From 6376ed8feca829039d31a208216b958f0e439d87 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 1 Feb 2023 11:04:24 +0100 Subject: [PATCH] powerpc/bpf/32: No need to zeroise r4 when not doing tail call r4 is cleared at function entry and used as tail call count. But when the function does not perform tail call, r4 is ignored, so no need to clear it. Replace it by a NOP in that case. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/9c5440b2b6d90a78600257433ac499b5c5101fbb.1675245773.git.christophe.leroy@csgroup.eu --- arch/powerpc/net/bpf_jit_comp32.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index a379b0ce19ff..4e6caee9c98a 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -114,7 +114,10 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) int i; /* Initialize tail_call_cnt, to be skipped if we do tail calls. */ - EMIT(PPC_RAW_LI(_R4, 0)); + if (ctx->seen & SEEN_TAILCALL) + EMIT(PPC_RAW_LI(_R4, 0)); + else + EMIT(PPC_RAW_NOP()); #define BPF_TAILCALL_PROLOGUE_SIZE 4 -- 2.11.0