This is a note to let you know that I've just added the patch titled
objtool: Make .altinstructions section entry size consistent
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
objtool-make-.altinstructions-section-entry-size-consistent.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Jul 12 05:07:35 PM CEST 2022
From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Date: Sun, 22 Aug 2021 18:50:36 -0400
Subject: objtool: Make .altinstructions section entry size consistent
From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
commit dc02368164bd0ec603e3f5b3dd8252744a667b8a upstream.
Commit e31694e0a7a7 ("objtool: Don't make .altinstructions writable")
aligned objtool-created and kernel-created .altinstructions section
flags, but there remains a minor discrepency in their use of a section
entry size: objtool sets one while the kernel build does not.
While sh_entsize of sizeof(struct alt_instr) seems intuitive, this small
deviation can cause failures with external tooling (kpatch-build).
Fix this by creating new .altinstructions sections with sh_entsize of 0
and then later updating sec->sh_size as alternatives are added to the
section. An added benefit is avoiding the data descriptor and buffer
created by elf_create_section(), but previously unused by
elf_add_alternative().
Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210822225037.54620-2-joe.lawrence@xxxxxxxxxx
Cc: Andy Lavr <andy.lavr@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/objtool/arch/x86/decode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -611,7 +611,7 @@ static int elf_add_alternative(struct el
sec = find_section_by_name(elf, ".altinstructions");
if (!sec) {
sec = elf_create_section(elf, ".altinstructions",
- SHF_ALLOC, size, 0);
+ SHF_ALLOC, 0, 0);
if (!sec) {
WARN_ELF("elf_create_section");
Patches currently in stable-queue which might be from joe.lawrence@xxxxxxxxxx are
queue-5.10/objtool-don-t-make-.altinstructions-writable.patch
queue-5.10/objtool-make-.altinstructions-section-entry-size-consistent.patch
