1 // Copyright (c) 2013 Google Inc.
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
8 // * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
13 // distribution.
14 // * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30 // stackwalker_ppc64.cc: ppc64-specific stackwalker.
31 //
32 // See stackwalker_ppc64.h for documentation.
33
34
35 #include "processor/stackwalker_ppc64.h"
36 #include "google_breakpad/processor/call_stack.h"
37 #include "google_breakpad/processor/memory_region.h"
38 #include "google_breakpad/processor/stack_frame_cpu.h"
39 #include "processor/logging.h"
40
41 #include <stdio.h>
42
43 namespace google_breakpad {
44
45
StackwalkerPPC64(const SystemInfo * system_info,const MDRawContextPPC64 * context,MemoryRegion * memory,const CodeModules * modules,StackFrameSymbolizer * resolver_helper)46 StackwalkerPPC64::StackwalkerPPC64(const SystemInfo* system_info,
47 const MDRawContextPPC64* context,
48 MemoryRegion* memory,
49 const CodeModules* modules,
50 StackFrameSymbolizer* resolver_helper)
51 : Stackwalker(system_info, memory, modules, resolver_helper),
52 context_(context) {
53 }
54
55
GetContextFrame()56 StackFrame* StackwalkerPPC64::GetContextFrame() {
57 if (!context_) {
58 BPLOG(ERROR) << "Can't get context frame without context";
59 return NULL;
60 }
61
62 StackFramePPC64* frame = new StackFramePPC64();
63
64 // The instruction pointer is stored directly in a register, so pull it
65 // straight out of the CPU context structure.
66 frame->context = *context_;
67 frame->context_validity = StackFramePPC64::CONTEXT_VALID_ALL;
68 frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
69 frame->instruction = frame->context.srr0;
70
71 return frame;
72 }
73
74
GetCallerFrame(const CallStack * stack,bool stack_scan_allowed)75 StackFrame* StackwalkerPPC64::GetCallerFrame(const CallStack* stack,
76 bool stack_scan_allowed) {
77 if (!memory_ || !stack) {
78 BPLOG(ERROR) << "Can't get caller frame without memory or stack";
79 return NULL;
80 }
81
82 // The instruction pointers for previous frames are saved on the stack.
83 // The typical ppc64 calling convention is for the called procedure to store
84 // its return address in the calling procedure's stack frame at 8(%r1),
85 // and to allocate its own stack frame by decrementing %r1 (the stack
86 // pointer) and saving the old value of %r1 at 0(%r1). Because the ppc64 has
87 // no hardware stack, there is no distinction between the stack pointer and
88 // frame pointer, and what is typically thought of as the frame pointer on
89 // an x86 is usually referred to as the stack pointer on a ppc64.
90
91 StackFramePPC64* last_frame = static_cast<StackFramePPC64*>(
92 stack->frames()->back());
93
94 // A caller frame must reside higher in memory than its callee frames.
95 // Anything else is an error, or an indication that we've reached the
96 // end of the stack.
97 uint64_t stack_pointer;
98 if (!memory_->GetMemoryAtAddress(last_frame->context.gpr[1],
99 &stack_pointer) ||
100 stack_pointer <= last_frame->context.gpr[1]) {
101 return NULL;
102 }
103
104 // Mac OS X/Darwin gives 1 as the return address from the bottom-most
105 // frame in a stack (a thread's entry point). I haven't found any
106 // documentation on this, but 0 or 1 would be bogus return addresses,
107 // so check for them here and return false (end of stack) when they're
108 // hit to avoid having a phantom frame.
109 uint64_t instruction;
110 if (!memory_->GetMemoryAtAddress(stack_pointer + 16, &instruction) ||
111 instruction <= 1) {
112 return NULL;
113 }
114
115 StackFramePPC64* frame = new StackFramePPC64();
116
117 frame->context = last_frame->context;
118 frame->context.srr0 = instruction;
119 frame->context.gpr[1] = stack_pointer;
120 frame->context_validity = StackFramePPC64::CONTEXT_VALID_SRR0 |
121 StackFramePPC64::CONTEXT_VALID_GPR1;
122 frame->trust = StackFrame::FRAME_TRUST_FP;
123
124 // frame->context.srr0 is the return address, which is one instruction
125 // past the branch that caused us to arrive at the callee. Set
126 // frame_ppc64->instruction to eight less than that. Since all ppc64
127 // instructions are 8 bytes wide, this is the address of the branch
128 // instruction. This allows source line information to match up with the
129 // line that contains a function call. Callers that require the exact
130 // return address value may access the context.srr0 field of StackFramePPC64.
131 frame->instruction = frame->context.srr0 - 8;
132
133 return frame;
134 }
135
136
137 } // namespace google_breakpad
138