libkern/gen/OSDebug.cpp

   1 /*
   2  * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 // NOTE:  This file is only c++ so I can get static initialisers going
  30 #include <libkern/OSDebug.h>
  31
  32 #include <sys/cdefs.h>
  33
  34 #include <stdarg.h>
  35 #include <mach/mach_types.h>
  36 #include <mach/kmod.h>
  37 #include <kern/lock.h>
  38
  39 #include <libkern/libkern.h>    // From bsd's libkern directory
  40 #include <mach/vm_param.h>
  41
  42 __BEGIN_DECLS
  43 // From osmfk/kern/thread.h but considered to be private
  44 extern vm_offset_t min_valid_stack_address(void);
  45 extern vm_offset_t max_valid_stack_address(void);
  46
  47 // From osfmk/kmod.c
  48 extern void kmod_dump_log(vm_offset_t *addr, unsigned int cnt);
  49
  50 extern addr64_t kvtophys(vm_offset_t va);
  51 __END_DECLS
  52
  53 static mutex_t *sOSReportLock = mutex_alloc(0);
  54
  55 /* Report a message with a 4 entry backtrace - very slow */
  56 void
  57 OSReportWithBacktrace(const char *str, ...)
  58 {
  59     char buf[128];
  60     void *bt[9];
  61     const unsigned cnt = sizeof(bt) / sizeof(bt[0]);
  62     va_list listp;
  63
  64     // Ignore the our and our callers stackframes, skipping frames 0 & 1
  65     (void) OSBacktrace(bt, cnt);
  66
  67     va_start(listp, str);
  68     vsnprintf(buf, sizeof(buf), str, listp);
  69     va_end(listp);
  70
  71     mutex_lock(sOSReportLock);
  72     {
  73         printf("%s\nBacktrace %p %p %p %p %p %p %p\n",
  74                 buf, bt[2], bt[3], bt[4], bt[5], bt[6], bt[7], bt[8]);
  75         kmod_dump_log((vm_offset_t *) &bt[2], cnt - 2);
  76     }
  77     mutex_unlock(sOSReportLock);
  78 }
  79
  80 static vm_offset_t minstackaddr = min_valid_stack_address();
  81 static vm_offset_t maxstackaddr = max_valid_stack_address();
  82
  83 #if __i386__
  84 #define i386_RETURN_OFFSET 4
  85
  86 static unsigned int
  87 i386_validate_stackptr(vm_offset_t stackptr)
  88 {
  89         /* Existence and alignment check
  90          */
  91         if (!stackptr || (stackptr & 0x3))
  92                 return 0;
  93
  94         /* Is a virtual->physical translation present?
  95          */
  96         if (!kvtophys(stackptr))
  97                 return 0;
  98
  99         /* Check if the return address lies on the same page;
 100          * If not, verify that a translation exists.
 101          */
 102         if (((PAGE_SIZE - (stackptr & PAGE_MASK)) < i386_RETURN_OFFSET) &&
 103             !kvtophys(stackptr + i386_RETURN_OFFSET))
 104                 return 0;
 105         return 1;
 106 }
 107
 108 static unsigned int
 109 i386_validate_raddr(vm_offset_t raddr)
 110 {
 111         return ((raddr > VM_MIN_KERNEL_ADDRESS) &&
 112             (raddr < VM_MAX_KERNEL_ADDRESS));
 113 }
 114 #endif
 115
 116 unsigned OSBacktrace(void **bt, unsigned maxAddrs)
 117 {
 118     unsigned frame;
 119
 120 #if __ppc__
 121     vm_offset_t stackptr, stackptr_prev;
 122     const vm_offset_t * const mem = (vm_offset_t *) 0;
 123     unsigned i = 0;
 124
 125     __asm__ volatile("mflr %0" : "=r" (stackptr));
 126     bt[i++] = (void *) stackptr;
 127
 128     __asm__ volatile("mr %0,r1" : "=r" (stackptr));
 129     for ( ; i < maxAddrs; i++) {
 130         // Validate we have a reasonable stackptr
 131         if ( !(minstackaddr <= stackptr && stackptr < maxstackaddr)
 132         || (stackptr & 3))
 133             break;
 134
 135         stackptr_prev = stackptr;
 136         stackptr = mem[stackptr_prev >> 2];
 137         if ((stackptr_prev ^ stackptr) > 8 * 1024)      // Sanity check
 138             break;
 139
 140         vm_offset_t addr = mem[(stackptr >> 2) + 2];
 141         if ((addr & 3) || (addr < 0x8000))      // More sanity checks
 142             break;
 143         bt[i] = (void *) addr;
 144     }
 145     frame = i;
 146
 147     for ( ; i < maxAddrs; i++)
 148             bt[i] = (void *) 0;
 149 #elif __i386__
 150 #define SANE_i386_FRAME_SIZE 8*1024
 151     vm_offset_t stackptr, stackptr_prev, raddr;
 152     unsigned frame_index = 0;
 153 /* Obtain current frame pointer */
 154     __asm__ volatile("movl %%ebp, %0" : "=m" (stackptr));
 155
 156     if (!i386_validate_stackptr(stackptr))
 157             goto pad;
 158
 159     raddr = *((vm_offset_t *) (stackptr + i386_RETURN_OFFSET));
 160
 161     if (!i386_validate_raddr(raddr))
 162             goto pad;
 163
 164     bt[frame_index++] = (void *) raddr;
 165
 166     for ( ; frame_index < maxAddrs; frame_index++) {
 167             stackptr_prev = stackptr;
 168             stackptr = *((vm_offset_t *) stackptr_prev);
 169
 170             if (!i386_validate_stackptr(stackptr))
 171                     break;
 172         /* Stack grows downwards */
 173             if (stackptr < stackptr_prev)
 174                     break;
 175
 176             if ((stackptr_prev ^ stackptr) > SANE_i386_FRAME_SIZE)
 177                     break;
 178
 179             raddr = *((vm_offset_t *) (stackptr + i386_RETURN_OFFSET));
 180
 181             if (!i386_validate_raddr(raddr))
 182                     break;
 183
 184             bt[frame_index] = (void *) raddr;
 185     }
 186 pad:
 187     frame = frame_index;
 188
 189     for ( ; frame_index < maxAddrs; frame_index++)
 190             bt[frame_index] = (void *) 0;
 191 #else
 192 #error arch
 193 #endif
 194     return frame;
 195 }