Changes hardware trapframe calls to use new struct
[akaros.git] / kern / arch / riscv / trap.c
1 #include <arch/arch.h>
2 #include <assert.h>
3 #include <trap.h>
4 #include <arch/console.h>
5 #include <console.h>
6 #include <string.h>
7 #include <process.h>
8 #include <syscall.h>
9 #include <monitor.h>
10 #include <manager.h>
11 #include <stdio.h>
12 #include <smp.h>
13 #include <slab.h>
14 #include <mm.h>
15 #include <umem.h>
16 #include <pmap.h>
17
18 /* These are the stacks the kernel will load when it receives a trap from user
19  * space.  The deal is that they get set right away in entry.S, and can always
20  * be used for finding the top of the stack (from which you should subtract the
21  * sizeof the trapframe.  Note, we need to have a junk value in the array so
22  * that this is NOT part of the BSS.  If it is in the BSS, it will get 0'd in
23  * kernel_init(), which is after these values get set.
24  *
25  * TODO: if these end up becoming contended cache lines, move this to
26  * per_cpu_info. */
27 uintptr_t core_stacktops[MAX_NUM_CPUS] = {0xcafebabe, 0};
28
29 void
30 advance_pc(struct hw_trapframe *state)
31 {
32         state->epc += 4;
33 }
34
35 /* Set stacktop for the current core to be the stack the kernel will start on
36  * when trapping/interrupting from userspace */
37 void set_stack_top(uintptr_t stacktop)
38 {
39         core_stacktops[core_id()] = stacktop;
40 }
41
42 /* Note the assertion assumes we are in the top page of the stack. */
43 uintptr_t get_stack_top(void)
44 {
45         register uintptr_t sp asm ("sp");
46         uintptr_t stacktop = core_stacktops[core_id()];
47         assert(ROUNDUP(sp, PGSIZE) == stacktop);
48         return stacktop;
49 }
50
51 void
52 idt_init(void)
53 {
54 }
55
56 void
57 sysenter_init(void)
58 {
59 }
60
61 /* Helper.  For now, this copies out the TF to pcpui, and sets cur_tf to point
62  * to it. */
63 static void
64 set_current_tf(struct per_cpu_info *pcpui, struct trapframe *tf)
65 {
66         if (irq_is_enabled())
67                 warn("Turn off IRQs until cur_tf is set!");
68         assert(!pcpui->cur_tf);
69         pcpui->actual_tf = *tf;
70         pcpui->cur_tf = &pcpui->actual_tf;
71 }
72
73 static int
74 format_trapframe(struct hw_trapframe *hw_tf, char* buf, int bufsz)
75 {
76         // slightly hackish way to read out the instruction that faulted.
77         // not guaranteed to be right 100% of the time
78         uint32_t insn;
79         if(!(current && !memcpy_from_user(current,&insn,(void*)hw_tf->epc,4)))
80                 insn = -1;
81
82         int len = snprintf(buf,bufsz,"TRAP frame at %p on core %d\n",
83                            hw_tf, core_id());
84         static const char* regnames[] = {
85           "z ", "ra", "v0", "v1", "a0", "a1", "a2", "a3",
86           "a4", "a5", "a6", "a7", "t0", "t1", "t2", "t3",
87           "t4", "t5", "t6", "t7", "s0", "s1", "s2", "s3",
88           "s4", "s5", "s6", "s7", "s8", "fp", "sp", "tp"
89         };
90         
91         hw_tf->gpr[0] = 0;
92         
93         for(int i = 0; i < 32; i+=4)
94         {
95                 for(int j = 0; j < 4; j++)
96                         len += snprintf(buf+len, bufsz-len,
97                                         "%s %016lx%c", regnames[i+j], hw_tf->gpr[i+j], 
98                                         j < 3 ? ' ' : '\n');
99         }
100         len += snprintf(buf+len, bufsz-len,
101                         "sr %016lx pc %016lx va %016lx insn       %08x\n",
102                                         hw_tf->sr, hw_tf->epc, hw_tf->badvaddr, insn);
103
104         buf[bufsz-1] = 0;
105         return len;
106 }
107
108 void
109 print_trapframe(struct hw_trapframe *hw_tf)
110 {
111         char buf[1024];
112         int len = format_trapframe(hw_tf, buf, sizeof(buf));
113         cputbuf(buf,len);
114 }
115
116 static void exit_halt_loop(struct hw_trapframe *hw_tf)
