[tip: x86/core] objtool: Track init section

tip-bot2 for Peter Zijlstra
2022-10-17T14:56:38Z

The following commit has been merged into the x86/core branch of tip:

Commit-ID: 6644ee846cb983437063da8fd24b7cae671fd019
Gitweb: https://git.kernel.org/tip/6644ee846cb983437063da8fd24b7cae671fd019
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 15 Sep 2022 13:11:08 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 17 Oct 2022 16:41:07 +02:00

objtool: Track init section

For future usage of .init.text exclusion track the init section in the
instruction decoder and use the result in retpoline validation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111145.910334431@infradead.org
---
tools/objtool/check.c | 17 ++++++++++-------
tools/objtool/include/objtool/elf.h | 2 +-
2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7174bba..bb7c819 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -382,6 +382,15 @@ static int decode_instructions(struct objtool_file *file)
!strncmp(sec->name, ".text.__x86.", 12))
sec->noinstr = true;

+ /*
+ * .init.text code is ran before userspace and thus doesn't
+ * strictly need retpolines, except for modules which are
+ * loaded late, they very much do need retpoline in their
+ * .init.text
+ */
+ if (!strcmp(sec->name, ".init.text") && !opts.module)
+ sec->init = true;
+
for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
insn = malloc(sizeof(*insn));
if (!insn) {
@@ -3748,13 +3757,7 @@ static int validate_retpoline(struct objtool_file *file)
if (insn->retpoline_safe)
continue;

- /*
- * .init.text code is ran before userspace and thus doesn't
- * strictly need retpolines, except for modules which are
- * loaded late, they very much do need retpoline in their
- * .init.text
- */
- if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
+ if (insn->sec->init)
continue;

if (insn->type == INSN_RETURN) {
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 16f4067..baa8085 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -38,7 +38,7 @@ struct section {
Elf_Data *data;
char *name;
int idx;
- bool changed, text, rodata, noinstr;
+ bool changed, text, rodata, noinstr, init;
};

struct symbol {