Re: [External] [PATCH 2/2] riscv: kexec_file: Support loading Image binary file

[yunhui cui <cuiyunhui@bytedance.com>]

Hi Shuai,

On Thu, Sep 14, 2023 at 10:09 AM Song Shuai <songshuaishuai@tinylab.org> wrote:
>
> This patch creates image_kexec_ops to load Image binary file
> for kexec_file_load() syscall.
>
> Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
> ---
>  arch/riscv/include/asm/image.h         |  2 +
>  arch/riscv/include/asm/kexec.h         |  1 +
>  arch/riscv/kernel/Makefile             |  2 +-
>  arch/riscv/kernel/kexec_image.c        | 97 ++++++++++++++++++++++++++
>  arch/riscv/kernel/machine_kexec_file.c |  1 +
>  5 files changed, 102 insertions(+), 1 deletion(-)
>  create mode 100644 arch/riscv/kernel/kexec_image.c
>
> diff --git a/arch/riscv/include/asm/image.h b/arch/riscv/include/asm/image.h
> index e0b319af3681..8927a6ea1127 100644
> --- a/arch/riscv/include/asm/image.h
> +++ b/arch/riscv/include/asm/image.h
> @@ -30,6 +30,8 @@
>                               RISCV_HEADER_VERSION_MINOR)
>
>  #ifndef __ASSEMBLY__
> +#define riscv_image_flag_field(flags, field)\
> +                              (((flags) >> field##_SHIFT) & field##_MASK)
>  /**
>   * struct riscv_image_header - riscv kernel image header
>   * @code0:             Executable code
> diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h
> index 518825fe4160..b9ee8346cc8c 100644
> --- a/arch/riscv/include/asm/kexec.h
> +++ b/arch/riscv/include/asm/kexec.h
> @@ -56,6 +56,7 @@ extern riscv_kexec_method riscv_kexec_norelocate;
>
>  #ifdef CONFIG_KEXEC_FILE
>  extern const struct kexec_file_ops elf_kexec_ops;
> +extern const struct kexec_file_ops image_kexec_ops;
>
>  struct purgatory_info;
>  int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index 1c62c639e875..9ecba3231a36 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -86,7 +86,7 @@ endif
>  obj-$(CONFIG_HOTPLUG_CPU)      += cpu-hotplug.o
>  obj-$(CONFIG_KGDB)             += kgdb.o
>  obj-$(CONFIG_KEXEC_CORE)       += kexec_relocate.o crash_save_regs.o machine_kexec.o
> -obj-$(CONFIG_KEXEC_FILE)       += kexec_elf.o machine_kexec_file.o
> +obj-$(CONFIG_KEXEC_FILE)       += kexec_elf.o kexec_image.o machine_kexec_file.o
>  obj-$(CONFIG_CRASH_DUMP)       += crash_dump.o
>  obj-$(CONFIG_CRASH_CORE)       += crash_core.o
>
> diff --git a/arch/riscv/kernel/kexec_image.c b/arch/riscv/kernel/kexec_image.c
> new file mode 100644
> index 000000000000..b6aa7f59bd53
> --- /dev/null
> +++ b/arch/riscv/kernel/kexec_image.c
> @@ -0,0 +1,97 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * RISC-V Kexec image loader
> + *
> + */
> +
> +#define pr_fmt(fmt)    "kexec_file(Image): " fmt
> +
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/kexec.h>
> +#include <linux/pe.h>
> +#include <linux/string.h>
> +#include <asm/byteorder.h>
> +#include <asm/image.h>
> +
> +static int image_probe(const char *kernel_buf, unsigned long kernel_len)
> +{
> +       const struct riscv_image_header *h =
> +               (const struct riscv_image_header *)(kernel_buf);
> +
> +       if (!h || (kernel_len < sizeof(*h)))
> +               return -EINVAL;
> +
> +       /* According to Documentation/riscv/boot-image-header.rst,
> +        * use "magic2" field to check when version >= 0.2.
> +        */
> +
> +       if (h->version >= RISCV_HEADER_VERSION &&
> +           memcmp(&h->magic2, RISCV_IMAGE_MAGIC2, sizeof(h->magic2)))
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
> +static void *image_load(struct kimage *image,
> +                               char *kernel, unsigned long kernel_len,
> +                               char *initrd, unsigned long initrd_len,
> +                               char *cmdline, unsigned long cmdline_len)
> +{
> +       struct riscv_image_header *h;
> +       u64 flags;
> +       bool be_image, be_kernel;
> +       struct kexec_buf kbuf;
> +       int ret;
> +
> +       /* Check Image header */
> +       h = (struct riscv_image_header *)kernel;
> +       if (!h->image_size) {
> +               ret = -EINVAL;
> +               goto out;
> +       }
> +
> +       /* Check endianness */
> +       flags = le64_to_cpu(h->flags);
> +       be_image = riscv_image_flag_field(flags, RISCV_IMAGE_FLAG_BE);
> +       be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
> +       if (be_image != be_kernel) {
> +               ret = -EINVAL;
> +               goto out;
> +       }
> +
> +       /* Load the kernel image */
> +       kbuf.image = image;
> +       kbuf.buf_min = 0;
> +       kbuf.buf_max = ULONG_MAX;
> +       kbuf.top_down = false;
> +
> +       kbuf.buffer = kernel;
> +       kbuf.bufsz = kernel_len;
> +       kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
> +       kbuf.memsz = le64_to_cpu(h->image_size);
> +       kbuf.buf_align = le64_to_cpu(h->text_offset);
> +
> +       ret = kexec_add_buffer(&kbuf);
> +       if (ret) {
> +               pr_err("Error add kernel image ret=%d\n", ret);
> +               goto out;
> +       }
> +
> +       image->start = kbuf.mem;
> +
> +       pr_info("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
> +                               kbuf.mem, kbuf.bufsz, kbuf.memsz);

pr_info() or pr_debug()?


> +
> +       ret = load_extra_segments(image, kbuf.mem, kbuf.memsz,
> +                                 initrd, initrd_len, cmdline, cmdline_len);
> +
> +out:
> +       return ret ? ERR_PTR(ret) : NULL;
> +}
> +
> +const struct kexec_file_ops image_kexec_ops = {
> +       .probe = image_probe,
> +       .load = image_load,
> +};
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index aedb8c16a283..5dc700834f1e 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -17,6 +17,7 @@
>
>  const struct kexec_file_ops * const kexec_file_loaders[] = {
>         &elf_kexec_ops,
> +       &image_kexec_ops,
>         NULL
>  };
>
> --
> 2.20.1
>

I tested these two patches. It works when
CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY is not enabled. When
CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY is enabled, the error is as
follows:

[45.712019] Unknown rela relocation: 34
[45.712258] Error loading purgatory ret=-8

How to fix it?

Thanks，
Yunhui

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