1 /* This file contains a simple exception handler. Exceptions in user
2 * processes are converted to signals. Exceptions in a kernel task cause
3 * a panic.
4 */
5
6 #include "kernel/kernel.h"
7 #include "arch_proto.h"
8 #include <signal.h>
9 #include <string.h>
10 #include <assert.h>
11 #include <machine/vm.h>
12
13 struct ex_s {
14 char *msg;
15 int signum;
16 int minprocessor;
17 };
18
19 static struct ex_s ex_data[] = {
20 { "Divide error", SIGFPE, 86 },
21 { "Debug exception", SIGTRAP, 86 },
22 { "Nonmaskable interrupt", SIGBUS, 86 },
23 { "Breakpoint", SIGEMT, 86 },
24 { "Overflow", SIGFPE, 86 },
25 { "Bounds check", SIGFPE, 186 },
26 { "Invalid opcode", SIGILL, 186 },
27 { "Coprocessor not available", SIGFPE, 186 },
28 { "Double fault", SIGBUS, 286 },
29 { "Coprocessor segment overrun", SIGSEGV, 286 },
30 { "Invalid TSS", SIGSEGV, 286 },
31 { "Segment not present", SIGSEGV, 286 },
32 { "Stack exception", SIGSEGV, 286 }, /* STACK_FAULT already used */
33 { "General protection", SIGSEGV, 286 },
34 { "Page fault", SIGSEGV, 386 }, /* not close */
35 { NULL, SIGILL, 0 }, /* probably software trap */
36 { "Coprocessor error", SIGFPE, 386 },
37 { "Alignment check", SIGBUS, 386 },
38 { "Machine check", SIGBUS, 386 },
39 { "SIMD exception", SIGFPE, 386 },
40 };
41
42 static void inkernel_disaster(struct proc *saved_proc,
43 struct exception_frame *frame, struct ex_s *ep, int is_nested);
44
45 extern int catch_pagefaults;
46
47 static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc);
48
pagefault(struct proc * pr,struct exception_frame * frame,int is_nested)49 static void pagefault( struct proc *pr,
50 struct exception_frame * frame,
51 int is_nested)
52 {
53 int in_physcopy = 0, in_memset = 0;
54
55 reg_t pagefaultcr2;
56 message m_pagefault;
57 int err;
58
59 pagefaultcr2 = read_cr2();
60
61 #if 0
62 printf("kernel: pagefault in pr %d, addr 0x%lx, his cr3 0x%lx, actual cr3 0x%lx\n",
63 pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
64 #endif
65
66 in_physcopy = (frame->eip > (vir_bytes) phys_copy) &&
67 (frame->eip < (vir_bytes) phys_copy_fault);
68
69 in_memset = (frame->eip > (vir_bytes) phys_memset) &&
70 (frame->eip < (vir_bytes) memset_fault);
71
72 if((is_nested || iskernelp(pr)) &&
73 catch_pagefaults && (in_physcopy || in_memset)) {
74 #if 0
75 printf("pf caught! addr 0x%lx\n", pagefaultcr2);
76 #endif
77 if (is_nested) {
78 if(in_physcopy) {
79 assert(!in_memset);
80 frame->eip = (reg_t) phys_copy_fault_in_kernel;
81 } else {
82 frame->eip = (reg_t) memset_fault_in_kernel;
83 }
84 }
85 else {
86 pr->p_reg.pc = (reg_t) phys_copy_fault;
87 pr->p_reg.retreg = pagefaultcr2;
88 }
89
90 return;
91 }
92
93 if(is_nested) {
94 printf("pagefault in kernel at pc 0x%lx address 0x%lx\n",
95 frame->eip, pagefaultcr2);
96 inkernel_disaster(pr, frame, NULL, is_nested);
97 }
98
99 /* VM can't handle page faults. */
100 if(pr->p_endpoint == VM_PROC_NR) {
101 /* Page fault we can't / don't want to
102 * handle.
