--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Test module for KHO
+ * Copyright (c) 2025 Microsoft Corporation.
+ *
+ * Authors:
+ * Saurabh Sengar <ssengar@microsoft.com>
+ * Mike Rapoport <rppt@kernel.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/libfdt.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/vmalloc.h>
+#include <linux/kexec_handover.h>
+
+#include <net/checksum.h>
+
+#define KHO_TEST_MAGIC 0x4b484f21 /* KHO! */
+#define KHO_TEST_FDT "kho_test"
+#define KHO_TEST_COMPAT "kho-test-v1"
+
+static long max_mem = (PAGE_SIZE << MAX_PAGE_ORDER) * 2;
+module_param(max_mem, long, 0644);
+
+struct kho_test_state {
+ unsigned int nr_folios;
+ struct folio **folios;
+ struct folio *fdt;
+ __wsum csum;
+};
+
+static struct kho_test_state kho_test_state;
+
+static int kho_test_notifier(struct notifier_block *self, unsigned long cmd,
+ void *v)
+{
+ struct kho_test_state *state = &kho_test_state;
+ struct kho_serialization *ser = v;
+ int err = 0;
+
+ switch (cmd) {
+ case KEXEC_KHO_ABORT:
+ return NOTIFY_DONE;
+ case KEXEC_KHO_FINALIZE:
+ /* Handled below */
+ break;
+ default:
+ return NOTIFY_BAD;
+ }
+
+ err |= kho_preserve_folio(state->fdt);
+ err |= kho_add_subtree(ser, KHO_TEST_FDT, folio_address(state->fdt));
+
+ return err ? NOTIFY_BAD : NOTIFY_DONE;
+}
+
+static struct notifier_block kho_test_nb = {
+ .notifier_call = kho_test_notifier,
+};
+
+static int kho_test_save_data(struct kho_test_state *state, void *fdt)
+{
+ phys_addr_t *folios_info __free(kvfree) = NULL;
+ int err = 0;
+
+ folios_info = kvmalloc_array(state->nr_folios, sizeof(*folios_info),
+ GFP_KERNEL);
+ if (!folios_info)
+ return -ENOMEM;
+
+ for (int i = 0; i < state->nr_folios; i++) {
+ struct folio *folio = state->folios[i];
+ unsigned int order = folio_order(folio);
+
+ folios_info[i] = virt_to_phys(folio_address(folio)) | order;
+
+ err = kho_preserve_folio(folio);
+ if (err)
+ return err;
+ }
+
+ err |= fdt_begin_node(fdt, "data");
+ err |= fdt_property(fdt, "nr_folios", &state->nr_folios,
+ sizeof(state->nr_folios));
+ err |= fdt_property(fdt, "folios_info", folios_info,
+ state->nr_folios * sizeof(*folios_info));
+ err |= fdt_property(fdt, "csum", &state->csum, sizeof(state->csum));
+ err |= fdt_end_node(fdt);
+
+ return err;
+}
+
+static int kho_test_prepare_fdt(struct kho_test_state *state)
+{
+ const char compatible[] = KHO_TEST_COMPAT;
+ unsigned int magic = KHO_TEST_MAGIC;
+ ssize_t fdt_size;
+ int err = 0;
+ void *fdt;
+
+ fdt_size = state->nr_folios * sizeof(phys_addr_t) + PAGE_SIZE;
+ state->fdt = folio_alloc(GFP_KERNEL, get_order(fdt_size));
+ if (!state->fdt)
+ return -ENOMEM;
+
+ fdt = folio_address(state->fdt);
+
+ err |= fdt_create(fdt, fdt_size);
+ err |= fdt_finish_reservemap(fdt);
+
+ err |= fdt_begin_node(fdt, "");
+ err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible));
+ err |= fdt_property(fdt, "magic", &magic, sizeof(magic));
+ err |= kho_test_save_data(state, fdt);
+ err |= fdt_end_node(fdt);
+
+ err |= fdt_finish(fdt);
+
+ if (err)
+ folio_put(state->fdt);
+
+ return err;
+}
+
+static int kho_test_generate_data(struct kho_test_state *state)
+{
+ size_t alloc_size = 0;
+ __wsum csum = 0;
+
+ while (alloc_size < max_mem) {
+ int order = get_random_u32() % NR_PAGE_ORDERS;
+ struct folio *folio;
+ unsigned int size;
+ void *addr;
+
+ /* cap allocation so that we won't exceed max_mem */
