6d3a825dbf
Add a CFIFrameInfo class (named for symmetry with WindowsFrameInfo) to represent the set of STACK CFI rules in effect at a given instruction, and apply them to a set of register values. Provide a SimpleCFIWalker class template, to allow the essential CFI code to be shared amongst the different architectures. Teach BasicSourceLineResolver to partially parse 'STACK CFI' records, and produce the set of rules in effect at a given instruction on demand, by combining the initial rule set and the appropriate rule deltas in a CFIFrameInfo object. Adapt StackwalkerX86 and StackFrameX86 to retrieve, store, and apply CFI stack walking information. Add validity flags for all the general-purpose registers to StackFrameX86::ContextValidity. a=jimblandy, r=mmentovai git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@549 4c0a9323-5329-0410-9bdc-e9ce6186880e
599 lines
27 KiB
C++
599 lines
27 KiB
C++
// Copyright (c) 2010 Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// stackwalker_x86.cc: x86-specific stackwalker.
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//
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// See stackwalker_x86.h for documentation.
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//
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// Author: Mark Mentovai
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#include "processor/postfix_evaluator-inl.h"
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#include "google_breakpad/processor/call_stack.h"
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#include "google_breakpad/processor/code_modules.h"
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#include "google_breakpad/processor/memory_region.h"
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#include "google_breakpad/processor/source_line_resolver_interface.h"
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#include "google_breakpad/processor/stack_frame_cpu.h"
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#include "processor/logging.h"
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#include "processor/scoped_ptr.h"
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#include "processor/stackwalker_x86.h"
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#include "processor/windows_frame_info.h"
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#include "processor/cfi_frame_info.h"
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namespace google_breakpad {
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const StackwalkerX86::CFIWalker::RegisterSet
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StackwalkerX86::cfi_register_map_[] = {
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// It may seem like $eip and $esp are callee-saves, because (with Unix or
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// cdecl calling conventions) the callee is responsible for having them
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// restored upon return. But the callee_saves flags here really means
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// that the walker should assume they're unchanged if the CFI doesn't
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// mention them, which is clearly wrong for $eip and $esp.
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{ "$eip", ".ra", false,
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StackFrameX86::CONTEXT_VALID_EIP, &MDRawContextX86::eip },
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{ "$esp", ".cfa", false,
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StackFrameX86::CONTEXT_VALID_ESP, &MDRawContextX86::esp },
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{ "$ebp", NULL, true,
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StackFrameX86::CONTEXT_VALID_EBP, &MDRawContextX86::ebp },
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{ "$eax", NULL, false,
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StackFrameX86::CONTEXT_VALID_EAX, &MDRawContextX86::eax },
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{ "$ebx", NULL, true,
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StackFrameX86::CONTEXT_VALID_EBX, &MDRawContextX86::ebx },
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{ "$ecx", NULL, false,
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StackFrameX86::CONTEXT_VALID_ECX, &MDRawContextX86::ecx },
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{ "$edx", NULL, false,
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StackFrameX86::CONTEXT_VALID_EDX, &MDRawContextX86::edx },
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{ "$esi", NULL, true,
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StackFrameX86::CONTEXT_VALID_ESI, &MDRawContextX86::esi },
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{ "$edi", NULL, true,
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StackFrameX86::CONTEXT_VALID_EDI, &MDRawContextX86::edi },
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};
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StackwalkerX86::StackwalkerX86(const SystemInfo *system_info,
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const MDRawContextX86 *context,
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MemoryRegion *memory,
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const CodeModules *modules,
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SymbolSupplier *supplier,
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SourceLineResolverInterface *resolver)
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: Stackwalker(system_info, memory, modules, supplier, resolver),
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context_(context),
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cfi_walker_(cfi_register_map_,
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(sizeof(cfi_register_map_) / sizeof(cfi_register_map_[0]))) {
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if (memory_->GetBase() + memory_->GetSize() - 1 > 0xffffffff) {
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// The x86 is a 32-bit CPU, the limits of the supplied stack are invalid.
