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Message-ID: <CAEf4BzYTMjWWVS8ZLXNs8W89_koAdo2-4ir++He=tXA11VU0xA@mail.gmail.com>
Date: Mon, 15 Mar 2021 21:49:07 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Florent Revest <revest@...omium.org>
Cc: bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Yonghong Song <yhs@...com>, KP Singh <kpsingh@...nel.org>,
Brendan Jackman <jackmanb@...omium.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next 5/5] selftests/bpf: Add a series of tests for bpf_snprintf
On Wed, Mar 10, 2021 at 2:02 PM Florent Revest <revest@...omium.org> wrote:
>
> This exercices most of the format specifiers when things go well.
typo: exercises
>
> Signed-off-by: Florent Revest <revest@...omium.org>
> ---
> .../selftests/bpf/prog_tests/snprintf.c | 71 +++++++++++++++++++
> .../selftests/bpf/progs/test_snprintf.c | 71 +++++++++++++++++++
> 2 files changed, 142 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c
> new file mode 100644
> index 000000000000..23af1dbd1eeb
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c
> @@ -0,0 +1,71 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2021 Google LLC. */
> +
> +#include <test_progs.h>
> +#include "test_snprintf.skel.h"
> +
> +static int duration;
if you drop CHECK() below, you won't need duration here at all
> +
> +#define EXP_NUM_OUT "-8 9 96 -424242 1337 DABBAD00"
> +#define EXP_NUM_RET sizeof(EXP_NUM_OUT)
> +
> +#define EXP_IP_OUT "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001"
> +#define EXP_IP_RET sizeof(EXP_IP_OUT)
> +
> +/* The third specifier, %pB, depends on compiler inlining so don't check it */
> +#define EXP_SYM_OUT "schedule schedule+0x0/"
> +#define MIN_SYM_RET sizeof(EXP_SYM_OUT)
> +
> +/* The third specifier, %p, is a hashed pointer which changes on every reboot */
> +#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 "
> +#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr")
> +
> +#define EXP_STR_OUT "str1 longstr"
> +#define EXP_STR_RET sizeof(EXP_STR_OUT)
> +
> +#define EXP_OVER_OUT {'%', 'o', 'v', 'e', 'r'}
> +#define EXP_OVER_RET 10
> +
> +void test_snprintf(void)
> +{
> + char exp_addr_out[] = EXP_ADDR_OUT;
> + char exp_over_out[] = EXP_OVER_OUT;
> + char exp_sym_out[] = EXP_SYM_OUT;
> + struct test_snprintf *skel;
> + int err;
> +
> + skel = test_snprintf__open_and_load();
> + if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n"))
ASSERT_OK_PTR
> + return;
> +
> + err = test_snprintf__attach(skel);
> + if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
ASSERT_OK
> + goto cleanup;
> +
> + /* trigger tracepoint */
> + usleep(1);
> +
> + ASSERT_STREQ(skel->bss->num_out, EXP_NUM_OUT, "num_out");
> + ASSERT_EQ(skel->bss->num_ret, EXP_NUM_RET, "num_ret");
> +
> + ASSERT_STREQ(skel->bss->ip_out, EXP_IP_OUT, "ip_out");
> + ASSERT_EQ(skel->bss->ip_ret, EXP_IP_RET, "ip_ret");
> +
> + ASSERT_OK(memcmp(skel->bss->sym_out, exp_sym_out,
> + sizeof(exp_sym_out) - 1), "sym_out");
> + ASSERT_LT(MIN_SYM_RET, skel->bss->sym_ret, "sym_ret");
> +
> + ASSERT_OK(memcmp(skel->bss->addr_out, exp_addr_out,
> + sizeof(exp_addr_out) - 1), "addr_out");
> + ASSERT_EQ(skel->bss->addr_ret, EXP_ADDR_RET, "addr_ret");
> +
> + ASSERT_STREQ(skel->bss->str_out, EXP_STR_OUT, "str_out");
> + ASSERT_EQ(skel->bss->str_ret, EXP_STR_RET, "str_ret");
> +
> + ASSERT_OK(memcmp(skel->bss->over_out, exp_over_out,
> + sizeof(exp_over_out)), "over_out");
> + ASSERT_EQ(skel->bss->over_ret, EXP_OVER_RET, "over_ret");
> +
> +cleanup:
> + test_snprintf__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_snprintf.c b/tools/testing/selftests/bpf/progs/test_snprintf.c
> new file mode 100644
> index 000000000000..6c8aa4988e69
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_snprintf.c
> @@ -0,0 +1,71 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2021 Google LLC. */
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf_endian.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +#define OUT_LEN 64
> +
> +/* Integer types */
> +static const char num_fmt[] = "%d %u %x %li %llu %lX";
> +#define NUMBERS -8, 9, 150, -424242, 1337, 0xDABBAD00
here I actually don't get the point of #define, can you please just
inline them at the invocation place? I think that will be nicer and
simpler (and will match common usage pattern)
> +
> +char num_out[OUT_LEN] = {};
> +long num_ret = 0;
> +
> +/* IP addresses */
> +static const char ip_fmt[] = "%pi4 %pI6";
> +static const __u8 dummy_ipv4[] = {127, 0, 0, 1}; /* 127.0.0.1 */
> +static const __u32 dummy_ipv6[] = {0, 0, 0, bpf_htonl(1)}; /* ::1/128 */
> +#define IPS &dummy_ipv4, &dummy_ipv6
> +
> +char ip_out[OUT_LEN] = {};
> +long ip_ret = 0;
> +
> +/* Symbol lookup formatting */
> +static const char sym_fmt[] = "%ps %pS %pB";
> +extern const void schedule __ksym;
> +#define SYMBOLS &schedule, &schedule, &schedule
> +
> +char sym_out[OUT_LEN] = {};
> +long sym_ret = 0;
> +
> +/* Kernel pointers */
> +static const char addr_fmt[] = "%pK %px %p";
> +#define ADDRESSES 0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55
> +
> +char addr_out[OUT_LEN] = {};
> +long addr_ret = 0;
> +
> +/* Strings embedding */
> +static const char str_fmt[] = "%s %+05s";
> +static const char str1[] = "str1";
> +static const char longstr[] = "longstr";
> +#define STRINGS str1, longstr
> +
> +char str_out[OUT_LEN] = {};
> +long str_ret = 0;
> +
> +/* Overflow */
> +static const char over_fmt[] = "%%overflow";
> +
> +#define OVER_OUT_LEN 6
> +char over_out[OVER_OUT_LEN] = {};
> +long over_ret = 0;
> +
same for all the above #defines, tests will be easier to follow if you
just use value in BPF_SNPRINTF below
> +SEC("raw_tp/sys_enter")
> +int handler(const void *ctx)
> +{
> + num_ret = BPF_SNPRINTF(num_out, OUT_LEN, num_fmt, NUMBERS);
> + ip_ret = BPF_SNPRINTF(ip_out, OUT_LEN, ip_fmt, IPS);
> + sym_ret = BPF_SNPRINTF(sym_out, OUT_LEN, sym_fmt, SYMBOLS);
> + addr_ret = BPF_SNPRINTF(addr_out, OUT_LEN, addr_fmt, ADDRESSES);
> + str_ret = BPF_SNPRINTF(str_out, OUT_LEN, str_fmt, STRINGS);
> + over_ret = BPF_SNPRINTF(over_out, OVER_OUT_LEN, over_fmt);
in practice you'd do BPF_SNPRINTF(num_out, sizeof(num_out), ...). So
use that in test code as well please.
> +
> + return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.30.1.766.gb4fecdf3b7-goog
>
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