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Breakpad processor: Segregate STACK WIN vs. traditional stack walking.

Browse source 
This patch moves the code for finding caller frames using STACK WIN
data and the code to do so using the traditional frame layout (%ebp
points at saved %ebp, pushed just after return address) into their own
functions. In addition to making things a little clearer, this is
preparation for adding support for STACK CFI records into the mix.

a=jimblandy, r=mmentovai


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@512 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
jimblandy 2010-02-05 18:04:56 +00:00
parent 89e07bf2c7
commit 7f1455601d
2 changed files with 245 additions and 169 deletions
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393
src/processor/stackwalker_x86.cc
View file

@ -36,13 +36,14 @@
#include "processor/postfix_evaluator-inl.h" #include "processor/postfix_evaluator-inl.h"
#include "processor/stackwalker_x86.h"
#include "google_breakpad/processor/call_stack.h" #include "google_breakpad/processor/call_stack.h"
#include "google_breakpad/processor/code_modules.h" #include "google_breakpad/processor/code_modules.h"
#include "google_breakpad/processor/memory_region.h" #include "google_breakpad/processor/memory_region.h"
#include "google_breakpad/processor/stack_frame_cpu.h"
#include "google_breakpad/processor/source_line_resolver_interface.h" #include "google_breakpad/processor/source_line_resolver_interface.h"
#include "google_breakpad/processor/stack_frame_cpu.h"
#include "processor/logging.h" #include "processor/logging.h"
#include "processor/scoped_ptr.h"
#include "processor/stackwalker_x86.h"
#include "processor/windows_frame_info.h" #include "processor/windows_frame_info.h"
namespace google_breakpad { namespace google_breakpad {
@ -72,7 +73,7 @@ StackFrameX86::~StackFrameX86() {
windows_frame_info = NULL; windows_frame_info = NULL;
} }
StackFrame* StackwalkerX86::GetContextFrame() { StackFrame *StackwalkerX86::GetContextFrame() {
if (!context_ || !memory_) { if (!context_ || !memory_) {
BPLOG(ERROR) << "Can't get context frame without context or memory"; BPLOG(ERROR) << "Can't get context frame without context or memory";
return NULL; return NULL;
@ -90,23 +91,23 @@ StackFrame* StackwalkerX86::GetContextFrame() {
return frame; return frame;
} }
StackFrameX86 *StackwalkerX86::GetCallerByWindowsFrameInfo(
StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) { const vector<StackFrame *> &frames,
if (!memory_ || !stack) { WindowsFrameInfo *last_frame_info) {
BPLOG(ERROR) << "Can't get caller frame without memory or stack";
return NULL;
}
StackFrameX86::FrameTrust trust = StackFrameX86::FRAME_TRUST_NONE; StackFrameX86::FrameTrust trust = StackFrameX86::FRAME_TRUST_NONE;
StackFrameX86 *last_frame = static_cast<StackFrameX86*>(
stack->frames()->back());
WindowsFrameInfo *last_frame_info StackFrameX86 *last_frame = static_cast<StackFrameX86 *>(frames.back());
= resolver_->FindWindowsFrameInfo(last_frame);
// Save the stack walking info we found, in case we need it later to // Save the stack walking info we found, in case we need it later to
// find the callee of the frame we're constructing now. // find the callee of the frame we're constructing now.
last_frame->windows_frame_info = last_frame_info; last_frame->windows_frame_info = last_frame_info;
// This function only covers the full STACK WIN case. If
// last_frame_info is VALID_PARAMETER_SIZE-only, then we should
// assume the traditional frame format or use some other strategy.
if (last_frame_info->valid != WindowsFrameInfo::VALID_ALL)
return NULL;
// This stackwalker sets each frame's %esp to its value immediately prior // This stackwalker sets each frame's %esp to its value immediately prior
// to the CALL into the callee. This means that %esp points to the last // to the CALL into the callee. This means that %esp points to the last
// callee argument pushed onto the stack, which may not be where %esp points // callee argument pushed onto the stack, which may not be where %esp points
@ -139,12 +140,11 @@ StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) {
// are unknown, 0 is also used in that case. When that happens, it should // are unknown, 0 is also used in that case. When that happens, it should
// be possible to walk to the next frame without reference to %esp. // be possible to walk to the next frame without reference to %esp.
