Re: [PATCH bpf-next v2 2/3] selftests/bpf: split test_attach_probe into multi subtests

From: Alan Maguire
Date: Mon Feb 20 2023 - 06:41:23 EST

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In reply to: menglong8 . dong: "[PATCH bpf-next v2 2/3] selftests/bpf: split test_attach_probe into multi subtests"
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On 20/02/2023 08:47, menglong8.dong@xxxxxxxxx wrote:
> From: Menglong Dong <imagedong@xxxxxxxxxxx>
>
> In order to adapt to the older kernel, now we split the "attach_probe"
> testing into multi subtests:
>
> manual // manual attach tests for kprobe/uprobe
> auto // auto-attach tests for kprobe and uprobe
> kprobe-sleepable // kprobe sleepable test
> uprobe-lib // uprobe tests for library function by name
> uprobe-sleepabel // uprobe sleepable test
> uprobe-ref_ctr // uprobe ref_ctr test
>
> As sleepable kprobe needs to set BPF_F_SLEEPABLE flag before loading,
> we need to move it to a stand alone skel file, in case of it is not
> supported by kernel and make the whole loading fail.
>
> Therefore, we can only enable part of the subtests for older kernel.
>
> Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx>

this is great work! One small typo in the ref counter subtest function
name below, but for the series:

Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>

> ---
> .../selftests/bpf/prog_tests/attach_probe.c | 268 +++++++++++-------
> .../bpf/progs/test_attach_kprobe_sleepable.c | 23 ++
> .../selftests/bpf/progs/test_attach_probe.c | 23 +-
> 3 files changed, 208 insertions(+), 106 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/progs/test_attach_kprobe_sleepable.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> index 56374c8b5436..9824a5eb8595 100644
> --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> @@ -1,5 +1,6 @@
> // SPDX-License-Identifier: GPL-2.0
> #include <test_progs.h>
> +#include "test_attach_kprobe_sleepable.skel.h"
> #include "test_attach_probe.skel.h"
>
> /* this is how USDT semaphore is actually defined, except volatile modifier */
> @@ -23,110 +24,63 @@ static noinline void trigger_func3(void)
> asm volatile ("");
> }
>
> +/* attach point for ref_ctr */
> +static noinline void trigger_func4(void)
> +{
> + asm volatile ("");
> +}
> +
> static char test_data[] = "test_data";
>
> -void test_attach_probe(void)
> +/* manual attach kprobe/kretprobe/uprobe/uretprobe testings */
> +static void test_attach_probe_manual(struct test_attach_probe *skel)
> {
> DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
> struct bpf_link *kprobe_link, *kretprobe_link;
> struct bpf_link *uprobe_link, *uretprobe_link;
> - struct test_attach_probe* skel;
> - ssize_t uprobe_offset, ref_ctr_offset;
> - struct bpf_link *uprobe_err_link;
> - FILE *devnull;
> - bool legacy;
> -
> - /* Check if new-style kprobe/uprobe API is supported.
> - * Kernels that support new FD-based kprobe and uprobe BPF attachment
> - * through perf_event_open() syscall expose
> - * /sys/bus/event_source/devices/kprobe/type and
> - * /sys/bus/event_source/devices/uprobe/type files, respectively. They
> - * contain magic numbers that are passed as "type" field of
> - * perf_event_attr. Lack of such file in the system indicates legacy
> - * kernel with old-style kprobe/uprobe attach interface through
> - * creating per-probe event through tracefs. For such cases
> - * ref_ctr_offset feature is not supported, so we don't test it.
> - */
> - legacy = access("/sys/bus/event_source/devices/kprobe/type", F_OK) != 0;
> + ssize_t uprobe_offset;
>
> uprobe_offset = get_uprobe_offset(&trigger_func);
> if (!ASSERT_GE(uprobe_offset, 0, "uprobe_offset"))
> return;
>
> - ref_ctr_offset = get_rel_offset((uintptr_t)&uprobe_ref_ctr);
> - if (!ASSERT_GE(ref_ctr_offset, 0, "ref_ctr_offset"))
> - return;
> -
> - skel = test_attach_probe__open();
> - if (!ASSERT_OK_PTR(skel, "skel_open"))
> - return;
> -
> - /* sleepable kprobe test case needs flags set before loading */
> - if (!ASSERT_OK(bpf_program__set_flags(skel->progs.handle_kprobe_sleepable,
> - BPF_F_SLEEPABLE), "kprobe_sleepable_flags"))
> - goto cleanup;
> -
> - if (!ASSERT_OK(test_attach_probe__load(skel), "skel_load"))
> - goto cleanup;
> - if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
> - goto cleanup;
> -
> /* manual-attach kprobe/kretprobe */
> kprobe_link = bpf_program__attach_kprobe(skel->progs.handle_kprobe,
> false /* retprobe */,
> SYS_NANOSLEEP_KPROBE_NAME);
> if (!ASSERT_OK_PTR(kprobe_link, "attach_kprobe"))
> - goto cleanup;
> + return;
> skel->links.handle_kprobe = kprobe_link;
>
> kretprobe_link = bpf_program__attach_kprobe(skel->progs.handle_kretprobe,
> true /* retprobe */,
> SYS_NANOSLEEP_KPROBE_NAME);
> if (!ASSERT_OK_PTR(kretprobe_link, "attach_kretprobe"))
> - goto cleanup;
> + return;
> skel->links.handle_kretprobe = kretprobe_link;
>
> - /* auto-attachable kprobe and kretprobe */
> - skel->links.handle_kprobe_auto = bpf_program__attach(skel->progs.handle_kprobe_auto);
> - ASSERT_OK_PTR(skel->links.handle_kprobe_auto, "attach_kprobe_auto");
> -
> - skel->links.handle_kretprobe_auto = bpf_program__attach(skel->progs.handle_kretprobe_auto);
> - ASSERT_OK_PTR(skel->links.handle_kretprobe_auto, "attach_kretprobe_auto");
> -
> - if (!legacy)
> - ASSERT_EQ(uprobe_ref_ctr, 0, "uprobe_ref_ctr_before");
> -
> + /* manual-attach uprobe/uretprobe */
> + uprobe_opts.ref_ctr_offset = 0;
> uprobe_opts.retprobe = false;
> - uprobe_opts.ref_ctr_offset = legacy ? 0 : ref_ctr_offset;
> uprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uprobe,
> 0 /* self pid */,
> "/proc/self/exe",
> uprobe_offset,
> &uprobe_opts);
> if (!ASSERT_OK_PTR(uprobe_link, "attach_uprobe"))
