| Message ID | 20231207163458.5554-4-khuey@kylehuey.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
On Thu, Dec 7, 2023 at 11:20 AM Marco Elver <elver@google.com> wrote: > > On Thu, 7 Dec 2023 at 20:12, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > > > On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote: > > > > > > The test sets a hardware breakpoint and uses a bpf program to suppress the > > > side effects of a perf event sample, including I/O availability signals, > > > SIGTRAPs, and decrementing the event counter limit, if the ip matches the > > > expected value. Then the function with the breakpoint is executed multiple > > > times to test that all effects behave as expected. > > > > > > Signed-off-by: Kyle Huey <khuey@kylehuey.com> > > > --- > > > .../selftests/bpf/prog_tests/perf_skip.c | 145 ++++++++++++++++++ > > > .../selftests/bpf/progs/test_perf_skip.c | 15 ++ > > > 2 files changed, 160 insertions(+) > > > create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c > > > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > new file mode 100644 > > > index 000000000000..f6fa9bfd9efa > > > --- /dev/null > > > +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > @@ -0,0 +1,145 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +#define _GNU_SOURCE > > > + > > > +/* We need the latest siginfo from the kernel repo. */ > > > +#include <asm/siginfo.h> > > > > selftests are built with UAPI headers' copies under tools/include, so > > CI did catch a real issue, I think. Try copying > > include/uapi/asm-generic/siginfo.h into > > tools/include/uapi/asm-generic/siginfo.h ? > > I believe parts of this were inspired by > tools/testing/selftests/perf_events/sigtrap_threads.c - getting the > kernel headers is allowed, as long as $(KHDR_INCLUDES) is added to > CFLAGS. See tools/testing/selftests/perf_events/Makefile. Not sure > it's appropriate for this test though, if you don't want to add > KHDR_INCLUDES for everything. Yes, that's right. Namhyung's commit message for 91c97b36bd69 leads me to believe that I should copy siginfo.h over into tools/include and fix the perf_events self tests too. - Kyle
On Thu, Dec 7, 2023 at 2:56 PM Kyle Huey <me@kylehuey.com> wrote: > > On Thu, Dec 7, 2023 at 11:20 AM Marco Elver <elver@google.com> wrote: > > > > On Thu, 7 Dec 2023 at 20:12, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > > > > > On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote: > > > > > > > > The test sets a hardware breakpoint and uses a bpf program to suppress the > > > > side effects of a perf event sample, including I/O availability signals, > > > > SIGTRAPs, and decrementing the event counter limit, if the ip matches the > > > > expected value. Then the function with the breakpoint is executed multiple > > > > times to test that all effects behave as expected. > > > > > > > > Signed-off-by: Kyle Huey <khuey@kylehuey.com> > > > > --- > > > > .../selftests/bpf/prog_tests/perf_skip.c | 145 ++++++++++++++++++ > > > > .../selftests/bpf/progs/test_perf_skip.c | 15 ++ > > > > 2 files changed, 160 insertions(+) > > > > create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > > create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c > > > > > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > > new file mode 100644 > > > > index 000000000000..f6fa9bfd9efa > > > > --- /dev/null > > > > +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c > > > > @@ -0,0 +1,145 @@ > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > +#define _GNU_SOURCE > > > > + > > > > +/* We need the latest siginfo from the kernel repo. */ > > > > +#include <asm/siginfo.h> > > > > > > selftests are built with UAPI headers' copies under tools/include, so > > > CI did catch a real issue, I think. Try copying > > > include/uapi/asm-generic/siginfo.h into > > > tools/include/uapi/asm-generic/siginfo.h ? > > > > I believe parts of this were inspired by > > tools/testing/selftests/perf_events/sigtrap_threads.c - getting the > > kernel headers is allowed, as long as $(KHDR_INCLUDES) is added to > > CFLAGS. See tools/testing/selftests/perf_events/Makefile. Not sure > > it's appropriate for this test though, if you don't want to add > > KHDR_INCLUDES for everything. > > Yes, that's right. Namhyung's commit message for 91c97b36bd69 leads me > to believe that I should copy siginfo.h over into tools/include and > fix the perf_events self tests too. > > - Kyle That doesn't really help (though perhaps it should be done anyway so the selftests aren't reaching into include/) because the glibc headers still redefine a ton of stuff in asm-generic/siginfo.h. - Kyle
