Re: [PATCH -next 1/3] arm64: efi-header: Mark efi header as data

[Chen Zhongjin]

Hi,

On 2022/9/22 21:13, Ard Biesheuvel wrote:
> On Thu, 22 Sept 2022 at 15:08, Chen Zhongjin <chenzhongjin@xxxxxxxxxx> wrote:
> > This file only contains a set of constants forming the efi header.
> >
> > Make the constants part of data symbols by wrapping them with
> > SYM_DATA.
> >
> > Signed-off-by: Julien Thierry <jthierry@xxxxxxxxxx>
> > Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
> > Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
> Why is this necessary? These are not emitted into a .text section, and
> are not even covered by the kernel's mapping of memory. So the .L
> prefixed labels are deliberate: it prevents the symbols from polluting
> the symbol namespace with symbols pointing nowhere.
This is basically because when I'm developing objtool and these 
constants will disrupts

the instruction decoding so I just mark them as x86 did.


I tried to sent this patch set is because now the objtool patch set is 
growing huge so I

want to split some independent part. But now I found you are right that 
this are

meaningless. They are not even inside vmlinux. I'll discard them.


Sorry for bothering and thanks for your advise and patient!

Best,

Chen

> > ---
> >   arch/arm64/kernel/efi-header.S | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arm64/kernel/efi-header.S b/arch/arm64/kernel/efi-header.S
> > index 28d8a5dca5f1..3eacd27ab761 100644
> > --- a/arch/arm64/kernel/efi-header.S
> > +++ b/arch/arm64/kernel/efi-header.S
> > @@ -28,6 +28,7 @@
> >          .macro  __EFI_PE_HEADER
> >   #ifdef CONFIG_EFI
> >          .set    .Lpe_header_offset, . - .L_head
> > +SYM_DATA_START_LOCAL(arm64_efi_header)
> >          .long   PE_MAGIC
> >          .short  IMAGE_FILE_MACHINE_ARM64                // Machine
> >          .short  .Lsection_count                         // NumberOfSections
> > @@ -160,6 +161,7 @@
> >
> >          .balign SEGMENT_ALIGN
> >   .Lefi_header_end:
> > +SYM_DATA_END_LABEL(arm64_efi_header, SYM_L_LOCAL, efi_header_end)
> >   #else
> >          .set    .Lpe_header_offset, 0x0
> >   #endif
> > --
> > 2.17.1