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[-next,2/3] arm64: head: Mark constants as data

Message ID 20220922130452.233323-3-chenzhongjin@huawei.com (mailing list archive)
State Not Applicable
Delegated to: Herbert Xu
Headers show
Series arm64: Mark constants in .S files as data | expand

Commit Message

Chen Zhongjin Sept. 22, 2022, 1:04 p.m. UTC 
Add data annotations to constants part of the image header.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/head.S | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Ard Biesheuvel Sept. 22, 2022, 1:17 p.m. UTC | #1 
On Thu, 22 Sept 2022 at 15:08, Chen Zhongjin <chenzhongjin@huawei.com> wrote:
>
> Add data annotations to constants part of the image header.
>
> Signed-off-by: Julien Thierry <jthierry@redhat.com>
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
> Reviewed-by: Mark Brown <broonie@kernel.org>
> ---
>  arch/arm64/kernel/head.S | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 814b6587ccb7..f298e88e2d23 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -57,9 +57,10 @@
>         /*
>          * DO NOT MODIFY. Image header expected by Linux boot-loaders.
>          */
> -       efi_signature_nop                       // special NOP to identity as PE/COFF executable
> +SYM_DATA_LOCAL(efi_nop, efi_signature_nop)     // special NOP to identity as PE/COFF executable

This is an instruction not data

>         b       primary_entry                   // branch to kernel start, magic
> -       .quad   0                               // Image load offset from start of RAM, little-endian
> +SYM_DATA_LOCAL(_zero_reserved, .quad   0)      // Image load offset from start of RAM, little-endian

Why convert this quad? And why does it need a symbol?

> +SYM_DATA_START_LOCAL(_arm64_common_header)
>         le64sym _kernel_size_le                 // Effective size of kernel image, little-endian
>         le64sym _kernel_flags_le                // Informative flags, little-endian
>         .quad   0                               // reserved

But not this one?

> @@ -67,6 +68,7 @@
>         .quad   0                               // reserved
>         .ascii  ARM64_IMAGE_MAGIC               // Magic number
>         .long   .Lpe_header_offset              // Offset to the PE header.
> +SYM_DATA_END(_arm64_common_header)
>
>         __EFI_PE_HEADER
>
> --
> 2.17.1
>
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Patch

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 814b6587ccb7..f298e88e2d23 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -57,9 +57,10 @@ 
 	/*
 	 * DO NOT MODIFY. Image header expected by Linux boot-loaders.
 	 */
-	efi_signature_nop			// special NOP to identity as PE/COFF executable
+SYM_DATA_LOCAL(efi_nop, efi_signature_nop)	// special NOP to identity as PE/COFF executable
 	b	primary_entry			// branch to kernel start, magic
-	.quad	0				// Image load offset from start of RAM, little-endian
+SYM_DATA_LOCAL(_zero_reserved, .quad	0)	// Image load offset from start of RAM, little-endian
+SYM_DATA_START_LOCAL(_arm64_common_header)
 	le64sym	_kernel_size_le			// Effective size of kernel image, little-endian
 	le64sym	_kernel_flags_le		// Informative flags, little-endian
 	.quad	0				// reserved
@@ -67,6 +68,7 @@ 
 	.quad	0				// reserved
 	.ascii	ARM64_IMAGE_MAGIC		// Magic number
 	.long	.Lpe_header_offset		// Offset to the PE header.
+SYM_DATA_END(_arm64_common_header)
 
 	__EFI_PE_HEADER