From: Martin KaFai Lau <martin.lau@linux.dev>
To: Paul Chaignon <paul.chaignon@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Amery Hung <ameryhung@gmail.com>,
bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v6 5/5] selftests/bpf: Test direct packet access on non-linear skbs
Date: Tue, 7 Oct 2025 11:01:32 -0700 [thread overview]
Message-ID: <62e288f3-9917-4218-84f7-01e2eb27130c@linux.dev> (raw)
In-Reply-To: <302cd8554710d04986925df1737c787c09b5ff65.1759843268.git.paul.chaignon@gmail.com>
On 10/7/25 6:38 AM, Paul Chaignon wrote:
> +#define access_test_non_linear(name, type, desc, retval, linear_sz, off) \
> + SEC(type) \
> + __description("direct packet access: " #name " (non-linear, " type ", " desc ")") \
> + __success __retval(retval) \
> + __linear_size(linear_sz) \
> + __naked void access_non_linear_##name(void) \
> + { \
> + asm volatile (" \
> + r2 = *(u32*)(r1 + %[skb_data]); \
> + r3 = *(u32*)(r1 + %[skb_data_end]); \
> + r0 = r2; \
> + r0 += %[offset]; \
> + if r0 > r3 goto l0_%=; \
> + r0 = *(u8*)(r0 - 1); \
> + r0 = 0; \
> + exit; \
> + l0_%=: r0 = 1; \
> + exit; \
> + " : \
> + : __imm_const(skb_data, offsetof(struct __sk_buff, data)), \
> + __imm_const(skb_data_end, offsetof(struct __sk_buff, data_end)), \
> + __imm_const(offset, off) \
> + : __clobber_all); \
> + }
> +
> +access_test_non_linear(test31, "tc", "too short eth", 1, ETH_HLEN, 22);
> +access_test_non_linear(test32, "tc", "too short 1", 1, 1, 22);
> +access_test_non_linear(test33, "tc", "long enough", 0, 22, 22);
> +access_test_non_linear(test34, "cgroup_skb/ingress", "too short eth", 1, ETH_HLEN, 8);
> +access_test_non_linear(test35, "cgroup_skb/ingress", "too short 1", 1, 1, 8);
> +access_test_non_linear(test36, "cgroup_skb/ingress", "long enough", 0, 22, 8);
> +
> +SEC("tc")
> +__description("direct packet access: test36 (non-linear, linearized)")
> +__success __retval(0)
> +__linear_size(ETH_HLEN)
> +__naked void access_non_linear_linearized(void)
> +{
> + asm volatile (" \
> + r6 = r1; \
> + r2 = 22; \
> + call %[bpf_skb_pull_data]; \
> + r2 = *(u32*)(r6 + %[skb_data]); \
> + r3 = *(u32*)(r6 + %[skb_data_end]); \
> + r0 = r2; \
> + r0 += 22; \
> + if r0 > r3 goto l0_%=; \
> + r0 = *(u8*)(r0 - 1); \
> + exit; \
> +l0_%=: r0 = 1; \
> + exit; \
> +" :
> + : __imm(bpf_skb_pull_data),
> + __imm_const(skb_data, offsetof(struct __sk_buff, data)),
> + __imm_const(skb_data_end, offsetof(struct __sk_buff, data_end))
> + : __clobber_all);
> +}
Does it have to be in asm?
next prev parent reply other threads:[~2025-10-07 18:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-07 13:36 [PATCH bpf-next v6 0/5] Support non-linear skbs for BPF_PROG_TEST_RUN Paul Chaignon
2025-10-07 13:37 ` [PATCH bpf-next v6 1/5] bpf: Refactor cleanup of bpf_prog_test_run_skb Paul Chaignon
2025-10-07 13:37 ` [PATCH bpf-next v6 2/5] bpf: Reorder bpf_prog_test_run_skb initialization Paul Chaignon
2025-10-07 13:38 ` [PATCH bpf-next v6 3/5] bpf: Craft non-linear skbs in BPF_PROG_TEST_RUN Paul Chaignon
2025-10-07 17:59 ` Martin KaFai Lau
2025-10-09 13:32 ` Paul Chaignon
2025-10-07 13:38 ` [PATCH bpf-next v6 4/5] selftests/bpf: Support non-linear flag in test loader Paul Chaignon
2025-10-07 13:38 ` [PATCH bpf-next v6 5/5] selftests/bpf: Test direct packet access on non-linear skbs Paul Chaignon
2025-10-07 18:01 ` Martin KaFai Lau [this message]
2025-10-09 13:44 ` Paul Chaignon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=62e288f3-9917-4218-84f7-01e2eb27130c@linux.dev \
--to=martin.lau@linux.dev \
--cc=ameryhung@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=paul.chaignon@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.