*
* In general, error checking / bounds checks are done in the main function
* (e.g. mmap()), and the work is done in a do_ function (e.g. do_mmap()).
- * Versions of those functions that are called when the memory lock (mm_lock) is
- * already held begin with __ (e.g. __do_munmap()).
+ * Versions of those functions that are called when the vmr lock is already held
+ * begin with __ (e.g. __do_munmap()).
*
* Note that if we were called from kern/src/syscall.c, we probably don't have
* an edible reference to p. */
struct kmem_cache *vmr_kcache;
+static int __vmr_free_pgs(struct proc *p, pte_t pte, void *va, void *arg);
+/* minor helper, will ease the file->chan transition */
+static struct page_map *file2pm(struct file *file)
+{
+ return file->f_mapping;
+}
+
void vmr_init(void)
{
vmr_kcache = kmem_cache_create("vm_regions", sizeof(struct vm_region),
vm_i = TAILQ_FIRST(&p->vm_regions);
/* This works for now, but if all we have is BRK_END ones, we'll start
* growing backwards (TODO) */
- if (!vm_i || (va + len < vm_i->vm_base)) {
+ if (!vm_i || (va + len <= vm_i->vm_base)) {
vmr = kmem_cache_alloc(vmr_kcache, 0);
if (!vmr)
panic("EOM!");
vmr->vm_end = vmr->vm_base + len;
}
if (!vmr)
- warn("Not making a VMR, wanted %08p, + %p = %p", va, len, va + len);
+ warn("Not making a VMR, wanted %p, + %p = %p", va, len, va + len);
return vmr;
}
new_vmr->vm_file = old_vmr->vm_file;
new_vmr->vm_foff = old_vmr->vm_foff +
old_vmr->vm_end - old_vmr->vm_base;
+ pm_add_vmr(file2pm(old_vmr->vm_file), new_vmr);
} else {
new_vmr->vm_file = 0;
new_vmr->vm_foff = 0;
* out the page table entries. */
void destroy_vmr(struct vm_region *vmr)
{
- if (vmr->vm_file)
+ if (vmr->vm_file) {
+ pm_remove_vmr(file2pm(vmr->vm_file), vmr);
kref_put(&vmr->vm_file->f_kref);
+ }
TAILQ_REMOVE(&vmr->vm_proc->vm_regions, vmr, vm_link);
kmem_cache_free(vmr_kcache, vmr);
}
split_vmr(vmr, va + len);
}
-/* Destroys all vmrs of a process - important for when files are mmap()d and
- * probably later when we share memory regions */
-void destroy_vmrs(struct proc *p)
+void unmap_and_destroy_vmrs(struct proc *p)
+{
+ struct vm_region *vmr_i, *vmr_temp;
+ /* this only gets called from __proc_free, so there should be no sync
+ * concerns. still, better safe than sorry. */
+ spin_lock(&p->vmr_lock);
+ p->vmr_history++;
+ spin_lock(&p->pte_lock);
+ TAILQ_FOREACH(vmr_i, &p->vm_regions, vm_link) {
+ /* note this CB sets the PTE = 0, regardless of if it was P or not */
+ env_user_mem_walk(p, (void*)vmr_i->vm_base,
+ vmr_i->vm_end - vmr_i->vm_base, __vmr_free_pgs, 0);
+ }
+ spin_unlock(&p->pte_lock);
+ /* need the safe style, since destroy_vmr modifies the list. also, we want
+ * to do this outside the pte lock, since it grabs the pm lock. */
+ TAILQ_FOREACH_SAFE(vmr_i, &p->vm_regions, vm_link, vmr_temp)
+ destroy_vmr(vmr_i);
+ spin_unlock(&p->vmr_lock);
+}
+
+/* Helper: copies the contents of pages from p to new p. For pages that aren't
+ * present, once we support swapping or CoW, we can do something more
+ * intelligent. 0 on success, -ERROR on failure. Can't handle jumbos. */
+static int copy_pages(struct proc *p, struct proc *new_p, uintptr_t va_start,
+ uintptr_t va_end)
{
- struct vm_region *vm_i;
- TAILQ_FOREACH(vm_i, &p->vm_regions, vm_link)
- destroy_vmr(vm_i);
+ /* Sanity checks. If these fail, we had a screwed up VMR.
+ * Check for: alignment, wraparound, or userspace addresses */
+ if ((PGOFF(va_start)) ||
+ (PGOFF(va_end)) ||
+ (va_end < va_start) || /* now, start > UMAPTOP -> end > UMAPTOP */
+ (va_end > UMAPTOP)) {
+ warn("VMR mapping is probably screwed up (%p - %p)", va_start,
+ va_end);
+ return -EINVAL;
+ }
+ int copy_page(struct proc *p, pte_t pte, void *va, void *arg) {
+ struct proc *new_p = (struct proc*)arg;
+ struct page *pp;
+ if (pte_is_unmapped(pte))
+ return 0;
+ /* pages could be !P, but right now that's only for file backed VMRs
+ * undergoing page removal, which isn't the caller of copy_pages. */
+ if (pte_is_mapped(pte)) {
+ /* TODO: check for jumbos */
+ if (upage_alloc(new_p, &pp, 0))
+ return -ENOMEM;
+ if (page_insert(new_p->env_pgdir, pp, va, pte_get_settings(pte))) {
+ page_decref(pp);
+ return -ENOMEM;
+ }
+ memcpy(page2kva(pp), KADDR(pte_get_paddr(pte)), PGSIZE);
+ page_decref(pp);
+ } else if (pte_is_paged_out(pte)) {
+ /* TODO: (SWAP) will need to either make a copy or CoW/refcnt the
+ * backend store. For now, this PTE will be the same as the
+ * original PTE */
+ panic("Swapping not supported!");
+ } else {
+ panic("Weird PTE %p in %s!", pte_print(pte), __FUNCTION__);
+ }
+ return 0;
+ }
+ return env_user_mem_walk(p, (void*)va_start, va_end - va_start, ©_page,
+ new_p);
}
-/* This will make new_p have the same VMRs as p, though it does nothing to
- * ensure the physical pages or whatever are shared/mapped/copied/whatever.
