libkern/gen/OSDebug.cpp

   1 /*
   2  * Copyright (c) 2005-2012 Apple 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 #include <IOKit/IOLib.h>
  32
  33 #include <sys/cdefs.h>
  34
  35 #include <stdarg.h>
  36 #include <mach/mach_types.h>
  37 #include <mach/kmod.h>
  38 #include <kern/locks.h>
  39
  40 #include <libkern/libkern.h>    // From bsd's libkern directory
  41 #include <mach/vm_param.h>
  42
  43 #include <sys/kdebug.h>
  44 #include <kern/thread.h>
  45
  46 #if defined(HAS_APPLE_PAC)
  47 #include <ptrauth.h>
  48 #endif
  49
  50 extern int etext;
  51 __BEGIN_DECLS
  52 // From osmfk/kern/thread.h but considered to be private
  53 extern vm_offset_t min_valid_stack_address(void);
  54 extern vm_offset_t max_valid_stack_address(void);
  55
  56 // From osfmk/kern/printf.c
  57 extern boolean_t doprnt_hide_pointers;
  58
  59 // From osfmk/kmod.c
  60 extern void kmod_dump_log(vm_offset_t *addr, unsigned int cnt, boolean_t doUnslide);
  61
  62 extern addr64_t kvtophys(vm_offset_t va);
  63 #if __arm__
  64 extern int copyinframe(vm_address_t fp, char *frame);
  65 #elif defined(__arm64__)
  66 extern int copyinframe(vm_address_t fp, char *frame, boolean_t is64bit);
  67 #endif
  68
  69 __END_DECLS
  70
  71 extern lck_grp_t *IOLockGroup;
  72
  73 static lck_mtx_t *sOSReportLock = lck_mtx_alloc_init(IOLockGroup, LCK_ATTR_NULL);
  74
  75 /* Use kernel_debug() to log a backtrace */
  76 void
  77 trace_backtrace(uint32_t debugid, uint32_t debugid2, uintptr_t size, uintptr_t data)
  78 {
  79         void *bt[16];
  80         const unsigned cnt = sizeof(bt) / sizeof(bt[0]);
  81         unsigned i;
  82         int found = 0;
  83
  84         OSBacktrace(bt, cnt);
  85
  86         /* find first non-kernel frame */
  87         for (i = 3; i < cnt && bt[i]; i++) {
  88                 if (bt[i] > (void*)&etext) {
  89                         found = 1;
  90                         break;
  91                 }
  92         }
  93         /*
  94          * if there are non-kernel frames, only log these
  95          * otherwise, log everything but the first two
  96          */
  97         if (!found) {
  98                 i = 2;
  99         }
 100
 101 #define safe_bt(a) (uintptr_t)(a<cnt ? bt[a] : NULL)
 102         kernel_debug(debugid, data, size, safe_bt(i), safe_bt(i + 1), 0);
 103         kernel_debug(debugid2, safe_bt(i + 2), safe_bt(i + 3), safe_bt(i + 4), safe_bt(i + 5), 0);
 104 }
 105
 106 /* Report a message with a 4 entry backtrace - very slow */
 107 void
 108 OSReportWithBacktrace(const char *str, ...)
 109 {
 110         char buf[128];
 111         void *bt[9] = {};
 112         const unsigned cnt = sizeof(bt) / sizeof(bt[0]);
 113         va_list listp;
 114
 115         // Ignore the our and our callers stackframes, skipping frames 0 & 1
 116         (void) OSBacktrace(bt, cnt);
 117
 118         va_start(listp, str);
 119         vsnprintf(buf, sizeof(buf), str, listp);
 120         va_end(listp);
 121
 122         lck_mtx_lock(sOSReportLock);
 123         {
 124                 boolean_t old_doprnt_hide_pointers = doprnt_hide_pointers;
 125                 doprnt_hide_pointers = FALSE;
 126                 printf("%s\nBacktrace 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n", buf,
 127                     (unsigned long) VM_KERNEL_UNSLIDE(bt[2]), (unsigned long) VM_KERNEL_UNSLIDE(bt[3]),
 128                     (unsigned long) VM_KERNEL_UNSLIDE(bt[4]), (unsigned long) VM_KERNEL_UNSLIDE(bt[5]),
 129                     (unsigned long) VM_KERNEL_UNSLIDE(bt[6]), (unsigned long) VM_KERNEL_UNSLIDE(bt[7]),
 130                     (unsigned long) VM_KERNEL_UNSLIDE(bt[8]));
 131                 kmod_dump_log((vm_offset_t *) &bt[2], cnt - 2, TRUE);
 132                 doprnt_hide_pointers = old_doprnt_hide_pointers;
 133         }
 134         lck_mtx_unlock(sOSReportLock);
 135 }
 136
 137 static vm_offset_t minstackaddr = min_valid_stack_address();
 138 static vm_offset_t maxstackaddr = max_valid_stack_address();
 139
 140
 141 #if __x86_64__
 142 #define x86_64_RETURN_OFFSET 8
 143 static unsigned int
 144 x86_64_validate_raddr(vm_offset_t raddr)
 145 {
 146         return (raddr > VM_MIN_KERNEL_AND_KEXT_ADDRESS) &&
 147                (raddr < VM_MAX_KERNEL_ADDRESS);
 148 }
 149 static unsigned int
 150 x86_64_validate_stackptr(vm_offset_t stackptr)
 151 {
 152         /* Existence and alignment check
 153          */
 154         if (!stackptr || (stackptr & 0x7) || !x86_64_validate_raddr(stackptr)) {
 155                 return 0;
 156         }
 157
 158         /* Is a virtual->physical translation present?
