This is a note to let you know that I've just added the patch titled
objtool: Support asm jump tables
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-support-asm-jump-tables.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: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Date: Wed, 24 Feb 2021 10:29:14 -0600
Subject: objtool: Support asm jump tables
From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
commit 99033461e685b48549ec77608b4bda75ddf772ce upstream.
Objtool detection of asm jump tables would normally just work, except
for the fact that asm retpolines use alternatives. Objtool thinks the
alternative code path (a jump to the retpoline) is a sibling call.
Don't treat alternative indirect branches as sibling calls when the
original instruction has a jump table.
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Tested-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Tested-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/objtool/check.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -107,6 +107,18 @@ static struct instruction *prev_insn_sam
for (insn = next_insn_same_sec(file, insn); insn; \
insn = next_insn_same_sec(file, insn))
+static bool is_jump_table_jump(struct instruction *insn)
+{
+ struct alt_group *alt_group = insn->alt_group;
+
+ if (insn->jump_table)
+ return true;
+
+ /* Retpoline alternative for a jump table? */
+ return alt_group && alt_group->orig_group &&
+ alt_group->orig_group->first_insn->jump_table;
+}
+
static bool is_sibling_call(struct instruction *insn)
{
/*
@@ -119,7 +131,7 @@ static bool is_sibling_call(struct instr
/* An indirect jump is either a sibling call or a jump to a table. */
if (insn->type == INSN_JUMP_DYNAMIC)
- return list_empty(&insn->alts);
+ return !is_jump_table_jump(insn);
/* add_jump_destinations() sets insn->call_dest for sibling calls. */
return (is_static_jump(insn) && insn->call_dest);
Patches currently in stable-queue which might be from jpoimboe@xxxxxxxxxx are
queue-5.10/x86-bugs-enable-stibp-for-jmp2ret.patch
queue-5.10/objtool-assume-only-elf-functions-do-sibling-calls.patch
queue-5.10/objtool-support-retpoline-jump-detection-for-vmlinux.o.patch
queue-5.10/x86-xen-support-objtool-vmlinux.o-validation-in-xen-head.s.patch
queue-5.10/objtool-x86-replace-alternatives-with-.retpoline_sites.patch
queue-5.10/objtool-don-t-make-.altinstructions-writable.patch
queue-5.10/x86-alternative-handle-jcc-__x86_indirect_thunk_-reg.patch
queue-5.10/x86-xen-support-objtool-validation-in-xen-asm.s.patch
queue-5.10/x86-retpoline-remove-unused-replacement-symbols.patch
queue-5.10/objtool-support-stack-layout-changes-in-alternatives.patch
queue-5.10/bpf-x86-respect-x86_feature_retpoline.patch
queue-5.10/objtool-fix-type-of-reloc-addend.patch
queue-5.10/x86-retpoline-create-a-retpoline-thunk-array.patch
queue-5.10/x86-asm-fix-register-order.patch
queue-5.10/objtool-make-.altinstructions-section-entry-size-consistent.patch
queue-5.10/bpf-x86-simplify-computing-label-offsets.patch
queue-5.10/objtool-refactor-orc-section-generation.patch
queue-5.10/objtool-fix-code-relocs-vs-weak-symbols.patch
queue-5.10/objtool-combine-unwind_hint_ret_offset-and-unwind_hint_func.patch
queue-5.10/x86-asm-fixup-odd-gen-for-each-reg.h-usage.patch
queue-5.10/x86-alternative-add-debug-prints-to-apply_retpolines.patch
queue-5.10/objtool-remove-reloc-symbol-type-checks-in-get_alt_entry.patch
queue-5.10/objtool-classify-symbols.patch
queue-5.10/objtool-add-alt_group-struct.patch
queue-5.10/x86-retpoline-move-the-retpoline-thunk-declarations-to-nospec-branch.h.patch
queue-5.10/objtool-support-asm-jump-tables.patch
queue-5.10/x86-alternative-implement-.retpoline_sites-support.patch
queue-5.10/x86-alternative-try-inline-spectre_v2-retpoline-amd.patch
queue-5.10/objtool-explicitly-avoid-self-modifying-code-in-.altinstr_replacement.patch
queue-5.10/objtool-create-reloc-sections-implicitly.patch
queue-5.10/objtool-default-ignore-int3-for-unreachable.patch
queue-5.10/objtool-teach-get_alt_entry-about-more-relocation-types.patch