+/* This will make new_p have the same VMRs as p, and it will make sure all
+ * physical pages are copied over, with the exception of MAP_SHARED files.
* This is used by fork().
*
* Note that if you are working on a VMR that is a file, you'll want to be
* careful about how it is mapped (SHARED, PRIVATE, etc). */
-void duplicate_vmrs(struct proc *p, struct proc *new_p)
+int duplicate_vmrs(struct proc *p, struct proc *new_p)
{
+ int ret = 0;
struct vm_region *vmr, *vm_i;
TAILQ_FOREACH(vm_i, &p->vm_regions, vm_link) {
vmr = kmem_cache_alloc(vmr_kcache, 0);
if (!vmr)
- panic("EOM!");
+ return -ENOMEM;
vmr->vm_proc = new_p;
vmr->vm_base = vm_i->vm_base;
vmr->vm_end = vm_i->vm_end;
vmr->vm_prot = vm_i->vm_prot;
vmr->vm_flags = vm_i->vm_flags;
- if (vm_i->vm_file)
- kref_get(&vm_i->vm_file->f_kref, 1);
vmr->vm_file = vm_i->vm_file;
vmr->vm_foff = vm_i->vm_foff;
+ if (vm_i->vm_file) {
+ kref_get(&vm_i->vm_file->f_kref, 1);
+ pm_add_vmr(file2pm(vm_i->vm_file), vmr);
+ }
+ if (!vmr->vm_file || vmr->vm_flags & MAP_PRIVATE) {
+ assert(!(vmr->vm_flags & MAP_SHARED));
+ /* Copy over the memory from one VMR to the other */
+ if ((ret = copy_pages(p, new_p, vmr->vm_base, vmr->vm_end)))
+ return ret;
+ }
TAILQ_INSERT_TAIL(&new_p->vm_regions, vmr, vm_link);
}
+ return 0;
}
void print_vmrs(struct proc *p)
struct vm_region *vmr;
printk("VM Regions for proc %d\n", p->pid);
TAILQ_FOREACH(vmr, &p->vm_regions, vm_link)
- printk("%02d: (0x%08x - 0x%08x): %08p, %08p, %08p, %08p\n", count++,
+ printk("%02d: (%p - %p): 0x%08x, 0x%08x, %p, %p\n", count++,
vmr->vm_base, vmr->vm_end, vmr->vm_prot, vmr->vm_flags,
vmr->vm_file, vmr->vm_foff);
}
+void enumerate_vmrs(struct proc *p,
+ void (*func)(struct vm_region *vmr, void *opaque),
+ void *opaque)
+{
+ struct vm_region *vmr;
+
+ spin_lock(&p->vmr_lock);
+ TAILQ_FOREACH(vmr, &p->vm_regions, vm_link)
+ func(vmr, opaque);
+ spin_unlock(&p->vmr_lock);
+}
/* Error values aren't quite comprehensive - check man mmap() once we do better
* with the FS.
set_errno(EBADF);
return MAP_FAILED;
}
- if ((addr + len > UMAPTOP) || (PGOFF(addr))) {
- set_errno(EINVAL);
- return MAP_FAILED;
- }
if (!len) {
set_errno(EINVAL);
return MAP_FAILED;
addr = BRK_END;
/* Still need to enforce this: */
addr = MAX(addr, MMAP_LOWEST_VA);
+ /* Need to check addr + len, after we do our addr adjustments */
+ if ((addr + len > UMAPTOP) || (PGOFF(addr))) {
+ set_errno(EINVAL);
+ return MAP_FAILED;
+ }
void *result = do_mmap(p, addr, len, prot, flags, file, offset);
if (file)
kref_put(&file->f_kref);
return result;
}
-void *do_mmap(struct proc *p, uintptr_t addr, size_t len, int prot, int flags,
- struct file *file, size_t offset)
+/* Helper: returns TRUE if the VMR is allowed to access the file with prot.
+ * This is a bit ghetto still: messes with the file mode and assumes it can walk
+ * the dentry/inode paths without locking. It also ignores the CoW stuff we'll
+ * need to do eventually. */
+static bool check_file_perms(struct vm_region *vmr, struct file *file, int prot)
+{
+ assert(file);
+ if (prot & PROT_READ) {
+ if (check_perms(file->f_dentry->d_inode, S_IRUSR))
+ goto out_error;
+ }
+ if (prot & PROT_WRITE) {
+ /* if vmr maps a file as MAP_SHARED, then we need to make sure the
+ * protection change is in compliance with the open mode of the
+ * file. */
+ if (vmr->vm_flags & MAP_SHARED) {
+ if (!(file->f_mode & S_IWUSR)) {
+ /* at this point, we have a file opened in the wrong mode,
+ * but we may be allowed to access it still. */
+ if (check_perms(file->f_dentry->d_inode, S_IWUSR)) {
+ goto out_error;
+ } else {
+ /* it is okay, though we need to change the file mode. (note
+ * the lack of a lock/protection (TODO) */
+ file->f_mode |= S_IWUSR;
+ }
+ }
+ } else { /* PRIVATE mapping */
+ /* TODO: we want a CoW mapping (like we want in handle_page_fault()),
+ * since there is a concern of a process having the page already
+ * mapped in to a file it does not have permissions to, and then
+ * mprotecting it so it can access it. So we can't just change
+ * the prot, and we don't know yet if a page is mapped in. To
+ * handle this, we ought to sort out the CoW bit, and then this
+ * will be easy. Til then, just do a permissions check. If we
+ * start having weird issues with libc overwriting itself (since
+ * procs mprotect that W), then change this. */
+ if (check_perms(file->f_dentry->d_inode, S_IWUSR))
+ goto out_error;
+ }
+ }
+ return TRUE;
+out_error: /* for debugging */
+ printk("[kernel] mmap perm check failed for %s for access %d\n",
+ file_name(file), prot);
+ return FALSE;
+}
+
+/* Helper, maps in page at addr, but only if nothing is mapped there. Returns
+ * 0 on success. If this is called by non-PM code, we'll store your ref in the
+ * PTE. */
+static int map_page_at_addr(struct proc *p, struct page *page, uintptr_t addr,
+ int prot)
{
- spin_lock(&p->mm_lock);
- void *ret = __do_mmap(p, addr, len, prot, flags, file, offset);
- spin_unlock(&p->mm_lock);
+ pte_t pte;
+ spin_lock(&p->pte_lock); /* walking and changing PTEs */