+ if (alloc_size + (PAGE_SIZE << order) > max_mem) {
+ order = get_order(max_mem - alloc_size);
+ if (order)
+ order--;
+ }
+ size = PAGE_SIZE << order;
+
+ folio = folio_alloc(GFP_KERNEL | __GFP_NORETRY, order);
+ if (!folio)
+ goto err_free_folios;
+
+ state->folios[state->nr_folios++] = folio;
+ addr = folio_address(folio);
+ get_random_bytes(addr, size);
+ csum = csum_partial(addr, size, csum);
+ alloc_size += size;
+ }
+
+ state->csum = csum;
+ return 0;
+
+err_free_folios:
+ for (int i = 0; i < state->nr_folios; i++)
+ folio_put(state->folios[i]);
+ return -ENOMEM;
+}
+
+static int kho_test_save(void)
+{
+ struct kho_test_state *state = &kho_test_state;
+ struct folio **folios __free(kvfree) = NULL;
+ unsigned long max_nr;
+ int err;
+
+ max_mem = PAGE_ALIGN(max_mem);
+ max_nr = max_mem >> PAGE_SHIFT;
+
+ folios = kvmalloc_array(max_nr, sizeof(*state->folios), GFP_KERNEL);
+ if (!folios)
+ return -ENOMEM;
+ state->folios = folios;
+
+ err = kho_test_generate_data(state);
+ if (err)
+ return err;
+
+ err = kho_test_prepare_fdt(state);
+ if (err)
+ return err;
+
+ return register_kho_notifier(&kho_test_nb);
+}
+
+static int kho_test_restore_data(const void *fdt, int node)
+{
+ const unsigned int *nr_folios;
+ const phys_addr_t *folios_info;
+ const __wsum *old_csum;
+ __wsum csum = 0;
+ int len;
+
+ node = fdt_path_offset(fdt, "/data");
+
+ nr_folios = fdt_getprop(fdt, node, "nr_folios", &len);
+ if (!nr_folios || len != sizeof(*nr_folios))
+ return -EINVAL;
+
+ old_csum = fdt_getprop(fdt, node, "csum", &len);
+ if (!old_csum || len != sizeof(*old_csum))
+ return -EINVAL;
+
+ folios_info = fdt_getprop(fdt, node, "folios_info", &len);
+ if (!folios_info || len != sizeof(*folios_info) * *nr_folios)
+ return -EINVAL;
+
+ for (int i = 0; i < *nr_folios; i++) {
+ unsigned int order = folios_info[i] & ~PAGE_MASK;
+ phys_addr_t phys = folios_info[i] & PAGE_MASK;
+ unsigned int size = PAGE_SIZE << order;
+ struct folio *folio;
+
+ folio = kho_restore_folio(phys);
+ if (!folio)
+ break;
+
+ if (folio_order(folio) != order)
+ break;
+
+ csum = csum_partial(folio_address(folio), size, csum);
+ folio_put(folio);
+ }
+
+ if (csum != *old_csum)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int kho_test_restore(phys_addr_t fdt_phys)
+{
+ void *fdt = phys_to_virt(fdt_phys);
+ const unsigned int *magic;
+ int node, len, err;
+
+ node = fdt_path_offset(fdt, "/");
+ if (node < 0)
+ return -EINVAL;
+
+ if (fdt_node_check_compatible(fdt, node, KHO_TEST_COMPAT))
+ return -EINVAL;
+
+ magic = fdt_getprop(fdt, node, "magic", &len);
+ if (!magic || len != sizeof(*magic))
+ return -EINVAL;
+
+ if (*magic != KHO_TEST_MAGIC)
+ return -EINVAL;
+
+ err = kho_test_restore_data(fdt, node);
+ if (err)
+ return err;
+
+ pr_info("KHO restore succeeded\n");
+ return 0;
+}
+
+static int __init kho_test_init(void)
+{
+ phys_addr_t fdt_phys;
+ int err;
+
+ err = kho_retrieve_subtree(KHO_TEST_FDT, &fdt_phys);
+ if (!err)
+ return kho_test_restore(fdt_phys);
+
+ if (err != -ENOENT) {
+ pr_warn("failed to retrieve %s FDT: %d\n", KHO_TEST_FDT, err);
+ return err;
+ }
+
+ return kho_test_save();
+}
+module_init(kho_test_init);
+
+static void kho_test_cleanup(void)
+{
+ for (int i = 0; i < kho_test_state.nr_folios; i++)
+ folio_put(kho_test_state.folios[i]);
+
+ kvfree(kho_test_state.folios);
+}
+
