Debug code to see remote kmsgs
[akaros.git] / kern / arch / riscv / trap.c
1 #include <arch/arch.h>
2 #include <assert.h>
3 #include <arch/trap.h>
4 #include <string.h>
5 #include <process.h>
6 #include <syscall.h>
7 #include <monitor.h>
8 #include <manager.h>
9 #include <stdio.h>
10 #include <smp.h>
11 #include <slab.h>
12 #include <mm.h>
13 #include <umem.h>
14 #include <pmap.h>
15
16 /* These are the stacks the kernel will load when it receives a trap from user
17  * space.  The deal is that they get set right away in entry.S, and can always
18  * be used for finding the top of the stack (from which you should subtract the
19  * sizeof the trapframe.  Note, we need to have a junk value in the array so
20  * that this is NOT part of the BSS.  If it is in the BSS, it will get 0'd in
21  * kernel_init(), which is after these values get set.
22  *
23  * TODO: if these end up becoming contended cache lines, move this to
24  * per_cpu_info. */
25 uintptr_t core_stacktops[MAX_NUM_CPUS] = {0xcafebabe, 0};
26
27 struct kmem_cache *kernel_msg_cache;
28 void kernel_msg_init(void)
29 {
30         kernel_msg_cache = kmem_cache_create("kernel_msgs",
31                            sizeof(struct kernel_message), HW_CACHE_ALIGN, 0, 0, 0);
32 }
33
34 spinlock_t kernel_message_buf_busy[MAX_NUM_CPUS] = {SPINLOCK_INITIALIZER};
35 kernel_message_t kernel_message_buf[MAX_NUM_CPUS];
36
37 /* This is mostly identical to x86's, minus the different send_ipi call. */
38 uint32_t send_kernel_message(uint32_t dst, amr_t pc, long arg0, long arg1,
39                              long arg2, int type)
40 {
41         kernel_message_t *k_msg;
42         assert(pc);
43         // note this will be freed on the destination core
44         k_msg = (kernel_message_t *CT(1))TC(kmem_cache_alloc(kernel_msg_cache, 0));
45         k_msg->srcid = core_id();
46         k_msg->pc = pc;
47         k_msg->arg0 = arg0;
48         k_msg->arg1 = arg1;
49         k_msg->arg2 = arg2;
50         switch (type) {
51                 case KMSG_IMMEDIATE:
52                         spin_lock_irqsave(&per_cpu_info[dst].immed_amsg_lock);
53                         STAILQ_INSERT_TAIL(&per_cpu_info[dst].immed_amsgs, k_msg, link);
54                         spin_unlock_irqsave(&per_cpu_info[dst].immed_amsg_lock);
55                         break;
56                 case KMSG_ROUTINE:
57                         spin_lock_irqsave(&per_cpu_info[dst].routine_amsg_lock);
58                         STAILQ_INSERT_TAIL(&per_cpu_info[dst].routine_amsgs, k_msg, link);
59                         spin_unlock_irqsave(&per_cpu_info[dst].routine_amsg_lock);
60                         break;
61                 default:
62                         panic("Unknown type of kernel message!");
63         }
64         /* if we're sending a routine message locally, we don't want/need an IPI */
65         if ((dst != k_msg->srcid) || (type == KMSG_IMMEDIATE))
66                 send_ipi(dst);
67         return 0;
68 }
69
70 void
71 advance_pc(trapframe_t* state)
72 {
73         state->epc += 4;
74 }
75
76 /* Set stacktop for the current core to be the stack the kernel will start on
77  * when trapping/interrupting from userspace */
78 void set_stack_top(uintptr_t stacktop)
79 {
80         core_stacktops[core_id()] = stacktop;
81 }
82
83 /* Note the assertion assumes we are in the top page of the stack. */
84 uintptr_t get_stack_top(void)
85 {
86         register uintptr_t sp asm ("sp");
87         uintptr_t stacktop = core_stacktops[core_id()];
88         assert(ROUNDUP(sp, PGSIZE) == stacktop);
89         return stacktop;
90 }
91
92 void
93 idt_init(void)
94 {
95 }
96
97 void
98 sysenter_init(void)
99 {
100 }
101
102 /* Helper.  For now, this copies out the TF to pcpui, and sets cur_tf to point
103  * to it. */
104 static void
105 set_current_tf(struct per_cpu_info *pcpui, struct trapframe *tf)
106 {
107         if (irq_is_enabled())
108                 warn("Turn off IRQs until cur_tf is set!");
109         assert(!pcpui->cur_tf);
110         pcpui->actual_tf = *tf;
111         pcpui->cur_tf = &pcpui->actual_tf;
112 }
113
114 static int
115 format_trapframe(trapframe_t *tf, char* buf, int bufsz)
116 {
117         // slightly hackish way to read out the instruction that faulted.
