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Message-ID: <20250326142404.256980-5-dwmw2@infradead.org>
Date: Wed, 26 Mar 2025 14:16:04 +0000
From: David Woodhouse <dwmw2@...radead.org>
To: kexec@...ts.infradead.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H . Peter Anvin" <hpa@...or.com>,
David Woodhouse <dwmw@...zon.co.uk>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Kai Huang <kai.huang@...el.com>,
Nikolay Borisov <nik.borisov@...e.com>,
linux-kernel@...r.kernel.org,
Simon Horman <horms@...nel.org>,
Dave Young <dyoung@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
jpoimboe@...nel.org,
bsz@...zon.de
Subject: [PATCH v9 4/4] selftests/kexec: Add x86_64 selftest for kexec-jump and exception handling
From: David Woodhouse <dwmw@...zon.co.uk>
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: David Woodhouse <dwmw@...zon.co.uk>
---
tools/testing/selftests/kexec/Makefile | 7 ++
.../testing/selftests/kexec/test_kexec_jump.c | 72 +++++++++++++++++++
.../selftests/kexec/test_kexec_jump.sh | 42 +++++++++++
3 files changed, 121 insertions(+)
create mode 100644 tools/testing/selftests/kexec/test_kexec_jump.c
create mode 100755 tools/testing/selftests/kexec/test_kexec_jump.sh
diff --git a/tools/testing/selftests/kexec/Makefile b/tools/testing/selftests/kexec/Makefile
index 67fe7a46cb62..e3000ccb9a5d 100644
--- a/tools/testing/selftests/kexec/Makefile
+++ b/tools/testing/selftests/kexec/Makefile
@@ -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
diff --git a/tools/testing/selftests/kexec/test_kexec_jump.c b/tools/testing/selftests/kexec/test_kexec_jump.c
new file mode 100644
index 000000000000..fbce287866f5
--- /dev/null
+++ b/tools/testing/selftests/kexec/test_kexec_jump.c
@@ -0,0 +1,72 @@
+#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;
+}
+
diff --git a/tools/testing/selftests/kexec/test_kexec_jump.sh b/tools/testing/selftests/kexec/test_kexec_jump.sh
new file mode 100755
index 000000000000..6ae977054ba2
--- /dev/null
+++ b/tools/testing/selftests/kexec/test_kexec_jump.sh
@@ -0,0 +1,42 @@
+#!/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
--
2.48.1
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