objtool: Skip magical retpoline .altinstr_replacement

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

diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 2c7fbda7b05573e41807dc635c087dcec28dc37b..07b21cfabf5c098365773f96f9cee5ad7d9511ed 100644 (file)
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -106,6 +106,14 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
                        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;
 
@@ -154,7 +162,9 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
                        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);