Hi Greg,
On Wed, Feb 21, 2024 at 02:07:11PM +0100, Greg Kroah-Hartman wrote:
> 5.15-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Nathan Chancellor <nathan@xxxxxxxxxx>
>
> commit e3a9ee963ad8ba677ca925149812c5932b49af69 upstream.
>
> Commit 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
> changed the ELF type of .btf.vmlinux.bin.o to ET_REL via dd, which works
> fine for little endian platforms:
>
> 00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
> -00000010 03 00 b7 00 01 00 00 00 00 00 00 80 00 80 ff ff |................|
> +00000010 01 00 b7 00 01 00 00 00 00 00 00 80 00 80 ff ff |................|
>
> However, for big endian platforms, it changes the wrong byte, resulting
> in an invalid ELF file type, which ld.lld rejects:
>
> 00000000 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 |.ELF............|
> -00000010 00 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
> +00000010 01 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
>
> Type: <unknown>: 103
>
> ld.lld: error: .btf.vmlinux.bin.o: unknown file type
>
> Fix this by updating the entire 16-bit e_type field rather than just a
> single byte, so that everything works correctly for all platforms and
> linkers.
>
> 00000000 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 |.ELF............|
> -00000010 00 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
> +00000010 00 01 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
>
> Type: REL (Relocatable file)
>
> While in the area, update the comment to mention that binutils 2.35+
> matches LLD's behavior of rejecting an ET_EXEC input, which occurred
> after the comment was added.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
> Link: https://github.com/llvm/llvm-project/pull/75643
> Suggested-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> Reviewed-by: Fangrui Song <maskray@xxxxxxxxxx>
> Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: Justin Stitt <justinstitt@xxxxxxxxxx>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> scripts/link-vmlinux.sh | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -236,8 +236,13 @@ gen_btf()
> ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
> --strip-all ${1} ${2} 2>/dev/null
> # Change e_type to ET_REL so that it can be used to link final vmlinux.
> - # Unlike GNU ld, lld does not allow an ET_EXEC input.
> - printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
> + # GNU ld 2.35+ and lld do not allow an ET_EXEC input.
> + if is_enabled CONFIG_CPU_BIG_ENDIAN; then
You may have missed my mail on the email saying this had been applied (I
didn't cc a lore list so no link):
I do not think this backport is correct for trees that do not have
commit 7d153696e5db ("kbuild: do not include include/config/auto.conf
from shell scripts"), even if it applies cleanly, as is_enabled() is not
available.
I think this diff should be squashed in to the patch for 5.15 and
earlier, you can add
[nathan: Fix silent conflict due to lack of 7d153696e5db in older trees]
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
to the resulting patch if you would like.
Cheers,
Nathan
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 007bb773b222..5a5a0cfad69d 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -237,7 +237,7 @@ gen_btf()
--strip-all ${1} ${2} 2>/dev/null
# Change e_type to ET_REL so that it can be used to link final vmlinux.
# GNU ld 2.35+ and lld do not allow an ET_EXEC input.
- if is_enabled CONFIG_CPU_BIG_ENDIAN; then
+ if [ -n "${CONFIG_CPU_BIG_ENDIAN}" ]; then
et_rel='\0\1'
else
et_rel='\1\0'
