gen/thread_stack_pcs.c

   1 /*
   2  * Copyright (c) 1999, 2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 /*      Bertrand from vmutils -> CF -> System */
  25
  26 #include <pthread.h>
  27 #include <mach/mach.h>
  28 #include <mach/vm_statistics.h>
  29 #include <stdlib.h>
  30
  31 #if defined(__i386__) || defined(__x86_64__) || defined(__arm__)
  32 #define FP_LINK_OFFSET 1
  33 #elif defined(__ppc__) || defined(__ppc64__)
  34 #define FP_LINK_OFFSET 2
  35 #else
  36 #error  ********** Unimplemented architecture
  37 #endif
  38
  39 #define INSTACK(a)      ((a) >= stackbot && (a) <= stacktop)
  40 #if defined(__ppc__) || defined(__ppc64__) || defined(__x86_64__)
  41 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 0)
  42 #elif defined(__arm__)
  43 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0x1) == 0)
  44 #elif defined(__i386__)
  45 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 8)
  46 #endif
  47
  48 __private_extern__  __attribute__((noinline))
  49 void
  50 _thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip)
  51 {
  52     void *frame, *next;
  53     pthread_t self = pthread_self();
  54     void *stacktop = pthread_get_stackaddr_np(self);
  55     void *stackbot = stacktop - pthread_get_stacksize_np(self);
  56
  57     *nb = 0;
  58
  59     /* make sure return address is never out of bounds */
  60     stacktop -= (FP_LINK_OFFSET + 1) * sizeof(void *);
  61
  62     /*
  63      * The original implementation called the first_frame_address() function,
  64      * which returned the stack frame pointer.  The problem was that in ppc,
  65      * it was a leaf function, so no new stack frame was set up with
  66      * optimization turned on (while a new stack frame was set up without
  67      * optimization).  We now inline the code to get the stack frame pointer,
  68      * so we are consistent about the stack frame.
  69      */
  70 #if defined(__i386__) || defined(__x86_64__) || defined(__arm__)
  71     frame = __builtin_frame_address(0);
  72 #elif defined(__ppc__) || defined(__ppc64__)
  73     /* __builtin_frame_address IS BROKEN IN BEAKER: RADAR #2340421 */
  74     __asm__ volatile("mr %0, r1" : "=r" (frame));
  75 #endif
  76     if(!INSTACK(frame) || !ISALIGNED(frame))
  77         return;
  78 #if defined(__ppc__) || defined(__ppc64__)
  79     /* back up the stack pointer up over the current stack frame */
  80     next = *(void **)frame;
  81     if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
  82         return;
  83     frame = next;
  84 #endif
  85     while (skip--) {
  86         next = *(void **)frame;
  87         if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
  88             return;
  89         frame = next;
  90     }
  91     while (max--) {
  92         buffer[*nb] = *(vm_address_t *)(((void **)frame) + FP_LINK_OFFSET);
  93         (*nb)++;
  94         next = *(void **)frame;
  95         if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
  96             return;
  97         frame = next;
  98     }
  99 }
 100
 101 void
 102 thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb)
 103 {
 104     _thread_stack_pcs(buffer, max, nb, 0);
 105
 106     // The following prevents thread_stack_pcs() from getting tail-call-optimized into _thread_stack_pcs() on 64-bit environments,
 107     // thus making the "number of hot frames to skip" be more predictable, giving more consistent backtraces.
 108     // See <rdar://problem/5364825> "stack logging: frames keep getting truncated" for why this is necessary.
 109     __asm__ volatile("");
 110 }