLEN + MAX_PATH_LEN + 1];

        init_empty_dir(&dir);
        dir.name = to_path;
        /* absolute paths need the mountpoint name stripped from them.
         * Once stripped, it still has to be an absolute path.
         */
        if (dir.name[0] == '/') {
                dir.name = to_path + mountpointlen;
                if (dir.name[0] != '/') {
                        set_errno(EINVAL);
                        goto done;
                }
        }

        mlen = convD2M(&dir, mbuf, sizeof(mbuf));
        if (!mlen) {
                printk("convD2M failed\n");
                set_errno(EINVAL);
                goto done;
        }

        if (waserror()) {
                printk("validstat failed: %s\n", current_errstr());
                goto done;
        }

        validstat(mbuf, mlen, 1);
        poperror();

        if (waserror()) {
                //cclose(oldchan);
                nexterror();
        }

        retval = devtab[oldchan->type].wstat(oldchan, mbuf, mlen);

        poperror();
        if (retval == mlen) {
                retval = mlen;
        } else {
                printk("syswstat did not go well\n");
                set_errno(EXDEV);
        };
        printk("syswstat returns %d\n", retval);

done:
        free_path(p, from_path);
        free_path(p, to_path);
        cclose(oldchan);
        cclose(newchan);
        return retval;
}

/* Careful: if an FD is busy, we don't close the old object, it just fails */
static intreg_t sys_dup_fds_to(struct proc *p, unsigned int pid,
                               struct childfdmap *map, unsigned int nentries)
{
        ssize_t ret = 0;
        struct proc *child;
        int slot;
        struct file *file;

        if (!is_user_rwaddr(map, sizeof(struct childfdmap) * nentries)) {
                set_errno(EINVAL);
                return -1;
        }
        child = get_controllable_proc(p, pid);
        if (!child)
                return -1;
        for (int i = 0; i < nentries; i++) {
                map[i].ok = -1;
                file = get_file_from_fd(&p->open_files, map[i].parentfd);
                if (file) {
                        slot = insert_file(&child->open_files, file, map[i].childfd, TRUE,
                                           FALSE);
                        if (slot == map[i].childfd) {
                                map[i].ok = 0;
                                ret++;
                        }
                        kref_put(&file->f_kref);
                        continue;
                }
                if (!sys_dup_to(p, map[i].parentfd, child, map[i].childfd)) {
                        map[i].ok = 0;
                        ret++;
                        continue;
                }
                /* probably a bug, could send EBADF, maybe via 'ok' */
                printk("[kernel] dup_fds_to: couldn't find %d\n", map[i].parentfd);
        }
        proc_decref(child);
        return ret;
}

/* 0 on success, anything else is an error, with errno/errstr set */
static int handle_tap_req(struct proc *p, struct fd_tap_req *req)
{
        switch (req->cmd) {
                case (FDTAP_CMD_ADD):
                        return add_fd_tap(p, req);
                case (FDTAP_CMD_REM):
                        return remove_fd_tap(p, req->fd);
                default:
                        set_error(ENOSYS, "FD Tap Command %d not supported", req->cmd);
                        return -1;
        }
}

/* Processes up to nr_reqs tap requests.  If a request errors out, we stop
 * immediately.  Returns the number processed.  If done != nr_reqs, check errno
 * and errstr for the last failure, which is for tap_reqs[done]. */
static intreg_t sys_tap_fds(struct proc *p, struct fd_tap_req *tap_reqs,
                            size_t nr_reqs)
{
        struct fd_tap_req *req_i = tap_reqs;
        int done;
        if (!is_user_rwaddr(tap_reqs, sizeof(struct fd_tap_req) * nr_reqs)) {
                set_errno(EINVAL);
                return 0;
        }
        for (done = 0; done < nr_reqs; done++, req_i++) {
                if (handle_tap_req(p, req_i))
                        break;
        }
        return done;
}

