tools/testing/selftests/x86/sigaltstack.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/x86/sigaltstack.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/x86/sigaltstack.c
Extension
.c
Size
2321 bytes
Lines
107
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only

#define _GNU_SOURCE
#include <signal.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <sys/mman.h>
#include <sys/auxv.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <setjmp.h>

#include "helpers.h"

/* sigaltstack()-enforced minimum stack */
#define ENFORCED_MINSIGSTKSZ	2048

#ifndef AT_MINSIGSTKSZ
#  define AT_MINSIGSTKSZ	51
#endif

static int nerrs;

static bool sigalrm_expected;

static unsigned long at_minstack_size;

static int setup_altstack(void *start, unsigned long size)
{
	stack_t ss;

	memset(&ss, 0, sizeof(ss));
	ss.ss_size = size;
	ss.ss_sp = start;

	return sigaltstack(&ss, NULL);
}

static jmp_buf jmpbuf;

static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
	if (sigalrm_expected) {
		printf("[FAIL]\tWrong signal delivered: SIGSEGV (expected SIGALRM).");
		nerrs++;
	} else {
		printf("[OK]\tSIGSEGV signal delivered.\n");
	}

	siglongjmp(jmpbuf, 1);
}

static void sigalrm(int sig, siginfo_t *info, void *ctx_void)
{
	if (!sigalrm_expected) {
		printf("[FAIL]\tWrong signal delivered: SIGALRM (expected SIGSEGV).");
		nerrs++;
	} else {
		printf("[OK]\tSIGALRM signal delivered.\n");
	}
}

static void test_sigaltstack(void *altstack, unsigned long size)
{
	if (setup_altstack(altstack, size))
		err(1, "sigaltstack()");

	sigalrm_expected = (size > at_minstack_size) ? true : false;

	sethandler(SIGSEGV, sigsegv, 0);
	sethandler(SIGALRM, sigalrm, SA_ONSTACK);

	if (!sigsetjmp(jmpbuf, 1)) {
		printf("[RUN]\tTest an alternate signal stack of %ssufficient size.\n",
		       sigalrm_expected ? "" : "in");
		printf("\tRaise SIGALRM. %s is expected to be delivered.\n",
		       sigalrm_expected ? "It" : "SIGSEGV");
		raise(SIGALRM);
	}

	clearhandler(SIGALRM);
	clearhandler(SIGSEGV);
}

int main(void)
{

Annotation

Implementation Notes