sig_longjmp.cpp

Go to the documentation of this file.

// setjmp/longjmp: non-C++ stack unwinding. cctlib has separate hooks for
// setjmp/longjmp (CaptureSigSetJmpCtxt/HoldLongJmpBuf/RestoreSigLongJmpCtxt).
// This test ensures the exception-path resolver changes don't regress that
// path. ITERS bounded so the CCT fits under Pin's Fini stack budget.
//
// sjlj_try_marker (before go_deep) and sjlj_landing_marker (post-longjmp
// on the setjmp-returns-nonzero path) verify both are direct children of
// main -- setjmp/longjmp's re-anchor must not leave the landing block
// dangling under go_deep's or __longjmp's subtree.
#include <cstdint>
#include <cstdio>
#include <setjmp.h>
#define ITERS 500
static volatile uint64_t sink;
static uint64_t buf[ITERS];
static jmp_buf jb;
 
extern "C" __attribute__((noinline)) void sjlj_try_marker(int i) {
    __asm__ __volatile__("" ::: "memory"); sink ^= (uint64_t)i;
}
extern "C" __attribute__((noinline)) void sjlj_landing_marker(int i) {
    __asm__ __volatile__("" ::: "memory"); sink ^= (uint64_t)i << 8;
}
 
static void go_deep(int i, int depth) {
    volatile uint64_t local = 0;
    if (depth == 0) {
        buf[i] = 0xEE;
        longjmp(jb, i + 1);   // never returns
    }
    go_deep(i, depth - 1);
    (void)local;
}
 
int main(int argc, char** argv) {
    (void)argc; (void)argv;
    int jumps = 0;
    for (int i = 0; i < ITERS; ++i) {
        int rc = setjmp(jb);
        if (rc == 0) {
            sjlj_try_marker(i);
            go_deep(i, 8);
        } else {
            sjlj_landing_marker(i);
            buf[i] ^= 0x77;
            ++jumps;
        }
    }
    for (int i = 0; i < ITERS; ++i) sink ^= buf[i];
    fprintf(stderr, "sig_longjmp: jumps=%d iters=%d sink=%llx\n",
            jumps, ITERS, (unsigned long long)sink);
    return jumps == ITERS ? 0 : 1;
}