+ /* find offending PTE (prob don't read this in). This might alloc an
+ * intermediate page table page. */
+ pte = pgdir_walk(p->env_pgdir, (void*)addr, TRUE);
+ if (!pte_walk_okay(pte)) {
+ spin_unlock(&p->pte_lock);
+ return -ENOMEM;
+ }
+ /* a spurious, valid PF is possible due to a legit race: the page might have
+ * been faulted in by another core already (and raced on the memory lock),
+ * in which case we should just return. */
+ if (pte_is_present(pte)) {
+ spin_unlock(&p->pte_lock);
+ /* callers expect us to eat the ref if we succeed. */
+ page_decref(page);
+ return 0;
+ }
+ if (pte_is_mapped(pte)) {
+ /* we're clobbering an old entry. if we're just updating the prot, then
+ * it's no big deal. o/w, there might be an issue. */
+ if (page2pa(page) != pte_get_paddr(pte)) {
+ warn_once("Clobbered a PTE mapping (%p -> %p)\n", pte_print(pte),
+ page2pa(page) | prot);
+ }
+ page_decref(pa2page(pte_get_paddr(pte)));
+ }
+ /* preserve the dirty bit - pm removal could be looking concurrently */
+ prot |= (pte_is_dirty(pte) ? PTE_D : 0);
+ /* We have a ref to page, which we are storing in the PTE */
+ pte_write(pte, page2pa(page), prot);
+ spin_unlock(&p->pte_lock);
+ return 0;
+}
+
+/* Helper: copies *pp's contents to a new page, replacing your page pointer. If
+ * this succeeds, you'll have a non-PM page, which matters for how you put it.*/
+static int __copy_and_swap_pmpg(struct proc *p, struct page **pp)
+{
+ struct page *new_page, *old_page = *pp;
+ if (upage_alloc(p, &new_page, FALSE))
+ return -ENOMEM;
+ memcpy(page2kva(new_page), page2kva(old_page), PGSIZE);
+ pm_put_page(old_page);
+ *pp = new_page;
+ return 0;
+}
+
+/* Hold the VMR lock when you call this - it'll assume the entire VA range is
+ * mappable, which isn't true if there are concurrent changes to the VMRs. */
+static int populate_anon_va(struct proc *p, uintptr_t va, unsigned long nr_pgs,
+ int pte_prot)
+{
+ struct page *page;
+ int ret;
+ for (long i = 0; i < nr_pgs; i++) {
+ if (upage_alloc(p, &page, TRUE))
+ return -ENOMEM;
+ /* could imagine doing a memwalk instead of a for loop */
+ ret = map_page_at_addr(p, page, va + i * PGSIZE, pte_prot);
+ if (ret) {
+ page_decref(page);
+ return ret;
+ }
+ }
+ return 0;
+}
+
+/* This will periodically unlock the vmr lock. */
+static int populate_pm_va(struct proc *p, uintptr_t va, unsigned long nr_pgs,
+ int pte_prot, struct page_map *pm, size_t offset,
+ int flags, bool exec)
+{
+ int ret = 0;
+ unsigned long pm_idx0 = offset >> PGSHIFT;
+ int vmr_history = ACCESS_ONCE(p->vmr_history);
+ struct page *page;
+
+ /* locking rules: start the loop holding the vmr lock, enter and exit the
+ * entire func holding the lock. */
+ for (long i = 0; i < nr_pgs; i++) {
+ ret = pm_load_page_nowait(pm, pm_idx0 + i, &page);
+ if (ret) {
+ if (ret != -EAGAIN)
+ break;
+ spin_unlock(&p->vmr_lock);
+ /* might block here, can't hold the spinlock */
+ ret = pm_load_page(pm, pm_idx0 + i, &page);
+ spin_lock(&p->vmr_lock);
+ if (ret)
+ break;
+ /* while we were sleeping, the VMRs could have changed on us. */
+ if (vmr_history != ACCESS_ONCE(p->vmr_history)) {
+ pm_put_page(page);
+ printk("[kernel] FYI: VMR changed during populate\n");
+ break;
+ }
+ }
+ if (flags & MAP_PRIVATE) {
+ ret = __copy_and_swap_pmpg(p, &page);
+ if (ret) {
+ pm_put_page(page);
+ break;
+ }
+ }
+ /* if this is an executable page, we might have to flush the
+ * instruction cache if our HW requires it.
+ * TODO: is this still needed? andrew put this in a while ago*/
+ if (exec)
+ icache_flush_page(0, page2kva(page));
+ ret = map_page_at_addr(p, page, va + i * PGSIZE, pte_prot);
+ if (atomic_read(&page->pg_flags) & PG_PAGEMAP)
+ pm_put_page(page);
+ if (ret)
+ break;
+ }
return ret;
}
-void *__do_mmap(struct proc *p, uintptr_t addr, size_t len, int prot, int flags,
- struct file *file, size_t offset)
+void *do_mmap(struct proc *p, uintptr_t addr, size_t len, int prot, int flags,
+ struct file *file, size_t offset)
{
len = ROUNDUP(len, PGSIZE);
- int num_pages = len / PGSIZE;
- int retval;
-
struct vm_region *vmr, *vmr_temp;
+ /* read/write vmr lock (will change the tree) */
+ spin_lock(&p->vmr_lock);
+ p->vmr_history++;
/* Sanity check, for callers that bypass mmap(). We want addr for anon
* memory to start above the break limit (BRK_END), but not 0. Keep this in
* sync with BRK_END in mmap(). */
if (addr == 0)
addr = BRK_END;
+ assert(!PGOFF(offset));
-#ifndef __CONFIG_DEMAND_PAGING__
- flags |= MAP_POPULATE;
-#endif
+ /* MCPs will need their code and data pinned. This check will start to fail
+ * after uthread_slim_init(), at which point userspace should have enough
+ * control over its mmaps (i.e. no longer done by LD or load_elf) that it
+ * can ask for pinned and populated pages. Except for dl_opens(). */
+ struct preempt_data *vcpd = &p->procdata->vcore_preempt_data[0];
+ if (file && (atomic_read(&vcpd->flags) & VC_SCP_NOVCCTX))
+ flags |= MAP_POPULATE | MAP_LOCKED;
/* Need to make sure nothing is in our way when we want a FIXED location.
