kernel/arch/i386/exception.c

   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
  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
 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  *===========================================================================*/
 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
 233   if(frame->vector == PAGE_FAULT_VECTOR) {
 234         pagefault(saved_proc, frame, is_nested);
 235         return;
 236   }
 237
 238   /* If an exception occurs while running a process, the is_nested variable
 239    * will be zero. Exceptions in interrupt handlers or system traps will make
 240    * is_nested non-zero.
 241    */
 242   if (is_nested == 0 && ! iskernelp(saved_proc)) {
 243 #if 0
 244         {
 245
 246                 printf(
 247   "vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
 248                         frame->vector, (unsigned long)frame->errcode,
 249                         (unsigned long)frame->eip, frame->cs,
 250                         (unsigned long)frame->eflags);
 251                 proc_stacktrace(saved_proc);
 252         }
 253
 254 #endif
 255         cause_sig(proc_nr(saved_proc), ep->signum);
 256         return;
 257   }
 258
 259   /* Exception in system code. This is not supposed to happen. */
 260   inkernel_disaster(saved_proc, frame, ep, is_nested);
 261
 262   panic("return from inkernel_disaster");
 263 }
 264
 265 #if USE_SYSDEBUG
 266 /*===========================================================================*
 267  *                              proc_stacktrace_execute                      *
 268  *===========================================================================*/
 269 static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc)
 270 {
 271         reg_t v_hbp;
 272         int iskernel;
 273         int n = 0;
 274
 275         iskernel = iskernelp(whichproc);
 276
 277         printf("%-8.8s %6d 0x%lx ",
 278                 whichproc->p_name, whichproc->p_endpoint, pc);
 279
 280         while(v_bp) {
 281                 reg_t v_pc;
 282
 283 #define PRCOPY(pr, pv, v, n) \
 284   (iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
 285      data_copy(pr->p_endpoint, pv, KERNEL, (vir_bytes) (v), n))
 286
 287                 if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
 288                         printf("(v_bp 0x%lx ?)", v_bp);
 289                         break;
 290                 }
 291                 if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
 292                         printf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
 293                         break;
 294                 }
 295                 printf("0x%lx ", (unsigned long) v_pc);
 296                 if(v_hbp != 0 && v_hbp <= v_bp) {
 297                         printf("(hbp %lx ?)", v_hbp);
 298                         break;
 299                 }
 300                 v_bp = v_hbp;
 301                 if(n++ > 50) {
 302                         printf("(truncated after %d steps) ", n);
 303                         break;
 304                 }
 305         }
 306         printf("\n");
 307 }
 308 #endif /* USE_SYSDEBUG */
 309
 310 /*===========================================================================*
 311  *                              proc_stacktrace                      *
 312  *===========================================================================*/
 313 void proc_stacktrace(struct proc *whichproc)
 314 {
 315 #if USE_SYSDEBUG
 316         proc_stacktrace_execute(whichproc, whichproc->p_reg.fp, whichproc->p_reg.pc);
 317 #endif /* USE_SYSDEBUG */
 318 }
 319
 320 void enable_fpu_exception(void)
 321 {
 322         u32_t cr0 = read_cr0();
 323         if(!(cr0 & I386_CR0_TS))
 324                 write_cr0(cr0 | I386_CR0_TS);
 325 }
 326
 327 void disable_fpu_exception(void)
 328 {
 329         clts();
 330 }
 331