103 */
104 printf("pagefault for VM on CPU %d, "
105 "pc = 0x%x, addr = 0x%x, flags = 0x%x, is_nested %d\n",
106 cpuid, pr->p_reg.pc, pagefaultcr2, frame->errcode,
107 is_nested);
108 proc_stacktrace(pr);
109 printf("pc of pagefault: 0x%lx\n", frame->eip);
110 panic("pagefault in VM");
111
112 return;
113 }
114
115 /* Don't schedule this process until pagefault is handled. */
116 RTS_SET(pr, RTS_PAGEFAULT);
117
118 /* tell Vm about the pagefault */
119 m_pagefault.m_source = pr->p_endpoint;
120 m_pagefault.m_type = VM_PAGEFAULT;
121 m_pagefault.VPF_ADDR = pagefaultcr2;
122 m_pagefault.VPF_FLAGS = frame->errcode;
123
124 if ((err = mini_send(pr, VM_PROC_NR,
125 &m_pagefault, FROM_KERNEL))) {
126 panic("WARNING: pagefault: mini_send returned %d\n", err);
127 }
128
129 return;
130 }
131
inkernel_disaster(struct proc * saved_proc,struct exception_frame * frame,struct ex_s * ep,int is_nested)132 static void inkernel_disaster(struct proc *saved_proc,
133 struct exception_frame * frame, struct ex_s *ep,
134 int is_nested)
135 {
136 #if USE_SYSDEBUG
137 if(ep) {
138 if (ep->msg == NULL)
139 printf("\nIntel-reserved exception %d\n", frame->vector);
140 else
141 printf("\n%s\n", ep->msg);
142 }
143
144 printf("cpu %d is_nested = %d ", cpuid, is_nested);
145
146 printf("vec_nr= %d, trap_errno= 0x%x, eip= 0x%x, "
147 "cs= 0x%x, eflags= 0x%x trap_esp 0x%08x\n",
148 frame->vector, frame->errcode, frame->eip,
149 frame->cs, frame->eflags, frame);
150 printf("KERNEL registers :\n");
151 #define REG(n) (((u32_t *)frame)[-n])
152 printf(
153 "\t%%eax 0x%08x %%ebx 0x%08x %%ecx 0x%08x %%edx 0x%08x\n"
154 "\t%%esp 0x%08x %%ebp 0x%08x %%esi 0x%08x %%edi 0x%08x\n",
155 REG(1), REG(2), REG(3), REG(4),
156 REG(5), REG(6), REG(7), REG(8));
157
158 {
159 reg_t k_ebp = REG(6);
160 printf("KERNEL stacktrace, starting with ebp = 0x%lx:\n", k_ebp);
161 proc_stacktrace_execute(proc_addr(SYSTEM), k_ebp, frame->eip);
162 }
163
164 if (saved_proc) {
165 printf("scheduled was: process %d (%s), ", saved_proc->p_endpoint, saved_proc->p_name);
166 printf("pc = 0x%x\n", (unsigned) saved_proc->p_reg.pc);
167 proc_stacktrace(saved_proc);
168
169 panic("Unhandled kernel exception");
170 }
171
172 /* in an early stage of boot process we don't have processes yet */
173 panic("exception in kernel while booting, no saved_proc yet");
174 #endif /* USE_SYSDEBUG */
175 }
176
177 /*===========================================================================*
178 * exception *
179 *===========================================================================*/
exception_handler(int is_nested,struct exception_frame * frame)180 void exception_handler(int is_nested, struct exception_frame * frame)
181 {
182 /* An exception or unexpected interrupt has occurred. */
183 register struct ex_s *ep;
184 struct proc *saved_proc;
185
186 /* Save proc_ptr, because it may be changed by debug statements. */
187 saved_proc = get_cpulocal_var(proc_ptr);
188
189 ep = &ex_data[frame->vector];
190
191 if (frame->vector == 2) { /* spurious NMI on some machines */
192 printf("got spurious NMI\n");
193 return;
194 }
195
196 /*
197 * handle special cases for nested problems as they might be tricky or filter
198 * them out quickly if the traps are not nested
199 */
200 if (is_nested) {
201 /*
202 * if a problem occured while copying a message from userspace because
203 * of a wrong pointer supplied by userland, handle it the only way we
204 * can handle it ...
205 */
206 if (((void*)frame->eip >= (void*)copy_msg_to_user &&
207 (void*)frame->eip <= (void*)__copy_msg_to_user_end) ||
208 ((void*)frame->eip >= (void*)copy_msg_from_user &&
209 (void*)frame->eip <= (void*)__copy_msg_from_user_end)) {
210 switch(frame->vector) {
211 /* these error are expected */
212 case PAGE_FAULT_VECTOR:
213 case PROTECTION_VECTOR:
214 frame->eip = (reg_t) __user_copy_msg_pointer_failure;
215 return;
216 default:
217 panic("Copy involving a user pointer failed unexpectedly!");
218 }
219 }
220
221 /* Pass any error resulting from restoring FPU state, as a FPU
222 * exception to the process.
223 */
224 if (((void*)frame->eip >= (void*)fxrstor &&
225 (void *)frame->eip <= (void*)__fxrstor_end) ||
226 ((void*)frame->eip >= (void*)frstor &&
227 (void *)frame->eip <= (void*)__frstor_end)) {
228 frame->eip = (reg_t) __frstor_failure;
229 return;
230 }
231
232 if(frame->vector == DEBUG_VECTOR
233 && (saved_proc->p_reg.psw & TRACEBIT)
234 && (saved_proc->p_seg.p_kern_trap_style == KTS_NONE)) {
235 /* Getting a debug trap in the kernel is legitimate
236 * if a traced process entered the kernel using sysenter
237 * or syscall; the trap flag is not cleared then.
