Hi Dave,
Thanks for your insight. Please see the comments inline below.
On Wed, Jul 19, 2023 at 11:00 AM Dave Young <dyoung@xxxxxxxxxx> wrote:
>
> Hi Pingfan, Simon,
>
> On 07/17/23 at 09:07pm, Pingfan Liu wrote:
> > As more complicated capsule kernel format occurs like zboot, where the
> > compressed kernel is stored as a payload. The straight forward
> > decompression can not meet the demand.
> >
> > As the first step, on aarch64, reading in the kernel file in a probe
> > method and decide how to unfold the content by the method itself.
> >
> > This series introduce a new image probe interface probe2(), which
> > returns three factors: kernel buffer, kernel size and kernel fd through
> > a struct parsed_info.
> > -1. the parsed kernel_buf should be returned so that it can be used by
> > the image load method later.
> > -2. the final fd passed to sys_kexec_file_load, since aarch64 kernel can
> > only work with Image format, the outer payload should be stripped and a
> > temporary file of Image should be created.
>
> I took a look at the Image.gz file load code, the current code can be
> simplified with passing a fd directly instead of creating temp files via
> memfd_create with the already decompressed kernel_buf.
>
> The current file load is like below:
>
> do_kexec_file_load():
> 1.slurp_decompress_file
> 2. probe
> 3. load
> 4. kexec_file_load
>
> In step 1, the Image.gz has been decompressed to kernel_buf, so just
> create a virtual memfd copy to it, then save the virtual fd for step 4
> use.
>
> Otherwise in step 2 it is some sanity checking, step 3 is setting
> something else eg. initrd_fd, cmdline. With the changes below Image and
> Image.gz will share same code. I think you can add the zboot
> detection/checking code in the Image probe, load functions, with a new
> info->kernel_fd, you can decompress the zboot kernel_buf and save to
> another virtual memfd, and set to the info->kernel_fd. Then in step 4
> the kexec_file_load can just use it.
>
This only results in a minor change in the interface, not like mine. I
prefer this method.
> The kernel_buf itself is only used for sanity checking of the formats,
> kernel only needs a file fd, so I think it should be fine and easier
> than the original ways.
>
Overall, this new method minimally affects the function interface, in
addition to the code simplification.
I will try to take it in the next version.
> Thoughts?
>
> ---
> kexec/arch/arm64/Makefile | 3
> kexec/arch/arm64/kexec-arm64.c | 1
> kexec/arch/arm64/kexec-arm64.h | 6
> kexec/arch/arm64/kexec-image-arm64.c | 2
> kexec/arch/arm64/kexec-zImage-arm64.c | 226 ----------------------------------
> kexec/kexec.c | 55 +++++---
> kexec/kexec.h | 1
> 7 files changed, 39 insertions(+), 255 deletions(-)
>
> Index: kexec-tools/kexec/arch/arm64/Makefile
> ===================================================================
> --- kexec-tools.orig/kexec/arch/arm64/Makefile
> +++ kexec-tools/kexec/arch/arm64/Makefile
> @@ -15,8 +15,7 @@ arm64_KEXEC_SRCS += \
> kexec/arch/arm64/kexec-arm64.c \
> kexec/arch/arm64/kexec-elf-arm64.c \
> kexec/arch/arm64/kexec-uImage-arm64.c \
> - kexec/arch/arm64/kexec-image-arm64.c \
> - kexec/arch/arm64/kexec-zImage-arm64.c
> + kexec/arch/arm64/kexec-image-arm64.c
>
> arm64_UIMAGE = kexec/kexec-uImage.c
>
> Index: kexec-tools/kexec/arch/arm64/kexec-arm64.c
> ===================================================================
> --- kexec-tools.orig/kexec/arch/arm64/kexec-arm64.c
> +++ kexec-tools/kexec/arch/arm64/kexec-arm64.c
> @@ -74,7 +74,6 @@ struct file_type file_type[] = {
> {"vmlinux", elf_arm64_probe, elf_arm64_load, elf_arm64_usage},
