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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Hao Luo <haoluo@google.com>, Networking <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>, Shuah Khan <shuah@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andriin@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>,
	Quentin Monnet <quentin@isovalent.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>, Andrey Ignatov <rdna@fb.com>,
	Jakub Sitnicki <jakub@cloudflare.com>
Subject: Re: [PATCH bpf-next v1 5/8] bpf/selftests: ksyms_btf to test typed ksyms
Date: Fri, 21 Aug 2020 16:03:03 -0700	[thread overview]
Message-ID: <CAEf4BzbmOnv1W4p2F6Ke8W_Gwi-QjtsOW8MFSifVoiaRY8jNVg@mail.gmail.com> (raw)
In-Reply-To: <29b8358f-64fb-9e82-acb0-20b5922afc81@fb.com>

On Thu, Aug 20, 2020 at 10:32 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 8/19/20 3:40 PM, Hao Luo wrote:
> > Selftests for typed ksyms. Tests two types of ksyms: one is a struct,
> > the other is a plain int. This tests two paths in the kernel. Struct
> > ksyms will be converted into PTR_TO_BTF_ID by the verifier while int
> > typed ksyms will be converted into PTR_TO_MEM.
> >
> > Signed-off-by: Hao Luo <haoluo@google.com>
> > ---
> >   .../selftests/bpf/prog_tests/ksyms_btf.c      | 77 +++++++++++++++++++
> >   .../selftests/bpf/progs/test_ksyms_btf.c      | 23 ++++++
> >   2 files changed, 100 insertions(+)
> >   create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> >   create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> > new file mode 100644
> > index 000000000000..1dad61ba7e99
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> > @@ -0,0 +1,77 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2020 Google */
> > +
> > +#include <test_progs.h>
> > +#include <bpf/libbpf.h>
> > +#include <bpf/btf.h>
> > +#include "test_ksyms_btf.skel.h"
> > +
> > +static int duration;
> > +
> > +static __u64 kallsyms_find(const char *sym)
> > +{
> > +     char type, name[500];
> > +     __u64 addr, res = 0;
> > +     FILE *f;
> > +
> > +     f = fopen("/proc/kallsyms", "r");
> > +     if (CHECK(!f, "kallsyms_fopen", "failed to open: %d\n", errno))
> > +             return 0;
>
> could you check whether libbpf API can provide this functionality for
> you? As far as I know, libbpf does parse /proc/kallsyms.

No need to use libbpf's implementation. We already have
kallsyms_find() in prog_tests/ksyms.c and a combination of
load_kallsyms() + ksym_get_addr() in trace_helpers.c. It would be good
to switch to one implementation for both prog_tests/ksyms.c and this
one.


>
> > +
> > +     while (fscanf(f, "%llx %c %499s%*[^\n]\n", &addr, &type, name) > 0) {
> > +             if (strcmp(name, sym) == 0) {
> > +                     res = addr;
> > +                     goto out;
> > +             }
> > +     }
> > +

[...]

> > diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> > new file mode 100644
> > index 000000000000..e04e31117f84
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> > @@ -0,0 +1,23 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2020 Google */
> > +
> > +#include "vmlinux.h"
> > +
> > +#include <bpf/bpf_helpers.h>
> > +
> > +__u64 out__runqueues = -1;
> > +__u64 out__bpf_prog_active = -1;
> > +
> > +extern const struct rq runqueues __ksym; /* struct type global var. */
> > +extern const int bpf_prog_active __ksym; /* int type global var. */
> > +
> > +SEC("raw_tp/sys_enter")
> > +int handler(const void *ctx)
> > +{
> > +     out__runqueues = (__u64)&runqueues;
> > +     out__bpf_prog_active = (__u64)&bpf_prog_active;
> > +

You didn't test accessing any of the members of runqueues, because BTF
only has per-CPU variables, right? Adding global/static variables was
adding too much data to BTF or something like that, is that right?

> > +     return 0;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> >

  reply	other threads:[~2020-08-21 23:03 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 22:40 [PATCH bpf-next v1 0/8] bpf: BTF support for ksyms Hao Luo
2020-08-19 22:40 ` [PATCH bpf-next v1 1/8] bpf: Introduce pseudo_btf_id Hao Luo
2020-08-20 15:22   ` Yonghong Song
2020-08-20 17:04     ` Hao Luo
2020-08-25  0:05     ` Hao Luo
2020-08-25  0:43       ` Yonghong Song
2020-08-20 16:43   ` Yonghong Song
2020-08-20 21:53   ` Alexei Starovoitov
2020-08-21  2:22     ` Hao Luo
2020-08-19 22:40 ` [PATCH bpf-next v1 2/8] bpf: Propagate BPF_PSEUDO_BTF_ID to uapi headers in /tools Hao Luo
2020-08-20 16:44   ` Yonghong Song
2020-08-19 22:40 ` [PATCH bpf-next v1 3/8] bpf: Introduce help function to validate ksym's type Hao Luo
2020-08-20 17:20   ` Yonghong Song
2020-08-21 21:50     ` Andrii Nakryiko
2020-08-22  0:43       ` Hao Luo
2020-08-22  2:43         ` Andrii Nakryiko
2020-08-22  7:04           ` Hao Luo
2020-08-19 22:40 ` [PATCH bpf-next v1 4/8] bpf/libbpf: BTF support for typed ksyms Hao Luo
2020-08-21 22:37   ` Andrii Nakryiko
2020-08-27 22:29     ` Hao Luo
2020-09-01 18:11       ` Andrii Nakryiko
2020-09-01 20:35         ` Hao Luo
2020-09-01 23:54           ` Andrii Nakryiko
2020-09-02  0:46             ` Hao Luo
2020-08-19 22:40 ` [PATCH bpf-next v1 5/8] bpf/selftests: ksyms_btf to test " Hao Luo
2020-08-20 17:28   ` Yonghong Song
2020-08-21 23:03     ` Andrii Nakryiko [this message]
2020-08-22  7:26       ` Hao Luo
2020-08-22  7:35         ` Andrii Nakryiko
2020-08-19 22:40 ` [PATCH bpf-next v1 6/8] bpf: Introduce bpf_per_cpu_ptr() Hao Luo
2020-08-22  3:26   ` Andrii Nakryiko
2020-08-22  3:31     ` Andrii Nakryiko
2020-08-22  7:49       ` Hao Luo
2020-08-22  7:55         ` Andrii Nakryiko
2020-08-25  1:03           ` Hao Luo
2020-08-19 22:40 ` [PATCH bpf-next v1 7/8] bpf: Propagate bpf_per_cpu_ptr() to /tools Hao Luo
2020-08-20 17:30   ` Yonghong Song
2020-08-19 22:40 ` [PATCH bpf-next v1 8/8] bpf/selftests: Test for bpf_per_cpu_ptr() Hao Luo
2020-08-22  3:30   ` Andrii Nakryiko
2020-08-28  3:42     ` Hao Luo
2020-09-01 18:12       ` Andrii Nakryiko
2020-09-01 19:47         ` Hao Luo

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