Commit fdf4eb63 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

selftests/rseq: Validate legacy behavior 



The RSEQ legacy mode behavior requires that the ID fields in the rseq
region are unconditionally updated on every context switch and before
signal delivery even if not required by the ABI specification.

To ensure that this behavior is preserved for legacy users in the future,
add a test which validates that with a sleep() and a signal sent to self.

Provide a run script which prevents GLIBC from registering a RSEQ region,
so that the test can register it's own legacy sized region.

Fixes: 566d8015 ("rseq: Avoid CPU/MM CID updates when no event pending")
Signed-off-by: default avatarThomas Gleixner <tglx@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarDmitry Vyukov <dvyukov@google.com>
Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
Link: https://patch.msgid.link/20260428224427.764705536%40kernel.org
Cc: stable@vger.kernel.org
parent d97cb2ef

tools/testing/selftests/rseq/Makefile

+3 −2
Original line number Diff line number Diff line
@@ -22,9 +22,10 @@ TEST_GEN_PROGS_EXTENDED = librseq.so \ 
	param_test_compare_twice \

	param_test_mm_cid \

	param_test_mm_cid_compare_twice \

	syscall_errors_test

	syscall_errors_test \

	legacy_check



TEST_PROGS = run_param_test.sh run_syscall_errors_test.sh

TEST_PROGS = run_param_test.sh run_syscall_errors_test.sh run_legacy_check.sh



TEST_FILES := settings

tools/testing/selftests/rseq/legacy_check.c

0 → 100644
+65 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#ifndef _GNU_SOURCE

#define _GNU_SOURCE

#endif



#include <errno.h>

#include <signal.h>

#include <stdint.h>

#include <unistd.h>



#include "rseq.h"



#include "../kselftest_harness.h"



FIXTURE(legacy)

{

};



static int cpu_id_in_sigfn = -1;



static void sigfn(int sig)

{

	struct rseq_abi *rs = rseq_get_abi();



	cpu_id_in_sigfn = rs->cpu_id_start;

}



FIXTURE_SETUP(legacy)

{

	int res = __rseq_register_current_thread(true, true);



	switch (res) {

	case -ENOSYS:

		SKIP(return, "RSEQ not enabled\n");

	case -EBUSY:

		SKIP(return, "GLIBC owns RSEQ. Disable GLIBC RSEQ registration\n");

	default:

		ASSERT_EQ(res, 0);

	}



	ASSERT_NE(signal(SIGUSR1, sigfn), SIG_ERR);

}



FIXTURE_TEARDOWN(legacy)

{

}



TEST_F(legacy, legacy_test)

{

	struct rseq_abi *rs = rseq_get_abi();



	ASSERT_NE(rs, NULL);



	/* Overwrite rs::cpu_id_start */

	rs->cpu_id_start = -1;

	sleep(1);

	ASSERT_NE(rs->cpu_id_start, -1);



	rs->cpu_id_start = -1;

	ASSERT_EQ(raise(SIGUSR1), 0);

	ASSERT_NE(rs->cpu_id_start, -1);

	ASSERT_NE(cpu_id_in_sigfn, -1);

}



TEST_HARNESS_MAIN

tools/testing/selftests/rseq/run_legacy_check.sh

0 → 100755
+4 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0



GLIBC_TUNABLES="${GLIBC_TUNABLES:-}:glibc.pthread.rseq=0" ./legacy_check