/************** Syscall Invokation **************/

const struct sys_table_entry syscall_table[] = {
        [SYS_null] = {(syscall_t)sys_null, "null"},
        [SYS_block] = {(syscall_t)sys_block, "block"},
        [SYS_cache_buster] = {(syscall_t)sys_cache_buster, "buster"},
        [SYS_cache_invalidate] = {(syscall_t)sys_cache_invalidate, "wbinv"},
        [SYS_reboot] = {(syscall_t)reboot, "reboot!"},
        [SYS_getpcoreid] = {(syscall_t)sys_getpcoreid, "getpcoreid"},
        [SYS_getvcoreid] = {(syscall_t)sys_getvcoreid, "getvcoreid"},
        [SYS_proc_create] = {(syscall_t)sys_proc_create, "proc_create"},
        [SYS_proc_run] = {(syscall_t)sys_proc_run, "proc_run"},
        [SYS_proc_destroy] = {(syscall_t)sys_proc_destroy, "proc_destroy"},
        [SYS_yield] = {(syscall_t)sys_proc_yield, "proc_yield"},
        [SYS_change_vcore] = {(syscall_t)sys_change_vcore, "change_vcore"},
        [SYS_fork] = {(syscall_t)sys_fork, "fork"},
        [SYS_exec] = {(syscall_t)sys_exec, "exec"},
        [SYS_waitpid] = {(syscall_t)sys_waitpid, "waitpid"},
        [SYS_mmap] = {(syscall_t)sys_mmap, "mmap"},
        [SYS_munmap] = {(syscall_t)sys_munmap, "munmap"},
        [SYS_mprotect] = {(syscall_t)sys_mprotect, "mprotect"},
        [SYS_shared_page_alloc] = {(syscall_t)sys_shared_page_alloc, "pa"},
        [SYS_shared_page_free] = {(syscall_t)sys_shared_page_free, "pf"},
        [SYS_provision] = {(syscall_t)sys_provision, "provision"},
        [SYS_notify] = {(syscall_t)sys_notify, "notify"},
        [SYS_self_notify] = {(syscall_t)sys_self_notify, "self_notify"},
        [SYS_vc_entry] = {(syscall_t)sys_vc_entry, "vc_entry"},
        [SYS_halt_core] = {(syscall_t)sys_halt_core, "halt_core"},
#ifdef CONFIG_ARSC_SERVER
        [SYS_init_arsc] = {(syscall_t)sys_init_arsc, "init_arsc"},
#endif
        [SYS_change_to_m] = {(syscall_t)sys_change_to_m, "change_to_m"},
        [SYS_vmm_setup] = {(syscall_t)sys_vmm_setup, "vmm_setup"},
        [SYS_vmm_poke_guest] = {(syscall_t)sys_vmm_poke_guest, "vmm_poke_guest"},
        [SYS_poke_ksched] = {(syscall_t)sys_poke_ksched, "poke_ksched"},
        [SYS_abort_sysc] = {(syscall_t)sys_abort_sysc, "abort_sysc"},
        [SYS_abort_sysc_fd] = {(syscall_t)sys_abort_sysc_fd, "abort_sysc_fd"},
        [SYS_populate_va] = {(syscall_t)sys_populate_va, "populate_va"},
        [SYS_nanosleep] = {(syscall_t)sys_nanosleep, "nanosleep"},
        [SYS_pop_ctx] = {(syscall_t)sys_pop_ctx, "pop_ctx"},