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// Mark memory_ = NULL, which will cause stackwalking to fail.
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BPLOG(ERROR) << "Memory out of range for stackwalking: " <<
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HexString(memory_->GetBase()) << "+" <<
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HexString(memory_->GetSize());
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memory_ = NULL;
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}
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}
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StackFrameX86::~StackFrameX86() {
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if (windows_frame_info)
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delete windows_frame_info;
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windows_frame_info = NULL;
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if (cfi_frame_info)
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delete cfi_frame_info;
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cfi_frame_info = NULL;
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}
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StackFrame *StackwalkerX86::GetContextFrame() {
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if (!context_ || !memory_) {
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BPLOG(ERROR) << "Can't get context frame without context or memory";
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return NULL;
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}
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StackFrameX86 *frame = new StackFrameX86();
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// The instruction pointer is stored directly in a register, so pull it
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// straight out of the CPU context structure.
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frame->context = *context_;
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frame->context_validity = StackFrameX86::CONTEXT_VALID_ALL;
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frame->trust = StackFrameX86::FRAME_TRUST_CONTEXT;
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frame->instruction = frame->context.eip;
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return frame;
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}
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StackFrameX86 *StackwalkerX86::GetCallerByWindowsFrameInfo(
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const vector<StackFrame *> &frames,
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WindowsFrameInfo *last_frame_info) {
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StackFrameX86::FrameTrust trust = StackFrameX86::FRAME_TRUST_NONE;
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StackFrameX86 *last_frame = static_cast<StackFrameX86 *>(frames.back());
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// Save the stack walking info we found, in case we need it later to
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// find the callee of the frame we're constructing now.
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last_frame->windows_frame_info = last_frame_info;
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// This function only covers the full STACK WIN case. If
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// last_frame_info is VALID_PARAMETER_SIZE-only, then we should
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// assume the traditional frame format or use some other strategy.
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if (last_frame_info->valid != WindowsFrameInfo::VALID_ALL)
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return NULL;
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// This stackwalker sets each frame's %esp to its value immediately prior
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// to the CALL into the callee. This means that %esp points to the last
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// callee argument pushed onto the stack, which may not be where %esp points
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// after the callee returns. Specifically, the value is correct for the
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// cdecl calling convention, but not other conventions. The cdecl
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// convention requires a caller to pop its callee's arguments from the
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// stack after the callee returns. This is usually accomplished by adding
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// the known size of the arguments to %esp. Other calling conventions,
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// including stdcall, thiscall, and fastcall, require the callee to pop any
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// parameters stored on the stack before returning. This is usually
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// accomplished by using the RET n instruction, which pops n bytes off
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// the stack after popping the return address.
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//
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// Because each frame's %esp will point to a location on the stack after
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// callee arguments have been PUSHed, when locating things in a stack frame
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// relative to %esp, the size of the arguments to the callee need to be
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// taken into account. This seems a little bit unclean, but it's better
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// than the alternative, which would need to take these same things into
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// account, but only for cdecl functions. With this implementation, we get
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// to be agnostic about each function's calling convention. Furthermore,
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// this is how Windows debugging tools work, so it means that the %esp
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// values produced by this stackwalker directly correspond to the %esp
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// values you'll see there.
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//
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// If the last frame has no callee (because it's the context frame), just
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// set the callee parameter size to 0: the stack pointer can't point to
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// callee arguments because there's no callee. This is correct as long
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// as the context wasn't captured while arguments were being pushed for
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// a function call. Note that there may be functions whose parameter sizes
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// are unknown, 0 is also used in that case. When that happens, it should
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// be possible to walk to the next frame without reference to %esp.