int frames_already_walked = stack->frames()->size();
u_int32_t last_frame_callee_parameter_size = 0; u_int32_t last_frame_callee_parameter_size = 0;
int frames_already_walked = frames.size();
if (frames_already_walked >= 2) { if (frames_already_walked >= 2) {
StackFrameX86 *last_frame_callee const StackFrameX86 *last_frame_callee
= static_cast<StackFrameX86 *>((*stack->frames()) = static_cast<StackFrameX86 *>(frames[frames_already_walked - 2]);
[frames_already_walked - 2]);
WindowsFrameInfo *last_frame_callee_info WindowsFrameInfo *last_frame_callee_info
= last_frame_callee->windows_frame_info; = last_frame_callee->windows_frame_info;
if (last_frame_callee_info && if (last_frame_callee_info &&
@ -157,148 +157,105 @@ StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) {
// Set up the dictionary for the PostfixEvaluator. %ebp and %esp are used // Set up the dictionary for the PostfixEvaluator. %ebp and %esp are used
// in each program string, and their previous values are known, so set them // in each program string, and their previous values are known, so set them
// here. .cbCalleeParams is a Breakpad extension that allows us to use // here.
// the PostfixEvaluator engine when certain types of debugging information
// are present without having to write the constants into the program string
// as literals.
PostfixEvaluator<u_int32_t>::DictionaryType dictionary; PostfixEvaluator<u_int32_t>::DictionaryType dictionary;
// Provide the current register values.
dictionary["$ebp"] = last_frame->context.ebp; dictionary["$ebp"] = last_frame->context.ebp;
dictionary["$esp"] = last_frame->context.esp; dictionary["$esp"] = last_frame->context.esp;
// Provide constants from the debug info for last_frame and its callee.
// .cbCalleeParams is a Breakpad extension that allows us to use the
// PostfixEvaluator engine when certain types of debugging information
// are present without having to write the constants into the program
// string as literals.
dictionary[".cbCalleeParams"] = last_frame_callee_parameter_size; dictionary[".cbCalleeParams"] = last_frame_callee_parameter_size;
dictionary[".cbSavedRegs"] = last_frame_info->saved_register_size;
dictionary[".cbLocals"] = last_frame_info->local_size;
dictionary[".raSearchStart"] = last_frame->context.esp +
last_frame_callee_parameter_size +
last_frame_info->local_size +
last_frame_info->saved_register_size;
dictionary[".cbParams"] = last_frame_info->parameter_size;
if (last_frame_info && last_frame_info->valid == WindowsFrameInfo::VALID_ALL) { // Decide what type of program string to use. The program string is in
// FPO debugging data is available. Initialize constants.
dictionary[".cbSavedRegs"] = last_frame_info->saved_register_size;
dictionary[".cbLocals"] = last_frame_info->local_size;
dictionary[".raSearchStart"] = last_frame->context.esp +
last_frame_callee_parameter_size +
last_frame_info->local_size +
last_frame_info->saved_register_size;
}
if (last_frame_info &&
last_frame_info->valid & WindowsFrameInfo::VALID_PARAMETER_SIZE) {
// This is treated separately because it can either come from FPO data or
// from other debugging data.
dictionary[".cbParams"] = last_frame_info->parameter_size;
}
// Decide what type of program string to use. The program string is in
// postfix notation and will be passed to PostfixEvaluator::Evaluate. // postfix notation and will be passed to PostfixEvaluator::Evaluate.
// Given the dictionary and the program string, it is possible to compute // Given the dictionary and the program string, it is possible to compute
// the return address and the values of other registers in the calling // the return address and the values of other registers in the calling
// function. When encountering a nontraditional frame (one which takes // function. Because of bugs described below, the stack may need to be
// advantage of FPO), the stack may need to be scanned for these values. // scanned for these values. The results of program string evaluation
// For traditional frames, simple deterministic dereferencing suffices
// without any need for scanning. The results of program string evaluation
// will be used to determine whether to scan for better values. // will be used to determine whether to scan for better values.
string program_string; string program_string;
bool traditional_frame = true;
bool recover_ebp = true; bool recover_ebp = true;
if (last_frame_info && last_frame_info->valid == WindowsFrameInfo::VALID_ALL) {
// FPO data available. trust = StackFrameX86::FRAME_TRUST_CFI;
traditional_frame = false; if (!last_frame_info->program_string.empty()) {
trust = StackFrameX86::FRAME_TRUST_CFI; // The FPO data has its own program string, which will tell us how to
if (!last_frame_info->program_string.empty()) { // get to the caller frame, and may even fill in the values of
// The FPO data has its own program string, which will tell us how to // nonvolatile registers and provide pointers to local variables and
// get to the caller frame, and may even fill in the values of // parameters. In some cases, particularly with program strings that use
// nonvolatile registers and provide pointers to local variables and // .raSearchStart, the stack may need to be scanned afterward.
