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ESP is zero in dumps created by CrashGenerationClient::RequestDump on i386 Linux

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Patch by Bruce Dawson <bruce.dawson@gmail.com>, R=ted at https://breakpad.appspot.com/533002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1149 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
ted.mielczarek@gmail.com 2013-04-16 17:51:10 +00:00
parent bc54c38679
commit 1974aaba51
1 changed files with 30 additions and 0 deletions
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30
src/client/linux/handler/exception_handler.cc
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@ -549,6 +549,13 @@ bool ExceptionHandler::WriteMinidump(const string& dump_path,
return eh.WriteMinidump();
}
// In order to making using EBP to calculate the desired value for ESP
// a valid operation, ensure that this function is compiled with a
// frame pointer using the following attribute. This attribute
// is supported on GCC but not on clang.
#if defined(__i386__) && defined(__GNUC__) && !defined(__clang__)
__attribute__((optimize("no-omit-frame-pointer")))
#endif
bool ExceptionHandler::WriteMinidump() {
if (!IsOutOfProcess() && !minidump_descriptor_.IsFD()) {
// Update the path of the minidump so that this can be called multiple times
@ -570,6 +577,29 @@ bool ExceptionHandler::WriteMinidump() {
int getcontext_result = getcontext(&context.context);
if (getcontext_result)
return false;
#if defined(__i386__)
// In CPUFillFromUContext in minidumpwriter.cc the stack pointer is retrieved
// from REG_UESP instead of from REG_ESP. REG_UESP is the user stack pointer
// and it only makes sense when running in kernel mode with a different stack
// pointer. When WriteMiniDump is called during normal processing REG_UESP is
// zero which leads to bad minidump files.
if (!context.context.uc_mcontext.gregs[REG_UESP]) {
// If REG_UESP is set to REG_ESP then that includes the stack space for the
// CrashContext object in this function, which is about 128 KB. Since the
// Linux dumper only records 32 KB of stack this would mean that nothing
// useful would be recorded. A better option is to set REG_UESP to REG_EBP,
// perhaps with a small negative offset in case there is any code that
// objects to them being equal.
context.context.uc_mcontext.gregs[REG_UESP] =
context.context.uc_mcontext.gregs[REG_EBP] - 16;
// The stack saving is based off of REG_ESP so it must be set to match the
// new REG_UESP.
context.context.uc_mcontext.gregs[REG_ESP] =
context.context.uc_mcontext.gregs[REG_UESP];
}
#endif
#if !defined(__ARM_EABI__)
// FPU state is not part of ARM EABI ucontext_t.
memcpy(&context.float_state, context.context.uc_mcontext.fpregs,