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u_int32_t last_frame_callee_parameter_size = 0;
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int frames_already_walked = frames.size();
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if (frames_already_walked >= 2) {
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const StackFrameX86 *last_frame_callee
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= static_cast<StackFrameX86 *>(frames[frames_already_walked - 2]);
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WindowsFrameInfo *last_frame_callee_info
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= last_frame_callee->windows_frame_info;
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if (last_frame_callee_info &&
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(last_frame_callee_info->valid
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& WindowsFrameInfo::VALID_PARAMETER_SIZE)) {
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last_frame_callee_parameter_size =
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last_frame_callee_info->parameter_size;
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}
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}
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// Set up the dictionary for the PostfixEvaluator. %ebp and %esp are used
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// in each program string, and their previous values are known, so set them
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// here.
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PostfixEvaluator<u_int32_t>::DictionaryType dictionary;
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// Provide the current register values.
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dictionary["$ebp"] = last_frame->context.ebp;
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dictionary["$esp"] = last_frame->context.esp;
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// Provide constants from the debug info for last_frame and its callee.
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// .cbCalleeParams is a Breakpad extension that allows us to use the
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// PostfixEvaluator engine when certain types of debugging information
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// are present without having to write the constants into the program
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// string as literals.
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dictionary[".cbCalleeParams"] = last_frame_callee_parameter_size;
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dictionary[".cbSavedRegs"] = last_frame_info->saved_register_size;
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dictionary[".cbLocals"] = last_frame_info->local_size;
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dictionary[".raSearchStart"] = last_frame->context.esp +
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last_frame_callee_parameter_size +
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last_frame_info->local_size +
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last_frame_info->saved_register_size;
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dictionary[".cbParams"] = last_frame_info->parameter_size;
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// Decide what type of program string to use. The program string is in
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// postfix notation and will be passed to PostfixEvaluator::Evaluate.
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// Given the dictionary and the program string, it is possible to compute
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// the return address and the values of other registers in the calling
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// function. Because of bugs described below, the stack may need to be
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// scanned for these values. The results of program string evaluation
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// will be used to determine whether to scan for better values.
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string program_string;
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bool recover_ebp = true;
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trust = StackFrameX86::FRAME_TRUST_CFI;
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if (!last_frame_info->program_string.empty()) {
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// The FPO data has its own program string, which will tell us how to
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// get to the caller frame, and may even fill in the values of
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// nonvolatile registers and provide pointers to local variables and
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// parameters. In some cases, particularly with program strings that use
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// .raSearchStart, the stack may need to be scanned afterward.
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program_string = last_frame_info->program_string;
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} else if (last_frame_info->allocates_base_pointer) {
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// The function corresponding to the last frame doesn't use the frame
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// pointer for conventional purposes, but it does allocate a new
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// frame pointer and use it for its own purposes. Its callee's
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// information is still accessed relative to %esp, and the previous
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// value of %ebp can be recovered from a location in its stack frame,
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// within the saved-register area.
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//
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// Functions that fall into this category use the %ebp register for
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// a purpose other than the frame pointer. They restore the caller's
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// %ebp before returning. These functions create their stack frame
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// after a CALL by decrementing the stack pointer in an amount
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// sufficient to store local variables, and then PUSHing saved
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// registers onto the stack. Arguments to a callee function, if any,
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// are PUSHed after that. Walking up to the caller, therefore,
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// can be done solely with calculations relative to the stack pointer
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// (%esp). The return address is recovered from the memory location
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// above the known sizes of the callee's parameters, saved registers,
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// and locals. The caller's stack pointer (the value of %esp when
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// the caller executed CALL) is the location immediately above the
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// saved return address. The saved value of %ebp to be restored for
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// the caller is at a known location in the saved-register area of
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// the stack frame.
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//
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// For this type of frame, MSVC 14 (from Visual Studio 8/2005) in
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// link-time code generation mode (/LTCG and /GL) can generate erroneous
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// debugging data. The reported size of saved registers can be 0,
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// which is clearly an error because these frames must, at the very
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// least, save %ebp. For this reason, in addition to those given above
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// about the use of .raSearchStart, the stack may need to be scanned
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// for a better return address and a better frame pointer after the
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// program string is evaluated.
