libkern/gen/OSDebug.cpp

   1 /*
   2  * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22
  23 // NOTE:  This file is only c++ so I can get static initialisers going
  24 #include <libkern/OSDebug.h>
  25
  26 #include <sys/cdefs.h>
  27
  28 #include <stdarg.h>
  29 #include <mach/mach_types.h>
  30 #include <mach/kmod.h>
  31 #include <kern/lock.h>
  32
  33 #include <libkern/libkern.h>    // From bsd's libkern directory
  34 #include <mach/vm_param.h>
  35
  36 __BEGIN_DECLS
  37 // From osmfk/kern/thread.h but considered to be private
  38 extern vm_offset_t min_valid_stack_address(void);
  39 extern vm_offset_t max_valid_stack_address(void);
  40
  41 // From osfmk/kmod.c
  42 extern void kmod_dump_log(vm_offset_t *addr, unsigned int cnt);
  43
  44 extern addr64_t kvtophys(vm_offset_t va);
  45 __END_DECLS
  46
  47 static mutex_t *sOSReportLock = mutex_alloc(0);
  48
  49 /* Report a message with a 4 entry backtrace - very slow */
  50 void
  51 OSReportWithBacktrace(const char *str, ...)
  52 {
  53     char buf[128];
  54     void *bt[9];
  55     const unsigned cnt = sizeof(bt) / sizeof(bt[0]);
  56     va_list listp;
  57
  58     // Ignore the our and our callers stackframes, skipping frames 0 & 1
  59     (void) OSBacktrace(bt, cnt);
  60
  61     va_start(listp, str);
  62     vsnprintf(buf, sizeof(buf), str, listp);
  63     va_end(listp);
  64
  65     mutex_lock(sOSReportLock);
  66     {
  67         printf("%s\nBacktrace %p %p %p %p %p %p %p\n",
  68                 buf, bt[2], bt[3], bt[4], bt[5], bt[6], bt[7], bt[8]);
  69         kmod_dump_log((vm_offset_t *) &bt[2], cnt - 2);
  70     }
  71     mutex_unlock(sOSReportLock);
  72 }
  73
  74 static vm_offset_t minstackaddr = min_valid_stack_address();
  75 static vm_offset_t maxstackaddr = max_valid_stack_address();
  76
  77 #if __i386__
  78 #define i386_RETURN_OFFSET 4
  79
  80 static unsigned int
  81 i386_validate_stackptr(vm_offset_t stackptr)
  82 {
  83         /* Existence and alignment check
  84          */
  85         if (!stackptr || (stackptr & 0x3))
  86                 return 0;
  87
  88         /* Is a virtual->physical translation present?
  89          */
  90         if (!kvtophys(stackptr))
  91                 return 0;
  92
  93         /* Check if the return address lies on the same page;
  94          * If not, verify that a translation exists.
  95          */
  96         if (((PAGE_SIZE - (stackptr & PAGE_MASK)) < i386_RETURN_OFFSET) &&
  97             !kvtophys(stackptr + i386_RETURN_OFFSET))
  98                 return 0;
  99         return 1;
 100 }
 101
 102 static unsigned int
 103 i386_validate_raddr(vm_offset_t raddr)
 104 {
 105         return ((raddr > VM_MIN_KERNEL_ADDRESS) &&
 106             (raddr < VM_MAX_KERNEL_ADDRESS));
 107 }
 108 #endif
 109
 110 unsigned OSBacktrace(void **bt, unsigned maxAddrs)
 111 {
 112     unsigned frame;
 113
 114 #if __ppc__
 115     vm_offset_t stackptr, stackptr_prev;
 116     const vm_offset_t * const mem = (vm_offset_t *) 0;
 117     unsigned i = 0;
 118
 119     __asm__ volatile("mflr %0" : "=r" (stackptr));
 120     bt[i++] = (void *) stackptr;
 121
 122     __asm__ volatile("mr %0,r1" : "=r" (stackptr));
 123     for ( ; i < maxAddrs; i++) {
 124         // Validate we have a reasonable stackptr
 125         if ( !(minstackaddr <= stackptr && stackptr < maxstackaddr)
 126         || (stackptr & 3))
 127             break;
 128
 129         stackptr_prev = stackptr;
 130         stackptr = mem[stackptr_prev >> 2];
 131         if ((stackptr_prev ^ stackptr) > 8 * 1024)      // Sanity check
 132             break;
 133
 134         vm_offset_t addr = mem[(stackptr >> 2) + 2];
 135         if ((addr & 3) || (addr < 0x8000))      // More sanity checks
 136             break;
 137         bt[i] = (void *) addr;
 138     }
 139     frame = i;
 140
 141     for ( ; i < maxAddrs; i++)
 142             bt[i] = (void *) 0;
 143 #elif __i386__
 144 #define SANE_i386_FRAME_SIZE 8*1024
 145     vm_offset_t stackptr, stackptr_prev, raddr;
 146     unsigned frame_index = 0;
 147 /* Obtain current frame pointer */
 148     __asm__ volatile("movl %%ebp, %0" : "=m" (stackptr));
 149
 150     if (!i386_validate_stackptr(stackptr))
 151             goto pad;
 152
 153     raddr = *((vm_offset_t *) (stackptr + i386_RETURN_OFFSET));
 154
 155     if (!i386_validate_raddr(raddr))
 156             goto pad;
 157
 158     bt[frame_index++] = (void *) raddr;
 159
 160     for ( ; frame_index < maxAddrs; frame_index++) {
 161             stackptr_prev = stackptr;
 162             stackptr = *((vm_offset_t *) stackptr_prev);
 163
 164             if (!i386_validate_stackptr(stackptr))
 165                     break;
 166         /* Stack grows downwards */
 167             if (stackptr < stackptr_prev)
 168                     break;
 169
 170             if ((stackptr_prev ^ stackptr) > SANE_i386_FRAME_SIZE)
 171                     break;
 172
 173             raddr = *((vm_offset_t *) (stackptr + i386_RETURN_OFFSET));
 174
 175             if (!i386_validate_raddr(raddr))
 176                     break;
 177
 178             bt[frame_index] = (void *) raddr;
 179     }
 180 pad:
 181     frame = frame_index;
 182
 183     for ( ; frame_index < maxAddrs; frame_index++)
 184             bt[frame_index] = (void *) 0;
 185 #else
 186 #error arch
 187 #endif
 188     return frame;
 189 }