* We just need to split on the end points (if they exist), and then remove
* everything in between. __do_munmap() will do this. Careful, this means
__do_munmap(p, addr, len);
vmr = create_vmr(p, addr, len);
if (!vmr) {
- printk("[kernel] do_mmap() aborted for %08p + %d!\n", addr, len);
+ printk("[kernel] do_mmap() aborted for %p + %d!\n", addr, len);
set_errno(ENOMEM);
- return MAP_FAILED; /* TODO: error propagation for mmap() */
+ spin_unlock(&p->vmr_lock);
+ return MAP_FAILED;
}
+ addr = vmr->vm_base;
vmr->vm_prot = prot;
vmr->vm_flags = flags;
- if (file)
+ if (file) {
+ if (!check_file_perms(vmr, file, prot)) {
+ assert(!vmr->vm_file);
+ destroy_vmr(vmr);
+ set_errno(EACCES);
+ spin_unlock(&p->vmr_lock);
+ return MAP_FAILED;
+ }
+ /* TODO: consider locking the file while checking (not as manadatory as
+ * in handle_page_fault() */
+ if (nr_pages(offset + len) > nr_pages(file->f_dentry->d_inode->i_size)) {
+ /* We're allowing them to set up the VMR, though if they attempt to
+ * fault in any pages beyond the file's limit, they'll fail. Since
+ * they might not access the region, we need to make sure POPULATE
+ * is off. FYI, 64 bit glibc shared libs map in an extra 2MB of
+ * unaligned space between their RO and RW sections, but then
+ * immediately mprotect it to PROT_NONE. */
+ flags &= ~MAP_POPULATE;
+ }
+ /* Prep the FS to make sure it can mmap the file. Slightly weird
+ * semantics: if we fail and had munmapped the space, they will have a
+ * hole in their VM now. */
+ if (file->f_op->mmap(file, vmr)) {
+ assert(!vmr->vm_file);
+ destroy_vmr(vmr);
+ set_errno(EACCES); /* not quite */
+ spin_unlock(&p->vmr_lock);
+ return MAP_FAILED;
+ }
kref_get(&file->f_kref, 1);
+ pm_add_vmr(file2pm(file), vmr);
+ }
vmr->vm_file = file;
vmr->vm_foff = offset;
- /* Prep the FS to make sure it can mmap the file. Slightly weird semantics:
- * they will have a hole in their VM now. */
- if (file && file->f_op->mmap(file, vmr)) {
- destroy_vmr(vmr);
- set_errno(EACCES); /* not quite */
- return MAP_FAILED;
- }
- addr = vmr->vm_base; /* so we know which pages to populate later */
vmr = merge_me(vmr); /* attempts to merge with neighbors */
- /* Fault in pages now if MAP_POPULATE. We want to populate the region
- * requested, but we need to be careful and only populate the requested
- * length and not any merged regions, which is why we set addr above and use
- * it here.
- *
- * If HPF errors out, we'll warn for now, since it is likely a bug in
- * userspace, though since POPULATE is an opportunistic thing, we don't need
- * to actually kill the process. If we do kill them, make sure to
- * incref/decref around proc_destroy, since we likely don't have an edible
- * reference to p. */
- if (flags & MAP_POPULATE)
- for (int i = 0; i < num_pages; i++) {
- retval = __handle_page_fault(p, addr + i * PGSIZE, vmr->vm_prot);
- if (retval) {
- warn("do_mmap() failing (%d) on addr %08p with prot %p\n",
- retval, addr + i * PGSIZE, vmr->vm_prot);
- break;
- }
+
+ if (flags & MAP_POPULATE && prot != PROT_NONE) {
+ int pte_prot = (prot & PROT_WRITE) ? PTE_USER_RW :
+ (prot & (PROT_READ|PROT_EXEC)) ? PTE_USER_RO : 0;
+ unsigned long nr_pgs = len >> PGSHIFT;
+ int ret = 0;
+ if (!file) {
+ ret = populate_anon_va(p, addr, nr_pgs, pte_prot);
+ } else {
+ /* Note: this will unlock if it blocks. our refcnt on the file
+ * keeps the pm alive when we unlock */
+ ret = populate_pm_va(p, addr, nr_pgs, pte_prot, file->f_mapping,
+ offset, flags, prot & PROT_EXEC);
}
- return (void*SAFE)TC(addr);
+ if (ret == -ENOMEM) {
+ spin_unlock(&p->vmr_lock);
+ printk("[kernel] ENOMEM, killing %d\n", p->pid);
+ proc_destroy(p);
+ return MAP_FAILED; /* will never make it back to userspace */
+ }
+ }
+ spin_unlock(&p->vmr_lock);
+ return (void*)addr;
}
int mprotect(struct proc *p, uintptr_t addr, size_t len, int prot)
{
- printd("mprotect: (addr %08p, len %08p, prot %08p)\n", addr, len, prot);
+ printd("mprotect: (addr %p, len %p, prot 0x%x)\n", addr, len, prot);
if (!len)
return 0;
if ((addr % PGSIZE) || (addr < MMAP_LOWEST_VA)) {
set_errno(ENOMEM);
return -1;
}
- spin_lock(&p->mm_lock);
+ /* read/write lock, will probably change the tree and settings */
+ spin_lock(&p->vmr_lock);
+ p->vmr_history++;
int ret = __do_mprotect(p, addr, len, prot);
- spin_unlock(&p->mm_lock);
+ spin_unlock(&p->vmr_lock);
return ret;
}
int __do_mprotect(struct proc *p, uintptr_t addr, size_t len, int prot)
{
struct vm_region *vmr, *next_vmr;
- pte_t *pte;
+ pte_t pte;
bool shootdown_needed = FALSE;
int pte_prot = (prot & PROT_WRITE) ? PTE_USER_RW :
- (prot & (PROT_READ|PROT_EXEC)) ? PTE_USER_RO : 0;
+ (prot & (PROT_READ|PROT_EXEC)) ? PTE_USER_RO : PTE_NONE;
/* TODO: this is aggressively splitting, when we might not need to if the
* prots are the same as the previous. Plus, there are three excessive
* scans. Finally, we might be able to merge when we are done. */
while (vmr && vmr->vm_base < addr + len) {
if (vmr->vm_prot == prot)
continue;
- if (vmr->vm_file && (prot & PROT_WRITE)) {
- /* if vmr maps a file as MAP_SHARED, then we need to make sure the
- * protection change is in compliance with the open mode of the
- * file. */
- if (vmr->vm_flags & MAP_SHARED) {
- if (!(vmr->vm_file->f_mode & S_IWUSR)) {
- /* at this point, we have a file opened in the wrong mode,
- * but we may be allowed to access it still. */
- if (check_perms(vmr->vm_file->f_dentry->d_inode, S_IWUSR)) {
- set_errno(EACCES);
- return -1;
- } else {
- /* it is okay, though we need to change the file mode.