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//
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// %eip_new = *(%esp_old + callee_params + saved_regs + locals)
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// %ebp_new = *(%esp_old + callee_params + saved_regs - 8)
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// %esp_new = %esp_old + callee_params + saved_regs + locals + 4
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program_string = "$eip .raSearchStart ^ = "
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"$ebp $esp .cbCalleeParams + .cbSavedRegs + 8 - ^ = "
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"$esp .raSearchStart 4 + =";
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} else {
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// The function corresponding to the last frame doesn't use %ebp at
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// all. The callee frame is located relative to %esp.
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//
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// The called procedure's instruction pointer and stack pointer are
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// recovered in the same way as the case above, except that no
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// frame pointer (%ebp) is used at all, so it is not saved anywhere
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// in the callee's stack frame and does not need to be recovered.
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// Because %ebp wasn't used in the callee, whatever value it has
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// is the value that it had in the caller, so it can be carried
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// straight through without bringing its validity into question.
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//
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// Because of the use of .raSearchStart, the stack will possibly be
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// examined to locate a better return address after program string
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// evaluation. The stack will not be examined to locate a saved
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// %ebp value, because these frames do not save (or use) %ebp.
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//
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// %eip_new = *(%esp_old + callee_params + saved_regs + locals)
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// %esp_new = %esp_old + callee_params + saved_regs + locals + 4
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// %ebp_new = %ebp_old
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program_string = "$eip .raSearchStart ^ = "
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"$esp .raSearchStart 4 + =";
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recover_ebp = false;
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}
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// Now crank it out, making sure that the program string set at least the
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// two required variables.
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PostfixEvaluator<u_int32_t> evaluator =
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PostfixEvaluator<u_int32_t>(&dictionary, memory_);
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PostfixEvaluator<u_int32_t>::DictionaryValidityType dictionary_validity;
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if (!evaluator.Evaluate(program_string, &dictionary_validity) ||
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dictionary_validity.find("$eip") == dictionary_validity.end() ||
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dictionary_validity.find("$esp") == dictionary_validity.end()) {
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// Program string evaluation failed. It may be that %eip is not somewhere
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// with stack frame info, and %ebp is pointing to non-stack memory, so
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// our evaluation couldn't succeed. We'll scan the stack for a return
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// address. This can happen if the stack is in a module for which
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// we don't have symbols, and that module is compiled without a
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// frame pointer.
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u_int32_t location_start = last_frame->context.esp;
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u_int32_t location, eip;
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if (!ScanForReturnAddress(location_start, &location, &eip)) {
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// if we can't find an instruction pointer even with stack scanning,
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// give up.
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return NULL;
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}
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// This seems like a reasonable return address. Since program string
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// evaluation failed, use it and set %esp to the location above the
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// one where the return address was found.
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dictionary["$eip"] = eip;
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dictionary["$esp"] = location + 4;
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trust = StackFrameX86::FRAME_TRUST_SCAN;
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}
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// Since this stack frame did not use %ebp in a traditional way,
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// locating the return address isn't entirely deterministic. In that
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// case, the stack can be scanned to locate the return address.
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//
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// However, if program string evaluation resulted in both %eip and
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// %ebp values of 0, trust that the end of the stack has been
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// reached and don't scan for anything else.
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if (dictionary["$eip"] != 0 || dictionary["$ebp"] != 0) {
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int offset = 0;
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// This scan can only be done if a CodeModules object is available, to
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// check that candidate return addresses are in fact inside a module.
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//
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// TODO(mmentovai): This ignores dynamically-generated code. One possible
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// solution is to check the minidump's memory map to see if the candidate
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// %eip value comes from a mapped executable page, although this would
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// require dumps that contain MINIDUMP_MEMORY_INFO, which the Breakpad
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// client doesn't currently write (it would need to call MiniDumpWriteDump
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// with the MiniDumpWithFullMemoryInfo type bit set). Even given this
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// ability, older OSes (pre-XP SP2) and CPUs (pre-P4) don't enforce
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// an independent execute privilege on memory pages.
