linux-kernel - [PATCH v2 4/9] powerpc/bpf/32: BPF prog is never called with more than one arg

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Date:   Wed,  1 Feb 2023 11:04:26 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        bpf@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>
Subject: [PATCH v2 4/9] powerpc/bpf/32: BPF prog is never called with more than one arg

BPF progs are never called with more than one argument, plus the
tail call count as a second argument when needed.

So, no need to retrieve 9th and 10th argument (5th 64 bits argument)
from the stack in prologue.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/net/bpf_jit_comp32.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 7f54d37bede6..7c129fe810f5 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -159,12 +159,6 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
 		if (bpf_is_seen_register(ctx, i))
 			EMIT(PPC_RAW_STW(i, _R1, bpf_jit_stack_offsetof(ctx, i)));
 
-	/* If needed retrieve arguments 9 and 10, ie 5th 64 bits arg.*/
-	if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_5))) {
-		EMIT(PPC_RAW_LWZ(bpf_to_ppc(BPF_REG_5) - 1, _R1, BPF_PPC_STACKFRAME(ctx)) + 8);
-		EMIT(PPC_RAW_LWZ(bpf_to_ppc(BPF_REG_5), _R1, BPF_PPC_STACKFRAME(ctx)) + 12);
-	}
-
 	/* Setup frame pointer to point to the bpf stack area */
 	if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) {
 		EMIT(PPC_RAW_LI(bpf_to_ppc(BPF_REG_FP) - 1, 0));
-- 
2.39.1