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// ---
// Author: Craig Silverstein
//
// This verifies that GetPC works correctly. This test uses a minimum
// of Google infrastructure, to make it very easy to port to various
// O/Ses and CPUs and test that GetPC is working.
#include "config.h"
#include "getpc.h" // should be first to get the _GNU_SOURCE dfn
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/time.h> // for setitimer
// Needs to be volatile so compiler doesn't try to optimize it away
static volatile void* getpc_retval = NULL; // what GetPC returns
static volatile bool prof_handler_called = false;
static void prof_handler(int sig, siginfo_t*, void* signal_ucontext) {
if (!prof_handler_called)
getpc_retval = GetPC(*reinterpret_cast<ucontext_t*>(signal_ucontext));
prof_handler_called = true; // only store the retval once
}
static void RoutineCallingTheSignal() {
struct sigaction sa;
sa.sa_sigaction = prof_handler;
sa.sa_flags = SA_RESTART | SA_SIGINFO;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGPROF, &sa, NULL) != 0) {
perror("sigaction");
exit(1);
}
struct itimerval timer;
timer.it_interval.tv_sec = 0;
timer.it_interval.tv_usec = 1000;
timer.it_value = timer.it_interval;
setitimer(ITIMER_PROF, &timer, 0);
// Now we need to do some work for a while, that doesn't call any
// other functions, so we can be guaranteed that when the SIGPROF
// fires, we're the routine executing.
int r = 0;
for (int i = 0; !prof_handler_called; ++i) {
for (int j = 0; j < i; j++) {
r ^= i;
r <<= 1;
r ^= j;
r >>= 1;
}
}
// Now make sure the above loop doesn't get optimized out
srand(r);
}
// This is an upper bound of how many bytes the instructions for
// RoutineCallingTheSignal might be. There's probably a more
// principled way to do this, but I don't know how portable it would be.
// (The function is 372 bytes when compiled with -g on Mac OS X 10.4.
// I can imagine it would be even bigger in 64-bit architectures.)
const int kRoutineSize = 512 * sizeof(void*)/4; // allow 1024 for 64-bit
int main(int argc, char** argv) {
RoutineCallingTheSignal();
// Annoyingly, C++ disallows casting pointer-to-function to
// pointer-to-object, so we use a C-style cast instead.
char* expected = (char*)&RoutineCallingTheSignal;
char* actual = (char*)getpc_retval;
// For ia64, ppc64, and parisc64, the function pointer is actually
// a struct. For instance, ia64's dl-fptr.h:
// struct fdesc { /* An FDESC is a function descriptor. */
// ElfW(Addr) ip; /* code entry point */
// ElfW(Addr) gp; /* global pointer */
// };
// We want the code entry point.
#if defined(__ia64) || defined(__ppc64) // NOTE: ppc64 is UNTESTED
expected = ((char**)expected)[0]; // this is "ip"
#endif
if (actual < expected || actual > expected + kRoutineSize) {
printf("Test FAILED: actual PC: %p, expected PC: %p\n", actual, expected);
return 1;
} else {
printf("PASS\n");
return 0;
}
}