From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>
Subject: [PATCH v1 03/10] powerpc/bpf/32: No need to zeroise r4 when not doing tail call
Date: Thu, 1 Dec 2022 08:56:28 +0100 [thread overview]
Message-ID: <e0c1e5ed8cfd63f4d9f4636a4265d28ed671e0d6.1669881248.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <fa025537f584599c0271fc129c5cf4f57fbe7505.1669881248.git.christophe.leroy@csgroup.eu>
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 --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
--
2.38.1
next prev parent reply other threads:[~2022-12-01 7:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-01 7:56 [PATCH v1 01/10] powerpc/bpf/32: Fix Oops on tail call tests Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 02/10] powerpc: Remove __kernel_text_address() in show_instructions() Christophe Leroy
2022-12-01 7:56 ` Christophe Leroy [this message]
2022-12-01 7:56 ` [PATCH v1 04/10] powerpc/bpf/32: Only set a stack frame when necessary Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 05/10] powerpc/bpf/32: BPF prog is never called with more than one arg Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 06/10] powerpc/bpf: Perform complete extra passes to update addresses Christophe Leroy
2022-12-13 10:23 ` Naveen N. Rao
2022-12-19 19:06 ` Christophe Leroy
2023-01-10 8:44 ` Naveen N. Rao
2023-01-31 9:52 ` Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 07/10] powerpc/bpf: Only pad length-variable code at initial pass Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 08/10] powerpc/bpf/32: Optimise some particular const operations Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 09/10] powerpc/bpf/32: introduce a second source register for ALU operations Christophe Leroy
2022-12-01 7:56 ` [PATCH v1 10/10] powerpc/bpf/32: perform three operands " Christophe Leroy
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