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#include "stack_logging.h"
31
32#if defined(__i386__) || defined(__x86_64__) || defined(__arm__)
33#define FP_LINK_OFFSET 1
34#elif defined(__ppc__) || defined(__ppc64__)
35#define FP_LINK_OFFSET 2
36#else
37#error  ********** Unimplemented architecture
38#endif
39
40#define	INSTACK(a)	((a) >= stackbot && (a) <= stacktop)
41#if defined(__ppc__) || defined(__ppc64__) || defined(__x86_64__)
42#define	ISALIGNED(a)	((((uintptr_t)(a)) & 0xf) == 0)
43#elif defined(__arm__)
44#define	ISALIGNED(a)	((((uintptr_t)(a)) & 0x1) == 0)
45#elif defined(__i386__)
46#define	ISALIGNED(a)	((((uintptr_t)(a)) & 0xf) == 8)
47#endif
48
49__private_extern__  __attribute__((noinline))
50void
51_thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip)
52{
53    void *frame, *next;
54    pthread_t self = pthread_self();
55    void *stacktop = pthread_get_stackaddr_np(self);
56    void *stackbot = stacktop - pthread_get_stacksize_np(self);
57
58    *nb = 0;
59
60    /* make sure return address is never out of bounds */
61    stacktop -= (FP_LINK_OFFSET + 1) * sizeof(void *);
62
63    /*
64     * The original implementation called the first_frame_address() function,
65     * which returned the stack frame pointer.  The problem was that in ppc,
66     * it was a leaf function, so no new stack frame was set up with
67     * optimization turned on (while a new stack frame was set up without
68     * optimization).  We now inline the code to get the stack frame pointer,
69     * so we are consistent about the stack frame.
70     */
71#if defined(__i386__) || defined(__x86_64__) || defined(__arm__)
72    frame = __builtin_frame_address(0);
73#elif defined(__ppc__) || defined(__ppc64__)
74    /* __builtin_frame_address IS BROKEN IN BEAKER: RADAR #2340421 */
75    __asm__ volatile("mr %0, r1" : "=r" (frame));
76#endif
77    if(!INSTACK(frame) || !ISALIGNED(frame))
78	return;
79#if defined(__ppc__) || defined(__ppc64__)
80    /* back up the stack pointer up over the current stack frame */
81    next = *(void **)frame;
82    if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
83	return;
84    frame = next;
85#endif
86    while (skip--) {
87	next = *(void **)frame;
88	if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
89	    return;
90	frame = next;
91    }
92    while (max--) {
93        buffer[*nb] = *(vm_address_t *)(((void **)frame) + FP_LINK_OFFSET);
94        (*nb)++;
95	next = *(void **)frame;
96	if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
97	    return;
98	frame = next;
99    }
100}
101
102void
103thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb)
104{
105    _thread_stack_pcs(buffer, max, nb, 0);
106
107    // The following prevents thread_stack_pcs() from getting tail-call-optimized into _thread_stack_pcs() on 64-bit environments,
108    // thus making the "number of hot frames to skip" be more predictable, giving more consistent backtraces.
109    // See <rdar://problem/5364825> "stack logging: frames keep getting truncated" for why this is necessary.
110    __asm__ volatile("");
111}
112