From 4ab7674f5951ac6a8ac4fa8828090edb64a4771f Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon, 18 Apr 2022 09:50:39 -0700
Subject: objtool: Make jump label hack optional
Objtool secretly does a jump label hack to overcome the limitations of
the toolchain. Make the hack explicit (and optional for other arches)
by turning it into a cmdline option and kernel config option.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/3bdcbfdd27ecb01ddec13c04bdf756a583b13d24.1650300597.git.jpoimboe@redhat.com
---
tools/objtool/builtin-check.c | 37 ++++++++++++++++++++++++++-------
tools/objtool/check.c | 2 +-
tools/objtool/include/objtool/builtin.h | 1 +
3 files changed, 31 insertions(+), 9 deletions(-)
(limited to 'tools/objtool')
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index c8c4d2bab42f..b2c626d9e2bf 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -31,8 +31,28 @@ static int parse_dump(const struct option *opt, const char *str, int unset)
return -1;
}
+static int parse_hacks(const struct option *opt, const char *str, int unset)
+{
+ bool found = false;
+
+ /*
+ * Use strstr() as a lazy method of checking for comma-separated
+ * options.
+ *
+ * No string provided == enable all options.
+ */
+
+ if (!str || strstr(str, "jump_label")) {
+ opts.hack_jump_label = true;
+ found = true;
+ }
+
+ return found ? 0 : -1;
+}
+
const struct option check_options[] = {
OPT_GROUP("Actions:"),
+ OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label", "patch toolchain bugs/limitations", parse_hacks),
OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
@@ -87,14 +107,15 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[])
static bool opts_valid(void)
{
- if (opts.ibt ||
- opts.mcount ||
- opts.noinstr ||
- opts.orc ||
- opts.retpoline ||
- opts.sls ||
- opts.stackval ||
- opts.static_call ||
+ if (opts.hack_jump_label ||
+ opts.ibt ||
+ opts.mcount ||
+ opts.noinstr ||
+ opts.orc ||
+ opts.retpoline ||
+ opts.sls ||
+ opts.stackval ||
+ opts.static_call ||
opts.uaccess) {
if (opts.dump_orc) {
fprintf(stderr, "--dump can't be combined with other options\n");
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b9ac351ea08b..d157978c58b3 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1592,7 +1592,7 @@ static int handle_jump_alt(struct objtool_file *file,
return -1;
}
- if (special_alt->key_addend & 2) {
+ if (opts.hack_jump_label && special_alt->key_addend & 2) {
struct reloc *reloc = insn_reloc(file, orig_insn);
if (reloc) {
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index dc4757205b8d..c6acf05ec859 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -12,6 +12,7 @@ extern const struct option check_options[];
struct opts {
/* actions: */
bool dump_orc;
+ bool hack_jump_label;
bool ibt;
bool mcount;
bool noinstr;
--
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