From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- tools/testing/selftests/kho/arm64.conf | 9 ++ tools/testing/selftests/kho/init.c | 75 +++++++++++++ tools/testing/selftests/kho/vmtest.sh | 190 +++++++++++++++++++++++++++++++++ tools/testing/selftests/kho/x86.conf | 7 ++ 4 files changed, 281 insertions(+) create mode 100644 tools/testing/selftests/kho/arm64.conf create mode 100644 tools/testing/selftests/kho/init.c create mode 100755 tools/testing/selftests/kho/vmtest.sh create mode 100644 tools/testing/selftests/kho/x86.conf (limited to 'tools/testing/selftests/kho') diff --git a/tools/testing/selftests/kho/arm64.conf b/tools/testing/selftests/kho/arm64.conf new file mode 100644 index 000000000..ee696807c --- /dev/null +++ b/tools/testing/selftests/kho/arm64.conf @@ -0,0 +1,9 @@ +QEMU_CMD="qemu-system-aarch64 -M virt -cpu max" +QEMU_KCONFIG=" +CONFIG_SERIAL_AMBA_PL010=y +CONFIG_SERIAL_AMBA_PL010_CONSOLE=y +CONFIG_SERIAL_AMBA_PL011=y +CONFIG_SERIAL_AMBA_PL011_CONSOLE=y +" +KERNEL_IMAGE="Image" +KERNEL_CMDLINE="console=ttyAMA0" diff --git a/tools/testing/selftests/kho/init.c b/tools/testing/selftests/kho/init.c new file mode 100644 index 000000000..88a41b6eb --- /dev/null +++ b/tools/testing/selftests/kho/init.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include + +/* from arch/x86/include/asm/setup.h */ +#define COMMAND_LINE_SIZE 2048 + +#define KERNEL_IMAGE "/kernel" + +static int mount_filesystems(void) +{ + if (mount("debugfs", "/debugfs", "debugfs", 0, NULL) < 0) + return -1; + + return mount("proc", "/proc", "proc", 0, NULL); +} + +static long kexec_file_load(int kernel_fd, int initrd_fd, + unsigned long cmdline_len, const char *cmdline, + unsigned long flags) +{ + return syscall(__NR_kexec_file_load, kernel_fd, initrd_fd, cmdline_len, + cmdline, flags); +} + +static int kexec_load(void) +{ + char cmdline[COMMAND_LINE_SIZE]; + ssize_t len; + int fd, err; + + fd = open("/proc/cmdline", O_RDONLY); + if (fd < 0) + return -1; + + len = read(fd, cmdline, sizeof(cmdline)); + close(fd); + if (len < 0) + return -1; + + /* replace \n with \0 */ + cmdline[len - 1] = 0; + fd = open(KERNEL_IMAGE, O_RDONLY); + if (fd < 0) + return -1; + + err = kexec_file_load(fd, -1, len, cmdline, KEXEC_FILE_NO_INITRAMFS); + close(fd); + + return err ? : 0; +} + +int main(int argc, char *argv[]) +{ + if (mount_filesystems()) + goto err_reboot; + + if (kexec_load()) + goto err_reboot; + + if (reboot(RB_KEXEC)) + goto err_reboot; + + return 0; + +err_reboot: + reboot(RB_AUTOBOOT); + return -1; +} diff --git a/tools/testing/selftests/kho/vmtest.sh b/tools/testing/selftests/kho/vmtest.sh new file mode 100755 index 000000000..0014bd76e --- /dev/null +++ b/tools/testing/selftests/kho/vmtest.sh @@ -0,0 +1,190 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +set -ue + +CROSS_COMPILE="${CROSS_COMPILE:-""}" + +test_dir=$(realpath "$(dirname "$0")") +kernel_dir=$(realpath "$test_dir/../../../..") + +tmp_dir=$(mktemp -d /tmp/kho-test.XXXXXXXX) +headers_dir="$tmp_dir/usr" +initrd="$tmp_dir/initrd.cpio" + +source "$test_dir/../kselftest/ktap_helpers.sh" + +function usage() { + cat < "$kho_config" </dev/null || skip "$opt is missing" + done < "$kho_config" + + $make_cmd "$kimage" + $make_cmd headers_install INSTALL_HDR_PATH="$headers_dir" +} + +function mkinitrd() { + local kernel=$1 + + "$CROSS_COMPILE"gcc -s -static -Os -nostdinc -nostdlib \ + -fno-asynchronous-unwind-tables -fno-ident \ + -I "$headers_dir/include" \ + -I "$kernel_dir/tools/include/nolibc" \ + -o "$tmp_dir/init" "$test_dir/init.c" + + cat > "$tmp_dir/cpio_list" < "$initrd" +} + +function run_qemu() { + local qemu_cmd=$1 + local cmdline=$2 + local kernel=$3 + local serial="$tmp_dir/qemu.serial" + + cmdline="$cmdline kho=on panic=-1" + + $qemu_cmd -m 1G -smp 2 -no-reboot -nographic -nodefaults \ + -accel kvm -accel hvf -accel tcg \ + -serial file:"$serial" \ + -append "$cmdline" \ + -kernel "$kernel" \ + -initrd "$initrd" + + grep "KHO restore succeeded" "$serial" &> /dev/null || fail "KHO failed" +} + +function target_to_arch() { + local target=$1 + + case $target in + aarch64) echo "arm64" ;; + x86_64) echo "x86" ;; + *) skip "architecture $target is not supported" + esac +} + +function main() { + local build_dir="$kernel_dir/.kho" + local jobs=$(($(nproc) * 2)) + local target="$(uname -m)" + + # skip the test if any of the preparation steps fails + set -o errtrace + trap skip ERR + + while getopts 'hd:j:t:' opt; do + case $opt in + d) + build_dir="$OPTARG" + ;; + j) + jobs="$OPTARG" + ;; + t) + target="$OPTARG" + ;; + h) + usage + exit 0 + ;; + *) + echo Unknown argument "$opt" + usage + exit 1 + ;; + esac + done + + ktap_print_header + ktap_set_plan 1 + + if [[ "$target" != "$(uname -m)" ]] && [[ -z "$CROSS_COMPILE" ]]; then + skip "Cross-platform testing needs to specify CROSS_COMPILE" + fi + + mkdir -p "$build_dir" + local arch=$(target_to_arch "$target") + source "$test_dir/$arch.conf" + + # build the kernel and create initrd + # initrd includes the kernel image that will be kexec'ed + local make_cmd="make ARCH=$arch CROSS_COMPILE=$CROSS_COMPILE -j$jobs" + build_kernel "$build_dir" "$make_cmd" "$QEMU_KCONFIG" "$KERNEL_IMAGE" + + local kernel="$build_dir/arch/$arch/boot/$KERNEL_IMAGE" + mkinitrd "$kernel" + + run_qemu "$QEMU_CMD" "$KERNEL_CMDLINE" "$kernel" + + ktap_test_pass "KHO succeeded" +} + +main "$@" diff --git a/tools/testing/selftests/kho/x86.conf b/tools/testing/selftests/kho/x86.conf new file mode 100644 index 000000000..b419e610c --- /dev/null +++ b/tools/testing/selftests/kho/x86.conf @@ -0,0 +1,7 @@ +QEMU_CMD=qemu-system-x86_64 +QEMU_KCONFIG=" +CONFIG_SERIAL_8250=y +CONFIG_SERIAL_8250_CONSOLE=y +" +KERNEL_IMAGE="bzImage" +KERNEL_CMDLINE="console=ttyS0" -- cgit v1.3.1