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 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 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 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