- */
- vmr->vm_file->f_mode |= S_IWUSR;
- }
- }
- } else { /* PRIVATE mapping */
- /* TODO: we want a CoW mapping (like we want in handle_page_fault()),
- * since there is a concern of a process having the page already
- * mapped in to a file it does not have permissions to, and then
- * mprotecting it so it can access it. So we can't just change
- * the prot, and we don't know yet if a page is mapped in. To
- * handle this, we ought to sort out the CoW bit, and then this
- * will be easy. Til then, just do a permissions check. If we
- * start having weird issues with libc overwriting itself (since
- * procs mprotect that W), then change this. */
- if (check_perms(vmr->vm_file->f_dentry->d_inode, S_IWUSR)) {
- set_errno(EACCES);
- return -1;
- }
- }
+ if (vmr->vm_file && !check_file_perms(vmr, vmr->vm_file, prot)) {
+ set_errno(EACCES);
+ return -1;
}
vmr->vm_prot = prot;
- for (uintptr_t va = vmr->vm_base; va < vmr->vm_end; va += PGSIZE) {
+ spin_lock(&p->pte_lock); /* walking and changing PTEs */
+ /* TODO: use a memwalk. At a minimum, we need to change every existing
+ * PTE that won't trigger a PF (meaning, present PTEs) to have the new
+ * prot. The others will fault on access, and we'll change the PTE
+ * then. In the off chance we have a mapped but not present PTE, we
+ * might as well change it too, since we're already here. */
+ for (uintptr_t va = vmr->vm_base; va < vmr->vm_end; va += PGSIZE) {
pte = pgdir_walk(p->env_pgdir, (void*)va, 0);
- if (pte && PAGE_PRESENT(*pte)) {
- *pte = (*pte & ~PTE_PERM) | pte_prot;
+ if (pte_walk_okay(pte) && pte_is_mapped(pte)) {
+ pte_replace_perm(pte, pte_prot);
shootdown_needed = TRUE;
}
}
+ spin_unlock(&p->pte_lock);
next_vmr = TAILQ_NEXT(vmr, vm_link);
vmr = next_vmr;
}
printd("munmap(addr %x, len %x)\n", addr, len);
if (!len)
return 0;
+ len = ROUNDUP(len, PGSIZE);
+
if ((addr % PGSIZE) || (addr < MMAP_LOWEST_VA)) {
set_errno(EINVAL);
return -1;
set_errno(EINVAL);
return -1;
}
- spin_lock(&p->mm_lock);
+ /* read/write: changing the vmrs (trees, properties, and whatnot) */
+ spin_lock(&p->vmr_lock);
+ p->vmr_history++;
int ret = __do_munmap(p, addr, len);
- spin_unlock(&p->mm_lock);
+ spin_unlock(&p->vmr_lock);
return ret;
}
+static int __munmap_mark_not_present(struct proc *p, pte_t pte, void *va,
+ void *arg)
+{
+ bool *shootdown_needed = (bool*)arg;
+ /* could put in some checks here for !P and also !0 */
+ if (!pte_is_present(pte)) /* unmapped (== 0) *ptes are also not PTE_P */
+ return 0;
+ pte_clear_present(pte);
+ *shootdown_needed = TRUE;
+ return 0;
+}
+
+/* If our page is actually in the PM, we don't do anything. All a page map
+ * really needs is for our VMR to no longer track it (vmr being in the pm's
+ * list) and to not point at its pages (mark it 0, dude).
+ *
+ * But private mappings mess with that a bit. Luckily, we can tell by looking
+ * at a page whether the specific page is in the PM or not. If it isn't, we
+ * still need to free our "VMR local" copy.
