[PATCH 5.10 033/130] objtool: Skip magical retpoline .altinstr_replacement

Greg Kroah-Hartman
2022-07-12T18:43:00Z

commit 50e7b4a1a1b264fc7df0698f2defb93cadf19a7b upstream.

When the .altinstr_replacement is a retpoline, skip the alternative.
We already special case retpolines anyway.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.259429287@infradead.org
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/objtool/special.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -104,6 +104,14 @@ static int get_alt_entry(struct elf *elf
return -1;
}

+ /*
+ * Skip retpoline .altinstr_replacement... we already rewrite the
+ * instructions for retpolines anyway, see arch_is_retpoline()
+ * usage in add_{call,jump}_destinations().
+ */
+ if (arch_is_retpoline(new_reloc->sym))
+ return 1;
+
alt->new_sec = new_reloc->sym->sec;
alt->new_off = (unsigned int)new_reloc->addend;

@@ -152,7 +160,9 @@ int special_get_alts(struct elf *elf, st
memset(alt, 0, sizeof(*alt));

ret = get_alt_entry(elf, entry, sec, idx, alt);
- if (ret)
+ if (ret > 0)
+ continue;
+ if (ret < 0)
return ret;

list_add_tail(&alt->list, alts);