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