The test sets a hardware breakpoint and uses a bpf program to suppress the
I/O availability signal if the ip matches the expected value.
Signed-off-by: Kyle Huey <[email protected]>
---
.../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
.../selftests/bpf/progs/test_perf_skip.c | 23 +++++
2 files changed, 118 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..b269a31669b7
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <test_progs.h>
+#include "test_perf_skip.skel.h"
+#include <linux/hw_breakpoint.h>
+#include <sys/mman.h>
+
+#define BPF_OBJECT "test_perf_skip.bpf.o"
+
+static void handle_sig(int)
+{
+ ASSERT_OK(1, "perf event not skipped");
+}
+
+static noinline int test_function(void)
+{
+ return 0;
+}
+
+void serial_test_perf_skip(void)
+{
+ sighandler_t previous;
+ int duration = 0;
+ struct test_perf_skip *skel = NULL;
+ int map_fd = -1;
+ long page_size = sysconf(_SC_PAGE_SIZE);
+ uintptr_t *ip = NULL;
+ int prog_fd = -1;
+ struct perf_event_attr attr = {0};
+ int perf_fd = -1;
+ struct f_owner_ex owner;
+ int err;
+
+ previous = signal(SIGIO, handle_sig);
+
+ skel = test_perf_skip__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_load"))
+ goto cleanup;
+
+ prog_fd = bpf_program__fd(skel->progs.handler);
+ if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))
+ goto cleanup;
+
+ map_fd = bpf_map__fd(skel->maps.ip);
+ if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))
+ goto cleanup;
+
+ ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
+ if (!ASSERT_OK_PTR(ip, "mmap bpf map"))
+ goto cleanup;
+
+ *ip = (uintptr_t)test_function;
+
+ 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;
+
+ perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
+ if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))
+ goto cleanup;
+
+ 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 = gettid();
+ err = fcntl(perf_fd, F_SETOWN_EX, &owner);
+ if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))
+ goto cleanup;
+
+ err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
+ if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))
+ goto cleanup;
+
+ test_function();
+
+cleanup:
+ if (perf_fd >= 0)
+ close(perf_fd);
+ if (ip)
+ munmap(ip, page_size);
+ if (skel)
+ test_perf_skip__destroy(skel);
+
+ signal(SIGIO, previous);
+}
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..ef01a9161afe
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __uint(map_flags, BPF_F_MMAPABLE);
+ __type(key, uint32_t);
+ __type(value, uintptr_t);
+} ip SEC(".maps");
+
+SEC("perf_event")
+int handler(struct bpf_perf_event_data *data)
+{
+ const uint32_t index = 0;
+ uintptr_t *v = bpf_map_lookup_elem(&ip, &index);
+
+ return !(v && *v == PT_REGS_IP(&data->regs));
+}
+
+char _license[] SEC("license") = "GPL";
--
2.34.1
On Mon, Dec 4, 2023 at 12:14 PM Kyle Huey <[email protected]> wrote:
>
> The test sets a hardware breakpoint and uses a bpf program to suppress the
> I/O availability signal if the ip matches the expected value.
>
> Signed-off-by: Kyle Huey <[email protected]>
> ---
> .../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
> .../selftests/bpf/progs/test_perf_skip.c | 23 +++++
> 2 files changed, 118 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..b269a31669b7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE
> +#include <test_progs.h>
> +#include "test_perf_skip.skel.h"
> +#include <linux/hw_breakpoint.h>
> +#include <sys/mman.h>
> +
> +#define BPF_OBJECT "test_perf_skip.bpf.o"
leftover?
> +
> +static void handle_sig(int)
> +{
> + ASSERT_OK(1, "perf event not skipped");
> +}
> +
> +static noinline int test_function(void)
> +{
please add
asm volatile ("");
here to prevent compiler from actually inlining at the call site
> + return 0;
> +}
> +
> +void serial_test_perf_skip(void)
> +{
> + sighandler_t previous;
> + int duration = 0;
> + struct test_perf_skip *skel = NULL;
> + int map_fd = -1;
> + long page_size = sysconf(_SC_PAGE_SIZE);
> + uintptr_t *ip = NULL;
> + int prog_fd = -1;
> + struct perf_event_attr attr = {0};
> + int perf_fd = -1;
> + struct f_owner_ex owner;
> + int err;
> +
> + previous = signal(SIGIO, handle_sig);
> +
> + skel = test_perf_skip__open_and_load();
> + if (!ASSERT_OK_PTR(skel, "skel_load"))
> + goto cleanup;
> +
> + prog_fd = bpf_program__fd(skel->progs.handler);
> + if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))
> + goto cleanup;
> +
> + map_fd = bpf_map__fd(skel->maps.ip);
> + if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))
> + goto cleanup;
> +
> + ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
> + if (!ASSERT_OK_PTR(ip, "mmap bpf map"))
> + goto cleanup;
> +
> + *ip = (uintptr_t)test_function;
> +
> + 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;
> +
> + perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
> + if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))
please don't use CHECK() macro, stick to ASSERT_xxx()
also, we are going to run all this on different hardware and VMs, see
how we skip tests if hardware support is not there. See test__skip
usage in prog_tests/perf_branches.c, as one example
> + goto cleanup;
> +
> + err = fcntl(perf_fd, F_SETFL, O_ASYNC);
I assume this is what will send SIGIO, right? Can you add a small
comment explicitly saying this?
