gen/thread_stack_pcs.c

   1 /*
   2  * Copyright (c) 1999-2018 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 #include <pthread/stack_np.h>
  31 #include "stack_logging.h"
  32
  33 #define INSTACK(a)      ((a) >= stackbot && (a) <= stacktop)
  34 #if defined(__x86_64__)
  35 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 0)
  36 #elif defined(__i386__)
  37 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 8)
  38 #elif defined(__arm__) || defined(__arm64__)
  39 #define ISALIGNED(a)    ((((uintptr_t)(a)) & 0x1) == 0)
  40 #endif
  41
  42 __attribute__((noinline))
  43 static void
  44 __thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb,
  45                 unsigned skip, void *startfp)
  46 {
  47         void *frame, *next;
  48         pthread_t self = pthread_self();
  49         void *stacktop = pthread_get_stackaddr_np(self);
  50         void *stackbot = stacktop - pthread_get_stacksize_np(self);
  51
  52         *nb = 0;
  53
  54         // Rely on the fact that our caller has an empty stackframe (no local vars)
  55         // to determine the minimum size of a stackframe (frame ptr & return addr)
  56         frame = __builtin_frame_address(0);
  57         next = (void*)pthread_stack_frame_decode_np((uintptr_t)frame, NULL);
  58
  59         /* make sure return address is never out of bounds */
  60         stacktop -= (next - frame);
  61
  62         if(!INSTACK(frame) || !ISALIGNED(frame))
  63                 return;
  64         while (startfp || skip--) {
  65                 if (startfp && startfp < next) break;
  66                 if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
  67                         return;
  68                 frame = next;
  69                 next = (void*)pthread_stack_frame_decode_np((uintptr_t)frame, NULL);
  70         }
  71         while (max--) {
  72                 uintptr_t retaddr;
  73                 next = (void*)pthread_stack_frame_decode_np((uintptr_t)frame, &retaddr);
  74                 buffer[*nb] = retaddr;
  75                 (*nb)++;
  76                 if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
  77                         return;
  78                 frame = next;
  79         }
  80 }
  81
  82 // Note that callee relies on this function having a minimal stackframe
  83 // to introspect (i.e. no tailcall and no local variables)
  84 __private_extern__ __attribute__((disable_tail_calls))
  85 void
  86 _thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb,
  87                 unsigned skip, void *startfp)
  88 {
  89         // skip this frame
  90         __thread_stack_pcs(buffer, max, nb, skip + 1, startfp);
  91 }
  92
  93 // Prevent thread_stack_pcs() from getting tail-call-optimized into
  94 // __thread_stack_pcs() on 64-bit environments, thus making the "number of hot
  95 // frames to skip" be more predictable, giving more consistent backtraces.
  96 //
  97 // See <rdar://problem/5364825> "stack logging: frames keep getting truncated"
  98 // for why this is necessary.
  99 //
 100 // Note that callee relies on this function having a minimal stackframe
 101 // to introspect (i.e. no tailcall and no local variables)
 102 __attribute__((disable_tail_calls))
 103 void
 104 thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb)
 105 {
 106         __thread_stack_pcs(buffer, max, nb, 0, NULL);
 107 }