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From: Luis Gerhorst <luis.gerhorst@fau.de>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Hari Bathini <hbathini@linux.ibm.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Naveen N Rao <naveen@kernel.org>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Luis Gerhorst <luis.gerhorst@fau.de>,
	bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org
Cc: kernel test robot <lkp@intel.com>
Subject: [PATCH bpf-next] powerpc/bpf: Fix warning for unused ori31_emitted
Date: Thu, 19 Jun 2025 16:26:47 +0200	[thread overview]
Message-ID: <20250619142647.2157017-1-luis.gerhorst@fau.de> (raw)

Without this, the compiler (clang21) might emit a warning under W=1
because the variable ori31_emitted is set but never used if
CONFIG_PPC_BOOK3S_64=n.

Without this patch:

$ make -j $(nproc) W=1 ARCH=powerpc SHELL=/bin/bash arch/powerpc/net
  [...]
  CC      arch/powerpc/net/bpf_jit_comp.o
  CC      arch/powerpc/net/bpf_jit_comp64.o
../arch/powerpc/net/bpf_jit_comp64.c: In function 'bpf_jit_build_body':
../arch/powerpc/net/bpf_jit_comp64.c:417:28: warning: variable 'ori31_emitted' set but not used [-Wunused-but-set-variable]
  417 |         bool sync_emitted, ori31_emitted;
      |                            ^~~~~~~~~~~~~
  AR      arch/powerpc/net/built-in.a

With this patch:

  [...]
  CC      arch/powerpc/net/bpf_jit_comp.o
  CC      arch/powerpc/net/bpf_jit_comp64.o
  AR      arch/powerpc/net/built-in.a

Fixes: dff883d9e93a ("bpf, arm64, powerpc: Change nospec to include v1 barrier")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506180402.uUXwVoSH-lkp@intel.com/
Signed-off-by: Luis Gerhorst <luis.gerhorst@fau.de>
---
 arch/powerpc/net/bpf_jit_comp64.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 3665ff8bb4bc..a25a6ffe7d7c 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -820,13 +820,12 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 		case BPF_ST | BPF_NOSPEC:
 			sync_emitted = false;
 			ori31_emitted = false;
-#ifdef CONFIG_PPC_E500
-			if (!bpf_jit_bypass_spec_v1()) {
+			if (IS_ENABLED(CONFIG_PPC_E500) &&
+			    !bpf_jit_bypass_spec_v1()) {
 				EMIT(PPC_RAW_ISYNC());
 				EMIT(PPC_RAW_SYNC());
 				sync_emitted = true;
 			}
-#endif
 			if (!bpf_jit_bypass_spec_v4()) {
 				switch (stf_barrier) {
 				case STF_BARRIER_EIEIO:
@@ -849,10 +848,10 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 					break;
 				}
 			}
-#ifdef CONFIG_PPC_BOOK3S_64
-			if (!bpf_jit_bypass_spec_v1() && !ori31_emitted)
+			if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&
+			    !bpf_jit_bypass_spec_v1() &&
+			    !ori31_emitted)
 				EMIT(PPC_RAW_ORI(_R31, _R31, 0));
-#endif
 			break;
 
 		/*

base-commit: cd7312a78f36e981939abe1cd1f21d355e083dfe
-- 
2.49.0


             reply	other threads:[~2025-06-19 14:28 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-19 14:26 Luis Gerhorst [this message]
2025-06-19 14:35 ` Christophe Leroy
2025-06-19 17:00 ` patchwork-bot+netdevbpf

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