// parameters. In some cases, particularly with program strings that use program_string = last_frame_info->program_string;
// .raSearchStart, the stack may need to be scanned afterward. } else if (last_frame_info->allocates_base_pointer) {
program_string = last_frame_info->program_string; // The function corresponding to the last frame doesn't use the frame
} else if (last_frame_info->allocates_base_pointer) { // pointer for conventional purposes, but it does allocate a new
// The function corresponding to the last frame doesn't use the frame // frame pointer and use it for its own purposes. Its callee's
// pointer for conventional purposes, but it does allocate a new // information is still accessed relative to %esp, and the previous
// frame pointer and use it for its own purposes. Its callee's // value of %ebp can be recovered from a location in its stack frame,
// information is still accessed relative to %esp, and the previous // within the saved-register area.
// value of %ebp can be recovered from a location in its stack frame, //
// within the saved-register area. // Functions that fall into this category use the %ebp register for
// // a purpose other than the frame pointer. They restore the caller's
// Functions that fall into this category use the %ebp register for // %ebp before returning. These functions create their stack frame
// a purpose other than the frame pointer. They restore the caller's // after a CALL by decrementing the stack pointer in an amount
// %ebp before returning. These functions create their stack frame // sufficient to store local variables, and then PUSHing saved
// after a CALL by decrementing the stack pointer in an amount // registers onto the stack. Arguments to a callee function, if any,
// sufficient to store local variables, and then PUSHing saved // are PUSHed after that. Walking up to the caller, therefore,
// registers onto the stack. Arguments to a callee function, if any, // can be done solely with calculations relative to the stack pointer
// are PUSHed after that. Walking up to the caller, therefore, // (%esp). The return address is recovered from the memory location
// can be done solely with calculations relative to the stack pointer // above the known sizes of the callee's parameters, saved registers,
// (%esp). The return address is recovered from the memory location // and locals. The caller's stack pointer (the value of %esp when
// above the known sizes of the callee's parameters, saved registers, // the caller executed CALL) is the location immediately above the
// and locals. The caller's stack pointer (the value of %esp when // saved return address. The saved value of %ebp to be restored for
// the caller executed CALL) is the location immediately above the // the caller is at a known location in the saved-register area of
// saved return address. The saved value of %ebp to be restored for // the stack frame.
// the caller is at a known location in the saved-register area of //
// the stack frame. // For this type of frame, MSVC 14 (from Visual Studio 8/2005) in
// // link-time code generation mode (/LTCG and /GL) can generate erroneous
// For this type of frame, MSVC 14 (from Visual Studio 8/2005) in // debugging data. The reported size of saved registers can be 0,
// link-time code generation mode (/LTCG and /GL) can generate erroneous // which is clearly an error because these frames must, at the very
// debugging data. The reported size of saved registers can be 0, // least, save %ebp. For this reason, in addition to those given above
// which is clearly an error because these frames must, at the very // about the use of .raSearchStart, the stack may need to be scanned
// least, save %ebp. For this reason, in addition to those given above // for a better return address and a better frame pointer after the
// about the use of .raSearchStart, the stack may need to be scanned // program string is evaluated.
// for a better return address and a better frame pointer after the //
// program string is evaluated. // %eip_new = *(%esp_old + callee_params + saved_regs + locals)
// // %ebp_new = *(%esp_old + callee_params + saved_regs - 8)
// %eip_new = *(%esp_old + callee_params + saved_regs + locals) // %esp_new = %esp_old + callee_params + saved_regs + locals + 4
// %ebp_new = *(%esp_old + callee_params + saved_regs - 8) program_string = "$eip .raSearchStart ^ = "
// %esp_new = %esp_old + callee_params + saved_regs + locals + 4 "$ebp $esp .cbCalleeParams + .cbSavedRegs + 8 - ^ = "
program_string = "$eip .raSearchStart ^ = " "$esp .raSearchStart 4 + =";
"$ebp $esp .cbCalleeParams + .cbSavedRegs + 8 - ^ = "
"$esp .raSearchStart 4 + =";
} else {
// The function corresponding to the last frame doesn't use %ebp at
// all. The callee frame is located relative to %esp.
