1 // Copyright (c) 2010 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_ppc.cc: ppc-specific stackwalker. 31 // 32 // See stackwalker_ppc.h for documentation. 33 // 34 // Author: Mark Mentovai 35 36 37 #include "processor/stackwalker_ppc.h" 38 #include "google_breakpad/processor/call_stack.h" 39 #include "google_breakpad/processor/memory_region.h" 40 #include "google_breakpad/processor/stack_frame_cpu.h" 41 #include "processor/logging.h" 42 43 namespace google_breakpad { 44 45 46 StackwalkerPPC::StackwalkerPPC(const SystemInfo* system_info, 47 const MDRawContextPPC* context, 48 MemoryRegion* memory, 49 const CodeModules* modules, 50 StackFrameSymbolizer* resolver_helper) 51 : Stackwalker(system_info, memory, modules, resolver_helper), 52 context_(context) { 53 if (memory_ && memory_->GetBase() + memory_->GetSize() - 1 > 0xffffffff) { 54 // This implementation only covers 32-bit ppc CPUs. The limits of the 55 // supplied stack are invalid. Mark memory_ = NULL, which will cause 56 // stackwalking to fail. 57 BPLOG(ERROR) << "Memory out of range for stackwalking: " << 58 HexString(memory_->GetBase()) << "+" << 59 HexString(memory_->GetSize()); 60 memory_ = NULL; 61 } 62 } 63 64 65 StackFrame* StackwalkerPPC::GetContextFrame() { 66 if (!context_) { 67 BPLOG(ERROR) << "Can't get context frame without context"; 68 return NULL; 69 } 70 71 StackFramePPC* frame = new StackFramePPC(); 72 73 // The instruction pointer is stored directly in a register, so pull it 74 // straight out of the CPU context structure. 75 frame->context = *context_; 76 frame->context_validity = StackFramePPC::CONTEXT_VALID_ALL; 77 frame->trust = StackFrame::FRAME_TRUST_CONTEXT; 78 frame->instruction = frame->context.srr0; 79 80 return frame; 81 } 82 83 84 StackFrame* StackwalkerPPC::GetCallerFrame(const CallStack* stack, 85 bool stack_scan_allowed) { 86 if (!memory_ || !stack) { 87 BPLOG(ERROR) << "Can't get caller frame without memory or stack"; 88 return NULL; 89 } 90 91 // The instruction pointers for previous frames are saved on the stack. 92 // The typical ppc calling convention is for the called procedure to store 93 // its return address in the calling procedure's stack frame at 8(%r1), 94 // and to allocate its own stack frame by decrementing %r1 (the stack 95 // pointer) and saving the old value of %r1 at 0(%r1). Because the ppc has 96 // no hardware stack, there is no distinction between the stack pointer and 97 // frame pointer, and what is typically thought of as the frame pointer on 98 // an x86 is usually referred to as the stack pointer on a ppc. 99 100 StackFramePPC* last_frame = static_cast<StackFramePPC*>( 101 stack->frames()->back()); 102 103 // A caller frame must reside higher in memory than its callee frames. 104 // Anything else is an error, or an indication that we've reached the 105 // end of the stack. 106 uint32_t stack_pointer; 107 if (!memory_->GetMemoryAtAddress(last_frame->context.gpr[1], 108 &stack_pointer) || 109 stack_pointer <= last_frame->context.gpr[1]) { 110 return NULL; 111 } 112 113 // Mac OS X/Darwin gives 1 as the return address from the bottom-most 114 // frame in a stack (a thread's entry point). I haven't found any 115 // documentation on this, but 0 or 1 would be bogus return addresses, 116 // so check for them here and return false (end of stack) when they're 117 // hit to avoid having a phantom frame. 118 uint32_t instruction; 119 if (!memory_->GetMemoryAtAddress(stack_pointer + 8, &instruction) || 120 instruction <= 1) { 121 return NULL; 122 } 123 124 StackFramePPC* frame = new StackFramePPC(); 125 126 frame->context = last_frame->context; 127 frame->context.srr0 = instruction; 128 frame->context.gpr[1] = stack_pointer; 129 frame->context_validity = StackFramePPC::CONTEXT_VALID_SRR0 | 130 StackFramePPC::CONTEXT_VALID_GPR1; 131 frame->trust = StackFrame::FRAME_TRUST_FP; 132 133 // frame->context.srr0 is the return address, which is one instruction 134 // past the branch that caused us to arrive at the callee. Set 135 // frame_ppc->instruction to four less than that. Since all ppc 136 // instructions are 4 bytes wide, this is the address of the branch 137 // instruction. This allows source line information to match up with the 138 // line that contains a function call. Callers that require the exact 139 // return address value may access the context.srr0 field of StackFramePPC. 140 frame->instruction = frame->context.srr0 - 4; 141 142 return frame; 143 } 144 145 146 } // namespace google_breakpad 147