117 {
118         extern char after_cpu_halt;
119         if ((char*)hw_tf->epc >= (char*)&cpu_halt &&
120             (char*)hw_tf->epc < &after_cpu_halt)
121                 hw_tf->epc = hw_tf->gpr[1];
122 }
123
124 static void handle_keypress(char c)
125 {
126         amr_t handler = c == 'G' ? __run_mon : __cons_add_char;
127         send_kernel_message(core_id(), handler, (long)&cons_buf, (long)c, 0,
128                             KMSG_ROUTINE);
129         cons_init();
130 }
131
132 static void handle_host_interrupt(struct hw_trapframe *hw_tf)
133 {
134         uintptr_t fh = mtpcr(PCR_FROMHOST, 0);
135         switch (fh >> 56)
136         {
137           case 0x00: return;
138           case 0x01: handle_keypress(fh); return;
139           default: assert(0);
140         }
141 }
142
143 static void handle_timer_interrupt(struct hw_trapframe *hw_tf)
144 {
145         timer_interrupt(hw_tf, NULL);
146 }
147
148 /* Assumes that any IPI you get is really a kernel message */
149 static void handle_interprocessor_interrupt(struct hw_trapframe *hw_tf)
150 {
151         clear_ipi();
152         handle_kmsg_ipi(hw_tf, 0);
153 }
154
155 static void
156 unhandled_trap(struct hw_trapframe *state, const char* name)
157 {
158         static spinlock_t screwup_lock = SPINLOCK_INITIALIZER;
159         spin_lock(&screwup_lock);
160
161         if(in_kernel(state))
162         {
163                 print_trapframe(state);
164                 panic("Unhandled trap in kernel!\nTrap type: %s", name);
165         }
166         else
167         {
168                 char tf_buf[1024];
169                 format_trapframe(state, tf_buf, sizeof(tf_buf));
170
171                 warn("Unhandled trap in user!\nTrap type: %s\n%s", name, tf_buf);
172                 backtrace();
173                 spin_unlock(&screwup_lock);
174
175                 assert(current);
176                 enable_irq();
177                 proc_destroy(current);
178         }
179 }
180
181 static void
182 handle_misaligned_fetch(struct hw_trapframe *state)
183 {
184         unhandled_trap(state, "Misaligned Fetch");
185 }
186
187 static void
188 handle_misaligned_load(struct hw_trapframe *state)
189 {
190         unhandled_trap(state, "Misaligned Load");
191 }
192
193 static void
194 handle_misaligned_store(struct hw_trapframe *state)
195 {
196         unhandled_trap(state, "Misaligned Store");
197 }
198
199 static void
200 handle_fault_fetch(struct hw_trapframe *state)
201 {
202         if(in_kernel(state))
203         {
204                 print_trapframe(state);
205                 panic("Instruction Page Fault in the Kernel at %p!", state->epc);
206         }
207
208         set_current_tf(&per_cpu_info[core_id()], state);
209
210         if(handle_page_fault(current, state->epc, PROT_EXEC))
211                 unhandled_trap(state, "Instruction Page Fault");
212 }
213
214 static void
215 handle_fault_load(struct hw_trapframe *state)
216 {
217         if(in_kernel(state))
218         {
219                 print_trapframe(state);
220                 panic("Load Page Fault in the Kernel at %p!", state->badvaddr);
221         }
222
223         set_current_tf(&per_cpu_info[core_id()], state);
224
225         if(handle_page_fault(current, state->badvaddr, PROT_READ))
226                 unhandled_trap(state, "Load Page Fault");
227 }
228
229 static void
230 handle_fault_store(struct hw_trapframe *state)
231 {
232         if(in_kernel(state))
233         {
234                 print_trapframe(state);
235                 panic("Store Page Fault in the Kernel at %p!", state->badvaddr);
236         }
237
238         set_current_tf(&per_cpu_info[core_id()], state);
239
240         if(handle_page_fault(current, state->badvaddr, PROT_WRITE))
241                 unhandled_trap(state, "Store Page Fault");
242 }
243
244 static void
245 handle_illegal_instruction(struct hw_trapframe *state)
246 {
