1 // Copyright 2013 Google LLC
2 //
3 // Redistribution and use in source and binary forms, with or without
4 // modification, are permitted provided that the following conditions are
5 // met:
6 //
7 // * Redistributions of source code must retain the above copyright
8 // notice, this list of conditions and the following disclaimer.
9 // * Redistributions in binary form must reproduce the above
10 // copyright notice, this list of conditions and the following disclaimer
11 // in the documentation and/or other materials provided with the
12 // distribution.
13 // * Neither the name of Google LLC nor the names of its
14 // contributors may be used to endorse or promote products derived from
15 // this software without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29 // stackwalker_ppc64.cc: ppc64-specific stackwalker.
30 //
31 // See stackwalker_ppc64.h for documentation.
32
33
34 #ifdef HAVE_CONFIG_H
35 #include <config.h> // Must come first
36 #endif
37
38 #include "common/scoped_ptr.h"
39 #include "processor/stackwalker_ppc64.h"
40 #include "google_breakpad/processor/call_stack.h"
41 #include "google_breakpad/processor/memory_region.h"
42 #include "google_breakpad/processor/stack_frame_cpu.h"
43 #include "processor/logging.h"
44
45 #include <stdio.h>
46
47 namespace google_breakpad {
48
49
StackwalkerPPC64(const SystemInfo * system_info,const MDRawContextPPC64 * context,MemoryRegion * memory,const CodeModules * modules,StackFrameSymbolizer * resolver_helper)50 StackwalkerPPC64::StackwalkerPPC64(const SystemInfo* system_info,
51 const MDRawContextPPC64* context,
52 MemoryRegion* memory,
53 const CodeModules* modules,
54 StackFrameSymbolizer* resolver_helper)
55 : Stackwalker(system_info, memory, modules, resolver_helper),
56 context_(context) {
57 }
58
59
GetContextFrame()60 StackFrame* StackwalkerPPC64::GetContextFrame() {
61 if (!context_) {
62 BPLOG(ERROR) << "Can't get context frame without context";
63 return NULL;
64 }
65
66 StackFramePPC64* frame = new StackFramePPC64();
67
68 // The instruction pointer is stored directly in a register, so pull it
69 // straight out of the CPU context structure.
70 frame->context = *context_;
71 frame->context_validity = StackFramePPC64::CONTEXT_VALID_ALL;
72 frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
73 frame->instruction = frame->context.srr0;
74
75 return frame;
76 }
77
78
GetCallerFrame(const CallStack * stack,bool stack_scan_allowed)79 StackFrame* StackwalkerPPC64::GetCallerFrame(const CallStack* stack,
80 bool stack_scan_allowed) {
81 if (!memory_ || !stack) {
82 BPLOG(ERROR) << "Can't get caller frame without memory or stack";
83 return NULL;
84 }
85
86 // The instruction pointers for previous frames are saved on the stack.
87 // The typical ppc64 calling convention is for the called procedure to store
88 // its return address in the calling procedure's stack frame at 8(%r1),
89 // and to allocate its own stack frame by decrementing %r1 (the stack
90 // pointer) and saving the old value of %r1 at 0(%r1). Because the ppc64 has
91 // no hardware stack, there is no distinction between the stack pointer and
92 // frame pointer, and what is typically thought of as the frame pointer on
93 // an x86 is usually referred to as the stack pointer on a ppc64.
94
95 StackFramePPC64* last_frame = static_cast<StackFramePPC64*>(
96 stack->frames()->back());
97
98 // A caller frame must reside higher in memory than its callee frames.
99 // Anything else is an error, or an indication that we've reached the
100 // end of the stack.
101 uint64_t stack_pointer;
102 if (!memory_->GetMemoryAtAddress(last_frame->context.gpr[1],
103 &stack_pointer) ||
104 stack_pointer <= last_frame->context.gpr[1]) {
105 return NULL;
106 }
107
108 // Mac OS X/Darwin gives 1 as the return address from the bottom-most
109 // frame in a stack (a thread's entry point). I haven't found any
110 // documentation on this, but 0 or 1 would be bogus return addresses,
111 // so check for them here and return false (end of stack) when they're
112 // hit to avoid having a phantom frame.
113 uint64_t instruction;
114 if (!memory_->GetMemoryAtAddress(stack_pointer + 16, &instruction) ||
115 instruction <= 1) {
116 return NULL;
117 }
118
119 scoped_ptr<StackFramePPC64> frame(new StackFramePPC64());
120
121 frame->context = last_frame->context;
122 frame->context.srr0 = instruction;
123 frame->context.gpr[1] = stack_pointer;
124 frame->context_validity = StackFramePPC64::CONTEXT_VALID_SRR0 |
125 StackFramePPC64::CONTEXT_VALID_GPR1;
126 frame->trust = StackFrame::FRAME_TRUST_FP;
127
128 // Should we terminate the stack walk? (end-of-stack or broken invariant)
129 if (TerminateWalk(instruction, stack_pointer, last_frame->context.gpr[1],
130 /*is_context_frame=*/last_frame->trust ==
131 StackFrame::FRAME_TRUST_CONTEXT)) {
132 return NULL;
133 }
134
135 // frame->context.srr0 is the return address, which is one instruction
136 // past the branch that caused us to arrive at the callee. Set
137 // frame_ppc64->instruction to eight less than that. Since all ppc64
138 // instructions are 8 bytes wide, this is the address of the branch
139 // instruction. This allows source line information to match up with the
140 // line that contains a function call. Callers that require the exact
141 // return address value may access the context.srr0 field of StackFramePPC64.
142 frame->instruction = frame->context.srr0 - 8;
143
144 return frame.release();
145 }
146
147
148 } // namespace google_breakpad
149