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u_int32_t eip = dictionary["$eip"];
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if (modules_ && !modules_->GetModuleForAddress(eip)) {
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// The instruction pointer at .raSearchStart was invalid, so start
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// looking one 32-bit word above that location.
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u_int32_t location_start = dictionary[".raSearchStart"] + 4;
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u_int32_t location;
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if (ScanForReturnAddress(location_start, &location, &eip)) {
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// This is a better return address that what program string
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// evaluation found. Use it, and set %esp to the location above the
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// one where the return address was found.
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dictionary["$eip"] = eip;
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dictionary["$esp"] = location + 4;
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offset = location - location_start;
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trust = StackFrameX86::FRAME_TRUST_CFI_SCAN;
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}
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}
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// When trying to recover the previous value of the frame pointer (%ebp),
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// start looking at the lowest possible address in the saved-register
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// area, and look at the entire saved register area, increased by the
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// size of |offset| to account for additional data that may be on the
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// stack. The scan is performed from the highest possible address to
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// the lowest, because we expect that the function's prolog would have
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// saved %ebp early.
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u_int32_t ebp = dictionary["$ebp"];
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u_int32_t value; // throwaway variable to check pointer validity
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if (recover_ebp && !memory_->GetMemoryAtAddress(ebp, &value)) {
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int fp_search_bytes = last_frame_info->saved_register_size + offset;
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u_int32_t location_end = last_frame->context.esp +
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last_frame_callee_parameter_size;
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for (u_int32_t location = location_end + fp_search_bytes;
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location >= location_end;
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location -= 4) {
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if (!memory_->GetMemoryAtAddress(location, &ebp))
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break;
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if (memory_->GetMemoryAtAddress(ebp, &value)) {
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// The candidate value is a pointer to the same memory region
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// (the stack). Prefer it as a recovered %ebp result.
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dictionary["$ebp"] = ebp;
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break;
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}
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}
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}
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}
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// Create a new stack frame (ownership will be transferred to the caller)
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// and fill it in.
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StackFrameX86 *frame = new StackFrameX86();
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frame->trust = trust;
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frame->context = last_frame->context;
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frame->context.eip = dictionary["$eip"];
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frame->context.esp = dictionary["$esp"];
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frame->context.ebp = dictionary["$ebp"];
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frame->context_validity = StackFrameX86::CONTEXT_VALID_EIP |
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StackFrameX86::CONTEXT_VALID_ESP |
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StackFrameX86::CONTEXT_VALID_EBP;
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// These are nonvolatile (callee-save) registers, and the program string
|
|
// may have filled them in.
|
|
if (dictionary_validity.find("$ebx") != dictionary_validity.end()) {
|
|
frame->context.ebx = dictionary["$ebx"];
|
|
frame->context_validity |= StackFrameX86::CONTEXT_VALID_EBX;
|
|
}
|
|
if (dictionary_validity.find("$esi") != dictionary_validity.end()) {
|
|
frame->context.esi = dictionary["$esi"];
|
|
frame->context_validity |= StackFrameX86::CONTEXT_VALID_ESI;
|
|
}
|
|
if (dictionary_validity.find("$edi") != dictionary_validity.end()) {
|
|
frame->context.edi = dictionary["$edi"];
|
|
frame->context_validity |= StackFrameX86::CONTEXT_VALID_EDI;
|
|
}
|
|
|
|
return frame;
|
|
}
|
|
|
|
StackFrameX86 *StackwalkerX86::GetCallerByCFIFrameInfo(
|
|
const vector<StackFrame*> &frames,
|
|
CFIFrameInfo *cfi_frame_info) {
|
|
StackFrameX86 *last_frame = static_cast<StackFrameX86*>(frames.back());
|
|
last_frame->cfi_frame_info = cfi_frame_info;
|
|
|
|
scoped_ptr<StackFrameX86> frame(new StackFrameX86());
|
|
if (!cfi_walker_
|
|
.FindCallerRegisters(*memory_, *cfi_frame_info,
|
|
last_frame->context, last_frame->context_validity,
|
|
&frame->context, &frame->context_validity))
|
|
return NULL;
|
|
|
|
// Make sure we recovered all the essentials.
