1d9055de56cc4d220a52292a22acd41e98bfd16f
[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 /* Helper.  For now, this copies out the TF to pcpui, and sets cur_ctx to point
57  * to it. */
58 static void set_current_ctx_hw(struct per_cpu_info *pcpui,
59                                struct hw_trapframe *hw_tf)
60 {
61         if (irq_is_enabled())
62                 warn("Turn off IRQs until cur_ctx is set!");
63         assert(!pcpui->cur_ctx);
64         pcpui->actual_ctx.type = ROS_HW_CTX;
65         pcpui->actual_ctx.tf.hw_tf = *hw_tf;
66         pcpui->cur_ctx = &pcpui->actual_ctx;
67 }
68
69 static void set_current_ctx_sw(struct per_cpu_info *pcpui,
70                                struct sw_trapframe *sw_tf)
71 {
72         if (irq_is_enabled())
73                 warn("Turn off IRQs until cur_ctx is set!");
74         assert(!pcpui->cur_ctx);
75         pcpui->actual_ctx.type = ROS_SW_CTX;
76         pcpui->actual_ctx.tf.sw_tf = *sw_tf;
77         pcpui->cur_ctx = &pcpui->actual_ctx;
78 }
79
80 static int
81 format_trapframe(struct hw_trapframe *hw_tf, char* buf, int bufsz)
82 {
83         // slightly hackish way to read out the instruction that faulted.
84         // not guaranteed to be right 100% of the time
85         uint32_t insn;
86         if(!(current && !memcpy_from_user(current,&insn,(void*)hw_tf->epc,4)))
87                 insn = -1;
88
89         int len = snprintf(buf,bufsz,"TRAP frame at %p on core %d\n",
90                            hw_tf, core_id());
91         static const char* regnames[] = {
92           "z ", "ra", "s0", "s1", "s2", "s3", "s4", "s5",
93           "s6", "s7", "s8", "s9", "sA", "sB", "sp", "tp",
94           "v0", "v1", "a0", "a1", "a2", "a3", "a4", "a5",
95           "a6", "a7", "a8", "a9", "aA", "aB", "aC", "aD"
96         };
97         
98         hw_tf->gpr[0] = 0;
99         
100         for(int i = 0; i < 32; i+=4)
101         {
102                 for(int j = 0; j < 4; j++)
103                         len += snprintf(buf+len, bufsz-len,
104                                         "%s %016lx%c", regnames[i+j], hw_tf->gpr[i+j], 
105                                         j < 3 ? ' ' : '\n');
106         }
107         len += snprintf(buf+len, bufsz-len,
108                         "sr %016lx pc %016lx va %016lx insn       %08x\n",
109                                         hw_tf->sr, hw_tf->epc, hw_tf->badvaddr, insn);
110
111         buf[bufsz-1] = 0;
112         return len;
113 }
114
115 void
116 print_trapframe(struct hw_trapframe *hw_tf)
117 {
118         char buf[1024];
119         int len = format_trapframe(hw_tf, buf, sizeof(buf));
120         cputbuf(buf,len);
121 }
122
123 static void exit_halt_loop(struct hw_trapframe *hw_tf)
124 {
125         extern char after_cpu_halt;
126         if ((char*)hw_tf->epc >= (char*)&cpu_halt &&
127             (char*)hw_tf->epc < &after_cpu_halt)
128                 hw_tf->epc = hw_tf->gpr[GPR_RA];
129 }
130
131 static void handle_keypress(char c)
132 {
133         /* brho: not sure if this will work on riscv or not... */
134         #define capchar2ctl(x) ((x) - '@')
135         amr_t handler = c == capchar2ctl('G') ? __run_mon : __cons_add_char;
136         send_kernel_message(core_id(), handler, (long)&cons_buf, (long)c, 0,
137                             KMSG_ROUTINE);
138         cons_init();
139 }
140
141 static void handle_host_interrupt(struct hw_trapframe *hw_tf)
142 {
143         uintptr_t fh = mtpcr(PCR_FROMHOST, 0);
144         switch (fh >> 56)
145         {
146           case 0x00: return;
147           case 0x01: handle_keypress(fh); return;
148           default: assert(0);
149         }
150 }
151
152 static void handle_timer_interrupt(struct hw_trapframe *hw_tf)
153 {
154         timer_interrupt(hw_tf, NULL);
155 }
156
157 /* Assumes that any IPI you get is really a kernel message */
158 static void handle_interprocessor_interrupt(struct hw_trapframe *hw_tf)
159 {
160         clear_ipi();
161         handle_kmsg_ipi(hw_tf, 0);
162 }
163
164 static void
165 unhandled_trap(struct hw_trapframe *state, const char* name)
166 {
167         static spinlock_t screwup_lock = SPINLOCK_INITIALIZER;
168         spin_lock(&screwup_lock);
169
170         if(in_kernel(state))
171         {
172                 print_trapframe(state);
173                 panic("Unhandled trap in kernel!\nTrap type: %s", name);
174         }
175         else
176         {
177                 char tf_buf[1024];
178                 format_trapframe(state, tf_buf, sizeof(tf_buf));
179
180                 warn("Unhandled trap in user!\nTrap type: %s\n%s", name, tf_buf);
181                 backtrace();
182                 spin_unlock(&screwup_lock);
183
184                 assert(current);
185                 enable_irq();
186                 proc_destroy(current);
