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[v2,2/3] arm64/efi: efistub: cover entire static mem footprint in PE/COFF .text

Message ID 1406717944-24725-3-git-send-email-ard.biesheuvel@linaro.org
State Accepted
Commit c16173fa568582113145daee70fc317b10bc51e0
Headers show

Commit Message

Ard Biesheuvel July 30, 2014, 10:59 a.m. UTC
The static memory footprint of a kernel Image at boot is larger than the
Image file itself. Things like .bss data and initial page tables are allocated
statically but populated dynamically so their content is not contained in the
Image file.

However, if EFI (or GRUB) has loaded the Image at precisely the desired offset
of base of DRAM + TEXT_OFFSET, the Image will be booted in place, and we have
to make sure that the allocation done by the PE/COFF loader is large enough.

Fix this by growing the PE/COFF .text section to cover the entire static
memory footprint. The part of the section that is not covered by the payload
will be zero initialised by the PE/COFF loader.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Salter <msalter@redhat.com>
---
 arch/arm64/kernel/head.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Mark Rutland Aug. 14, 2014, 11:31 a.m. UTC | #1
On Wed, Jul 30, 2014 at 11:59:03AM +0100, Ard Biesheuvel wrote:
> The static memory footprint of a kernel Image at boot is larger than the
> Image file itself. Things like .bss data and initial page tables are allocated
> statically but populated dynamically so their content is not contained in the
> Image file.
> 
> However, if EFI (or GRUB) has loaded the Image at precisely the desired offset
> of base of DRAM + TEXT_OFFSET, the Image will be booted in place, and we have
> to make sure that the allocation done by the PE/COFF loader is large enough.
> 
> Fix this by growing the PE/COFF .text section to cover the entire static
> memory footprint. The part of the section that is not covered by the payload
> will be zero initialised by the PE/COFF loader.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Acked-by: Mark Salter <msalter@redhat.com>

This looks sane to me and it seems we do the same for x86 as of
c7fb93ec51d4 (x86/efi: Include a .bss section within the PE/COFF
headers). So:

Acked-by: Mark Rutland <mark.rutland@arm.com>

> ---
>  arch/arm64/kernel/head.S | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 144f10567f82..b6ca95aee348 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -151,7 +151,7 @@ optional_header:
>  	.short	0x20b				// PE32+ format
>  	.byte	0x02				// MajorLinkerVersion
>  	.byte	0x14				// MinorLinkerVersion
> -	.long	_edata - stext			// SizeOfCode
> +	.long	_end - stext			// SizeOfCode
>  	.long	0				// SizeOfInitializedData
>  	.long	0				// SizeOfUninitializedData
>  	.long	efi_stub_entry - efi_head	// AddressOfEntryPoint
> @@ -169,7 +169,7 @@ extra_header_fields:
>  	.short	0				// MinorSubsystemVersion
>  	.long	0				// Win32VersionValue
>  
> -	.long	_edata - efi_head		// SizeOfImage
> +	.long	_end - efi_head			// SizeOfImage
>  
>  	// Everything before the kernel image is considered part of the header
>  	.long	stext - efi_head		// SizeOfHeaders
> @@ -216,7 +216,7 @@ section_table:
>  	.byte	0
>  	.byte	0
>  	.byte	0        		// end of 0 padding of section name
> -	.long	_edata - stext		// VirtualSize
> +	.long	_end - stext		// VirtualSize
>  	.long	stext - efi_head	// VirtualAddress
>  	.long	_edata - stext		// SizeOfRawData
>  	.long	stext - efi_head	// PointerToRawData
> -- 
> 1.8.3.2
> 
> --
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diff mbox

Patch

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 144f10567f82..b6ca95aee348 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -151,7 +151,7 @@  optional_header:
 	.short	0x20b				// PE32+ format
 	.byte	0x02				// MajorLinkerVersion
 	.byte	0x14				// MinorLinkerVersion
-	.long	_edata - stext			// SizeOfCode
+	.long	_end - stext			// SizeOfCode
 	.long	0				// SizeOfInitializedData
 	.long	0				// SizeOfUninitializedData
 	.long	efi_stub_entry - efi_head	// AddressOfEntryPoint
@@ -169,7 +169,7 @@  extra_header_fields:
 	.short	0				// MinorSubsystemVersion
 	.long	0				// Win32VersionValue
 
-	.long	_edata - efi_head		// SizeOfImage
+	.long	_end - efi_head			// SizeOfImage
 
 	// Everything before the kernel image is considered part of the header
 	.long	stext - efi_head		// SizeOfHeaders
@@ -216,7 +216,7 @@  section_table:
 	.byte	0
 	.byte	0
 	.byte	0        		// end of 0 padding of section name
-	.long	_edata - stext		// VirtualSize
+	.long	_end - stext		// VirtualSize
 	.long	stext - efi_head	// VirtualAddress
 	.long	_edata - stext		// SizeOfRawData
 	.long	stext - efi_head	// PointerToRawData