 159          */
 160         if (!kvtophys(stackptr)) {
 161                 return 0;
 162         }
 163
 164         /* Check if the return address lies on the same page;
 165          * If not, verify that a translation exists.
 166          */
 167         if (((PAGE_SIZE - (stackptr & PAGE_MASK)) < x86_64_RETURN_OFFSET) &&
 168             !kvtophys(stackptr + x86_64_RETURN_OFFSET)) {
 169                 return 0;
 170         }
 171         return 1;
 172 }
 173 #endif
 174
 175 void
 176 OSPrintBacktrace(void)
 177 {
 178         void * btbuf[20];
 179         int tmp = OSBacktrace(btbuf, 20);
 180         int i;
 181         for (i = 0; i < tmp; i++) {
 182                 kprintf("bt[%.2d] = %p\n", i, btbuf[i]);
 183         }
 184 }
 185
 186 unsigned
 187 OSBacktrace(void **bt, unsigned maxAddrs)
 188 {
 189         unsigned frame;
 190         if (!current_thread()) {
 191                 return 0;
 192         }
 193
 194 #if   __x86_64__
 195 #define SANE_x86_64_FRAME_SIZE (kernel_stack_size >> 1)
 196         vm_offset_t stackptr, stackptr_prev, raddr;
 197         unsigned frame_index = 0;
 198 /* Obtain current frame pointer */
 199
 200         __asm__ volatile ("movq %%rbp, %0" : "=m" (stackptr));
 201
 202         if (!x86_64_validate_stackptr(stackptr)) {
 203                 goto pad;
 204         }
 205
 206         raddr = *((vm_offset_t *) (stackptr + x86_64_RETURN_OFFSET));
 207
 208         if (!x86_64_validate_raddr(raddr)) {
 209                 goto pad;
 210         }
 211
 212         bt[frame_index++] = (void *) raddr;
 213
 214         for (; frame_index < maxAddrs; frame_index++) {
 215                 stackptr_prev = stackptr;
 216                 stackptr = *((vm_offset_t *) stackptr_prev);
 217
 218                 if (!x86_64_validate_stackptr(stackptr)) {
 219                         break;
 220                 }
 221                 /* Stack grows downwards */
 222                 if (stackptr < stackptr_prev) {
 223                         break;
 224                 }
 225
 226                 if ((stackptr - stackptr_prev) > SANE_x86_64_FRAME_SIZE) {
 227                         break;
 228                 }
 229
 230                 raddr = *((vm_offset_t *) (stackptr + x86_64_RETURN_OFFSET));
 231
 232                 if (!x86_64_validate_raddr(raddr)) {
 233                         break;
 234                 }
 235
 236                 bt[frame_index] = (void *) raddr;
 237         }
 238 pad:
 239         frame = frame_index;
 240
 241         for (; frame_index < maxAddrs; frame_index++) {
 242                 bt[frame_index] = (void *) NULL;
 243         }
 244 #elif __arm__ || __arm64__
 245         uint32_t i = 0;
 246         uintptr_t frameb[2];
 247         uintptr_t fp = 0;
 248
 249         // get the current frame pointer for this thread
 250 #if defined(__arm__)
 251 #define OSBacktraceFrameAlignOK(x) (((x) & 0x3) == 0)
 252         __asm__ volatile ("mov %0,r7" : "=r" (fp));
 253 #elif defined(__arm64__)
 254 #define OSBacktraceFrameAlignOK(x) (((x) & 0xf) == 0)
 255         __asm__ volatile ("mov %0, fp" : "=r" (fp));
 256 #else
 257 #error Unknown architecture.
 258 #endif
 259
 260         // now crawl up the stack recording the link value of each frame
 261         do {
 262                 // check bounds
 263                 if ((fp == 0) || (!OSBacktraceFrameAlignOK(fp)) || (fp > VM_MAX_KERNEL_ADDRESS) || (fp < VM_MIN_KERNEL_AND_KEXT_ADDRESS)) {
 264                         break;
 265                 }
 266                 // safely read frame
 267 #ifdef __arm64__
 268                 if (copyinframe(fp, (char*)frameb, TRUE) != 0) {
 269 #else
 270                 if (copyinframe(fp, (char*)frameb) != 0) {
 271 #endif
 272                         break;
 273                 }
 274
 275                 // No need to use copyin as this is always a kernel address, see check above
 276 #if defined(HAS_APPLE_PAC)
 277                 /* return addresses on stack signed by arm64e ABI */
 278                 bt[i] = ptrauth_strip((void*)frameb[1], ptrauth_key_return_address); // link register
 279 #else
 280                 bt[i] = (void*)frameb[1]; // link register
 281 #endif
 282                 fp = frameb[0];
 283         } while (++i < maxAddrs);
 284         frame = i;
 285 #else
 286 #error arch
 287 #endif
 288         return frame;
 289 }