187         }
188 }
189
190 static void
191 handle_misaligned_fetch(struct hw_trapframe *state)
192 {
193         unhandled_trap(state, "Misaligned Fetch");
194 }
195
196 static void
197 handle_misaligned_load(struct hw_trapframe *state)
198 {
199         unhandled_trap(state, "Misaligned Load");
200 }
201
202 static void
203 handle_misaligned_store(struct hw_trapframe *state)
204 {
205         unhandled_trap(state, "Misaligned Store");
206 }
207
208 static void
209 handle_fault_fetch(struct hw_trapframe *state)
210 {
211         if(in_kernel(state))
212         {
213                 print_trapframe(state);
214                 panic("Instruction Page Fault in the Kernel at %p!", state->epc);
215         }
216
217         set_current_ctx_hw(&per_cpu_info[core_id()], state);
218
219 #warning "returns EAGAIN if you should reflect the fault"
220         if(handle_page_fault(current, state->epc, PROT_EXEC))
221                 unhandled_trap(state, "Instruction Page Fault");
222 }
223
224 static void
225 handle_fault_load(struct hw_trapframe *state)
226 {
227         if(in_kernel(state))
228         {
229                 print_trapframe(state);
230                 panic("Load Page Fault in the Kernel at %p!", state->badvaddr);
231         }
232
233         set_current_ctx_hw(&per_cpu_info[core_id()], state);
234
235 #warning "returns EAGAIN if you should reflect the fault"
236         if(handle_page_fault(current, state->badvaddr, PROT_READ))
237                 unhandled_trap(state, "Load Page Fault");
238 }
239
240 static void
241 handle_fault_store(struct hw_trapframe *state)
242 {
243         if(in_kernel(state))
244         {
245                 print_trapframe(state);
246                 panic("Store Page Fault in the Kernel at %p!", state->badvaddr);
247         }
248
249         set_current_ctx_hw(&per_cpu_info[core_id()], state);
250
251         if(handle_page_fault(current, state->badvaddr, PROT_WRITE))
252                 unhandled_trap(state, "Store Page Fault");
253 }
254
255 static void
256 handle_illegal_instruction(struct hw_trapframe *state)
257 {
258         assert(!in_kernel(state));
259
260         struct per_cpu_info *pcpui = &per_cpu_info[core_id()];
261         set_current_ctx_hw(pcpui, state);
262         if (emulate_fpu(state) == 0)
263         {
264                 advance_pc(&pcpui->cur_ctx->tf.hw_tf);
265                 return;
266         }
267
268         unhandled_trap(state, "Illegal Instruction");
269 }
270
271 static void
272 handle_syscall(struct hw_trapframe *state)
273 {
274         uintptr_t a0 = state->gpr[GPR_A0];
275         uintptr_t a1 = state->gpr[GPR_A1];
276
277         advance_pc(state);
278         set_current_ctx_hw(&per_cpu_info[core_id()], state);
279         enable_irq();
280         prep_syscalls(current, (struct syscall*)a0, a1);
281 }
282
283 static void
284 handle_breakpoint(struct hw_trapframe *state)
285 {
286         advance_pc(state);
287         monitor(state);
288 }
289
290 void
291 handle_trap(struct hw_trapframe *hw_tf)
292 {
293         static void (*const trap_handlers[])(struct hw_trapframe *) = {
294           [CAUSE_MISALIGNED_FETCH] = handle_misaligned_fetch,
295           [CAUSE_FAULT_FETCH] = handle_fault_fetch,
296           [CAUSE_ILLEGAL_INSTRUCTION] = handle_illegal_instruction,
297           [CAUSE_PRIVILEGED_INSTRUCTION] = handle_illegal_instruction,
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_ctx_hw(&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                 #warning "if a trap wasn't handled fully, like an MCP pf, reflect it
340                 reflect_unhandled_trap(hw_tf->tf_trapno, hw_tf->tf_err, aux);
341         }
342         
343         extern void pop_hw_tf(struct hw_trapframe *tf); /* in asm */
344         /* Return to the current process, which should be runnable.  If we're the
345          * kernel, we should just return naturally.  Note that current and tf need
346          * to still be okay (might not be after blocking) */
347         if (in_kernel(hw_tf))
348                 pop_hw_tf(hw_tf);
349         else
350                 proc_restartcore();
351 }
352
353 /* We don't have NMIs now. */
354 void send_nmi(uint32_t os_coreid)
355 {
356         printk("%s not implemented\n", __FUNCTION);
357 }
358
359 int register_irq(int irq, isr_t handler, void *irq_arg, uint32_t tbdf)
360 {
361         printk("%s not implemented\n", __FUNCTION);
362         return -1;
363 }
364
365 int route_irqs(int cpu_vec, int coreid)
366 {
367         printk("%s not implemented\n", __FUNCTION);
368         return -1;
369 }
370
371 void __arch_reflect_trap_hwtf(struct hw_trapframe *hw_tf, unsigned int trap_nr,
372                               unsigned int err, unsigned long aux)
373 {
374         printk("%s not implemented\n", __FUNCTION);
375 }