238 *
239 * It triggers on the first kernel entry so the trap
240 * style is still KTS_NONE.
241 */
242
243 frame->eflags &= ~TRACEBIT;
244
245 return;
246
247 /* If control passes, this case is not recognized as legitimate
248 * and we panic later on after all.
249 */
250 }
251 }
252
253 if(frame->vector == PAGE_FAULT_VECTOR) {
254 pagefault(saved_proc, frame, is_nested);
255 return;
256 }
257
258 /* If an exception occurs while running a process, the is_nested variable
259 * will be zero. Exceptions in interrupt handlers or system traps will make
260 * is_nested non-zero.
261 */
262 if (is_nested == 0 && ! iskernelp(saved_proc)) {
263 #if 0
264 {
265
266 printf(
267 "vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
268 frame->vector, (unsigned long)frame->errcode,
269 (unsigned long)frame->eip, frame->cs,
270 (unsigned long)frame->eflags);
271 proc_stacktrace(saved_proc);
272 }
273
274 #endif
275 cause_sig(proc_nr(saved_proc), ep->signum);
276 return;
277 }
278
279 /* Exception in system code. This is not supposed to happen. */
280 inkernel_disaster(saved_proc, frame, ep, is_nested);
281
282 panic("return from inkernel_disaster");
283 }
284
285 #if USE_SYSDEBUG
286 /*===========================================================================*
287 * proc_stacktrace_execute *
288 *===========================================================================*/
proc_stacktrace_execute(struct proc * whichproc,reg_t v_bp,reg_t pc)289 static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc)
290 {
291 reg_t v_hbp;
292 int iskernel;
293 int n = 0;
294
295 iskernel = iskernelp(whichproc);
296
297 printf("%-8.8s %6d 0x%lx ",
298 whichproc->p_name, whichproc->p_endpoint, pc);
299
300 while(v_bp) {
301 reg_t v_pc;
302
303 #define PRCOPY(pr, pv, v, n) \
304 (iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
305 data_copy(pr->p_endpoint, pv, KERNEL, (vir_bytes) (v), n))
306
307 if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
308 printf("(v_bp 0x%lx ?)", v_bp);
309 break;
310 }
311 if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
312 printf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
313 break;
314 }
315 printf("0x%lx ", (unsigned long) v_pc);
316 if(v_hbp != 0 && v_hbp <= v_bp) {
317 printf("(hbp 0x%lx ?)", v_hbp);
318 break;
319 }
320 v_bp = v_hbp;
321 if(n++ > 50) {
322 printf("(truncated after %d steps) ", n);
323 break;
324 }
325 }
326 printf("\n");
327 }
328 #endif /* USE_SYSDEBUG */
329
330 /*===========================================================================*
331 * proc_stacktrace *
332 *===========================================================================*/
proc_stacktrace(struct proc * whichproc)333 void proc_stacktrace(struct proc *whichproc)
334 {
335 u32_t use_bp;
336
337 if(whichproc->p_seg.p_kern_trap_style == KTS_NONE) {
338 printf("WARNING: stacktrace of running process\n");
339 }
340
341 switch(whichproc->p_seg.p_kern_trap_style) {
342 case KTS_SYSENTER:
343 case KTS_SYSCALL:
344 {
345 u32_t sp = whichproc->p_reg.sp;
346
347 /* Full context is not available in the p_reg
348 * struct. Obtain it from the user's stack.
349 * The use stack pointer is always available.
350 * The fact that it's there, and the 16 byte offset,
351 * is a dependency on the trap code in
352 * kernel/arch/i386/usermapped_glo_ipc.S.
353 */
354
355 if(data_copy(whichproc->p_endpoint, sp+16,
356 KERNEL, (vir_bytes) &use_bp,
357 sizeof(use_bp)) != OK) {
358 printf("stacktrace: aborting, copy failed\n");
359 return;
360 }
361
362 break;
363 }
364 default:
365 /* Full context is available; use the stored ebp */
366 use_bp = whichproc->p_reg.fp;
367 break;
368 }
369
370 #if USE_SYSDEBUG
371 proc_stacktrace_execute(whichproc, use_bp, whichproc->p_reg.pc);
372 #endif /* USE_SYSDEBUG */
373 }
374
enable_fpu_exception(void)375 void enable_fpu_exception(void)
376 {
377 u32_t cr0 = read_cr0();
378 if(!(cr0 & I386_CR0_TS))
379 write_cr0(cr0 | I386_CR0_TS);
380 }
381
disable_fpu_exception(void)382 void disable_fpu_exception(void)
383 {
384 clts();
385 }
386
387