//
// The called procedure's instruction pointer and stack pointer are
// recovered in the same way as the case above, except that no
// frame pointer (%ebp) is used at all, so it is not saved anywhere
// in the callee's stack frame and does not need to be recovered.
// Because %ebp wasn't used in the callee, whatever value it has
// is the value that it had in the caller, so it can be carried
// straight through without bringing its validity into question.
//
// Because of the use of .raSearchStart, the stack will possibly be
// examined to locate a better return address after program string
// evaluation. The stack will not be examined to locate a saved
// %ebp value, because these frames do not save (or use) %ebp.
//
// %eip_new = *(%esp_old + callee_params + saved_regs + locals)
// %esp_new = %esp_old + callee_params + saved_regs + locals + 4
// %ebp_new = %ebp_old
program_string = "$eip .raSearchStart ^ = "
"$esp .raSearchStart 4 + =";
recover_ebp = false;
}
} else { } else {
// No FPO information is available for the last frame. Assume that the // The function corresponding to the last frame doesn't use %ebp at
// standard %ebp-using x86 calling convention is in use. // all. The callee frame is located relative to %esp.
// //
// The typical x86 calling convention, when frame pointers are present, // The called procedure's instruction pointer and stack pointer are
// is for the calling procedure to use CALL, which pushes the return // recovered in the same way as the case above, except that no
// address onto the stack and sets the instruction pointer (%eip) to // frame pointer (%ebp) is used at all, so it is not saved anywhere
// the entry point of the called routine. The called routine then // in the callee's stack frame and does not need to be recovered.
// PUSHes the calling routine's frame pointer (%ebp) onto the stack // Because %ebp wasn't used in the callee, whatever value it has
// before copying the stack pointer (%esp) to the frame pointer (%ebp). // is the value that it had in the caller, so it can be carried
// Therefore, the calling procedure's frame pointer is always available // straight through without bringing its validity into question.
// 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.
// //
// Instruction and frame pointer recovery for these traditional frames is // Because of the use of .raSearchStart, the stack will possibly be
// entirely deterministic, and the stack will not be scanned after // examined to locate a better return address after program string
// recovering these values. // evaluation. The stack will not be examined to locate a saved
// %ebp value, because these frames do not save (or use) %ebp.
// //
// %eip_new = *(%ebp_old + 4) // %eip_new = *(%esp_old + callee_params + saved_regs + locals)
// %esp_new = %ebp_old + 8 // %esp_new = %esp_old + callee_params + saved_regs + locals + 4
// %ebp_new = *(%ebp_old) // %ebp_new = %ebp_old
trust = StackFrameX86::FRAME_TRUST_FP; program_string = "$eip .raSearchStart ^ = "
program_string = "$eip $ebp 4 + ^ = " "$esp .raSearchStart 4 + =";
"$esp $ebp 8 + = " recover_ebp = false;
"$ebp $ebp ^ =";
} }
// Now crank it out, making sure that the program string set at least the // Now crank it out, making sure that the program string set at least the
@ -331,15 +288,14 @@ StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) {
trust = StackFrameX86::FRAME_TRUST_SCAN; trust = StackFrameX86::FRAME_TRUST_SCAN;
} }
// If this stack frame did not use %ebp in a traditional way, locating the // Since this stack frame did not use %ebp in a traditional way,
// return address isn't entirely deterministic. In that case, the stack // locating the return address isn't entirely deterministic. In that
// can be scanned to locate the return address. // case, the stack can be scanned to locate the return address.
