Attachment 577270 Details for Bug 810668 – Reproducer

Reproducer

fp2.c (text/plain), 1.21 KB, created by Chuck Ebbert on 2012-04-13 08:34:09 UTC

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Creator: Chuck Ebbert

Created: 2012-04-13 08:34:09 UTC

Size: 1.21 KB

patch

obsolete

>#define _GNU_SOURCE
>#include <unistd.h>
>#include <assert.h>
>#include <sys/wait.h>
>#include <sys/procfs.h>
>#include <sys/ptrace.h>
>
>int main(int argc, char **argv)
>{
>	pid_t child;
>	elf_fpregset_t fpregs;
>	int i, j, status;
>
>	child = fork();
>	assert(child != -1);
>
>	if (child == 0) {
>		ptrace(PTRACE_TRACEME, 0, NULL, NULL);
>		__asm__ __volatile__("fldz; fld1; fld1; fadd %st,%st"); /* stack: 0 1 2 <--top */
>
>		for (i = 0; i < 20; i++) {
>			kill(getpid(), SIGSTOP);
>			__asm__ __volatile__("fadd %st(2), %st;"); /* use FPU; do nothing */
>		}
>
>		return 0;
>	}
>
>#define fpstack(n) (*(__float80 *)((char *)(&fpregs.st_space) + (n)*16))
>	for (j = 0; j < 20+1; j++) {
>		waitpid(child, &status, 0);
>		if (WIFEXITED(status) || WIFSIGNALED(status))
>			break;
>
>		assert(!ptrace(PTRACE_GETFPREGS, child, NULL, &fpregs));
>		assert(fpstack(1) == 1.0 && fpstack(2) == 0.0);
>
>		if (j == 10) { /* replace 2 on stack top with 42 */
>			assert(fpstack(0) == 2.0);
>			fpstack(0) = 42.0;
>			assert(!ptrace(PTRACE_SETFPREGS, child, NULL, &fpregs));
>		} else if (j > 10) /* parent should now be seeing 42 */
>			assert(fpstack(0) == 42.0);
>
>		usleep(1000); /* let other processes run */
>		ptrace(PTRACE_CONT, child, NULL, NULL);
>	}
>
>	assert(j == 20);
>	return 0;
>}
>
>

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Attachments on bug 810668: 575976 | 577270 | 577491 | 578300