mirror of
https://github.com/ioacademy-jikim/debugging
synced 2025-06-08 00:16:11 +00:00
96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
/* Test if values in rax, rbx, rcx, rdx, rsi and rdi are correctly propagated
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into and out of a signal handler and also check that the same applies for
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uninitialised values and their origins. */
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#include <assert.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <sys/ucontext.h>
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static siginfo_t si;
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static ucontext_t uc;
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/* x0 is always zero, but is visible to Valgrind as uninitialised. */
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static long x0;
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void break_out(void);
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static void sighandler(int sig, siginfo_t *sip, ucontext_t *ucp)
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{
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si = *sip;
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uc = *ucp;
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ucp->uc_mcontext.gregs[REG_RCX] = x0;
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/* Break out of the endless loop. */
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*(uintptr_t*)&ucp->uc_mcontext.gregs[REG_RIP] = (uintptr_t)break_out;
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}
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int main(void)
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{
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struct sigaction sa;
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long rax, rbx, rcx, rdx, rsi, rdi;
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long y0;
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/* Uninitialised, but we know px[0] is 0x0. */
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long *px = malloc(sizeof(*px));
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x0 = px[0];
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/* Uninitialised, but we know py[0] is 0x0. */
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long *py = malloc(sizeof(*py));
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y0 = py[0];
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sa.sa_handler = sighandler;
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sa.sa_flags = SA_SIGINFO;
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if (sigfillset(&sa.sa_mask)) {
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perror("sigfillset");
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return 1;
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}
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if (sigaction(SIGALRM, &sa, NULL)) {
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perror("sigaction");
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return 1;
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}
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alarm(2);
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__asm__ __volatile__(
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/* Set values in general purpose registers. */
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"movq $0xf0, %%rax\n"
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"movq %[y0], %%rbx\n"
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"movq $0xf1, %%rcx\n"
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"movq $0xf2, %%rdx\n"
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"movq $0xf3, %%rsi\n"
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"movq $0xf4, %%rdi\n"
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/* Loopity loop, this is where the SIGALRM is triggered. */
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"1:\n"
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"jmp 1b\n"
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"break_out:\n"
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: "=a" (rax), "=b" (rbx), "=c" (rcx), "=d" (rdx), "=S" (rsi),
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"=D" (rdi)
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: [y0] "m" (y0)
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: "cc", "memory");
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printf("Values in the signal handler:\n");
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printf(" rax=%#lx, rcx=%#lx, rdx=%#lx, rsi=%#lx, rdi=%#lx\n",
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uc.uc_mcontext.gregs[REG_RAX], uc.uc_mcontext.gregs[REG_RCX],
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uc.uc_mcontext.gregs[REG_RDX], uc.uc_mcontext.gregs[REG_RSI],
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uc.uc_mcontext.gregs[REG_RDI]);
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/* Check that rbx contains an uninitialised value (origin is py[0]). */
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if (uc.uc_mcontext.gregs[REG_RBX])
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assert(0);
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printf("Values after the return from the signal handler:\n");
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printf(" rax=%#lx, rdx=%#lx, rsi=%#lx, rdi=%#lx\n", rax, rdx, rsi, rdi);
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/* Check that rbx and rcx contain uninitialised values (origin is py[0]
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and px[0], respectively). */
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if (rbx || rcx)
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assert(0);
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return 0;
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}
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