On 12/7/23 5:08 PM, Kyle Huey wrote: > On Thu, Dec 7, 2023 at 2:56 PM Kyle Huey <me@kylehuey.com> wrote: >> On Thu, Dec 7, 2023 at 11:20 AM Marco Elver <elver@google.com> wrote: >>> On Thu, 7 Dec 2023 at 20:12, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: >>>> On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote: >>>>> The test sets a hardware breakpoint and uses a bpf program to suppress the >>>>> side effects of a perf event sample, including I/O availability signals, >>>>> SIGTRAPs, and decrementing the event counter limit, if the ip matches the >>>>> expected value. Then the function with the breakpoint is executed multiple >>>>> times to test that all effects behave as expected. >>>>> >>>>> Signed-off-by: Kyle Huey <khuey@kylehuey.com> >>>>> --- >>>>> .../selftests/bpf/prog_tests/perf_skip.c | 145 ++++++++++++++++++ >>>>> .../selftests/bpf/progs/test_perf_skip.c | 15 ++ >>>>> 2 files changed, 160 insertions(+) >>>>> create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c >>>>> create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c >>>>> >>>>> diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c >>>>> new file mode 100644 >>>>> index 000000000000..f6fa9bfd9efa >>>>> --- /dev/null >>>>> +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c >>>>> @@ -0,0 +1,145 @@ >>>>> +// SPDX-License-Identifier: GPL-2.0 >>>>> +#define _GNU_SOURCE >>>>> + >>>>> +/* We need the latest siginfo from the kernel repo. */ >>>>> +#include <asm/siginfo.h> >>>> selftests are built with UAPI headers' copies under tools/include, so >>>> CI did catch a real issue, I think. Try copying >>>> include/uapi/asm-generic/siginfo.h into >>>> tools/include/uapi/asm-generic/siginfo.h ? >>> I believe parts of this were inspired by >>> tools/testing/selftests/perf_events/sigtrap_threads.c - getting the >>> kernel headers is allowed, as long as $(KHDR_INCLUDES) is added to >>> CFLAGS. See tools/testing/selftests/perf_events/Makefile. Not sure >>> it's appropriate for this test though, if you don't want to add >>> KHDR_INCLUDES for everything. >> Yes, that's right. Namhyung's commit message for 91c97b36bd69 leads me >> to believe that I should copy siginfo.h over into tools/include and >> fix the perf_events self tests too. >> >> - Kyle > That doesn't really help (though perhaps it should be done anyway so > the selftests aren't reaching into include/) because the glibc headers > still redefine a ton of stuff in asm-generic/siginfo.h. Just for testing purpose, I think you can avoid includeasm/siginfo.h and directly define necessary structures in the C file directly, right? > > - Kyle
On Fri, Dec 8, 2023 at 12:07 AM Marco Elver <elver@google.com> wrote:
> I think that's easy to fix by just defining TRAP_PERF yourself
Yeah that would work here.
- Kyle
diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c new file mode 100644 index 000000000000..f6fa9bfd9efa --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +/* We need the latest siginfo from the kernel repo. */ +#include <asm/siginfo.h> +#define __have_siginfo_t 1 +#define __have_sigval_t 1 +#define __have_sigevent_t 1 +#define __siginfo_t_defined +#define __sigval_t_defined +#define __sigevent_t_defined +#define _BITS_SIGINFO_CONSTS_H 1 +#define _BITS_SIGEVENT_CONSTS_H 1 + +#include <test_progs.h> +#include "test_perf_skip.skel.h" +#include <linux/compiler.h> +#include <linux/hw_breakpoint.h> +#include <sys/mman.h> + +int signals_unexpected = 1; +int sigio_count, sigtrap_count; + +static void handle_sigio(int sig __always_unused) +{ + ASSERT_OK(signals_unexpected, "perf event not skipped"); + ++sigio_count; +} + +static void handle_sigtrap(int signum __always_unused, + siginfo_t *info, + void *ucontext __always_unused) +{ + ASSERT_OK(signals_unexpected, "perf event not skipped"); + ASSERT_EQ(info->si_code, TRAP_PERF, "wrong si_code"); + ++sigtrap_count; +} + +static noinline int test_function(void) +{ + asm volatile (""); + return 0; +} + +void serial_test_perf_skip(void) +{ + struct sigaction action = {}; + struct sigaction previous_sigtrap; + sighandler_t previous_sigio; + struct test_perf_skip *skel = NULL; + struct perf_event_attr attr = {}; + int perf_fd = -1; + int err; + struct f_owner_ex owner; + struct bpf_link *prog_link = NULL; + + action.sa_flags = SA_SIGINFO | SA_NODEFER; + action.sa_sigaction = handle_sigtrap; + sigemptyset(&action.sa_mask); + if (!ASSERT_OK(sigaction(SIGTRAP, &action, &previous_sigtrap), "sigaction")) + return; + + previous_sigio = signal(SIGIO, handle_sigio); + + skel = test_perf_skip__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_load")) + goto cleanup; + + attr.type = PERF_TYPE_BREAKPOINT; + attr.size = sizeof(attr); + attr.bp_type = HW_BREAKPOINT_X; + attr.bp_addr = (uintptr_t)test_function; + attr.bp_len = sizeof(long); + attr.sample_period = 1; + attr.sample_type = PERF_SAMPLE_IP; + attr.pinned = 1; + attr.exclude_kernel = 1; + attr.exclude_hv = 1; + attr.precise_ip = 3; + attr.sigtrap = 1; + attr.remove_on_exec = 1; + + perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0); + if (perf_fd < 0 && (errno == ENOENT || errno == EOPNOTSUPP)) { + printf("SKIP:no PERF_TYPE_BREAKPOINT/HW_BREAKPOINT_X\n"); + test__skip(); + goto cleanup; + } + if (!ASSERT_OK(perf_fd < 0, "perf_event_open")) + goto cleanup; + + // Configure the perf event to signal on sample. + err = fcntl(perf_fd, F_SETFL, O_ASYNC); + if (!ASSERT_OK(err, "fcntl(F_SETFL, O_ASYNC)")) + goto cleanup; + + owner.type = F_OWNER_TID; + owner.pid = syscall(__NR_gettid); + err = fcntl(perf_fd, F_SETOWN_EX, &owner); + if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)")) + goto cleanup; + + // Allow at most one sample. A sample rejected by bpf should + // not count against this. + err = ioctl(perf_fd, PERF_EVENT_IOC_REFRESH, 1); + if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_REFRESH)")) + goto cleanup; + + prog_link = bpf_program__attach_perf_event(skel->progs.handler, perf_fd); + if (!ASSERT_OK_PTR(prog_link, "bpf_program__attach_perf_event")) + goto cleanup; + + // Configure the bpf program to suppress the sample. + skel->bss->ip = (uintptr_t)test_function; + test_function(); + + ASSERT_EQ(sigio_count, 0, "sigio_count"); + ASSERT_EQ(sigtrap_count, 0, "sigtrap_count"); + + // Configure the bpf program to allow the sample. + skel->bss->ip = 0; + signals_unexpected = 0; + test_function(); + + ASSERT_EQ(sigio_count, 1, "sigio_count"); + ASSERT_EQ(sigtrap_count, 1, "sigtrap_count"); + + // Test that the sample above is the only one allowed (by perf, not + // by bpf) + test_function(); + + ASSERT_EQ(sigio_count, 1, "sigio_count"); + ASSERT_EQ(sigtrap_count, 1, "sigtrap_count"); + +cleanup: + if (prog_link) + bpf_link__destroy(prog_link); + if (perf_fd >= 0) + close(perf_fd); + if (skel) + test_perf_skip__destroy(skel); + + signal(SIGIO, previous_sigio); + sigaction(SIGTRAP, &previous_sigtrap, NULL); +} diff --git a/tools/testing/selftests/bpf/progs/test_perf_skip.c b/tools/testing/selftests/bpf/progs/test_perf_skip.c new file mode 100644 index 000000000000..417a9db3b770 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +uintptr_t ip; + +SEC("perf_event") +int handler(struct bpf_perf_event_data *data) +{ + // Skip events that have the correct ip. + return ip != PT_REGS_IP(&data->regs); +} + +char _license[] SEC("license") = "GPL";
The test sets a hardware breakpoint and uses a bpf program to suppress the side effects of a perf event sample, including I/O availability signals, SIGTRAPs, and decrementing the event counter limit, if the ip matches the expected value. Then the function with the breakpoint is executed multiple times to test that all effects behave as expected. Signed-off-by: Kyle Huey <khuey@kylehuey.com> --- .../selftests/bpf/prog_tests/perf_skip.c | 145 ++++++++++++++++++ .../selftests/bpf/progs/test_perf_skip.c | 15 ++ 2 files changed, 160 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c