        [SYS_read] = {(syscall_t)sys_read, "read"},
        [SYS_write] = {(syscall_t)sys_write, "write"},
        [SYS_openat] = {(syscall_t)sys_openat, "openat"},
        [SYS_close] = {(syscall_t)sys_close, "close"},
        [SYS_fstat] = {(syscall_t)sys_fstat, "fstat"},
        [SYS_stat] = {(syscall_t)sys_stat, "stat"},
        [SYS_lstat] = {(syscall_t)sys_lstat, "lstat"},
        [SYS_fcntl] = {(syscall_t)sys_fcntl, "fcntl"},
        [SYS_access] = {(syscall_t)sys_access, "access"},
        [SYS_umask] = {(syscall_t)sys_umask, "umask"},
        [SYS_llseek] = {(syscall_t)sys_llseek, "llseek"},
        [SYS_link] = {(syscall_t)sys_link, "link"},
        [SYS_unlink] = {(syscall_t)sys_unlink, "unlink"},
        [SYS_symlink] = {(syscall_t)sys_symlink, "symlink"},
        [SYS_readlink] = {(syscall_t)sys_readlink, "readlink"},
        [SYS_chdir] = {(syscall_t)sys_chdir, "chdir"},
        [SYS_fchdir] = {(syscall_t)sys_fchdir, "fchdir"},
        [SYS_getcwd] = {(syscall_t)sys_getcwd, "getcwd"},
        [SYS_mkdir] = {(syscall_t)sys_mkdir, "mkdir"},
        [SYS_rmdir] = {(syscall_t)sys_rmdir, "rmdir"},
        [SYS_tcgetattr] = {(syscall_t)sys_tcgetattr, "tcgetattr"},
        [SYS_tcsetattr] = {(syscall_t)sys_tcsetattr, "tcsetattr"},
        [SYS_setuid] = {(syscall_t)sys_setuid, "setuid"},
        [SYS_setgid] = {(syscall_t)sys_setgid, "setgid"},
        /* special! */
        [SYS_nbind] ={(syscall_t)sys_nbind, "nbind"},
        [SYS_nmount] ={(syscall_t)sys_nmount, "nmount"},
        [SYS_nunmount] ={(syscall_t)sys_nunmount, "nunmount"},
        [SYS_fd2path] ={(syscall_t)sys_fd2path, "fd2path"},
        [SYS_wstat] ={(syscall_t)sys_wstat, "wstat"},
        [SYS_fwstat] ={(syscall_t)sys_fwstat, "fwstat"},
        [SYS_rename] ={(syscall_t)sys_rename, "rename"},
        [SYS_dup_fds_to] = {(syscall_t)sys_dup_fds_to, "dup_fds_to"},
        [SYS_tap_fds] = {(syscall_t)sys_tap_fds, "tap_fds"},
};
const int max_syscall = sizeof(syscall_table)/sizeof(syscall_table[0]);

/* Executes the given syscall.
 *
 * Note tf is passed in, which points to the tf of the context on the kernel
 * stack.  If any syscall needs to block, it needs to save this info, as well as
 * any silly state.
 *
 * This syscall function is used by both local syscall and arsc, and should
 * remain oblivious of the caller. */
intreg_t syscall(struct proc *p, uintreg_t sc_num, uintreg_t a0, uintreg_t a1,
                 uintreg_t a2, uintreg_t a3, uintreg_t a4, uintreg_t a5)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        intreg_t ret = -1;
        ERRSTACK(1);

        if (sc_num > max_syscall || syscall_table[sc_num].call == NULL) {
                printk("[kernel] Invalid syscall %d for proc %d\n", sc_num, p->pid);
                printk("\tArgs: %p, %p, %p, %p, %p, %p\n", a0, a1, a2, a3, a4, a5);
                print_user_ctx(per_cpu_info[core_id()].cur_ctx);
                return -1;
        }

        /* N.B. This is going away. */
        if (waserror()){
                printk("Plan 9 system call returned via waserror()\n");
                printk("String: '%s'\n", current_errstr());
                /* if we got here, then the errbuf was right.
                 * no need to check!
                 */
                return -1;
        }
        //printd("before syscall errstack %p\n", errstack);
        //printd("before syscall errstack base %p\n", get_cur_errbuf());
        ret = syscall_table[sc_num].call(p, a0, a1, a2, a3, a4, a5);
        //printd("after syscall errstack base %p\n", get_cur_errbuf());
        if (get_cur_errbuf() != &errstack[0]) {
                /* Can't trust coreid and vcoreid anymore, need to check the trace */
                printk("[%16llu] Syscall %3d (%12s):(%p, %p, %p, %p, "
                       "%p, %p) proc: %d\n", read_tsc(),
                       sc_num, syscall_table[sc_num].name, a0, a1, a2, a3,
                       a4, a5, p->pid);
                if (sc_num != SYS_fork)
                        printk("YOU SHOULD PANIC: errstack mismatch");
        }
        return ret;
}

/* Execute the syscall on the local core */
void run_local_syscall(struct syscall *sysc)
{
        struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
        struct proc *p = pcpui->cur_proc;