// //
// Even in nontraditional frames, if program string evaluation resulted in // However, if program string evaluation resulted in both %eip and
// both %eip and %ebp values of 0, trust that the end of the stack has been // %ebp values of 0, trust that the end of the stack has been
// reached and don't scan for anything else. // reached and don't scan for anything else.
if (!traditional_frame && if (dictionary["$eip"] != 0 || dictionary["$ebp"] != 0) {
(dictionary["$eip"] != 0 || dictionary["$ebp"] != 0)) {
int offset = 0; int offset = 0;
// This scan can only be done if a CodeModules object is available, to // This scan can only be done if a CodeModules object is available, to
@ -401,13 +357,6 @@ StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) {
} }
} }
// Treat an instruction address of 0 as end-of-stack. Treat incorrect stack
// direction as end-of-stack to enforce progress and avoid infinite loops.
if (dictionary["$eip"] == 0 ||
dictionary["$esp"] <= last_frame->context.esp) {
return NULL;
}
// Create a new stack frame (ownership will be transferred to the caller) // Create a new stack frame (ownership will be transferred to the caller)
// and fill it in. // and fill it in.
StackFrameX86 *frame = new StackFrameX86(); StackFrameX86 *frame = new StackFrameX86();
@ -436,19 +385,129 @@ StackFrame* StackwalkerX86::GetCallerFrame(const CallStack *stack) {
frame->context_validity |= StackFrameX86::CONTEXT_VALID_EDI; frame->context_validity |= StackFrameX86::CONTEXT_VALID_EDI;
} }
// frame->context.eip is the return address, which is one instruction return frame;
// past the CALL that caused us to arrive at the callee. Set }
// 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 StackFrameX86 *StackwalkerX86::GetCallerByEBPAtBase(
// CALL, which is sufficient to get the source line information to match up const vector<StackFrame *> &frames) {
// with the line that contains a function call. Callers that require the StackFrameX86::FrameTrust trust;
// exact return address value may access the context.eip field of StackFrameX86 *last_frame = static_cast<StackFrameX86 *>(frames.back());
// StackFrameX86. u_int32_t last_esp = last_frame->context.esp;
frame->instruction = frame->context.eip - 1; 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; 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 we have 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));
// Otherwise, hope that we're 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, bool StackwalkerX86::ScanForReturnAddress(u_int32_t location_start,
u_int32_t *location_found, u_int32_t *location_found,
u_int32_t *eip_found) { u_int32_t *eip_found) {

21
src/processor/stackwalker_x86.h
View file

@ -1,3 +1,5 @@
// -*- mode: c++ -*-
// Copyright (c) 2006, Google Inc. // Copyright (c) 2006, Google Inc.
// All rights reserved. // All rights reserved.
// //
@ -42,6 +44,7 @@
#include "google_breakpad/common/breakpad_types.h" #include "google_breakpad/common/breakpad_types.h"
#include "google_breakpad/common/minidump_format.h" #include "google_breakpad/common/minidump_format.h"
#include "google_breakpad/processor/stackwalker.h" #include "google_breakpad/processor/stackwalker.h"
#include "google_breakpad/processor/stack_frame_cpu.h"
namespace google_breakpad { namespace google_breakpad {
@ -66,8 +69,22 @@ class StackwalkerX86 : public Stackwalker {
// stack conventions (saved %ebp at [%ebp], saved %eip at 4[%ebp], or // stack conventions (saved %ebp at [%ebp], saved %eip at 4[%ebp], or
// alternate conventions as guided by any WindowsFrameInfo available for the // alternate conventions as guided by any WindowsFrameInfo available for the
// code in question.). // code in question.).
virtual StackFrame* GetContextFrame(); virtual StackFrame *GetContextFrame();
virtual StackFrame* GetCallerFrame(const CallStack *stack); virtual StackFrame *GetCallerFrame(const CallStack *stack);
// Use windows_frame_info (derived from STACK WIN and FUNC records)
// to construct the frame that called frames.back(). The caller
// takes ownership of the returned frame. Return NULL on failure.
StackFrameX86 *GetCallerByWindowsFrameInfo(
const vector<StackFrame*> &frames,
WindowsFrameInfo *windows_frame_info);
// Assuming a traditional frame layout --- where the caller's %ebp
// has been pushed just after the return address and the callee's
// %ebp points to the saved %ebp --- construct the frame that called
// frames.back(). The caller takes ownership of the returned frame.
// Return NULL on failure.
StackFrameX86 *GetCallerByEBPAtBase(const vector<StackFrame*> &frames);
// Scan the stack starting at location_start, looking for an address // Scan the stack starting at location_start, looking for an address
// that looks like a valid instruction pointer. Addresses must // that looks like a valid instruction pointer. Addresses must