Breakpad Linux client: Simplify VerifyStackReadWithMultipleThreads unit test.

As written, the VerifyStackReadWithMultipleThreads unit test makes
assumptions about the layout of thread_function's stack frame. As a result,
the test will fail when compiled with some compilers, or built with certain
optimization levels.

As an extension to C++, the GNU compilers allow you to request that a
variable be placed in a specific register. Using this, we can have
thread_function put the thread id in place where the test can find it
reliably.

a=jimblandy, r=nealsid


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@558 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
jimblandy 2010-03-29 18:23:42 +00:00
parent 18dd9d0104
commit b68b800189
2 changed files with 19 additions and 10 deletions

View file

@ -108,16 +108,16 @@ TEST(LinuxDumperTest, VerifyStackReadWithMultipleThreads) {
ThreadInfo one_thread;
for(size_t i = 0; i < dumper.threads().size(); ++i) {
EXPECT_TRUE(dumper.ThreadInfoGet(dumper.threads()[i], &one_thread));
// We know the threads are in a function which has allocated exactly
// one word off the stack to store its thread id.
// In the helper program, we stored a pointer to the thread id in a
// specific register. Check that we can recover its value.
#if defined(__ARM_EABI__)
void* process_tid_location = (void *)(one_thread.regs.uregs[11] - 8);
pid_t *process_tid_location = (pid_t *)(one_thread.regs.uregs[3]);
#elif defined(__i386)
void* process_tid_location = (void *)(one_thread.regs.ebp - 4);
pid_t *process_tid_location = (pid_t *)(one_thread.regs.ecx);
#elif defined(__x86_64)
void* process_tid_location = (void *)(one_thread.regs.rbp - 4);
pid_t *process_tid_location = (pid_t *)(one_thread.regs.rcx);
#else
#error Platform not supported!
#error This test has not been ported to this platform.
#endif
pid_t one_thread_id;
dumper.CopyFromProcess(&one_thread_id,

View file

@ -37,13 +37,22 @@
#include <sys/syscall.h>
#include <unistd.h>
#pragma GCC optimize ("O0")
void *thread_function(void *data) __attribute__((noinline, optimize("O2")));
#if defined(__ARM_EABI__)
#define TID_PTR_REGISTER "r3"
#elif defined(__i386)
#define TID_PTR_REGISTER "ecx"
#elif defined(__x86_64)
#define TID_PTR_REGISTER "rcx"
#else
#error This test has not been ported to this platform.
#endif
void *thread_function(void *data) {
pid_t thread_id = syscall(SYS_gettid);
while (true) ;
asm("");
register pid_t *thread_id_ptr asm(TID_PTR_REGISTER) = &thread_id;
while (true)
asm("" : : "r" (thread_id_ptr));
return NULL;
}
int main(int argc, char *argv[]) {