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| author | Joe Lawrence <joe.lawrence@redhat.com> | 2021-08-22 18:50:36 -0400 |
|---|---|---|
| committer | Josh Poimboeuf <jpoimboe@redhat.com> | 2021-10-05 12:03:20 -0700 |
| commit | dc02368164bd0ec603e3f5b3dd8252744a667b8a (patch) | |
| tree | 37bdf201a6df6c0818324c3985a587d22eb5b20d /tools | |
| parent | 4d8b35968bbf9e42b6b202eedb510e2c82ad8b38 (diff) | |
| download | lwn-dc02368164bd0ec603e3f5b3dd8252744a667b8a.tar.gz lwn-dc02368164bd0ec603e3f5b3dd8252744a667b8a.zip | |
objtool: Make .altinstructions section entry size consistent
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@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210822225037.54620-2-joe.lawrence@redhat.com
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index bc821056aba9..0893436cc09f 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -684,7 +684,7 @@ static int elf_add_alternative(struct elf *elf, 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"); |