Re: [PATCH for-4.5] EFI: Fix efi_arch_allocate_mmap_buffer() to return new size

[Ian Campbell <Ian.Campbell@citrix.com>]

On Tue, 2014-10-21 at 21:18 -0700, Roy Franz wrote:
> efi_arch_allocate_mmap_buffer() allocates a buffer for the EFI memory map, and
> for ARM it allocates a larger buffer than requested. This is done to account
> for the increase in the map size that may occur when the allocation is made.
> The previous code allocated a larger buffer, but did not adjust the size to
> match.  This caused the later call to GetMemoryMap() to fail with a
> BUFFER_TOO_SMALL error, since the original, smaller size was used.  This patch
> changes the argument to efi_arch_allocate_mmap_buffer() to be a pointer to
> UINTN, and the ARM version updates the size on a successful allocation.
> The x86 version uses a different allocation method, so only the function
> argument type is changed.
> Also add decode of the BUFFER_TOO_SMALL error code to PrintErrMesg().
> 
> Signed-off-by: Roy Franz <roy.franz@linaro.org>

For the arm side:
Acked-by: Ian Campbell <ian.campbell@citrix.com>

> ---
>  xen/arch/arm/efi/efi-boot.h | 6 ++++--
>  xen/arch/x86/efi/efi-boot.h | 4 ++--
>  xen/common/efi/boot.c       | 5 ++++-
>  3 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index d40d8b2..639942d 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -370,14 +370,16 @@ static void __init efi_arch_cfg_file_late(EFI_FILE_HANDLE dir_handle, char *sect
>  {
>  }
>  
> -static void *__init efi_arch_allocate_mmap_buffer(UINTN map_size)
> +static void *__init efi_arch_allocate_mmap_buffer(UINTN *map_size)
>  {
>      void *ptr;
>      EFI_STATUS status;
> +    UINTN map_size_alloc = *map_size + EFI_PAGE_SIZE;
>  
> -    status = efi_bs->AllocatePool(EfiLoaderData, map_size + EFI_PAGE_SIZE, &ptr);
> +    status = efi_bs->AllocatePool(EfiLoaderData, map_size_alloc, &ptr);
>      if ( status != EFI_SUCCESS )
>          return NULL;
> +    *map_size = map_size_alloc;
>      return ptr;
>  }
>  
> diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
> index 4348cfe..454ffb6 100644
> --- a/xen/arch/x86/efi/efi-boot.h
> +++ b/xen/arch/x86/efi/efi-boot.h
> @@ -190,10 +190,10 @@ static void __init efi_arch_process_memory_map(EFI_SYSTEM_TABLE *SystemTable,
>  
>  }
>  
> -static void *__init efi_arch_allocate_mmap_buffer(UINTN map_size)
> +static void *__init efi_arch_allocate_mmap_buffer(UINTN *map_size)
>  {
>      place_string(&mbi.mem_upper, NULL);
> -    mbi.mem_upper -= map_size;
> +    mbi.mem_upper -= *map_size;
>      mbi.mem_upper &= -__alignof__(EFI_MEMORY_DESCRIPTOR);
>      if ( mbi.mem_upper < xen_phys_start )
>          return NULL;
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index f272171..4257341 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -271,6 +271,9 @@ static void __init PrintErrMesg(const CHAR16 *mesg, EFI_STATUS ErrCode)
>      case EFI_COMPROMISED_DATA:
>          mesg = L"Compromised data";
>          break;
> +    case EFI_BUFFER_TOO_SMALL:
> +        mesg = L"Buffer too small";
> +        break;
>      default:
>          PrintErr(L"ErrCode: ");
>          DisplayUint(ErrCode, 0);
> @@ -1038,7 +1041,7 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>  
>      efi_bs->GetMemoryMap(&efi_memmap_size, NULL, &map_key,
>                           &efi_mdesc_size, &mdesc_ver);
> -    efi_memmap = efi_arch_allocate_mmap_buffer(efi_memmap_size);
> +    efi_memmap = efi_arch_allocate_mmap_buffer(&efi_memmap_size);
>      if ( !efi_memmap )
>          blexit(L"Unable to allocate memory for EFI memory map");
>