1 // -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
2 // Copyright (c) 2011, Google Inc.
3 // All rights reserved.
4 //
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6 // modification, are permitted provided that the following conditions are
7 // met:
8 //
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10 // notice, this list of conditions and the following disclaimer.
11 // * Redistributions in binary form must reproduce the above
12 // copyright notice, this list of conditions and the following disclaimer
13 // in the documentation and/or other materials provided with the
14 // distribution.
15 // * Neither the name of Google Inc. nor the names of its
16 // contributors may be used to endorse or promote products derived from
17 // this software without specific prior written permission.
18 //
19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31 // ---
32 // Author: Doug Kwan
33 // This is inspired by Craig Silverstein's PowerPC stacktrace code.
34 //
35
36 #ifndef BASE_STACKTRACE_ARM_INL_H_
37 #define BASE_STACKTRACE_ARM_INL_H_
38 // Note: this file is included into stacktrace.cc more than once.
39 // Anything that should only be defined once should be here:
40
41 #include <stdint.h> // for uintptr_t
42 #include "base/basictypes.h" // for NULL
43 #include <gperftools/stacktrace.h>
44
45 // WARNING:
46 // This only works if all your code is in either ARM or THUMB mode. With
47 // interworking, the frame pointer of the caller can either be in r11 (ARM
48 // mode) or r7 (THUMB mode). A callee only saves the frame pointer of its
49 // mode in a fixed location on its stack frame. If the caller is a different
50 // mode, there is no easy way to find the frame pointer. It can either be
51 // still in the designated register or saved on stack along with other callee
52 // saved registers.
53
54 // Given a pointer to a stack frame, locate and return the calling
55 // stackframe, or return NULL if no stackframe can be found. Perform sanity
56 // checks (the strictness of which is controlled by the boolean parameter
57 // "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
58 template<bool STRICT_UNWINDING>
NextStackFrame(void ** old_sp)59 static void **NextStackFrame(void **old_sp) {
60 void **new_sp = (void**) old_sp[-1];
61
62 // Check that the transition from frame pointer old_sp to frame
63 // pointer new_sp isn't clearly bogus
64 if (STRICT_UNWINDING) {
65 // With the stack growing downwards, older stack frame must be
66 // at a greater address that the current one.
67 if (new_sp <= old_sp) return NULL;
68 // Assume stack frames larger than 100,000 bytes are bogus.
69 if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return NULL;
70 } else {
71 // In the non-strict mode, allow discontiguous stack frames.
72 // (alternate-signal-stacks for example).
73 if (new_sp == old_sp) return NULL;
74 // And allow frames upto about 1MB.
75 if ((new_sp > old_sp)
76 && ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return NULL;
77 }
78 if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return NULL;
79 return new_sp;
80 }
81
82 // This ensures that GetStackTrace stes up the Link Register properly.
83 #ifdef __GNUC__
84 void StacktraceArmDummyFunction() __attribute__((noinline));
StacktraceArmDummyFunction()85 void StacktraceArmDummyFunction() { __asm__ volatile(""); }
86 #else
87 # error StacktraceArmDummyFunction() needs to be ported to this platform.
88 #endif
89 #endif // BASE_STACKTRACE_ARM_INL_H_
90
91 // Note: this part of the file is included several times.
92 // Do not put globals below.
93
94 // The following 4 functions are generated from the code below:
95 // GetStack{Trace,Frames}()
96 // GetStack{Trace,Frames}WithContext()
97 //
98 // These functions take the following args:
99 // void** result: the stack-trace, as an array
100 // int* sizes: the size of each stack frame, as an array
101 // (GetStackFrames* only)
102 // int max_depth: the size of the result (and sizes) array(s)
103 // int skip_count: how many stack pointers to skip before storing in result
104 // void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
105 static int GET_STACK_TRACE_OR_FRAMES {
106 #ifdef __GNUC__
107 void **sp = reinterpret_cast<void**>(__builtin_frame_address(0));
108 #else
109 # error reading stack point not yet supported on this platform.
110 #endif
111
112 // On ARM, the return address is stored in the link register (r14).
113 // This is not saved on the stack frame of a leaf function. To
114 // simplify code that reads return addresses, we call a dummy
115 // function so that the return address of this function is also
116 // stored in the stack frame. This works at least for gcc.
117 StacktraceArmDummyFunction();
118
119 skip_count++; // skip parent frame due to indirection in stacktrace.cc
120
121 int n = 0;
122 while (sp && n < max_depth) {
123 // The GetStackFrames routine is called when we are in some
124 // informational context (the failure signal handler for example).
125 // Use the non-strict unwinding rules to produce a stack trace
126 // that is as complete as possible (even if it contains a few bogus
127 // entries in some rare cases).
128 void **next_sp = NextStackFrame<IS_STACK_FRAMES == 0>(sp);
129
130 if (skip_count > 0) {
131 skip_count--;
132 } else {
133 result[n] = *sp;
134
135 #if IS_STACK_FRAMES
136 if (next_sp > sp) {
137 sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
138 } else {
139 // A frame-size of 0 is used to indicate unknown frame size.
140 sizes[n] = 0;
141 }
142 #endif
143 n++;
144 }
145 sp = next_sp;
146 }
147 return n;
148 }
149