| Message ID | 1486554947-3964-5-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | arm64+ARM: efi: PE/COFF cleanup/hardening | expand |
On Wed, Feb 08, 2017 at 11:55:37AM +0000, Ard Biesheuvel wrote: > After having split off the PE header, clean up the bits that remain: > use .long consistently, merge two adjacent #ifdef CONFIG_EFI blocks, > fix the offset of the PE header pointer and remove the redundant .align > that follows it. > > Also, since we will be eliminating all open coded constants from the > EFI header in subsequent patches, let's replace the open coded "ARM\x64" > magic number with its .ascii equivalent. > > No changes to the resulting binary image are intended. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > arch/arm64/kernel/head.S | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index f779a7483736..aa8f6cd8c33f 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -91,20 +91,19 @@ _head: > .quad 0 // reserved > .quad 0 // reserved > .quad 0 // reserved > - .byte 0x41 // Magic number, "ARM\x64" > - .byte 0x52 > - .byte 0x4d > - .byte 0x64 > + .ascii "ARM\x64" // Magic number > #ifdef CONFIG_EFI > + /* > + * PE/COFF requires the offset to the PE header > + * to be stored at offset 0x3c into the file. > + */ > + .org _head + 0x3c > .long pe_header - _head // Offset to the PE header. Do we really need the .org? We expect all the other fields to stay in place without one, and it seems odd to special-case the PE header. Otherwise, this looks good to me. Thanks, Mark. > -#else > - .word 0 // reserved > -#endif > > -#ifdef CONFIG_EFI > - .align 3 > pe_header: > __EFI_PE_HEADER > +#else > + .long 0 // reserved > #endif > > __INIT > -- > 2.7.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10 February 2017 at 10:11, Mark Rutland <mark.rutland@arm.com> wrote: > On Wed, Feb 08, 2017 at 11:55:37AM +0000, Ard Biesheuvel wrote: >> After having split off the PE header, clean up the bits that remain: >> use .long consistently, merge two adjacent #ifdef CONFIG_EFI blocks, >> fix the offset of the PE header pointer and remove the redundant .align >> that follows it. >> >> Also, since we will be eliminating all open coded constants from the >> EFI header in subsequent patches, let's replace the open coded "ARM\x64" >> magic number with its .ascii equivalent. >> >> No changes to the resulting binary image are intended. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> --- >> arch/arm64/kernel/head.S | 17 ++++++++--------- >> 1 file changed, 8 insertions(+), 9 deletions(-) >> >> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S >> index f779a7483736..aa8f6cd8c33f 100644 >> --- a/arch/arm64/kernel/head.S >> +++ b/arch/arm64/kernel/head.S >> @@ -91,20 +91,19 @@ _head: >> .quad 0 // reserved >> .quad 0 // reserved >> .quad 0 // reserved >> - .byte 0x41 // Magic number, "ARM\x64" >> - .byte 0x52 >> - .byte 0x4d >> - .byte 0x64 >> + .ascii "ARM\x64" // Magic number >> #ifdef CONFIG_EFI >> + /* >> + * PE/COFF requires the offset to the PE header >> + * to be stored at offset 0x3c into the file. >> + */ >> + .org _head + 0x3c >> .long pe_header - _head // Offset to the PE header. > > > Do we really need the .org? We expect all the other fields to stay in > place without one, and it seems odd to special-case the PE header. > No, we don't. But the PE header offset is the only header field that covered by a requirement that goes beyond what we stipulate ourselves, so it makes sense to make that explicit imo. However, I'm happy to drop it if people disagree. > Otherwise, this looks good to me. > Cheers, -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index f779a7483736..aa8f6cd8c33f 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -91,20 +91,19 @@ _head: .quad 0 // reserved .quad 0 // reserved .quad 0 // reserved - .byte 0x41 // Magic number, "ARM\x64" - .byte 0x52 - .byte 0x4d - .byte 0x64 + .ascii "ARM\x64" // Magic number #ifdef CONFIG_EFI + /* + * PE/COFF requires the offset to the PE header + * to be stored at offset 0x3c into the file. + */ + .org _head + 0x3c .long pe_header - _head // Offset to the PE header. -#else - .word 0 // reserved -#endif -#ifdef CONFIG_EFI - .align 3 pe_header: __EFI_PE_HEADER +#else + .long 0 // reserved #endif __INIT
After having split off the PE header, clean up the bits that remain: use .long consistently, merge two adjacent #ifdef CONFIG_EFI blocks, fix the offset of the PE header pointer and remove the redundant .align that follows it. Also, since we will be eliminating all open coded constants from the EFI header in subsequent patches, let's replace the open coded "ARM\x64" magic number with its .ascii equivalent. No changes to the resulting binary image are intended. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/kernel/head.S | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html