> - goto cleanup;
> + return;
> skel->links.handle_uprobe = uprobe_link;
>
> - if (!legacy)
> - ASSERT_GT(uprobe_ref_ctr, 0, "uprobe_ref_ctr_after");
> -
> - /* if uprobe uses ref_ctr, uretprobe has to use ref_ctr as well */
> uprobe_opts.retprobe = true;
> - uprobe_opts.ref_ctr_offset = legacy ? 0 : ref_ctr_offset;
> uretprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uretprobe,
> -1 /* any pid */,
> "/proc/self/exe",
> uprobe_offset, &uprobe_opts);
> if (!ASSERT_OK_PTR(uretprobe_link, "attach_uretprobe"))
> - goto cleanup;
> + return;
> skel->links.handle_uretprobe = uretprobe_link;
>
> - /* verify auto-attach fails for old-style uprobe definition */
> - uprobe_err_link = bpf_program__attach(skel->progs.handle_uprobe_byname);
> - if (!ASSERT_EQ(libbpf_get_error(uprobe_err_link), -EOPNOTSUPP,
> - "auto-attach should fail for old-style name"))
> - goto cleanup;
> -
> + /* attach uprobe by function name manually */
> uprobe_opts.func_name = "trigger_func2";
> uprobe_opts.retprobe = false;
> uprobe_opts.ref_ctr_offset = 0;
> @@ -136,13 +90,62 @@ void test_attach_probe(void)
> "/proc/self/exe",
> 0, &uprobe_opts);
> if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname, "attach_uprobe_byname"))
> - goto cleanup;
> + return;
> +
> + /* trigger & validate kprobe && kretprobe */
> + usleep(1);
> +
> + /* trigger & validate uprobe & uretprobe */
> + trigger_func();
> +
> + /* trigger & validate uprobe attached by name */
> + trigger_func2();
> +
> + ASSERT_EQ(skel->bss->kprobe_res, 1, "check_kprobe_res");
> + ASSERT_EQ(skel->bss->kretprobe_res, 2, "check_kretprobe_res");
> + ASSERT_EQ(skel->bss->uprobe_res, 3, "check_uprobe_res");
> + ASSERT_EQ(skel->bss->uretprobe_res, 4, "check_uretprobe_res");
> + ASSERT_EQ(skel->bss->uprobe_byname_res, 5, "check_uprobe_byname_res");
> +}
> +
> +static void test_attach_probe_auto(struct test_attach_probe *skel)
> +{
> + struct bpf_link *uprobe_err_link;
> +
> + /* auto-attachable kprobe and kretprobe */
> + skel->links.handle_kprobe_auto = bpf_program__attach(skel->progs.handle_kprobe_auto);
> + ASSERT_OK_PTR(skel->links.handle_kprobe_auto, "attach_kprobe_auto");
> +
> + skel->links.handle_kretprobe_auto = bpf_program__attach(skel->progs.handle_kretprobe_auto);
> + ASSERT_OK_PTR(skel->links.handle_kretprobe_auto, "attach_kretprobe_auto");
> +
> + /* verify auto-attach fails for old-style uprobe definition */
> + uprobe_err_link = bpf_program__attach(skel->progs.handle_uprobe_byname);
> + if (!ASSERT_EQ(libbpf_get_error(uprobe_err_link), -EOPNOTSUPP,
> + "auto-attach should fail for old-style name"))
> + return;
>
> /* verify auto-attach works */
> skel->links.handle_uretprobe_byname =
> bpf_program__attach(skel->progs.handle_uretprobe_byname);
> if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname, "attach_uretprobe_byname"))
> - goto cleanup;
> + return;
> +
> + /* trigger & validate kprobe && kretprobe */
> + usleep(1);
> +
> + /* trigger & validate uprobe attached by name */
> + trigger_func2();
> +
> + ASSERT_EQ(skel->bss->kprobe2_res, 11, "check_kprobe_auto_res");
> + ASSERT_EQ(skel->bss->kretprobe2_res, 22, "check_kretprobe_auto_res");
> + ASSERT_EQ(skel->bss->uretprobe_byname_res, 6, "check_uretprobe_byname_res");
> +}
> +
> +static void test_uprobe_lib(struct test_attach_probe *skel)
> +{
> + DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
> + FILE *devnull;
>
> /* test attach by name for a library function, using the library
> * as the binary argument. libc.so.6 will be resolved via dlopen()/dlinfo().
> @@ -155,7 +158,7 @@ void test_attach_probe(void)
> "libc.so.6",
> 0, &uprobe_opts);
> if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname2, "attach_uprobe_byname2"))
> - goto cleanup;
> + return;
>
> uprobe_opts.func_name = "fclose";
> uprobe_opts.retprobe = true;
> @@ -165,62 +168,137 @@ void test_attach_probe(void)
> "libc.so.6",
> 0, &uprobe_opts);
> if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname2, "attach_uretprobe_byname2"))
> + return;
> +
> + /* trigger & validate shared library u[ret]probes attached by name */
> + devnull = fopen("/dev/null", "r");
> + fclose(devnull);
> +
> + ASSERT_EQ(skel->bss->uprobe_byname2_res, 7, "check_uprobe_byname2_res");
> + ASSERT_EQ(skel->bss->uretprobe_byname2_res, 8, "check_uretprobe_byname2_res");
> +}
> +
> +static void test_uporbe_ref_ctr(struct test_attach_probe *skel)

