From: Eduard Zingerman <eddyz87@gmail.com>
To: 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>,
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>,
Xu Kuohai <xukuohai@huaweicloud.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v7 6/6] selftests/bpf: Add tests for arena fault reporting
Date: Thu, 11 Sep 2025 11:19:51 -0700 [thread overview]
Message-ID: <137b87da5a7393602ec77d51cfd6398406cda9fb.camel@gmail.com> (raw)
In-Reply-To: <20250911145808.58042-7-puranjay@kernel.org>
On Thu, 2025-09-11 at 14:58 +0000, Puranjay Mohan wrote:
> Add selftests for testing the reporting of arena page faults through BPF
> streams. Two new bpf programs are added that read and write to an
> unmapped arena address and the fault reporting is verified in the
> userspace through streams.
>
> The added bpf programs need to access the user_vm_start in struct
> bpf_arena, this is done by casting &arena to struct bpf_arena *, but
> barrier_var() is used on this ptr before accessing ptr->user_vm_start;
> to stop GCC from issuing an out-of-bound access due to the cast from
> smaller map struct to larger "struct bpf_arena"
>
> Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
> +SEC("syscall")
> +__arch_x86_64
> +__arch_arm64
> +__success __retval(0)
> +__stderr("ERROR: Arena WRITE access at unmapped address 0x{{.*}}")
> +__stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")
> +__stderr("Call trace:\n"
> +"{{([a-zA-Z_][a-zA-Z0-9_]*\\+0x[0-9a-fA-F]+/0x[0-9a-fA-F]+\n"
> +"|[ \t]+[^\n]+\n)*}}")
Nit: here and in other tests, the regex is a bit hard to read.
How wrong would it be to write it down as follows:
__stderr("Call trace:")
__stderr("bpf_stream_stage_dump_stack+0x{{.*}}/0x{{.*}}")
?
(or at-least add a comment).
[...]
next prev parent reply other threads:[~2025-09-11 18:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-11 14:57 [PATCH bpf-next v7 0/6] bpf: report arena faults to BPF streams Puranjay Mohan
2025-09-11 14:58 ` [PATCH bpf-next v7 1/6] bpf: arm64: simplify exception table handling Puranjay Mohan
2025-09-11 14:58 ` [PATCH bpf-next v7 2/6] bpf: core: introduce main_prog_aux for stream access Puranjay Mohan
2025-09-11 18:30 ` Eduard Zingerman
2025-09-11 14:58 ` [PATCH bpf-next v7 3/6] bpf: Report arena faults to BPF stderr Puranjay Mohan
2025-09-11 14:58 ` [PATCH bpf-next v7 4/6] selftests: bpf: introduce __stderr and __stdout Puranjay Mohan
2025-09-11 17:39 ` Eduard Zingerman
2025-09-11 14:58 ` [PATCH bpf-next v7 5/6] selftests: bpf: use __stderr in stream error tests Puranjay Mohan
2025-09-11 18:02 ` Eduard Zingerman
2025-09-11 14:58 ` [PATCH bpf-next v7 6/6] selftests/bpf: Add tests for arena fault reporting Puranjay Mohan
2025-09-11 18:19 ` Eduard Zingerman [this message]
2025-09-11 20:02 ` Alexei Starovoitov
2025-09-11 20:10 ` [PATCH bpf-next v7 0/6] bpf: report arena faults to BPF streams patchwork-bot+netdevbpf
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