Re: [PATCH bpf-next 7/8] selftests/bpf: Verify zero-extension behavior in load-acquire tests

From: Pu Lehui <pulehui@huawei.com>
To: Peilin Ye <yepeilin@google.com>, <bpf@vger.kernel.org>
Cc: linux-riscv@lists.infradead.org,
	"Andrea Parri" <parri.andrea@gmail.com>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Puranjay Mohan" <puranjay@kernel.org>,
	"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>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	"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>,
	"Luke Nelson" <luke.r.nels@gmail.com>,
	"Xi Wang" <xi.wang@gmail.com>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Mykola Lysenko" <mykolal@fb.com>,
	"Shuah Khan" <shuah@kernel.org>, "Josh Don" <joshdon@google.com>,
	"Barret Rhoden" <brho@google.com>,
	"Neel Natu" <neelnatu@google.com>,
	"Benjamin Segall" <bsegall@google.com>
Subject: Re: [PATCH bpf-next 7/8] selftests/bpf: Verify zero-extension behavior in load-acquire tests
Date: Tue, 6 May 2025 22:23:21 +0800	[thread overview]
Message-ID: <25395de2-6bb7-42b7-bb42-698af2a8d87b@huawei.com> (raw)
In-Reply-To: <9bab433f2b7e48519b26c1b8f2004635f6c179d2.1745970908.git.yepeilin@google.com>


On 2025/4/30 8:51, Peilin Ye wrote:
> Verify that 8-, 16- and 32-bit load-acquires are zero-extending by using
> immediate values with their highest bit set.  Do the same for the 64-bit
> variant to keep the style consistent.
> 
> Signed-off-by: Peilin Ye <yepeilin@google.com>
> ---
>   tools/testing/selftests/bpf/progs/verifier_load_acquire.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/progs/verifier_load_acquire.c b/tools/testing/selftests/bpf/progs/verifier_load_acquire.c
> index a696ab84bfd6..74f4f19c10b8 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_load_acquire.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_load_acquire.c
> @@ -15,7 +15,7 @@ __naked void load_acquire_8(void)
>   {
>   	asm volatile (
>   	"r0 = 0;"
> -	"w1 = 0x12;"
> +	"w1 = 0xfe;"
>   	"*(u8 *)(r10 - 1) = w1;"
>   	".8byte %[load_acquire_insn];" // w2 = load_acquire((u8 *)(r10 - 1));
>   	"if r2 == r1 goto 1f;"
> @@ -35,7 +35,7 @@ __naked void load_acquire_16(void)
>   {
>   	asm volatile (
>   	"r0 = 0;"
> -	"w1 = 0x1234;"
> +	"w1 = 0xfedc;"
>   	"*(u16 *)(r10 - 2) = w1;"
>   	".8byte %[load_acquire_insn];" // w2 = load_acquire((u16 *)(r10 - 2));
>   	"if r2 == r1 goto 1f;"
> @@ -55,7 +55,7 @@ __naked void load_acquire_32(void)
>   {
>   	asm volatile (
>   	"r0 = 0;"
> -	"w1 = 0x12345678;"
> +	"w1 = 0xfedcba09;"
>   	"*(u32 *)(r10 - 4) = w1;"
>   	".8byte %[load_acquire_insn];" // w2 = load_acquire((u32 *)(r10 - 4));
>   	"if r2 == r1 goto 1f;"
> @@ -75,7 +75,7 @@ __naked void load_acquire_64(void)
>   {
>   	asm volatile (
>   	"r0 = 0;"
> -	"r1 = 0x1234567890abcdef ll;"
> +	"r1 = 0xfedcba0987654321 ll;"
>   	"*(u64 *)(r10 - 8) = r1;"
>   	".8byte %[load_acquire_insn];" // r2 = load_acquire((u64 *)(r10 - 8));
>   	"if r2 == r1 goto 1f;"
Reviewed-by: Pu Lehui <pulehui@huawei.com>

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