118         // not guaranteed to be right 100% of the time
119         uint32_t insn;
120         if(!(current && !memcpy_from_user(current,&insn,(void*)tf->epc,4)))
121                 insn = -1;
122
123         int len = snprintf(buf,bufsz,"TRAP frame at %p on core %d\n",
124                            tf, core_id());
125         static const char* regnames[] = {
126           "z ", "ra", "v0", "v1", "a0", "a1", "a2", "a3",
127           "a4", "a5", "a6", "a7", "t0", "t1", "t2", "t3",
128           "t4", "t5", "t6", "t7", "s0", "s1", "s2", "s3",
129           "s4", "s5", "s6", "s7", "s8", "fp", "sp", "tp"
130         };
131         
132         tf->gpr[0] = 0;
133         
134         for(int i = 0; i < 32; i+=4)
135         {
136                 for(int j = 0; j < 4; j++)
137                         len += snprintf(buf+len, bufsz-len,
138                                         "%s %016lx%c", regnames[i+j], tf->gpr[i+j], 
139                                         j < 3 ? ' ' : '\n');
140         }
141         len += snprintf(buf+len, bufsz-len,
142                         "sr %016lx pc %016lx va %016lx insn       %08x\n",
143                                         tf->sr, tf->epc, tf->badvaddr, insn);
144
145         buf[bufsz-1] = 0;
146         return len;
147 }
148
149 void
150 print_trapframe(trapframe_t* tf)
151 {
152         char buf[1024];
153         int len = format_trapframe(tf,buf,sizeof(buf));
154         cputbuf(buf,len);
155 }
156
157 /* Helper function.  Returns 0 if the list was empty. */
158 static kernel_message_t *get_next_amsg(struct kernel_msg_list *list_head,
159                                        spinlock_t *list_lock)
160 {
161         kernel_message_t *k_msg;
162         spin_lock_irqsave(list_lock);
163         k_msg = STAILQ_FIRST(list_head);
164         if (k_msg)
165                 STAILQ_REMOVE_HEAD(list_head, link);
166         spin_unlock_irqsave(list_lock);
167         return k_msg;
168 }
169
170 static void exit_halt_loop(trapframe_t* tf)
171 {
172         extern char after_cpu_halt;
173         if ((char*)tf->epc >= (char*)&cpu_halt && (char*)tf->epc < &after_cpu_halt)
174                 tf->epc = tf->gpr[1];
175 }
176
177 /* Mostly the same as x86's implementation.  Keep them in sync.  This assumes
178  * you can send yourself an IPI, and that IPIs can get squashed like on x86. */
179 static void
180 handle_ipi(trapframe_t* tf)
181 {
182
183         if (!in_kernel(tf))
184                 set_current_tf(&per_cpu_info[core_id()], tf);
185         else
186                 exit_halt_loop(tf);
187         
188         clear_ipi();
189
190         per_cpu_info_t *myinfo = &per_cpu_info[core_id()];
191         kernel_message_t msg_cp, *k_msg;
192
193         while (1) { // will break out when there are no more messages
194                 /* Try to get an immediate message.  Exec and free it. */
195                 k_msg = get_next_amsg(&myinfo->immed_amsgs, &myinfo->immed_amsg_lock);
196                 if (k_msg) {
197                         assert(k_msg->pc);
198                         k_msg->pc(tf, k_msg->srcid, k_msg->arg0, k_msg->arg1, k_msg->arg2);
199                         kmem_cache_free(kernel_msg_cache, (void*)k_msg);
200                 } else { // no immediate, might be a routine
201                         if (in_kernel(tf))
202                                 return; // don't execute routine msgs if we were in the kernel
203                         k_msg = get_next_amsg(&myinfo->routine_amsgs,
204                                               &myinfo->routine_amsg_lock);
205                         if (!k_msg) // no routines either
206                                 return;
207                         /* copy in, and then free, in case we don't return */
208                         msg_cp = *k_msg;
209                         kmem_cache_free(kernel_msg_cache, (void*)k_msg);
210                         /* make sure an IPI is pending if we have more work */
211                         /* techincally, we don't need to lock when checking */
212                         if (!STAILQ_EMPTY(&myinfo->routine_amsgs))
213                                 send_ipi(core_id());
214                         /* Execute the kernel message */
215                         assert(msg_cp.pc);
216                         msg_cp.pc(tf, msg_cp.srcid, msg_cp.arg0, msg_cp.arg1, msg_cp.arg2);
217                 }
218         }
219 }
220
221 /* Same as in x86.  Might be diff in the future if there is no way to check for
222  * immediate messages or there is the ability to selectively mask IPI vectors.*/
223 void
224 process_routine_kmsg(struct trapframe *tf)
225 {
226         per_cpu_info_t *myinfo = &per_cpu_info[core_id()];
227         kernel_message_t msg_cp, *k_msg;
228         int8_t irq_state = 0;
229
230         disable_irqsave(&irq_state);
231         /* If we were told what our TF was, use that.  o/w, go with current_tf. */
232         tf = tf ? tf : current_tf;
233         while (1) {
234                 /* normally, we want ints disabled, so we don't have an empty self-ipi
235                  * for every routine message. (imagine a long list of routines).  But we
236                  * do want immediates to run ahead of routines.  This enabling should
237                  * work (might not in some shitty VMs).  Also note we can receive an
238                  * extra self-ipi for routine messages before we turn off irqs again.
