Re: [PATCH v1 1/2] zboot: enable arm64 kexec_load for zboot image

[Baoquan He <bhe@redhat.com>]

On 09/14/23 at 04:49pm, Dave Young wrote:
> kexec_file_load support of zboot kernel image decompressed the vmlinuz,
> so in kexec_load code just load the kernel with reading the decompressed
> kernel fd into a new buffer and use it directly.
> 
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---
>  include/kexec-pe-zboot.h               |  3 ++-
>  kexec/arch/arm64/kexec-vmlinuz-arm64.c | 26 +++++++++++++++++++++++---
>  kexec/kexec-pe-zboot.c                 |  4 +++-
>  kexec/kexec.c                          |  2 +-
>  kexec/kexec.h                          |  1 +
>  5 files changed, 30 insertions(+), 6 deletions(-)

I got this problem too on arm64 machine, applied this patch to test, can
confirm it works to fix the load failure when kexec_load is taken.

Tested-by: Baoquan He <bhe@redhat.com>

> 
> diff --git a/include/kexec-pe-zboot.h b/include/kexec-pe-zboot.h
> index e2e0448a81f2..374916cbe883 100644
> --- a/include/kexec-pe-zboot.h
> +++ b/include/kexec-pe-zboot.h
> @@ -11,5 +11,6 @@ struct linux_pe_zboot_header {
>  	uint32_t compress_type;
>  };
>  
> -int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd);
> +int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd,
> +		off_t *kernel_size);
>  #endif
> diff --git a/kexec/arch/arm64/kexec-vmlinuz-arm64.c b/kexec/arch/arm64/kexec-vmlinuz-arm64.c
> index c0ee47c8f50a..e291a34c97ad 100644
> --- a/kexec/arch/arm64/kexec-vmlinuz-arm64.c
> +++ b/kexec/arch/arm64/kexec-vmlinuz-arm64.c
> @@ -34,6 +34,7 @@
>  #include "arch/options.h"
>  
>  static int kernel_fd = -1;
> +static off_t decompressed_size;
>  
>  /* Returns:
>   * -1 : in case of error/invalid format (not a valid PE+compressed ZBOOT format.
> @@ -72,7 +73,7 @@ int pez_arm64_probe(const char *kernel_buf, off_t kernel_size)
>  		return -1;
>  	}
>  
> -	ret = pez_prepare(buf, buf_sz, &kernel_fd);
> +	ret = pez_prepare(buf, buf_sz, &kernel_fd, &decompressed_size);
>  
>  	if (!ret) {
>  	    /* validate the arm64 specific header */
> @@ -98,8 +99,27 @@ bad_header:
>  int pez_arm64_load(int argc, char **argv, const char *buf, off_t len,
>  			struct kexec_info *info)
>  {
> -	info->kernel_fd = kernel_fd;
> -	return image_arm64_load(argc, argv, buf, len, info);
> +	if (kernel_fd > 0 && decompressed_size > 0) {
> +		char *kbuf;
> +		off_t nread;
> +		int fd;
> +
> +		info->kernel_fd = kernel_fd;
> +		fd = dup(kernel_fd);
> +		if (fd < 0) {
> +			dbgprintf("%s: dup fd failed.\n", __func__);
> +			return -1;
> +		}
> +		kbuf = slurp_fd(fd, NULL, decompressed_size, &nread);
> +		if (!kbuf || nread != decompressed_size) {
> +			dbgprintf("%s: slurp_fd failed.\n", __func__);
> +			return -1;
> +		}
> +		return image_arm64_load(argc, argv, kbuf, decompressed_size, info);
> +	}
> +
> +	dbgprintf("%s: wrong kernel file descriptor.\n", __func__);
> +	return -1;
>  }
>  
>  void pez_arm64_usage(void)
> diff --git a/kexec/kexec-pe-zboot.c b/kexec/kexec-pe-zboot.c
> index 2f2e052b76c5..3abd17d9fe59 100644
> --- a/kexec/kexec-pe-zboot.c
> +++ b/kexec/kexec-pe-zboot.c
> @@ -37,7 +37,8 @@
>   *
>   * crude_buf: the content, which is read from the kernel file without any processing
>   */
> -int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd)
> +int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd,
> +		off_t *kernel_size)
>  {
>  	int ret = -1;
>  	int fd = 0;
> @@ -110,6 +111,7 @@ int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd)
>  		goto fail_bad_header;
>  	}
>  
> +	*kernel_size = decompressed_size;
>  	dbgprintf("%s: done\n", __func__);
>  
>  	ret = 0;
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index c3b182e254e0..1edbd349c86d 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -489,7 +489,7 @@ static int add_backup_segments(struct kexec_info *info,
>  	return 0;
>  }
>  
> -static char *slurp_fd(int fd, const char *filename, off_t size, off_t *nread)
> +char *slurp_fd(int fd, const char *filename, off_t size, off_t *nread)
>  {
>  	char *buf;
>  	off_t progress;
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index ed3b499a80f2..093338969c57 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -267,6 +267,7 @@ extern void die(const char *fmt, ...)
>  	__attribute__ ((format (printf, 1, 2)));
>  extern void *xmalloc(size_t size);
>  extern void *xrealloc(void *ptr, size_t size);
> +extern char *slurp_fd(int fd, const char *filename, off_t size, off_t *nread);
>  extern char *slurp_file(const char *filename, off_t *r_size);
>  extern char *slurp_file_mmap(const char *filename, off_t *r_size);
>  extern char *slurp_file_len(const char *filename, off_t size, off_t *nread);
> -- 
> 2.37.2
> 
> 
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