+ *
+ * For pages in a PM, we're racing with PM removers. Both of us sync with the
+ * mm lock, so once we hold the lock, it's a matter of whether or not the PTE is
+ * 0 or not. If it isn't, then we're still okay to look at the page. Consider
+ * the PTE a weak ref on the page. So long as you hold the mm lock, you can
+ * look at the PTE and know the page isn't being freed. */
+static int __vmr_free_pgs(struct proc *p, pte_t pte, void *va, void *arg)
+{
+ struct page *page;
+ if (pte_is_unmapped(pte))
+ return 0;
+ page = pa2page(pte_get_paddr(pte));
+ pte_clear(pte);
+ if (!(atomic_read(&page->pg_flags) & PG_PAGEMAP))
+ page_decref(page);
+ return 0;
+}
+
int __do_munmap(struct proc *p, uintptr_t addr, size_t len)
{
- struct vm_region *vmr, *next_vmr;
- pte_t *pte;
+ struct vm_region *vmr, *next_vmr, *first_vmr;
bool shootdown_needed = FALSE;
/* TODO: this will be a bit slow, since we end up doing three linear
* searches (two in isolate, one in find_first). */
isolate_vmrs(p, addr, len);
- vmr = find_first_vmr(p, addr);
+ first_vmr = find_first_vmr(p, addr);
+ vmr = first_vmr;
+ spin_lock(&p->pte_lock); /* changing PTEs */
while (vmr && vmr->vm_base < addr + len) {
- for (uintptr_t va = vmr->vm_base; va < vmr->vm_end; va += PGSIZE) {
- pte = pgdir_walk(p->env_pgdir, (void*)va, 0);
- if (!pte)
- continue;
- if (PAGE_PRESENT(*pte)) {
- /* TODO: (TLB) race here, where the page can be given out before
- * the shootdown happened. Need to put it on a temp list. */
- page_t *page = ppn2page(PTE2PPN(*pte));
- *pte = 0;
- page_decref(page);
- shootdown_needed = TRUE;
- } else if (PAGE_PAGED_OUT(*pte)) {
- /* TODO: (SWAP) mark free in the swapfile or whatever. For now,
- * PAGED_OUT is also being used to mean "hasn't been mapped
- * yet". Note we now allow PAGE_UNMAPPED, unlike older
- * versions of mmap(). */
- panic("Swapping not supported!");
- *pte = 0;
- }
- }
+ env_user_mem_walk(p, (void*)vmr->vm_base, vmr->vm_end - vmr->vm_base,
+ __munmap_mark_not_present, &shootdown_needed);
+ vmr = TAILQ_NEXT(vmr, vm_link);
+ }
+ spin_unlock(&p->pte_lock);
+ /* we haven't freed the pages yet; still using the PTEs to store the them.
+ * There should be no races with inserts/faults, since we still hold the mm
+ * lock since the previous CB. */
+ if (shootdown_needed)
+ proc_tlbshootdown(p, addr, addr + len);
+ vmr = first_vmr;
+ while (vmr && vmr->vm_base < addr + len) {
+ /* there is rarely more than one VMR in this loop. o/w, we'll need to
+ * gather up the vmrs and destroy outside the pte_lock. */
+ spin_lock(&p->pte_lock); /* changing PTEs */
+ env_user_mem_walk(p, (void*)vmr->vm_base, vmr->vm_end - vmr->vm_base,
+ __vmr_free_pgs, 0);
+ spin_unlock(&p->pte_lock);
next_vmr = TAILQ_NEXT(vmr, vm_link);
destroy_vmr(vmr);
vmr = next_vmr;
}
- if (shootdown_needed)
- proc_tlbshootdown(p, addr, addr + len);
return 0;
}
-int handle_page_fault(struct proc* p, uintptr_t va, int prot)
+/* Helper - drop the page differently based on where it is from */
+static void __put_page(struct page *page)
{
- va = ROUNDDOWN(va,PGSIZE);
+ if (atomic_read(&page->pg_flags) & PG_PAGEMAP)
+ pm_put_page(page);
+ else
+ page_decref(page);
+}
- if (prot != PROT_READ && prot != PROT_WRITE && prot != PROT_EXEC)
- panic("bad prot!");
- spin_lock(&p->mm_lock);
- int ret = __handle_page_fault(p, va, prot);
- spin_unlock(&p->mm_lock);
- return ret;
+static int __hpf_load_page(struct proc *p, struct page_map *pm,
+ unsigned long idx, struct page **page, bool first)
+{
+ int ret = 0;
+ int coreid = core_id();
+ struct per_cpu_info *pcpui = &per_cpu_info[coreid];
+ bool wake_scp = FALSE;
+ spin_lock(&p->proc_lock);
+ switch (p->state) {
+ case (PROC_RUNNING_S):
+ wake_scp = TRUE;
+ __proc_set_state(p, PROC_WAITING);
+ /* it's possible for HPF to loop a few times; we can only save the
+ * first time, o/w we could clobber. */
+ if (first) {
+ __proc_save_context_s(p, pcpui->cur_ctx);
+ __proc_save_fpu_s(p);
+ /* We clear the owner, since userspace doesn't run here
+ * anymore, but we won't abandon since the fault handler
+ * still runs in our process. */
+ clear_owning_proc(coreid);
+ }
+ /* other notes: we don't currently need to tell the ksched
+ * we switched from running to waiting, though we probably
+ * will later for more generic scheds. */
+ break;
+ case (PROC_RUNNABLE_M):
+ case (PROC_RUNNING_M):
+ spin_unlock(&p->proc_lock);
+ return -EAGAIN; /* will get reflected back to userspace */
+ case (PROC_DYING):
+ spin_unlock(&p->proc_lock);
+ return -EINVAL;
+ default:
+ /* shouldn't have any waitings, under the current yield style. if
+ * this becomes an issue, we can branch on is_mcp(). */
+ printk("HPF unexpectecd state(%s)", procstate2str(p->state));
+ spin_unlock(&p->proc_lock);
+ return -EINVAL;
+ }
+ spin_unlock(&p->proc_lock);
+ ret = pm_load_page(pm, idx, page);
+ if (wake_scp)
+ proc_wakeup(p);
+ if (ret) {
+ printk("load failed with ret %d\n", ret);
+ return ret;
+ }
+ /* need to put our old ref, next time around HPF will get another. */
+ pm_put_page(*page);
+ return 0;
}
-/* Returns 0 on success, or an appropriate -error code. Assumes you hold the
- * mm_lock.
+/* Returns 0 on success, or an appropriate -error code.
