> /* test if signal handling preserves XMM registers */
> #include <stdio.h>
> #include <unistd.h>
> #include <signal.h>
>
> int count;
>
> void sighandler(int signum)
> {
> count++;
>
> /* alarm(1) without calling libc */
> asm("mov $0x1,%rdi");
> asm("mov $0x25,%rax");
> asm("syscall");
>
> asm("movq $0xdeadbeef,%r11");
> /* the following two instructions
> * modify xmm0 and xmm1 registers */
> asm("vmovq %r11,%xmm0");
> asm("vmovq %r11,%xmm1");
> }
>
> int main()
> {
> struct sigaction act;
> double a = 3.14159, b = 2.71828;
>
> act.sa_handler = sighandler;
> act.sa_flags = 0;
> sigemptyset(&act.sa_mask);
> sigaction(SIGALRM, &act, NULL);
>
> alarm(1);
>
> /* this loop should run indefinitely */
> while (a + b == a + b) ;
>
> printf("count = %d\n", count);
if you put a break here in gdb, and dump the FPU regs, what does it
say?
Can be that either we a lacking or missplaced a fwait (to flush FPU)
> return 1;
> }
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