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authorJosh Poimboeuf <jpoimboe@redhat.com>2021-02-24 19:29:14 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-07-25 12:26:18 +0300
commitf3fe1b141d2cd956ca59d142ef3b5f5cf4e5149c (patch)
tree72721e8be4217f698f28d902d22185fe366e332f /tools/objtool
parent0b2c8bf4983bdefbb69337c7d68cbe7c2d47a61a (diff)
downloadlinux-f3fe1b141d2cd956ca59d142ef3b5f5cf4e5149c.tar.xz
objtool: Support asm jump tables
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@redhat.com> Tested-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@redhat.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6d62ad940fce..eb180c78f440 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -107,6 +107,18 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
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 instruction *insn)
/* 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);