|
|
static const int essentials = (StackFrameX86::CONTEXT_VALID_EIP
|
|
| StackFrameX86::CONTEXT_VALID_ESP
|
|
| StackFrameX86::CONTEXT_VALID_EBP);
|
|
if ((frame->context_validity & essentials) != essentials)
|
|
return NULL;
|
|
|
|
frame->trust = StackFrameX86::FRAME_TRUST_CFI;
|
|
|
|
return frame.release();
|
|
}
|
|
|
|
StackFrameX86 *StackwalkerX86::GetCallerByEBPAtBase(
|
|
const vector<StackFrame *> &frames) {
|
|
StackFrameX86::FrameTrust trust;
|
|
StackFrameX86 *last_frame = static_cast<StackFrameX86 *>(frames.back());
|
|
u_int32_t last_esp = last_frame->context.esp;
|
|
u_int32_t last_ebp = last_frame->context.ebp;
|
|
|
|
// Assume that the standard %ebp-using x86 calling convention is in
|
|
// use.
|
|
//
|
|
// The typical x86 calling convention, when frame pointers are present,
|
|
// is for the calling procedure to use CALL, which pushes the return
|
|
// address onto the stack and sets the instruction pointer (%eip) to
|
|
// the entry point of the called routine. The called routine then
|
|
// PUSHes the calling routine's frame pointer (%ebp) onto the stack
|
|
// before copying the stack pointer (%esp) to the frame pointer (%ebp).
|
|
// Therefore, the calling procedure's frame pointer is always available
|
|
// by dereferencing the called procedure's frame pointer, and the return
|
|
// address is always available at the memory location immediately above
|
|
// the address pointed to by the called procedure's frame pointer. The
|
|
// calling procedure's stack pointer (%esp) is 8 higher than the value
|
|
// of the called procedure's frame pointer at the time the calling
|
|
// procedure made the CALL: 4 bytes for the return address pushed by the
|
|
// CALL itself, and 4 bytes for the callee's PUSH of the caller's frame
|
|
// pointer.
|
|
//
|
|
// %eip_new = *(%ebp_old + 4)
|
|
// %esp_new = %ebp_old + 8
|
|
// %ebp_new = *(%ebp_old)
|
|
|
|
u_int32_t caller_eip, caller_esp, caller_ebp;
|
|
|
|
if (memory_->GetMemoryAtAddress(last_ebp + 4, &caller_eip) &&
|
|
memory_->GetMemoryAtAddress(last_ebp, &caller_ebp)) {
|
|
caller_esp = last_ebp + 8;
|
|
trust = StackFrameX86::FRAME_TRUST_FP;
|
|
} else {
|
|
// We couldn't read the memory %ebp refers to. It may be that %ebp
|
|
// is pointing to non-stack memory. We'll scan the stack for a
|
|
// return address. This can happen if last_frame is executing code
|
|
// for a module for which we don't have symbols, and that module
|
|
// is compiled without a frame pointer.
|
|
if (!ScanForReturnAddress(last_esp, &caller_esp, &caller_eip)) {
|
|
// if we can't find an instruction pointer even with stack scanning,
|
|
// give up.
|
|
return false;
|
|
}
|
|
|
|
// ScanForReturnAddress found a reasonable return address. Advance
|
|
// %esp to the location above the one where the return address was
|
|
// found. Assume that %ebp is unchanged.
|
|
caller_esp += 4;
|
|
caller_ebp = last_ebp;
|
|
|
|
trust = StackFrameX86::FRAME_TRUST_SCAN;
|
|
}
|
|
|
|
// Create a new stack frame (ownership will be transferred to the caller)
|
|
// and fill it in.