typo, should be test_uprobe_ref_ctr

> +{
> + DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
> + struct bpf_link *uprobe_link, *uretprobe_link;
> + ssize_t uprobe_offset, ref_ctr_offset;
> +
> + uprobe_offset = get_uprobe_offset(&trigger_func4);
> + if (!ASSERT_GE(uprobe_offset, 0, "uprobe_offset_ref_ctr"))
> + return;
> +
> + ref_ctr_offset = get_rel_offset((uintptr_t)&uprobe_ref_ctr);
> + if (!ASSERT_GE(ref_ctr_offset, 0, "ref_ctr_offset"))
> + return;
> +
> + ASSERT_EQ(uprobe_ref_ctr, 0, "uprobe_ref_ctr_before");
> +
> + uprobe_opts.retprobe = false;
> + uprobe_opts.ref_ctr_offset = ref_ctr_offset;
> + uprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uprobe_ref_ctr,
> + 0 /* self pid */,
> + "/proc/self/exe",
> + uprobe_offset,
> + &uprobe_opts);
> + if (!ASSERT_OK_PTR(uprobe_link, "attach_uprobe_ref_ctr"))
> + return;
> + skel->links.handle_uprobe_ref_ctr = uprobe_link;
> +
> + ASSERT_GT(uprobe_ref_ctr, 0, "uprobe_ref_ctr_after");
> +
> + /* if uprobe uses ref_ctr, uretprobe has to use ref_ctr as well */
> + uprobe_opts.retprobe = true;
> + uprobe_opts.ref_ctr_offset = ref_ctr_offset;
> + uretprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uretprobe_ref_ctr,
> + -1 /* any pid */,
> + "/proc/self/exe",
> + uprobe_offset, &uprobe_opts);
> + if (!ASSERT_OK_PTR(uretprobe_link, "attach_uretprobe_ref_ctr"))
> + return;
> + skel->links.handle_uretprobe_ref_ctr = uretprobe_link;
> +}
> +
> +static void test_kprobe_sleepable(void)
> +{
> + struct test_attach_kprobe_sleepable *skel;
> +
> + skel = test_attach_kprobe_sleepable__open();
> + if (!ASSERT_OK_PTR(skel, "skel_kprobe_sleepable_open"))
> + return;
> +
> + /* sleepable kprobe test case needs flags set before loading */
> + if (!ASSERT_OK(bpf_program__set_flags(skel->progs.handle_kprobe_sleepable,
> + BPF_F_SLEEPABLE), "kprobe_sleepable_flags"))
> + goto cleanup;
> +
> + if (!ASSERT_OK(test_attach_kprobe_sleepable__load(skel),
> + "skel_kprobe_sleepable_load"))
> goto cleanup;
>
> /* sleepable kprobes should not attach successfully */
> skel->links.handle_kprobe_sleepable = bpf_program__attach(skel->progs.handle_kprobe_sleepable);
> - if (!ASSERT_ERR_PTR(skel->links.handle_kprobe_sleepable, "attach_kprobe_sleepable"))
> - goto cleanup;
> + ASSERT_ERR_PTR(skel->links.handle_kprobe_sleepable, "attach_kprobe_sleepable");
> +
> +cleanup:
> + test_attach_kprobe_sleepable__destroy(skel);
> +}
>
> +static void test_uprobe_sleepable(struct test_attach_probe *skel)
> +{
> /* test sleepable uprobe and uretprobe variants */
> skel->links.handle_uprobe_byname3_sleepable = bpf_program__attach(skel->progs.handle_uprobe_byname3_sleepable);
> if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname3_sleepable, "attach_uprobe_byname3_sleepable"))
> - goto cleanup;
> + return;
>
> skel->links.handle_uprobe_byname3 = bpf_program__attach(skel->progs.handle_uprobe_byname3);
> if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname3, "attach_uprobe_byname3"))
> - goto cleanup;
> + return;
>
> skel->links.handle_uretprobe_byname3_sleepable = bpf_program__attach(skel->progs.handle_uretprobe_byname3_sleepable);
> if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname3_sleepable, "attach_uretprobe_byname3_sleepable"))
> - goto cleanup;
> + return;
>
> skel->links.handle_uretprobe_byname3 = bpf_program__attach(skel->progs.handle_uretprobe_byname3);
> if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname3, "attach_uretprobe_byname3"))
> - goto cleanup;
> + return;
>
> skel->bss->user_ptr = test_data;
>
> - /* trigger & validate kprobe && kretprobe */
> - usleep(1);
> -
> - /* trigger & validate shared library u[ret]probes attached by name */
> - devnull = fopen("/dev/null", "r");
> - fclose(devnull);
> -
> - /* trigger & validate uprobe & uretprobe */
> - trigger_func();
> -
> - /* trigger & validate uprobe attached by name */
> - trigger_func2();
> -
> /* trigger & validate sleepable uprobe attached by name */
> trigger_func3();
>
> - ASSERT_EQ(skel->bss->kprobe_res, 1, "check_kprobe_res");
> - ASSERT_EQ(skel->bss->kprobe2_res, 11, "check_kprobe_auto_res");
> - ASSERT_EQ(skel->bss->kretprobe_res, 2, "check_kretprobe_res");
> - ASSERT_EQ(skel->bss->kretprobe2_res, 22, "check_kretprobe_auto_res");
> - ASSERT_EQ(skel->bss->uprobe_res, 3, "check_uprobe_res");
> - ASSERT_EQ(skel->bss->uretprobe_res, 4, "check_uretprobe_res");
> - ASSERT_EQ(skel->bss->uprobe_byname_res, 5, "check_uprobe_byname_res");
> - ASSERT_EQ(skel->bss->uretprobe_byname_res, 6, "check_uretprobe_byname_res");
> - ASSERT_EQ(skel->bss->uprobe_byname2_res, 7, "check_uprobe_byname2_res");
> - ASSERT_EQ(skel->bss->uretprobe_byname2_res, 8, "check_uretprobe_byname2_res");
> ASSERT_EQ(skel->bss->uprobe_byname3_sleepable_res, 9, "check_uprobe_byname3_sleepable_res");
> ASSERT_EQ(skel->bss->uprobe_byname3_res, 10, "check_uprobe_byname3_res");
> ASSERT_EQ(skel->bss->uretprobe_byname3_sleepable_res, 11, "check_uretprobe_byname3_sleepable_res");
> ASSERT_EQ(skel->bss->uretprobe_byname3_res, 12, "check_uretprobe_byname3_res");
> +}
> +
> +void test_attach_probe(void)
> +{
> + struct test_attach_probe *skel;
> +
> + skel = test_attach_probe__open();
> + if (!ASSERT_OK_PTR(skel, "skel_open"))
> + return;
> +
> + if (!ASSERT_OK(test_attach_probe__load(skel), "skel_load"))
> + goto cleanup;
> + if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
> + goto cleanup;
> +
> + if (test__start_subtest("manual"))
> + test_attach_probe_manual(skel);
> + if (test__start_subtest("auto"))
> + test_attach_probe_auto(skel);
> + if (test__start_subtest("kprobe-sleepable"))
> + test_kprobe_sleepable();
> + if (test__start_subtest("uprobe-lib"))
> + test_uprobe_lib(skel);
> + if (test__start_subtest("uprobe-sleepable"))
> + test_uprobe_sleepable(skel);
> + if (test__start_subtest("uprobe-ref_ctr"))
> + test_uporbe_ref_ctr(skel);

