From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
netdev@vger.kernel.org, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team@fb.com
Subject: Re: [RFC PATCH bpf-next 09/16] bpf: add bpf_seq_printf and bpf_seq_write helpers
Date: Thu, 9 Apr 2020 20:26:08 -0700 [thread overview]
Message-ID: <20200410032608.x5hloyizpfyxnudz@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20200408232531.2676134-1-yhs@fb.com>
On Wed, Apr 08, 2020 at 04:25:31PM -0700, Yonghong Song wrote:
>
> +BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, u64, arg1,
> + u64, arg2)
> +{
> + bool buf_used = false;
> + int i, copy_size;
> + int mod[2] = {};
> + int fmt_cnt = 0;
> + u64 unsafe_addr;
> + char buf[64];
> +
> + /*
> + * bpf_check()->check_func_arg()->check_stack_boundary()
> + * guarantees that fmt points to bpf program stack,
> + * fmt_size bytes of it were initialized and fmt_size > 0
> + */
> + if (fmt[--fmt_size] != 0)
> + return -EINVAL;
...
> +/* Horrid workaround for getting va_list handling working with different
> + * argument type combinations generically for 32 and 64 bit archs.
> + */
> +#define __BPF_SP_EMIT() __BPF_ARG2_SP()
> +#define __BPF_SP(...) \
> + seq_printf(m, fmt, ##__VA_ARGS__)
> +
> +#define __BPF_ARG1_SP(...) \
> + ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \
> + ? __BPF_SP(arg1, ##__VA_ARGS__) \
> + : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \
> + ? __BPF_SP((long)arg1, ##__VA_ARGS__) \
> + : __BPF_SP((u32)arg1, ##__VA_ARGS__)))
> +
> +#define __BPF_ARG2_SP(...) \
> + ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \
> + ? __BPF_ARG1_SP(arg2, ##__VA_ARGS__) \
> + : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \
> + ? __BPF_ARG1_SP((long)arg2, ##__VA_ARGS__) \
> + : __BPF_ARG1_SP((u32)arg2, ##__VA_ARGS__)))
> +
> + __BPF_SP_EMIT();
> + return seq_has_overflowed(m);
> +}
This function is mostly a copy-paste of bpf_trace_printk() with difference
of printing via seq_printf vs __trace_printk.
Please find a way to share the code.
next prev parent reply other threads:[~2020-04-10 3:26 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-08 23:25 [RFC PATCH bpf-next 00/16] bpf: implement bpf based dumping of kernel data structures Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 01/16] net: refactor net assignment for seq_net_private structure Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 02/16] bpf: create /sys/kernel/bpfdump mount file system Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 03/16] bpf: provide a way for targets to register themselves Yonghong Song
2020-04-10 22:18 ` Andrii Nakryiko
2020-04-10 23:24 ` Yonghong Song
2020-04-13 19:31 ` Andrii Nakryiko
2020-04-15 22:57 ` Yonghong Song
2020-04-10 22:25 ` Andrii Nakryiko
2020-04-10 23:25 ` Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 04/16] bpf: allow loading of a dumper program Yonghong Song
2020-04-10 22:36 ` Andrii Nakryiko
2020-04-10 23:28 ` Yonghong Song
2020-04-13 19:33 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 05/16] bpf: create file or anonymous dumpers Yonghong Song
2020-04-10 3:00 ` Alexei Starovoitov
2020-04-10 6:09 ` Yonghong Song
2020-04-10 22:42 ` Yonghong Song
2020-04-10 22:53 ` Andrii Nakryiko
2020-04-10 23:47 ` Yonghong Song
2020-04-11 23:11 ` Alexei Starovoitov
2020-04-12 6:51 ` Yonghong Song
2020-04-13 20:48 ` Andrii Nakryiko
2020-04-10 22:51 ` Andrii Nakryiko
2020-04-10 23:41 ` Yonghong Song
2020-04-13 19:45 ` Andrii Nakryiko
2020-04-10 23:25 ` Andrii Nakryiko
2020-04-11 0:23 ` Yonghong Song
2020-04-11 23:17 ` Alexei Starovoitov
2020-04-13 21:04 ` Andrii Nakryiko
2020-04-13 19:59 ` Andrii Nakryiko
2020-04-14 5:56 ` Andrii Nakryiko
2020-04-14 23:59 ` Yonghong Song
2020-04-15 4:45 ` Andrii Nakryiko
2020-04-15 16:46 ` Alexei Starovoitov
2020-04-16 1:48 ` Andrii Nakryiko
2020-04-16 7:15 ` Yonghong Song
2020-04-16 17:04 ` Alexei Starovoitov
2020-04-16 19:35 ` Andrii Nakryiko
2020-04-16 23:18 ` Alexei Starovoitov
2020-04-17 5:11 ` Andrii Nakryiko
2020-04-19 6:11 ` Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 06/16] bpf: add netlink and ipv6_route targets Yonghong Song
2020-04-10 23:13 ` Andrii Nakryiko
2020-04-10 23:52 ` Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 07/16] bpf: add bpf_map target Yonghong Song
2020-04-13 22:18 ` Andrii Nakryiko
2020-04-13 22:47 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 08/16] bpf: add task and task/file targets Yonghong Song
2020-04-10 3:22 ` Alexei Starovoitov
2020-04-10 6:19 ` Yonghong Song
2020-04-10 21:31 ` Alexei Starovoitov
2020-04-10 21:33 ` Alexei Starovoitov
2020-04-13 23:00 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 09/16] bpf: add bpf_seq_printf and bpf_seq_write helpers Yonghong Song
2020-04-10 3:26 ` Alexei Starovoitov [this message]
2020-04-10 6:12 ` Yonghong Song
2020-04-14 5:28 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 10/16] bpf: support variable length array in tracing programs Yonghong Song
2020-04-14 0:13 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 11/16] bpf: implement query for target_proto and file dumper prog_id Yonghong Song
2020-04-10 3:10 ` Alexei Starovoitov
2020-04-10 6:11 ` Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 12/16] tools/libbpf: libbpf support for bpfdump Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 13/16] tools/bpftool: add bpf dumper support Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 14/16] tools/bpf: selftests: add dumper programs for ipv6_route and netlink Yonghong Song
2020-04-14 5:39 ` Andrii Nakryiko
2020-04-08 23:25 ` [RFC PATCH bpf-next 15/16] tools/bpf: selftests: add dumper progs for bpf_map/task/task_file Yonghong Song
2020-04-10 3:33 ` Alexei Starovoitov
2020-04-10 6:41 ` Yonghong Song
2020-04-08 23:25 ` [RFC PATCH bpf-next 16/16] tools/bpf: selftests: add a selftest for anonymous dumper Yonghong Song
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