|
|
StackFrameX86 *frame = new StackFrameX86();
|
|
|
|
frame->trust = trust;
|
|
frame->context = last_frame->context;
|
|
frame->context.eip = caller_eip;
|
|
frame->context.esp = caller_esp;
|
|
frame->context.ebp = caller_ebp;
|
|
frame->context_validity = StackFrameX86::CONTEXT_VALID_EIP |
|
|
StackFrameX86::CONTEXT_VALID_ESP |
|
|
StackFrameX86::CONTEXT_VALID_EBP;
|
|
|
|
return frame;
|
|
}
|
|
|
|
StackFrame *StackwalkerX86::GetCallerFrame(const CallStack *stack) {
|
|
if (!memory_ || !stack) {
|
|
BPLOG(ERROR) << "Can't get caller frame without memory or stack";
|
|
return NULL;
|
|
}
|
|
|
|
const vector<StackFrame *> &frames = *stack->frames();
|
|
StackFrameX86 *last_frame = static_cast<StackFrameX86 *>(frames.back());
|
|
scoped_ptr<StackFrameX86> new_frame;
|
|
|
|
// If the resolver has Windows stack walking information, use that.
|
|
WindowsFrameInfo *windows_frame_info
|
|
= resolver_->FindWindowsFrameInfo(last_frame);
|
|
if (windows_frame_info)
|
|
new_frame.reset(GetCallerByWindowsFrameInfo(frames, windows_frame_info));
|
|
|
|
// If the resolver has DWARF CFI information, use that.
|
|
if (!new_frame.get()) {
|
|
CFIFrameInfo *cfi_frame_info = resolver_->FindCFIFrameInfo(last_frame);
|
|
if (cfi_frame_info)
|
|
new_frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info));
|
|
}
|
|
|
|
// Otherwise, hope that the program was using a traditional frame structure.
|
|
if (!new_frame.get())
|
|
new_frame.reset(GetCallerByEBPAtBase(frames));
|
|
|
|
// If nothing worked, tell the caller.
|
|
if (!new_frame.get())
|
|
return NULL;
|
|
|
|
// Treat an instruction address of 0 as end-of-stack.
|
|
if (new_frame->context.eip == 0)
|
|
return NULL;
|
|
|
|
// If the new stack pointer is at a lower address than the old, then
|
|
// that's clearly incorrect. Treat this as end-of-stack to enforce
|
|
// progress and avoid infinite loops.
|
|
if (new_frame->context.esp <= last_frame->context.esp)
|
|
return NULL;
|
|
|
|
// new_frame->context.eip is the return address, which is one instruction
|
|
// past the CALL that caused us to arrive at the callee. Set
|
|
// new_frame->instruction to one less than that. This won't reference the
|
|
// beginning of the CALL instruction, but it's guaranteed to be within
|
|
// the CALL, which is sufficient to get the source line information to
|
|
// match up with the line that contains a function call. Callers that
|
|
// require the exact return address value may access the context.eip
|
|
// field of StackFrameX86.
|
|
new_frame->instruction = new_frame->context.eip - 1;
|
|
|
|
return new_frame.release();
|
|
}
|
|
|
|
bool StackwalkerX86::ScanForReturnAddress(u_int32_t location_start,
|
|
u_int32_t *location_found,
|
|
u_int32_t *eip_found) {
|
|
const int kRASearchWords = 15;
|
|
for (u_int32_t location = location_start;
|
|
location <= location_start + kRASearchWords * 4;
|
|
location += 4) {
|
|
u_int32_t eip;
|
|
if (!memory_->GetMemoryAtAddress(location, &eip))
|
|
break;
|
|
|
|
if (modules_ && modules_->GetModuleForAddress(eip) &&
|
|
InstructionAddressSeemsValid(eip)) {
|
|
|
|
*eip_found = eip;
|
|
*location_found = location;
|
|
return true;
|
|
}
|
|
}
|
|
// nothing found
|
|
return false;
|
|
}
|
|
|
|
} // namespace google_breakpad
|