...and here.

>
> cleanup:
> test_attach_probe__destroy(skel);
> diff --git a/tools/testing/selftests/bpf/progs/test_attach_kprobe_sleepable.c b/tools/testing/selftests/bpf/progs/test_attach_kprobe_sleepable.c
> new file mode 100644
> index 000000000000..f548b7446218
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_attach_kprobe_sleepable.c
> @@ -0,0 +1,23 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2017 Facebook
> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <bpf/bpf_core_read.h>
> +#include "bpf_misc.h"
> +
> +int kprobe_res = 0;
> +
> +/**
> + * This program will be manually made sleepable on the userspace side
> + * and should thus be unattachable.
> + */
> +SEC("kprobe/" SYS_PREFIX "sys_nanosleep")
> +int handle_kprobe_sleepable(struct pt_regs *ctx)
> +{
> + kprobe_res = 1;
> + return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/progs/test_attach_probe.c b/tools/testing/selftests/bpf/progs/test_attach_probe.c
> index 3b5dc34d23e9..9e1e7163bb67 100644
> --- a/tools/testing/selftests/bpf/progs/test_attach_probe.c
> +++ b/tools/testing/selftests/bpf/progs/test_attach_probe.c
> @@ -37,17 +37,6 @@ int BPF_KSYSCALL(handle_kprobe_auto, struct __kernel_timespec *req, struct __ker
> return 0;
> }
>
> -/**
> - * This program will be manually made sleepable on the userspace side
> - * and should thus be unattachable.
> - */
> -SEC("kprobe/" SYS_PREFIX "sys_nanosleep")
> -int handle_kprobe_sleepable(struct pt_regs *ctx)
> -{
> - kprobe_res = 2;
> - return 0;
> -}
> -
> SEC("kretprobe")
> int handle_kretprobe(struct pt_regs *ctx)
> {
> @@ -76,6 +65,18 @@ int handle_uretprobe(struct pt_regs *ctx)
> return 0;
> }
>
> +SEC("uprobe")
> +int handle_uprobe_ref_ctr(struct pt_regs *ctx)
> +{
> + return 0;
> +}
> +
> +SEC("uretprobe")
> +int handle_uretprobe_ref_ctr(struct pt_regs *ctx)
> +{
> + return 0;
> +}
> +
> SEC("uprobe")
> int handle_uprobe_byname(struct pt_regs *ctx)
> {
>

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In reply to: menglong8 . dong: "[PATCH bpf-next v2 2/3] selftests/bpf: split test_attach_probe into multi subtests"
Next in thread: Menglong Dong: "Re: [PATCH bpf-next v2 2/3] selftests/bpf: split test_attach_probe into multi subtests"
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