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From: Yonghong Song <yonghong.song@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	kernel-team@fb.com, Martin KaFai Lau <martin.lau@kernel.org>
Subject: [PATCH bpf-next] selftests/bpf: Using llvm may_goto inline asm for cond_break macro
Date: Mon,  1 Apr 2024 19:54:46 -0700	[thread overview]
Message-ID: <20240402025446.3215182-1-yonghong.song@linux.dev> (raw)

Currently, cond_break macro uses bytes to encode the may_goto insn.
Patch [1] in llvm implemented may_goto insn in BPF backend.
Replace byte-level encoding with llvm inline asm for better usability.
Using llvm may_goto insn is controlled by macro __BPF_FEATURE_MAY_GOTO.

  [1] https://github.com/llvm/llvm-project/commit/0e0bfacff71859d1f9212205f8f873d47029d3fb

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 tools/testing/selftests/bpf/bpf_experimental.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index a5b9df38c162..3329ea080865 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -326,6 +326,16 @@ l_true:												\
        })
 #endif
 
+#ifdef __BPF_FEATURE_MAY_GOTO
+#define cond_break					\
+	({ __label__ l_break, l_continue;		\
+	 asm volatile goto("may_goto %l[l_break]"	\
+		      :::: l_break);			\
+	goto l_continue;				\
+	l_break: break;					\
+	l_continue:;					\
+	})
+#else
 #define cond_break					\
 	({ __label__ l_break, l_continue;		\
 	 asm volatile goto("1:.byte 0xe5;			\
@@ -337,6 +347,7 @@ l_true:												\
 	l_break: break;					\
 	l_continue:;					\
 	})
+#endif
 
 #ifndef bpf_nop_mov
 #define bpf_nop_mov(var) \
-- 
2.43.0


             reply	other threads:[~2024-04-02  2:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-02  2:54 Yonghong Song [this message]
2024-04-02  4:29 ` [PATCH bpf-next] selftests/bpf: Using llvm may_goto inline asm for cond_break macro John Fastabend
2024-04-02 14:20 ` patchwork-bot+netdevbpf

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