> {"Image", image_arm64_probe, image_arm64_load, image_arm64_usage},
> {"uImage", uImage_arm64_probe, uImage_arm64_load, uImage_arm64_usage},
> - {"zImage", zImage_arm64_probe, zImage_arm64_load, zImage_arm64_usage},
> };
>
> int file_types = sizeof(file_type) / sizeof(file_type[0]);
> Index: kexec-tools/kexec/arch/arm64/kexec-arm64.h
> ===================================================================
> --- kexec-tools.orig/kexec/arch/arm64/kexec-arm64.h
> +++ kexec-tools/kexec/arch/arm64/kexec-arm64.h
> @@ -44,12 +44,6 @@ int uImage_arm64_load(int argc, char **a
> struct kexec_info *info);
> void uImage_arm64_usage(void);
>
> -int zImage_arm64_probe(const char *kernel_buf, off_t kernel_size);
> -int zImage_arm64_load(int argc, char **argv, const char *kernel_buf,
> - off_t kernel_size, struct kexec_info *info);
> -void zImage_arm64_usage(void);
> -
> -
> extern off_t initrd_base;
> extern off_t initrd_size;
>
> Index: kexec-tools/kexec/arch/arm64/kexec-image-arm64.c
> ===================================================================
> --- kexec-tools.orig/kexec/arch/arm64/kexec-image-arm64.c
> +++ kexec-tools/kexec/arch/arm64/kexec-image-arm64.c
> @@ -114,6 +114,6 @@ exit:
> void image_arm64_usage(void)
> {
> printf(
> -" An ARM64 binary image, uncompressed, big or little endian.\n"
> +" An ARM64 binary image, compressed or not, big or little endian.\n"
> " Typically an Image file.\n\n");
> }
> Index: kexec-tools/kexec/arch/arm64/kexec-zImage-arm64.c
> ===================================================================
> --- kexec-tools.orig/kexec/arch/arm64/kexec-zImage-arm64.c
> +++ /dev/null
> @@ -1,226 +0,0 @@
> -/*
> - * ARM64 kexec zImage (Image.gz) support.
> - *
> - * Several distros use 'make zinstall' rule inside
> - * 'arch/arm64/boot/Makefile' to install the arm64
> - * Image.gz compressed file inside the boot destination
> - * directory (for e.g. /boot).
> - *
> - * Currently we cannot use kexec_file_load() to load vmlinuz
> - * (or Image.gz).
> - *
> - * To support Image.gz, we should:
> - * a). Copy the contents of Image.gz to a temporary file.
> - * b). Decompress (gunzip-decompress) the contents inside the
> - * temporary file.
> - * c). Pass the 'fd' of the temporary file to the kernel space.
> - *
> - * So basically the kernel space still gets a decompressed
> - * kernel image to load via kexec-tools.
> - */
> -
> -#define _GNU_SOURCE
> -
> -#include <errno.h>
> -#include <fcntl.h>
> -#include <limits.h>
> -#include <stdlib.h>
> -#include "crashdump-arm64.h"
> -#include "image-header.h"
> -#include "kexec.h"
> -#include "kexec-arm64.h"
> -#include "kexec-syscall.h"
> -#include "kexec-zlib.h"
> -#include "arch/options.h"
> -
> -#define FILENAME_IMAGE "/tmp/ImageXXXXXX"
> -
> -/* Returns:
> - * -1 : in case of error/invalid format (not a valid Image.gz format.
> - * fd : File descriptor of the temp file containing the decompressed
> - * Image.
> - */
> -int zImage_arm64_probe(const char *kernel_buf, off_t kernel_size)
> -{
> - int ret = -1;
> - int fd = 0;
> - int kernel_fd = 0;
> - char *fname = NULL;
> - char *kernel_uncompressed_buf = NULL;
> - const struct arm64_image_header *h;
> -
> - if (!is_zlib_file(kernel_buf, &kernel_size)) {
> - dbgprintf("%s: Not an zImage file (Image.gz).\n", __func__);
> - return -1;
> - }
> -
> - if (!(fname = strdup(FILENAME_IMAGE))) {
> - dbgprintf("%s: Can't duplicate strings %s\n", __func__,
> - fname);
> - return -1;
> - }
> -
> - if ((fd = mkstemp(fname)) < 0) {
> - dbgprintf("%s: Can't open file %s\n", __func__,
> - fname);
> - ret = -1;
> - goto fail_mkstemp;
> - }
> -
> - kernel_uncompressed_buf =
> - (char *) calloc(kernel_size, sizeof(off_t));
