objtool: Only rewrite unconditional retpoline thunk calls

It turns out that the compilers generate conditional branches to the
retpoline thunks like:

  5d5:   0f 85 00 00 00 00       jne    5db <cpuidle_reflect+0x22>
	5d7: R_X86_64_PLT32     __x86_indirect_thunk_r11-0x4

while the rewrite can only handle JMP/CALL to the thunks. The result
is the alternative wrecking the code. Make sure to skip writing the
alternatives for conditional branches.

Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Lukasz Majczak <lma@semihalf.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 24295d3..523aa41 100644 (file)
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -747,6 +747,10 @@ int arch_rewrite_retpolines(struct objtool_file *file)
 
        list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
 
+               if (insn->type != INSN_JUMP_DYNAMIC &&
+                   insn->type != INSN_CALL_DYNAMIC)
+                       continue;
+
                if (!strcmp(insn->sec->name, ".text.__x86.indirect_thunk"))
                        continue;