| /* 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/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, ucontext_t *ucp) |
| { |
| 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_handler = 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; |
| } |
| |