Re: [Xen-devel] [PATCH v3 06/25] libelf-loader: introduce elf_load_image

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.12.11 at 17:30, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> Implement a new function, called elf_load_image, to perform the actually
> copy of the elf image and clearing the padding.
> The function is implemented as memcpy and memset when the library is
> built as part of the tools, but it is implemented as raw_copy_to_guest and
> raw_clear_guest when built as part of Xen, so that it can be safely called
> with an HVM style dom0.
> 
> 
> Changes in v3:
> 
> - switch to raw_copy_to_guest and raw_clear_guest.
> 
> 
> Changes in v2:
> 
> - remove CONFIG_KERNEL_NO_RELOC.
> 
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> ---
>  xen/common/libelf/libelf-loader.c |   17 +++++++++++++++--
>  1 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/libelf/libelf-loader.c 
> b/xen/common/libelf/libelf-loader.c
> index 1ccf7d3..d2cb5b3 100644
> --- a/xen/common/libelf/libelf-loader.c
> +++ b/xen/common/libelf/libelf-loader.c
> @@ -107,11 +107,25 @@ void elf_set_log(struct elf_binary *elf, 
> elf_log_callback *log_callback,
>      elf->log_caller_data = log_caller_data;
>      elf->verbose = verbose;
>  }
> +
> +static void elf_load_image(void *dst, const void *src, uint64_t filesz, 
> uint64_t memsz)
> +{
> +    memcpy(dst, src, filesz);
> +    memset(dst + filesz, 0, memsz - filesz);
> +}
>  #else
> +#include <asm/guest_access.h>
> +
>  void elf_set_verbose(struct elf_binary *elf)
>  {
>      elf->verbose = 1;
>  }
> +
> +static void elf_load_image(void *dst, const void *src, uint64_t filesz, 
> uint64_t memsz)
> +{
> +    raw_copy_to_guest(dst, src, filesz);
> +    raw_clear_guest(dst + filesz, memsz - filesz);

I thought I had mentioned this already - calling user/guest access
functions without checking their return value is bogus.

Jan

> +}
>  #endif
>  
>  /* Calculate the required additional kernel space for the elf image */
> @@ -256,8 +270,7 @@ void elf_load_binary(struct elf_binary *elf)
>          dest = elf_get_ptr(elf, paddr);
>          elf_msg(elf, "%s: phdr %" PRIu64 " at 0x%p -> 0x%p\n",
>                  __func__, i, dest, dest + filesz);
> -        memcpy(dest, elf->image + offset, filesz);
> -        memset(dest + filesz, 0, memsz - filesz);
> +        elf_load_image(dest, elf->image + offset, filesz, memsz);
>      }
>  
>      elf_load_bsdsyms(elf);
> -- 
> 1.7.2.5




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