diff mbox series

[v2,2/9] powerpc/bpf/32: No need to zeroise r4 when not doing tail call

Message ID 9c5440b2b6d90a78600257433ac499b5c5101fbb.1675245773.git.christophe.leroy@csgroup.eu (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series [v2,1/9] powerpc: Remove __kernel_text_address() in show_instructions() | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch
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Commit Message

Christophe Leroy Feb. 1, 2023, 10:04 a.m. UTC 
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 <christophe.leroy@csgroup.eu>
---
 arch/powerpc/net/bpf_jit_comp32.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

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