239                  * Not a big deal, since we will process it right away. */
240                 if (!STAILQ_EMPTY(&myinfo->immed_amsgs)) {
241                         enable_irq();
242                         cpu_relax();
243                         disable_irq();
244                 }
245                 k_msg = get_next_amsg(&myinfo->routine_amsgs,
246                                       &myinfo->routine_amsg_lock);
247                 if (!k_msg) {
248                         enable_irqsave(&irq_state);
249                         return;
250                 }
251                 /* copy in, and then free, in case we don't return */
252                 msg_cp = *k_msg;
253                 kmem_cache_free(kernel_msg_cache, (void*)k_msg);
254                 /* make sure an IPI is pending if we have more work */
255                 if (!STAILQ_EMPTY(&myinfo->routine_amsgs))
256                         send_ipi(core_id());
257                 /* Execute the kernel message */
258                 assert(msg_cp.pc);
259                 msg_cp.pc(tf, msg_cp.srcid, msg_cp.arg0, msg_cp.arg1, msg_cp.arg2);
260         }
261 }
262
263 /* extremely dangerous and racy: prints out the immed and routine kmsgs for a
264  * specific core (so possibly remotely).  Same as x86. */
265 void print_kmsgs(uint32_t coreid)
266 {
267         struct per_cpu_info *pcpui = &per_cpu_info[coreid];
268         void __print_kmsgs(struct kernel_msg_list *list, char *type)
269         {
270                 char *fn_name;
271                 struct kernel_message *kmsg_i;
272                 STAILQ_FOREACH(kmsg_i, list, link) {
273                         fn_name = get_fn_name((long)kmsg_i->pc);
274                         printk("%s KMSG on %d from %d to run %08p(%s)\n", type,
275                                kmsg_i->dstid, kmsg_i->srcid, kmsg_i->pc, fn_name); 
276                         kfree(fn_name);
277                 }
278         }
279         __print_kmsgs(&pcpui->immed_amsgs, "Immedte");
280         __print_kmsgs(&pcpui->routine_amsgs, "Routine");
281 }
282
283 static void
284 unhandled_trap(trapframe_t* state, const char* name)
285 {
286         static spinlock_t screwup_lock = SPINLOCK_INITIALIZER;
287         spin_lock(&screwup_lock);
288
289         if(in_kernel(state))
290         {
291                 print_trapframe(state);
292                 panic("Unhandled trap in kernel!\nTrap type: %s", name);
293         }
294         else
295         {
296                 char tf_buf[1024];
297                 format_trapframe(state, tf_buf, sizeof(tf_buf));
298
299                 warn("Unhandled trap in user!\nTrap type: %s\n%s", name, tf_buf);
300                 backtrace();
301                 spin_unlock(&screwup_lock);
302
303                 assert(current);
304                 proc_destroy(current);
305         }
306 }
307
308 static void
309 handle_timer_interrupt(trapframe_t* tf)
310 {
311         if (!in_kernel(tf))
312                 set_current_tf(&per_cpu_info[core_id()], tf);
313         else
314                 exit_halt_loop(tf);
315         
316         timer_interrupt(tf, NULL);
317 }
318
319 static void
320 handle_misaligned_fetch(trapframe_t* state)
321 {
322         unhandled_trap(state, "Misaligned Fetch");
323 }
324
325 static void
326 handle_misaligned_load(trapframe_t* state)
327 {
328         unhandled_trap(state, "Misaligned Load");
329 }
330
331 static void
332 handle_misaligned_store(trapframe_t* state)
333 {
334         unhandled_trap(state, "Misaligned Store");
335 }
336
337 static void
338 handle_fault_fetch(trapframe_t* state)
339 {
340         if(in_kernel(state))
341         {
342                 print_trapframe(state);
343                 panic("Instruction Page Fault in the Kernel at %p!", state->epc);
344         }
345
346         set_current_tf(&per_cpu_info[core_id()], state);
347
348         if(handle_page_fault(current, state->epc, PROT_EXEC))
349                 unhandled_trap(state, "Instruction Page Fault");
350 }
351