> - if (!kernel_uncompressed_buf) {
> - dbgprintf("%s: Can't calloc %ld bytes\n",
> - __func__, kernel_size);
> - ret= -ENOMEM;
> - goto fail_calloc;
> - }
> -
> - /* slurp in the input kernel */
> - dbgprintf("%s: ", __func__);
> - kernel_uncompressed_buf = slurp_decompress_file(kernel_buf,
> - &kernel_size);
> -
> - /* check for correct header magic */
> - if (kernel_size < sizeof(struct arm64_image_header)) {
> - dbgprintf("%s: No arm64 image header.\n", __func__);
> - ret = -1;
> - goto fail_bad_header;
> - }
> -
> - h = (const struct arm64_image_header *)(kernel_uncompressed_buf);
> -
> - if (!arm64_header_check_magic(h)) {
> - dbgprintf("%s: Bad arm64 image header.\n", __func__);
> - ret = -1;
> - goto fail_bad_header;
> - }
> -
> - if (write(fd, kernel_uncompressed_buf,
> - kernel_size) != kernel_size) {
> - dbgprintf("%s: Can't write the uncompressed file %s\n",
> - __func__, fname);
> - ret = -1;
> - goto fail_bad_header;
> - }
> -
> - close(fd);
> -
> - /* Open the tmp file again, this time in O_RDONLY mode, as
> - * opening the file in O_RDWR and calling kexec_file_load()
> - * causes the kernel to return -ETXTBSY
> - */
> - kernel_fd = open(fname, O_RDONLY);
> - if (kernel_fd == -1) {
> - dbgprintf("%s: Failed to open file %s\n",
> - __func__, fname);
> - ret = -1;
> - goto fail_bad_header;
> - }
> -
> - unlink(fname);
> -
> - free(kernel_uncompressed_buf);
> - free(fname);
> -
> - return kernel_fd;
> -
> -fail_bad_header:
> - free(kernel_uncompressed_buf);
> -
> -fail_calloc:
> - if (fd >= 0)
> - close(fd);
> -
> - unlink(fname);
> -
> -fail_mkstemp:
> - free(fname);
> -
> - return ret;
> -}
> -
> -int zImage_arm64_load(int argc, char **argv, const char *kernel_buf,
> - off_t kernel_size, struct kexec_info *info)
> -{
> - const struct arm64_image_header *header;
> - unsigned long kernel_segment;
> - int result;
> -
> - if (info->file_mode) {
> - if (arm64_opts.initrd) {
> - info->initrd_fd = open(arm64_opts.initrd, O_RDONLY);
> - if (info->initrd_fd == -1) {
> - fprintf(stderr,
> - "Could not open initrd file %s:%s\n",
> - arm64_opts.initrd, strerror(errno));
> - result = EFAILED;
> - goto exit;
> - }
> - }
> -
> - if (arm64_opts.command_line) {
> - info->command_line = (char *)arm64_opts.command_line;
> - info->command_line_len =
> - strlen(arm64_opts.command_line) + 1;
> - }
> -
> - return 0;
> - }
> -
> - header = (const struct arm64_image_header *)(kernel_buf);
> -
> - if (arm64_process_image_header(header))
> - return EFAILED;
> -
> - kernel_segment = arm64_locate_kernel_segment(info);
> -
> - if (kernel_segment == ULONG_MAX) {
> - dbgprintf("%s: Kernel segment is not allocated\n", __func__);
> - result = EFAILED;
> - goto exit;
> - }
> -
> - dbgprintf("%s: kernel_segment: %016lx\n", __func__, kernel_segment);
> - dbgprintf("%s: text_offset: %016lx\n", __func__,
> - arm64_mem.text_offset);
> - dbgprintf("%s: image_size: %016lx\n", __func__,
> - arm64_mem.image_size);
> - dbgprintf("%s: phys_offset: %016lx\n", __func__,
> - arm64_mem.phys_offset);
> - dbgprintf("%s: vp_offset: %016lx\n", __func__,
> - arm64_mem.vp_offset);
> - dbgprintf("%s: PE format: %s\n", __func__,
> - (arm64_header_check_pe_sig(header) ? "yes" : "no"));
> -
> - /* create and initialize elf core header segment */
> - if (info->kexec_flags & KEXEC_ON_CRASH) {
> - result = load_crashdump_segments(info);
> - if (result) {
> - dbgprintf("%s: Creating eflcorehdr failed.\n",
> - __func__);
> - goto exit;
> - }
> - }
> -
> - /* load the kernel */
> - add_segment_phys_virt(info, kernel_buf, kernel_size,
> - kernel_segment + arm64_mem.text_offset,
> - arm64_mem.image_size, 0);
> -
