Commit 7615b94b authored by David Woodhouse's avatar David Woodhouse Committed by Ingo Molnar
Browse files

selftests/kexec: Add x86_64 selftest for kexec-jump and exception handling 



Add a self test which exercises both the kexec-jump facility, and the
kexec exception handling.

Invoke a trivial payload which just does an int3 and returns,
flip-flopping its entry point for the next invocation between two
implementations of the same thing.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250326142404.256980-5-dwmw2@infradead.org
parent de085ddd

tools/testing/selftests/kexec/Makefile

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@@ -8,6 +8,13 @@ ifeq ($(ARCH_PROCESSED),$(filter $(ARCH_PROCESSED),x86 ppc64le)) 
TEST_PROGS := test_kexec_load.sh test_kexec_file_load.sh

TEST_FILES := kexec_common_lib.sh



include ../../../scripts/Makefile.arch



ifeq ($(IS_64_BIT)$(ARCH_PROCESSED),1x86)

TEST_PROGS += test_kexec_jump.sh

test_kexec_jump.sh: $(OUTPUT)/test_kexec_jump

endif



include ../lib.mk



endif

tools/testing/selftests/kexec/test_kexec_jump.c

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Original line number Diff line number Diff line 
#include <unistd.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <linux/kexec.h>

#include <linux/reboot.h>

#include <sys/reboot.h>

#include <sys/syscall.h>



asm(

    "  .code64\n"

    "  .data\n"

    "purgatory_start:\n"



    // Trigger kexec debug exception handling

    "  int3\n"



    // Set load address for next time

    "  leaq purgatory_start_b(%rip), %r11\n"

    "  movq %r11, 8(%rsp)\n"



    // Back to Linux

    "  ret\n"



    // Same again

    "purgatory_start_b:\n"



    // Trigger kexec debug exception handling

    "  int3\n"



    // Set load address for next time

    "  leaq purgatory_start(%rip), %r11\n"

    "  movq %r11, 8(%rsp)\n"



    // Back to Linux

    "  ret\n"



    "purgatory_end:\n"

    ".previous"

);

extern char purgatory_start[], purgatory_end[];



int main (void)

{

        struct kexec_segment segment = {};

	int ret;



	segment.buf = purgatory_start;

	segment.bufsz = purgatory_end - purgatory_start;

	segment.mem = (void *)0x400000;

	segment.memsz = 0x1000;

	ret = syscall(__NR_kexec_load, 0x400000, 1, &segment, KEXEC_PRESERVE_CONTEXT);

	if (ret) {

		perror("kexec_load");

		exit(1);

	}



	ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_KEXEC);

	if (ret) {

		perror("kexec reboot");

		exit(1);

	}



	ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_KEXEC);

	if (ret) {

		perror("kexec reboot");

		exit(1);

	}

	printf("Success\n");

	return 0;

}

tools/testing/selftests/kexec/test_kexec_jump.sh

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#!/bin/sh

# SPDX-License-Identifier: GPL-2.0

#

# Prevent loading a kernel image via the kexec_load syscall when

# signatures are required.  (Dependent on CONFIG_IMA_ARCH_POLICY.)



TEST="$0"

. ./kexec_common_lib.sh



# kexec requires root privileges

require_root_privileges



# get the kernel config

get_kconfig



kconfig_enabled "CONFIG_KEXEC_JUMP=y" "kexec_jump is enabled"

if [ $? -eq 0 ]; then

	log_skip "kexec_jump is not enabled"

fi



kconfig_enabled "CONFIG_IMA_APPRAISE=y" "IMA enabled"

ima_appraise=$?



kconfig_enabled "CONFIG_IMA_ARCH_POLICY=y" \

	"IMA architecture specific policy enabled"

arch_policy=$?



get_secureboot_mode

secureboot=$?



if [ $secureboot -eq 1 ] && [ $arch_policy -eq 1 ]; then

    log_skip "Secure boot and CONFIG_IMA_ARCH_POLICY are enabled"

fi



./test_kexec_jump

if [ $? -eq 0 ]; then

    log_pass "kexec_jump succeeded"

else

    # The more likely failure mode if anything went wrong is that the

    # kernel just crashes. But if we get back here, sure, whine anyway.

    log_fail "kexec_jump failed"

fi