*
* Notes: if your TLB caches negative results, you'll need to flush the
* appropriate tlb entry. Also, you could have a weird race where a present PTE
* shootdown is on its way. Userspace should have waited for the mprotect to
* return before trying to write (or whatever), so we don't care and will fault
* them. */
-int __handle_page_fault(struct proc *p, uintptr_t va, int prot)
+int handle_page_fault(struct proc *p, uintptr_t va, int prot)
{
struct vm_region *vmr;
struct page *a_page;
unsigned int f_idx; /* index of the missing page in the file */
- int retval;
+ int ret = 0;
+ bool first = TRUE;
+ va = ROUNDDOWN(va,PGSIZE);
+refault:
+ /* read access to the VMRs TODO: RCU */
+ spin_lock(&p->vmr_lock);
/* Check the vmr's protection */
vmr = find_vmr(p, va);
- if (!vmr) /* not mapped at all */
- return -EFAULT;
- if (!(vmr->vm_prot & prot)) /* wrong prots for this vmr */
- return -EPERM;
- /* find offending PTE (prob don't read this in). This might alloc an
- * intermediate page table page. */
- pte_t *pte = pgdir_walk(p->env_pgdir, (void*)va, 1);
- if (!pte)
- return -ENOMEM;
- /* a spurious, valid PF is possible due to a legit race: the page might have
- * been faulted in by another core already (and raced on the memory lock),
- * in which case we should just return. */
- if (PAGE_PRESENT(*pte)) {
- return 0;
- } else if (PAGE_PAGED_OUT(*pte)) {
- /* TODO: (SWAP) bring in the paged out frame. (BLK) */
- panic("Swapping not supported!");
- return -1;
+ if (!vmr) { /* not mapped at all */
+ printd("fault: %p not mapped\n", va);
+ ret = -EFAULT;
+ goto out;
+ }
+ if (!(vmr->vm_prot & prot)) { /* wrong prots for this vmr */
+ ret = -EPERM;
+ goto out;
}
if (!vmr->vm_file) {
/* No file - just want anonymous memory */
- if (upage_alloc(p, &a_page, TRUE))
- return -ENOMEM;
+ if (upage_alloc(p, &a_page, TRUE)) {
+ ret = -ENOMEM;
+ goto out;
+ }
} else {
+ /* If this fails, either something got screwed up with the VMR, or the
+ * permissions changed after mmap/mprotect. Either way, I want to know
+ * (though it's not critical). */
+ if (!check_file_perms(vmr, vmr->vm_file, prot))
+ printk("[kernel] possible issue with VMR prots on file %s!\n",
+ file_name(vmr->vm_file));
/* Load the file's page in the page cache.
* TODO: (BLK) Note, we are holding the mem lock! We need to rewrite
* this stuff so we aren't hold the lock as excessively as we are, and
* such that we can block and resume later. */
+ assert(!PGOFF(va - vmr->vm_base + vmr->vm_foff));
f_idx = (va - vmr->vm_base + vmr->vm_foff) >> PGSHIFT;
- retval = pm_load_page(vmr->vm_file->f_mapping, f_idx, &a_page);
- if (retval)
- return retval;
- /* If we want a private map that is writable, we'll preemptively give
- * you a new page. In the future, we want to CoW this. */
- if ((vmr->vm_flags |= MAP_PRIVATE) && (vmr->vm_prot |= PROT_WRITE)) {
- struct page *cache_page = a_page;
- if (upage_alloc(p, &a_page, FALSE)) {
- page_decref(cache_page); /* was the original a_page */
- return -ENOMEM;
- }
- memcpy(page2kva(a_page), page2kva(cache_page), PGSIZE);
- page_decref(cache_page); /* was the original a_page */
+ /* TODO: need some sort of lock on the file to deal with someone
+ * concurrently shrinking it. Adding 1 to f_idx, since it is
+ * zero-indexed */
+ if (f_idx + 1 > nr_pages(vmr->vm_file->f_dentry->d_inode->i_size)) {
+ /* We're asking for pages that don't exist in the file */
+ /* TODO: unlock the file */
+ ret = -ESPIPE; /* linux sends a SIGBUS at access time */
+ goto out;
+ }
+ ret = pm_load_page_nowait(vmr->vm_file->f_mapping, f_idx, &a_page);
+ if (ret) {
+ if (ret != -EAGAIN)
+ goto out;
+ /* keep the file alive after we unlock */
+ kref_get(&vmr->vm_file->f_kref, 1);
+ spin_unlock(&p->vmr_lock);
+ ret = __hpf_load_page(p, vmr->vm_file->f_mapping, f_idx, &a_page,
+ first);
+ first = FALSE;
+ kref_put(&vmr->vm_file->f_kref);
+ if (ret)
+ return ret;
+ goto refault;
+ }
+ /* If we want a private map, we'll preemptively give you a new page. We
+ * used to just care if it was private and writable, but were running
+ * into issues with libc changing its mapping (map private, then
+ * mprotect to writable...) In the future, we want to CoW this anyway,
+ * so it's not a big deal. */
+ if ((vmr->vm_flags & MAP_PRIVATE)) {
+ ret = __copy_and_swap_pmpg(p, &a_page);
+ if (ret)
+ goto out_put_pg;
}
/* if this is an executable page, we might have to flush the instruction
* cache if our HW requires it. */
* separately (file, no file) */
int pte_prot = (vmr->vm_prot & PROT_WRITE) ? PTE_USER_RW :
(vmr->vm_prot & (PROT_READ|PROT_EXEC)) ? PTE_USER_RO : 0;
- /* We have a ref to a_page, which we are storing in the PTE */
- *pte = PTE(page2ppn(a_page), PTE_P | pte_prot);
- return 0;
+ ret = map_page_at_addr(p, a_page, va, pte_prot);
+ if (ret) {
+ printd("map_page_at for %p fails with %d\n", va, ret);
+ }
+ /* fall through, even for errors */
+out_put_pg:
+ /* the VMR's existence in the PM (via the mmap) allows us to have PTE point