> - /* load additional data */
> - result = arm64_load_other_segments(info, kernel_segment
> - + arm64_mem.text_offset);
> -
> -exit:
> - if (result)
> - fprintf(stderr, "kexec: load failed.\n");
> - return result;
> -}
> -
> -void zImage_arm64_usage(void)
> -{
> - printf(
> -" An ARM64 zImage, compressed, big or little endian.\n"
> -" Typically an Image.gz or Image.lzma file.\n\n");
> -}
> Index: kexec-tools/kexec/kexec.c
> ===================================================================
> --- kexec-tools.orig/kexec/kexec.c
> +++ kexec-tools/kexec/kexec.c
> @@ -638,6 +638,21 @@ char *slurp_decompress_file(const char *
> return kernel_buf;
> }
>
> +int copybuf_memfd(const char *kernel_buf, size_t size)
> +{
> + int fd, count;
> +
> + fd = memfd_create("kernel", MFD_ALLOW_SEALING);
> + if (fd == -1)
> + return fd;
> +
> + count = write(fd, kernel_buf, size);
> + if (count < 0)
> + return -1;
> +
> + return fd;
> +}
> +
> static void update_purgatory(struct kexec_info *info)
> {
> static const uint8_t null_buf[256];
> @@ -1263,7 +1278,7 @@ static int do_kexec_file_load(int filein
> unsigned long flags) {
>
> char *kernel;
> - int kernel_fd, i;
> + int kernel_fd, i, fd;
> struct kexec_info info;
> int ret = 0;
> char *kernel_buf;
> @@ -1277,6 +1292,7 @@ static int do_kexec_file_load(int filein
> info.kexec_flags = flags;
>
> info.file_mode = 1;
> + info.kernel_fd = -1;
> info.initrd_fd = -1;
>
> if (!is_kexec_file_load_implemented())
> @@ -1299,22 +1315,16 @@ static int do_kexec_file_load(int filein
>
> /* slurp in the input kernel */
> kernel_buf = slurp_decompress_file(kernel, &kernel_size);
> + fd = copybuf_memfd(kernel_buf, kernel_size);
> + if (fd < 0)
> + fprintf(stderr, "Failed to copy decompressed buf\n");
> + else {
> + kernel_fd = fd;
> + }
>
> for (i = 0; i < file_types; i++) {
> -#ifdef __aarch64__
> - /* handle Image.gz like cases */
> - if (is_zlib_file(kernel, &kernel_size)) {
> - if ((ret = file_type[i].probe(kernel, kernel_size)) >= 0) {
Just a clarification for this:
After removing the condition macro snippet, the later patches, which
implements pez_arm64_probe() should take the original kernel image
instead of kernel file as the first parameter. It is fine.
Thanks,
Pingfan
> - kernel_fd = ret;
> - break;
> - }
> - } else
> - if (file_type[i].probe(kernel_buf, kernel_size) >= 0)
> - break;
> -#else
> if (file_type[i].probe(kernel_buf, kernel_size) >= 0)
> break;
> -#endif
> }
>
> if (i == file_types) {
> @@ -1324,12 +1334,19 @@ static int do_kexec_file_load(int filein
> return EFAILED;
> }
>
> - ret = file_type[i].load(argc, argv, kernel_buf, kernel_size, &info);
> - if (ret < 0) {
> - fprintf(stderr, "Cannot load %s\n", kernel);
> - close(kernel_fd);
> - return ret;
> - }
> + ret = file_type[i].load(argc, argv, kernel_buf, kernel_size, &info);
> + if (ret < 0) {
> + fprintf(stderr, "Cannot load %s\n", kernel);
> + close(kernel_fd);
> + return ret;
> + }
> +
> + /*
> + * image type specific load functioin detect the capsule kernel type
> + * and create another fd for file load. For example the zboot kernel.
> + */
> + if (info.kernel_fd != -1)
> + kernel_fd = info.kernel_fd;
>
> /*
> * If there is no initramfs, set KEXEC_FILE_NO_INITRAMFS flag so that
> Index: kexec-tools/kexec/kexec.h
> ===================================================================
> --- kexec-tools.orig/kexec/kexec.h
> +++ kexec-tools/kexec/kexec.h
> @@ -164,6 +164,7 @@ struct kexec_info {
> unsigned long file_mode :1;
>
> /* Filled by kernel image processing code */
> + int kernel_fd;
> int initrd_fd;
> char *command_line;
> int command_line_len;
>
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