247         assert(!in_kernel(state));
248
249         struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
250         set_current_tf(pcpui, state);
251         if (emulate_fpu(state) == 0)
252         {
253                 advance_pc(pcpui->cur_tf);
254                 return;
255         }
256
257         unhandled_trap(state, "Illegal Instruction");
258 }
259
260 static void
261 handle_fp_disabled(struct hw_trapframe *hw_tf)
262 {
263         if (in_kernel(hw_tf))
264                 panic("kernel executed an FP instruction!");
265
266         hw_tf->sr |= SR_EF;
267         env_pop_tf(hw_tf); /* We didn't save our TF, so don't proc_restartcore */
268 }
269
270 static void
271 handle_syscall(struct hw_trapframe *state)
272 {
273         uintptr_t a0 = state->gpr[4];
274         uintptr_t a1 = state->gpr[5];
275
276         advance_pc(state);
277         set_current_tf(&per_cpu_info[core_id()], state);
278         enable_irq();
279         prep_syscalls(current, (struct syscall*)a0, a1);
280 }
281
282 static void
283 handle_breakpoint(struct hw_trapframe *state)
284 {
285         advance_pc(state);
286         monitor(state);
287 }
288
289 void
290 handle_trap(struct hw_trapframe *hw_tf)
291 {
292         static void (*const trap_handlers[])(struct hw_trapframe *) = {
293           [CAUSE_MISALIGNED_FETCH] = handle_misaligned_fetch,
294           [CAUSE_FAULT_FETCH] = handle_fault_fetch,
295           [CAUSE_ILLEGAL_INSTRUCTION] = handle_illegal_instruction,
296           [CAUSE_PRIVILEGED_INSTRUCTION] = handle_illegal_instruction,
297           [CAUSE_FP_DISABLED] = handle_fp_disabled,
298           [CAUSE_SYSCALL] = handle_syscall,
299           [CAUSE_BREAKPOINT] = handle_breakpoint,
300           [CAUSE_MISALIGNED_LOAD] = handle_misaligned_load,
301           [CAUSE_MISALIGNED_STORE] = handle_misaligned_store,
302           [CAUSE_FAULT_LOAD] = handle_fault_load,
303           [CAUSE_FAULT_STORE] = handle_fault_store,
304         };
305
306         static void (*const irq_handlers[])(struct hw_trapframe *) = {
307           [IRQ_TIMER] = handle_timer_interrupt,
308           [IRQ_HOST] = handle_host_interrupt,
309           [IRQ_IPI] = handle_interprocessor_interrupt,
310         };
311         
312         struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
313         if (hw_tf->cause < 0)
314         {
315                 uint8_t irq = hw_tf->cause;
316                 assert(irq < sizeof(irq_handlers)/sizeof(irq_handlers[0]) &&
317                        irq_handlers[irq]);
318
319                 if (in_kernel(hw_tf))
320                         exit_halt_loop(hw_tf);
321                 else
322                         set_current_tf(&per_cpu_info[core_id()], hw_tf);
323
324                 inc_irq_depth(pcpui);
325                 irq_handlers[irq](hw_tf);
326                 dec_irq_depth(pcpui);
327         }
328         else
329         {
330                 assert(hw_tf->cause < sizeof(trap_handlers)/sizeof(trap_handlers[0]) &&
331                        trap_handlers[hw_tf->cause]);
332                 if (in_kernel(hw_tf)) {
333                         inc_ktrap_depth(pcpui);
334                         trap_handlers[hw_tf->cause](hw_tf);
335                         dec_ktrap_depth(pcpui);
336                 } else {
337                         trap_handlers[hw_tf->cause](hw_tf);
338                 }
339         }
340         
341         /* Return to the current process, which should be runnable.  If we're the
342          * kernel, we should just return naturally.  Note that current and tf need
343          * to still be okay (might not be after blocking) */
344         if (in_kernel(hw_tf))
345                 env_pop_tf(hw_tf);      /* TODO: for a kernel tf?  change names? */
346         else
347                 proc_restartcore();
348 }
349
350 /* We don't have NMIs now. */
351 void send_nmi(uint32_t os_coreid)
352 {
353 }