> + if (!ASSERT_OK(err, "fcntl(F_SETFL, O_ASYNC)"))
> + goto cleanup;
> +
> + owner.type = F_OWNER_TID;
> + owner.pid = gettid();
> + err = fcntl(perf_fd, F_SETOWN_EX, &owner);
> + if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))
> + goto cleanup;
> +
> + err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> + if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))
> + goto cleanup;
we have a better way to do this, please use
bpf_program__attach_perf_event() instead
> +
> + test_function();
> +
> +cleanup:
> + if (perf_fd >= 0)
> + close(perf_fd);
> + if (ip)
> + munmap(ip, page_size);
> + if (skel)
> + test_perf_skip__destroy(skel);
> +
> + signal(SIGIO, previous);
> +}
> 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..ef01a9161afe
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c
> @@ -0,0 +1,23 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __uint(max_entries, 1);
> + __uint(map_flags, BPF_F_MMAPABLE);
> + __type(key, uint32_t);
> + __type(value, uintptr_t);
> +} ip SEC(".maps");
please use global variable:
__u64 ip;
and then access it from user-space side through skeleton
skel->bss.ip = &test_function;
> +
> +SEC("perf_event")
> +int handler(struct bpf_perf_event_data *data)
> +{
> + const uint32_t index = 0;
> + uintptr_t *v = bpf_map_lookup_elem(&ip, &index);
> +
> + return !(v && *v == PT_REGS_IP(&data->regs));
and so we the above global var suggestion this will be just:
return ip == PT_REGS_IP(&data->regs);
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.34.1
>
On Mon, Dec 04, 2023 at 12:14:06PM -0800, Kyle Huey wrote:
> The test sets a hardware breakpoint and uses a bpf program to suppress the
> I/O availability signal if the ip matches the expected value.
>
> Signed-off-by: Kyle Huey <[email protected]>
> ---
> .../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
> .../selftests/bpf/progs/test_perf_skip.c | 23 +++++
> 2 files changed, 118 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..b269a31669b7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE
> +#include <test_progs.h>
> +#include "test_perf_skip.skel.h"
> +#include <linux/hw_breakpoint.h>
> +#include <sys/mman.h>
> +
> +#define BPF_OBJECT "test_perf_skip.bpf.o"
> +
> +static void handle_sig(int)
> +{
> + ASSERT_OK(1, "perf event not skipped");
> +}
> +
> +static noinline int test_function(void)
> +{
> + return 0;
> +}
> +
> +void serial_test_perf_skip(void)
does it need to be serial?
jirka
On 12/4/23 3:14 PM, Kyle Huey wrote:
> The test sets a hardware breakpoint and uses a bpf program to suppress the
> I/O availability signal if the ip matches the expected value.
>
> Signed-off-by: Kyle Huey <[email protected]>
> ---
> .../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
> .../selftests/bpf/progs/test_perf_skip.c | 23 +++++
> 2 files changed, 118 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..b269a31669b7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE
> +#include <test_progs.h>
> +#include "test_perf_skip.skel.h"
> +#include <linux/hw_breakpoint.h>
> +#include <sys/mman.h>
> +
> +#define BPF_OBJECT "test_perf_skip.bpf.o"
> +
> +static void handle_sig(int)
I hit a warning here:
home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:10:27: error: omitting the parameter name in a function definition is a C23 extension [-Werror,-Wc23-extensions]
10 | static void handle_sig(int)
|
Add a parameter and marked as unused can resolve the issue.
#define __always_unused __attribute__((__unused__))
static void handle_sig(int unused __always_unused)
{
ASSERT_OK(1, "perf event not skipped");
}
> +{
> + ASSERT_OK(1, "perf event not skipped");
> +}
> +
> +static noinline int test_function(void)
> +{
> + return 0;
> +}
> +
> +void serial_test_perf_skip(void)
> +{
> + sighandler_t previous;
> + int duration = 0;
> + struct test_perf_skip *skel = NULL;
> + int map_fd = -1;
> + long page_size = sysconf(_SC_PAGE_SIZE);
> + uintptr_t *ip = NULL;
> + int prog_fd = -1;
> + struct perf_event_attr attr = {0};
> + int perf_fd = -1;
> + struct f_owner_ex owner;
> + int err;
> +
> + previous = signal(SIGIO, handle_sig);
> +
> + skel = test_perf_skip__open_and_load();
> + if (!ASSERT_OK_PTR(skel, "skel_load"))
> + goto cleanup;
> +
> + prog_fd = bpf_program__fd(skel->progs.handler);
> + if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))
> + goto cleanup;
> +
> + map_fd = bpf_map__fd(skel->maps.ip);
> + if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))
> + goto cleanup;
> +
> + ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
> + if (!ASSERT_OK_PTR(ip, "mmap bpf map"))
> + goto cleanup;
> +
> + *ip = (uintptr_t)test_function;
> +
> + 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;
> +
> + perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
> + if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))
> + goto cleanup;
> +
> + 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 = gettid();
I hit a compilation failure here:
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:75:14: error: call to undeclared function 'gettid'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
75 | owner.pid = gettid();
| ^
If you looked at some other examples, the common usage is do 'syscall(SYS_gettid)'.
