]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commitdiff
objtool: Only rewrite unconditional retpoline thunk calls
authorPeter Zijlstra <peterz@infradead.org>
Thu, 10 Jun 2021 07:04:29 +0000 (09:04 +0200)
committerPeter Zijlstra <peterz@infradead.org>
Fri, 11 Jun 2021 06:53:06 +0000 (08:53 +0200)
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>
tools/objtool/arch/x86/decode.c

index 24295d39713b26e0e2af9063b77a2f3ab664b591..523aa4157f801c82686f19a2cc9403a6ca6113bb 100644 (file)
@@ -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;