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powerpc/bpf/32: No need to zeroise r4 when not doing tail call

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9c5440b2b6d90a78600257433ac499b5c5101fbb.1675245773.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2023-02-01 11:04:24 +01:00 committed by Michael Ellerman
parent d9ab6da64f
commit 6376ed8fec
1 changed files with 4 additions and 1 deletions
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5
arch/powerpc/net/bpf_jit_comp32.c
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@ -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