352 static void
353 handle_fault_load(trapframe_t* state)
354 {
355         if(in_kernel(state))
356         {
357                 print_trapframe(state);
358                 panic("Load Page Fault in the Kernel at %p!", state->badvaddr);
359         }
360
361         set_current_tf(&per_cpu_info[core_id()], state);
362
363         if(handle_page_fault(current, state->badvaddr, PROT_READ))
364                 unhandled_trap(state, "Load Page Fault");
365 }
366
367 static void
368 handle_fault_store(trapframe_t* state)
369 {
370         if(in_kernel(state))
371         {
372                 print_trapframe(state);
373                 panic("Store Page Fault in the Kernel at %p!", state->badvaddr);
374         }
375         
376         set_current_tf(&per_cpu_info[core_id()], state);
377
378         if(handle_page_fault(current, state->badvaddr, PROT_WRITE))
379                 unhandled_trap(state, "Store Page Fault");
380 }
381
382 static void
383 handle_illegal_instruction(trapframe_t* state)
384 {
385         set_current_tf(&per_cpu_info[core_id()], state);
386
387         if (emulate_fpu(state) == 0)
388         {
389                 advance_pc(per_cpu_info[core_id()].cur_tf);
390                 return;
391         }
392
393         unhandled_trap(state, "Illegal Instruction");
394 }
395
396 static void
397 handle_fp_disabled(trapframe_t* tf)
398 {
399         if(in_kernel(tf))
400                 panic("kernel executed an FP instruction!");
401
402         tf->sr |= SR_EF;
403         env_pop_tf(tf); /* We didn't save our TF, so don't use proc_restartcore */
404 }
405
406 static void
407 handle_syscall(trapframe_t* state)
408 {
409         uintptr_t a0 = state->gpr[4];
410         uintptr_t a1 = state->gpr[5];
411
412         advance_pc(state);
413         set_current_tf(&per_cpu_info[core_id()], state);
414         enable_irq();
415         prep_syscalls(current, (struct syscall*)a0, a1);
416 }
417
418 static void
419 handle_breakpoint(trapframe_t* state)
420 {
421         advance_pc(state);
422         monitor(state);
423 }
424
425 void
426 handle_trap(trapframe_t* tf)
427 {
428         static void (*const trap_handlers[])(trapframe_t*) = {
429           [CAUSE_MISALIGNED_FETCH] = handle_misaligned_fetch,
430           [CAUSE_FAULT_FETCH] = handle_fault_fetch,
431           [CAUSE_ILLEGAL_INSTRUCTION] = handle_illegal_instruction,
432           [CAUSE_PRIVILEGED_INSTRUCTION] = handle_illegal_instruction,
433           [CAUSE_FP_DISABLED] = handle_fp_disabled,
434           [CAUSE_SYSCALL] = handle_syscall,
435           [CAUSE_BREAKPOINT] = handle_breakpoint,
436           [CAUSE_MISALIGNED_LOAD] = handle_misaligned_load,
437           [CAUSE_MISALIGNED_STORE] = handle_misaligned_store,
438           [CAUSE_FAULT_LOAD] = handle_fault_load,
439           [CAUSE_FAULT_STORE] = handle_fault_store,
440         };
441
442         static void (*const irq_handlers[])(trapframe_t*) = {
443           [IRQ_TIMER] = handle_timer_interrupt,
444           [IRQ_IPI] = handle_ipi,
445         };
446         
447         if (tf->cause < 0)
448         {
449                 uint8_t irq = tf->cause;
450                 assert(irq < sizeof(irq_handlers)/sizeof(irq_handlers[0]) &&
451                        irq_handlers[irq]);
452                 irq_handlers[irq](tf);
453         }
454         else
455         {
456                 assert(tf->cause < sizeof(trap_handlers)/sizeof(trap_handlers[0]) &&
457                        trap_handlers[tf->cause]);
458                 trap_handlers[tf->cause](tf);
459         }
460         
461         /* Return to the current process, which should be runnable.  If we're the
462          * kernel, we should just return naturally.  Note that current and tf need
463          * to still be okay (might not be after blocking) */
464         if (in_kernel(tf))
465                 env_pop_tf(tf);
466         else
467                 proc_restartcore();
468 }
469
470 /* We don't have NMIs now. */
471 void send_nmi(uint32_t os_coreid)
472 {
473 }