+ * to a_page without it magically being reallocated. For non-PM memory
+ * (anon memory or private pages) we transferred the ref to the PTE. */
+ if (atomic_read(&a_page->pg_flags) & PG_PAGEMAP)
+ pm_put_page(a_page);
+out:
+ spin_unlock(&p->vmr_lock);
+ return ret;
+}
+
+/* Attempts to populate the pages, as if there was a page faults. Bails on
+ * errors, and returns the number of pages populated. */
+unsigned long populate_va(struct proc *p, uintptr_t va, unsigned long nr_pgs)
+{
+ struct vm_region *vmr, vmr_copy;
+ unsigned long nr_pgs_this_vmr;
+ unsigned long nr_filled = 0;
+ struct page *page;
+ int pte_prot;
+
+ /* we can screw around with ways to limit the find_vmr calls (can do the
+ * next in line if we didn't unlock, etc., but i don't expect us to do this
+ * for more than a single VMR in most cases. */
+ spin_lock(&p->vmr_lock);
+ while (nr_pgs) {
+ vmr = find_vmr(p, va);
+ if (!vmr)
+ break;
+ if (vmr->vm_prot == PROT_NONE)
+ break;
+ pte_prot = (vmr->vm_prot & PROT_WRITE) ? PTE_USER_RW :
+ (vmr->vm_prot & (PROT_READ|PROT_EXEC)) ? PTE_USER_RO : 0;
+ nr_pgs_this_vmr = MIN(nr_pgs, (vmr->vm_end - va) >> PGSHIFT);
+ if (!vmr->vm_file) {
+ if (populate_anon_va(p, va, nr_pgs_this_vmr, pte_prot)) {
+ /* on any error, we can just bail. we might be underestimating
+ * nr_filled. */
+ break;
+ }
+ } else {
+ /* need to keep the file alive in case we unlock/block */
+ kref_get(&vmr->vm_file->f_kref, 1);
+ if (populate_pm_va(p, va, nr_pgs_this_vmr, pte_prot,
+ vmr->vm_file->f_mapping,
+ vmr->vm_foff - (va - vmr->vm_base),
+ vmr->vm_flags, vmr->vm_prot & PROT_EXEC)) {
+ /* we might have failed if the underlying file doesn't cover the
+ * mmap window, depending on how we'll deal with truncation. */
+ break;
+ }
+ kref_put(&vmr->vm_file->f_kref);
+ }
+ nr_filled += nr_pgs_this_vmr;
+ va += nr_pgs_this_vmr << PGSHIFT;
+ nr_pgs -= nr_pgs_this_vmr;
+ }
+ spin_unlock(&p->vmr_lock);
+ return nr_filled;
}
/* Kernel Dynamic Memory Mappings */
uintptr_t put_vmap_segment(uintptr_t vaddr, unsigned long num_pages)
{
/* TODO: use vmem regions for adjustable vmap segments */
- panic("Unsupported.\n");
+ warn("Not implemented, leaking vmem space.\n");
+ return 0;
}
/* Map a virtual address chunk to physical addresses. Make sure you got a vmap
* isn't enough, since there might be a race on outer levels of page tables.
* For now, we'll just use the dyn_vmap_lock (which technically works). */
spin_lock(&dyn_vmap_lock);
- pte_t *pte;
-#ifdef __i386__
+ pte_t pte;
+#ifdef CONFIG_X86
perm |= PTE_G;
#endif
for (int i = 0; i < num_pages; i++) {
pte = pgdir_walk(boot_pgdir, (void*)(vaddr + i * PGSIZE), 1);
- if (!pte) {
+ if (!pte_walk_okay(pte)) {
spin_unlock(&dyn_vmap_lock);
return -ENOMEM;
}
/* You probably should have unmapped first */
- if (*pte)
- warn("Existing PTE value %08p\n", *pte);
- *pte = PTE(pa2ppn(paddr + i * PGSIZE), perm);
+ if (pte_is_mapped(pte))
+ warn("Existing PTE value %p\n", pte_print(pte));
+ pte_write(pte, paddr + i * PGSIZE, perm);
}
spin_unlock(&dyn_vmap_lock);
return 0;
int unmap_vmap_segment(uintptr_t vaddr, unsigned long num_pages)
{
/* Not a big deal - won't need this til we do something with kthreads */
- panic("Incomplete, don't call this yet.");
+ warn("Incomplete, don't call this yet.");
spin_lock(&dyn_vmap_lock);
/* TODO: For all pgdirs */
- pte_t *pte;
+ pte_t pte;
for (int i = 0; i < num_pages; i++) {
pte = pgdir_walk(boot_pgdir, (void*)(vaddr + i * PGSIZE), 1);
- *pte = 0;
+ if (pte_walk_okay(pte))
+ pte_clear(pte);
}
/* TODO: TLB shootdown. Also note that the global flag is set on the PTE
* (for x86 for now), which requires a global shootdown. bigger issue is
spin_unlock(&dyn_vmap_lock);
return 0;
}
+
+/* This can handle unaligned paddrs */
+static uintptr_t vmap_pmem_flags(uintptr_t paddr, size_t nr_bytes, int flags)
+{
+ uintptr_t vaddr;
+ unsigned long nr_pages;
+ assert(nr_bytes && paddr);
+ nr_bytes += PGOFF(paddr);
+ nr_pages = ROUNDUP(nr_bytes, PGSIZE) >> PGSHIFT;
+ vaddr = get_vmap_segment(nr_pages);
+ if (!vaddr) {
+ warn("Unable to get a vmap segment"); /* probably a bug */
+ return 0;
+ }
+ /* it's not strictly necessary to drop paddr's pgoff, but it might save some
+ * vmap heartache in the future. */
+ if (map_vmap_segment(vaddr, PG_ADDR(paddr), nr_pages,
+ PTE_KERN_RW | flags)) {
+ warn("Unable to map a vmap segment"); /* probably a bug */
+ return 0;
+ }
+ return vaddr + PGOFF(paddr);
+}
+
+uintptr_t vmap_pmem(uintptr_t paddr, size_t nr_bytes)
+{
+ return vmap_pmem_flags(paddr, nr_bytes, 0);
+}
+
+uintptr_t vmap_pmem_nocache(uintptr_t paddr, size_t nr_bytes)
+{
+ return vmap_pmem_flags(paddr, nr_bytes, PTE_NOCACHE);
+}
+
+int vunmap_vmem(uintptr_t vaddr, size_t nr_bytes)
+{
+ unsigned long nr_pages = ROUNDUP(nr_bytes, PGSIZE) >> PGSHIFT;
+ unmap_vmap_segment(vaddr, nr_pages);
+ put_vmap_segment(vaddr, nr_pages);
+ return 0;
+}
projects / akaros.git / blobdiff