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authorPeter Zijlstra <peterz@infradead.org>2021-06-10 10:04:29 +0300
committerPeter Zijlstra <peterz@infradead.org>2021-06-11 09:53:06 +0300
commit2d49b721dc18c113d5221f4cf5a6104eb66cb7f2 (patch)
treeab75c8cfd9dafa5f54af3988bcb7c595380e307c
parent584fd3b31889852d0d6f3dd1e3d8e9619b660d2c (diff)
downloadlinux-2d49b721dc18c113d5221f4cf5a6104eb66cb7f2.tar.xz
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>
-rw-r--r--tools/objtool/arch/x86/decode.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 24295d39713b..523aa4157f80 100644
--- 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;