+static void __exit kho_test_exit(void)
+{
+ unregister_kho_notifier(&kho_test_nb);
+ kho_test_cleanup();
+}
+module_exit(kho_test_exit);
+
+MODULE_AUTHOR("Mike Rapoport <rppt@kernel.org>");
+MODULE_DESCRIPTION("KHO test module");
+MODULE_LICENSE("GPL");
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef NOLIBC
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <syscall.h>
+#include <sys/mount.h>
+#include <sys/reboot.h>
+#endif
+
+/* from arch/x86/include/asm/setup.h */
+#define COMMAND_LINE_SIZE 2048
+
+/* from include/linux/kexex.h */
+#define KEXEC_FILE_NO_INITRAMFS 0x00000004
+
+#define KHO_FINILIZE "/debugfs/kho/out/finalize"
+#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 int kho_enable(void)
+{
+ const char enable[] = "1";
+ int fd;
+
+ fd = open(KHO_FINILIZE, O_RDWR);
+ if (fd < 0)
+ return -1;
+
+ if (write(fd, enable, sizeof(enable)) != sizeof(enable))
+ return 1;
+
+ close(fd);
+ return 0;
+}
+
+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 (kho_enable())
+ 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;
+}
--- /dev/null
+#!/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="$tmp_dir/usr"
+initrd_dir="$tmp_dir/initrd"
+initrd="$tmp_dir/initrd.cpio"
+
+source "$test_dir/../kselftest/ktap_helpers.sh"
+
+function usage() {
+ cat <<EOF
+$0 [-d build_dir] [-j jobs] [-t target_arch] [-h]
+Options:
+ -d) path to the kernel build directory
+ -j) number of jobs for compilation, similar to -j in make
+ -t) run test for target_arch, requires CROSS_COMPILE set
+ supported targets: aarch64, x86_64
+ -h) display this help
+EOF
+}
+
+function cleanup() {
+ rm -fr "$tmp_dir"
+ ktap_finished
+}
+trap cleanup EXIT
+
+function skip() {
+ local msg=${1:-""}
+
+ ktap_test_skip "$msg"
+ exit "$KSFT_SKIP"
+}
+
+function fail() {
+ local msg=${1:-""}
+
+ ktap_test_fail "$msg"
+ exit "$KSFT_FAIL"
+}
+
+function build_kernel() {
+ local build_dir=$1
+ local make_cmd=$2
+ local arch_kconfig=$3
+ local kimage=$4
+
+ local kho_config="$tmp_dir/kho.config"
+ local kconfig="$build_dir/.config"
+
+ # enable initrd, KHO and KHO test in kernel configuration
+ tee "$kconfig" > "$kho_config" <<EOF
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_KEXEC_HANDOVER=y
+CONFIG_TEST_KEXEC_HANDOVER=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_VM=y
+$arch_kconfig
+EOF
+
+ make_cmd="$make_cmd -C $kernel_dir O=$build_dir"
+ $make_cmd olddefconfig
+
+ # verify that kernel confiration has all necessary options
+ while read -r opt ; do
+ grep "$opt" "$kconfig" &>/dev/null || skip "$opt is missing"
+ done < "$kho_config"
+
+ $make_cmd "$kimage"
+ $make_cmd headers_install INSTALL_HDR_PATH="$headers_dir"
+}
+
+function mkinitrd() {
+ local kernel=$1
+
+ mkdir -p "$initrd_dir"/{dev,debugfs,proc}
+ sudo mknod "$initrd_dir/dev/console" c 5 1
+
+ "$CROSS_COMPILE"gcc -s -static -Os -nostdinc -I"$headers_dir/include" \
+ -fno-asynchronous-unwind-tables -fno-ident -nostdlib \
+ -include "$test_dir/../../../include/nolibc/nolibc.h" \
+ -o "$initrd_dir/init" "$test_dir/init.c" \
+
+ cp "$kernel" "$initrd_dir/kernel"
+
+ pushd "$initrd_dir" &>/dev/null
+ find . | cpio -H newc --create > "$initrd" 2>/dev/null
+ popd &>/dev/null
+}
+
+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" "$kernel"
+
+ ktap_test_pass "KHO succeeded"
+}
+
+main "$@"
projects / users / dwmw2 / linux.git / commitdiff