        /* In lieu of pinning, we just check the sysc and will PF on the user addr
         * later (if the addr was unmapped).  Which is the plan for all UMEM. */
        if (!is_user_rwaddr(sysc, sizeof(struct syscall))) {
                printk("[kernel] bad user addr %p (+%p) in %s (user bug)\n", sysc,
                       sizeof(struct syscall), __FUNCTION__);
                return;
        }
        pcpui->cur_kthread->sysc = sysc;        /* let the core know which sysc it is */
        systrace_start_trace(pcpui->cur_kthread, sysc);
        alloc_sysc_str(pcpui->cur_kthread);
        /* syscall() does not return for exec and yield, so put any cleanup in there
         * too. */
        sysc->retval = syscall(pcpui->cur_proc, sysc->num, sysc->arg0, sysc->arg1,
                               sysc->arg2, sysc->arg3, sysc->arg4, sysc->arg5);
        /* Need to re-load pcpui, in case we migrated */
        pcpui = &per_cpu_info[core_id()];
        free_sysc_str(pcpui->cur_kthread);
        systrace_finish_trace(pcpui->cur_kthread, sysc->retval);
        /* Some 9ns paths set errstr, but not errno.  glibc will ignore errstr.
         * this is somewhat hacky, since errno might get set unnecessarily */
        if ((current_errstr()[0] != 0) && (!sysc->err))
                sysc->err = EUNSPECIFIED;
        finish_sysc(sysc, pcpui->cur_proc);
        pcpui->cur_kthread->sysc = NULL;        /* No longer working on sysc */
}

/* A process can trap and call this function, which will set up the core to
 * handle all the syscalls.  a.k.a. "sys_debutante(needs, wants)".  If there is
 * at least one, it will run it directly. */
void prep_syscalls(struct proc *p, struct syscall *sysc, unsigned int nr_syscs)
{
        /* Careful with pcpui here, we could have migrated */
        if (!nr_syscs) {
                printk("[kernel] No nr_sysc, probably a bug, user!\n");
                return;
        }
        /* For all after the first call, send ourselves a KMSG (TODO). */
        if (nr_syscs != 1)
                warn("Only one supported (Debutante calls: %d)\n", nr_syscs);
        /* Call the first one directly.  (we already checked to make sure there is
         * 1) */
        run_local_syscall(sysc);
}

/* Call this when something happens on the syscall where userspace might want to
 * get signaled.  Passing p, since the caller should know who the syscall
 * belongs to (probably is current).
 *
 * You need to have SC_K_LOCK set when you call this. */
void __signal_syscall(struct syscall *sysc, struct proc *p)
{
        struct event_queue *ev_q;
        struct event_msg local_msg;
        /* User sets the ev_q then atomically sets the flag (races with SC_DONE) */
        if (atomic_read(&sysc->flags) & SC_UEVENT) {
                rmb();  /* read the ev_q after reading the flag */
                ev_q = sysc->ev_q;
                if (ev_q) {
                        memset(&local_msg, 0, sizeof(struct event_msg));
                        local_msg.ev_type = EV_SYSCALL;
                        local_msg.ev_arg3 = sysc;
                        send_event(p, ev_q, &local_msg, 0);
                }
        }
}

bool syscall_uses_fd(struct syscall *sysc, int fd)
{
        switch (sysc->num) {
                case (SYS_read):
                case (SYS_write):
                case (SYS_close):
                case (SYS_fstat):
                case (SYS_fcntl):
                case (SYS_llseek):
                case (SYS_nmount):
                case (SYS_fd2path):
                        if (sysc->arg0 == fd)
                                return TRUE;
                        return FALSE;
                case (SYS_mmap):
                        /* mmap always has to be special. =) */
                        if (sysc->arg4 == fd)
                                return TRUE;
                        return FALSE;
                default:
                        return FALSE;
        }
}

void print_sysc(struct proc *p, struct syscall *sysc)
{
        uintptr_t old_p = switch_to(p);
        printk("SYS_%d, flags %p, a0 %p, a1 %p, a2 %p, a3 %p, a4 %p, a5 %p\n",
               sysc->num, atomic_read(&sysc->flags),
               sysc->arg0, sysc->arg1, sysc->arg2, sysc->arg3, sysc->arg4,
               sysc->arg5);
        switch_back(p, old_p);
}