michael@0: // Copyright (c) 2010 Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // stackwalker_ppc.cc: ppc-specific stackwalker.
michael@0: //
michael@0: // See stackwalker_ppc.h for documentation.
michael@0: //
michael@0: // Author: Mark Mentovai
michael@0: 
michael@0: 
michael@0: #include "processor/stackwalker_ppc.h"
michael@0: #include "google_breakpad/processor/call_stack.h"
michael@0: #include "google_breakpad/processor/memory_region.h"
michael@0: #include "google_breakpad/processor/stack_frame_cpu.h"
michael@0: #include "common/logging.h"
michael@0: 
michael@0: namespace google_breakpad {
michael@0: 
michael@0: 
michael@0: StackwalkerPPC::StackwalkerPPC(const SystemInfo* system_info,
michael@0:                                const MDRawContextPPC* context,
michael@0:                                MemoryRegion* memory,
michael@0:                                const CodeModules* modules,
michael@0:                                StackFrameSymbolizer* resolver_helper)
michael@0:     : Stackwalker(system_info, memory, modules, resolver_helper),
michael@0:       context_(context) {
michael@0:   if (memory_ && memory_->GetBase() + memory_->GetSize() - 1 > 0xffffffff) {
michael@0:     // This implementation only covers 32-bit ppc CPUs.  The limits of the
michael@0:     // supplied stack are invalid.  Mark memory_ = NULL, which will cause
michael@0:     // stackwalking to fail.
michael@0:     BPLOG(ERROR) << "Memory out of range for stackwalking: " <<
michael@0:                     HexString(memory_->GetBase()) << "+" <<
michael@0:                     HexString(memory_->GetSize());
michael@0:     memory_ = NULL;
michael@0:   }
michael@0: }
michael@0: 
michael@0: 
michael@0: StackFrame* StackwalkerPPC::GetContextFrame() {
michael@0:   if (!context_) {
michael@0:     BPLOG(ERROR) << "Can't get context frame without context";
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   StackFramePPC* frame = new StackFramePPC();
michael@0: 
michael@0:   // The instruction pointer is stored directly in a register, so pull it
michael@0:   // straight out of the CPU context structure.
michael@0:   frame->context = *context_;
michael@0:   frame->context_validity = StackFramePPC::CONTEXT_VALID_ALL;
michael@0:   frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
michael@0:   frame->instruction = frame->context.srr0;
michael@0: 
michael@0:   return frame;
michael@0: }
michael@0: 
michael@0: 
michael@0: StackFrame* StackwalkerPPC::GetCallerFrame(const CallStack* stack,
michael@0:                                            bool stack_scan_allowed) {
michael@0:   if (!memory_ || !stack) {
michael@0:     BPLOG(ERROR) << "Can't get caller frame without memory or stack";
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   // The instruction pointers for previous frames are saved on the stack.
michael@0:   // The typical ppc calling convention is for the called procedure to store
michael@0:   // its return address in the calling procedure's stack frame at 8(%r1),
michael@0:   // and to allocate its own stack frame by decrementing %r1 (the stack
michael@0:   // pointer) and saving the old value of %r1 at 0(%r1).  Because the ppc has
michael@0:   // no hardware stack, there is no distinction between the stack pointer and
michael@0:   // frame pointer, and what is typically thought of as the frame pointer on
michael@0:   // an x86 is usually referred to as the stack pointer on a ppc.
michael@0: 
michael@0:   StackFramePPC* last_frame = static_cast<StackFramePPC*>(
michael@0:       stack->frames()->back());
michael@0: 
michael@0:   // A caller frame must reside higher in memory than its callee frames.
michael@0:   // Anything else is an error, or an indication that we've reached the
michael@0:   // end of the stack.
michael@0:   uint32_t stack_pointer;
michael@0:   if (!memory_->GetMemoryAtAddress(last_frame->context.gpr[1],
michael@0:                                    &stack_pointer) ||
michael@0:       stack_pointer <= last_frame->context.gpr[1]) {
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   // Mac OS X/Darwin gives 1 as the return address from the bottom-most
michael@0:   // frame in a stack (a thread's entry point).  I haven't found any
michael@0:   // documentation on this, but 0 or 1 would be bogus return addresses,
michael@0:   // so check for them here and return false (end of stack) when they're
michael@0:   // hit to avoid having a phantom frame.
michael@0:   uint32_t instruction;
michael@0:   if (!memory_->GetMemoryAtAddress(stack_pointer + 8, &instruction) ||
michael@0:       instruction <= 1) {
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   StackFramePPC* frame = new StackFramePPC();
michael@0: 
michael@0:   frame->context = last_frame->context;
michael@0:   frame->context.srr0 = instruction;
michael@0:   frame->context.gpr[1] = stack_pointer;
michael@0:   frame->context_validity = StackFramePPC::CONTEXT_VALID_SRR0 |
michael@0:                             StackFramePPC::CONTEXT_VALID_GPR1;
michael@0:   frame->trust = StackFrame::FRAME_TRUST_FP;
michael@0: 
michael@0:   // frame->context.srr0 is the return address, which is one instruction
michael@0:   // past the branch that caused us to arrive at the callee.  Set
michael@0:   // frame_ppc->instruction to four less than that.  Since all ppc
michael@0:   // instructions are 4 bytes wide, this is the address of the branch
michael@0:   // instruction.  This allows source line information to match up with the
michael@0:   // line that contains a function call.  Callers that require the exact
michael@0:   // return address value may access the context.srr0 field of StackFramePPC.
michael@0:   frame->instruction = frame->context.srr0 - 4;
michael@0: 
michael@0:   return frame;
michael@0: }
michael@0: 
michael@0: 
michael@0: }  // namespace google_breakpad