Commit f7a5d72e authored by Mark Brown's avatar Mark Brown Committed by Catalin Marinas
Browse files

kselftest/arm64: Add a test case for TPIDR2 restore 



Due to the fact that TPIDR2 is intended to be managed by libc we don't
currently test modifying it via the signal context since that might
disrupt libc's usage of it and cause instability. We can however test the
opposite case with less risk, modifying TPIDR2 in a signal handler and
making sure that the original value is restored after returning from the
signal handler. Add a test which does this.

Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230621-arm64-fix-tpidr2-signal-restore-v2-2-c8e8fcc10302@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 616cb2f4

tools/testing/selftests/arm64/signal/.gitignore

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ fake_sigreturn_* 
sme_*

ssve_*

sve_*

tpidr2_siginfo

tpidr2_*

za_*

zt_*

!*.[ch]

tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c

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// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (C) 2023 ARM Limited

 *

 * Verify that the TPIDR2 register context in signal frames is restored.

 */



#include <signal.h>

#include <ucontext.h>

#include <sys/auxv.h>

#include <sys/prctl.h>

#include <unistd.h>

#include <asm/sigcontext.h>



#include "test_signals_utils.h"

#include "testcases.h"



#define SYS_TPIDR2 "S3_3_C13_C0_5"



static uint64_t get_tpidr2(void)

{

	uint64_t val;



	asm volatile (

		"mrs	%0, " SYS_TPIDR2 "\n"

		: "=r"(val)

		:

		: "cc");



	return val;

}



static void set_tpidr2(uint64_t val)

{

	asm volatile (

		"msr	" SYS_TPIDR2 ", %0\n"

		:

		: "r"(val)

		: "cc");

}





static uint64_t initial_tpidr2;



static bool save_tpidr2(struct tdescr *td)

{

	initial_tpidr2 = get_tpidr2();

	fprintf(stderr, "Initial TPIDR2: %lx\n", initial_tpidr2);



	return true;

}



static int modify_tpidr2(struct tdescr *td, siginfo_t *si, ucontext_t *uc)

{

	uint64_t my_tpidr2 = get_tpidr2();



	my_tpidr2++;

	fprintf(stderr, "Setting TPIDR2 to %lx\n", my_tpidr2);

	set_tpidr2(my_tpidr2);



	return 0;

}



static void check_tpidr2(struct tdescr *td)

{

	uint64_t tpidr2 = get_tpidr2();



	td->pass = tpidr2 == initial_tpidr2;



	if (td->pass)

		fprintf(stderr, "TPIDR2 restored\n");

	else

		fprintf(stderr, "TPIDR2 was %lx but is now %lx\n",

			initial_tpidr2, tpidr2);

}



struct tdescr tde = {

	.name = "TPIDR2 restore",

	.descr = "Validate that TPIDR2 is restored from the sigframe",

	.feats_required = FEAT_SME,

	.timeout = 3,

	.sig_trig = SIGUSR1,

	.init = save_tpidr2,

	.run = modify_tpidr2,

	.check_result = check_tpidr2,

};