From be8a096521ca1a252bf078b347f96ce94582612e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 28 Mar 2022 13:13:41 +0200 Subject: x86,bpf: Avoid IBT objtool warning Clang can inline emit_indirect_jump() and then folds constants, which results in: | vmlinux.o: warning: objtool: emit_bpf_dispatcher()+0x6a4: relocation to !ENDBR: .text.__x86.indirect_thunk+0x40 | vmlinux.o: warning: objtool: emit_bpf_dispatcher()+0x67d: relocation to !ENDBR: .text.__x86.indirect_thunk+0x40 | vmlinux.o: warning: objtool: emit_bpf_tail_call_indirect()+0x386: relocation to !ENDBR: .text.__x86.indirect_thunk+0x20 | vmlinux.o: warning: objtool: emit_bpf_tail_call_indirect()+0x35d: relocation to !ENDBR: .text.__x86.indirect_thunk+0x20 Suppress the optimization such that it must emit a code reference to the __x86_indirect_thunk_array[] base. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Alexei Starovoitov Link: https://lkml.kernel.org/r/20220405075531.GB30877@worktop.programming.kicks-ass.net --- arch/x86/net/bpf_jit_comp.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 8fe35ed11fd6..16b6efacf7c6 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -412,6 +412,7 @@ static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip) EMIT_LFENCE(); EMIT2(0xFF, 0xE0 + reg); } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) { + OPTIMIZER_HIDE_VAR(reg); emit_jump(&prog, &__x86_indirect_thunk_array[reg], ip); } else #endif -- cgit v1.2.3