So the following patch should fix the compilation error:
#include <sys/syscall.h>
...
owner.pid = syscall(SYS_gettid);
...
> + err = fcntl(perf_fd, F_SETOWN_EX, &owner);
> + if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))
> + goto cleanup;
> +
> + err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> + if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))
> + goto cleanup;
> +
> + test_function();
As Andrii has mentioned in previous comments, we will have
issue is RELEASE version of selftest is built
RELEASE=1 make ...
See https://lore.kernel.org/bpf/[email protected]
> +
> +cleanup:
> + if (perf_fd >= 0)
> + close(perf_fd);
> + if (ip)
> + munmap(ip, page_size);
> + if (skel)
> + test_perf_skip__destroy(skel);
> +
> + signal(SIGIO, previous);
> +}
> 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..ef01a9161afe
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c
> @@ -0,0 +1,23 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __uint(max_entries, 1);
> + __uint(map_flags, BPF_F_MMAPABLE);
> + __type(key, uint32_t);
> + __type(value, uintptr_t);
> +} ip SEC(".maps");
> +
> +SEC("perf_event")
> +int handler(struct bpf_perf_event_data *data)
> +{
> + const uint32_t index = 0;
> + uintptr_t *v = bpf_map_lookup_elem(&ip, &index);
> +
> + return !(v && *v == PT_REGS_IP(&data->regs));
> +}
> +
> +char _license[] SEC("license") = "GPL";
On Tue, Dec 5, 2023 at 8:54 AM Yonghong Song <[email protected]> wrote:
>
>
> On 12/4/23 3:14 PM, Kyle Huey wrote:
> > The test sets a hardware breakpoint and uses a bpf program to suppress the
> > I/O availability signal if the ip matches the expected value.
> >
> > Signed-off-by: Kyle Huey <[email protected]>
> > ---
> > .../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
> > .../selftests/bpf/progs/test_perf_skip.c | 23 +++++
> > 2 files changed, 118 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..b269a31669b7
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
> > @@ -0,0 +1,95 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#define _GNU_SOURCE
> > +#include <test_progs.h>
> > +#include "test_perf_skip.skel.h"
> > +#include <linux/hw_breakpoint.h>
> > +#include <sys/mman.h>
> > +
> > +#define BPF_OBJECT "test_perf_skip.bpf.o"
> > +
> > +static void handle_sig(int)
>
> I hit a warning here:
> home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:10:27: error: omitting the parameter name in a function definition is a C23 extension [-Werror,-Wc23-extensions]
Yeah, Meta's kernel-ci bot sent me off-list email about this one.
>
> 10 | static void handle_sig(int)
> |
>
> Add a parameter and marked as unused can resolve the issue.
>
> #define __always_unused __attribute__((__unused__))
>
> static void handle_sig(int unused __always_unused)
> {
> ASSERT_OK(1, "perf event not skipped");
> }
>
>
> > +{
> > + ASSERT_OK(1, "perf event not skipped");
> > +}
> > +
> > +static noinline int test_function(void)
> > +{
> > + return 0;
> > +}
> > +
> > +void serial_test_perf_skip(void)
> > +{
> > + sighandler_t previous;
> > + int duration = 0;
> > + struct test_perf_skip *skel = NULL;
> > + int map_fd = -1;
> > + long page_size = sysconf(_SC_PAGE_SIZE);
> > + uintptr_t *ip = NULL;
> > + int prog_fd = -1;
> > + struct perf_event_attr attr = {0};
> > + int perf_fd = -1;
> > + struct f_owner_ex owner;
> > + int err;
> > +
> > + previous = signal(SIGIO, handle_sig);
> > +
> > + skel = test_perf_skip__open_and_load();
> > + if (!ASSERT_OK_PTR(skel, "skel_load"))
> > + goto cleanup;
> > +
> > + prog_fd = bpf_program__fd(skel->progs.handler);
> > + if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))
> > + goto cleanup;
> > +
> > + map_fd = bpf_map__fd(skel->maps.ip);
> > + if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))
> > + goto cleanup;
> > +
> > + ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
> > + if (!ASSERT_OK_PTR(ip, "mmap bpf map"))
> > + goto cleanup;
> > +
> > + *ip = (uintptr_t)test_function;
> > +
> > + 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;
> > +
> > + perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
> > + if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))
> > + goto cleanup;
> > +
> > + 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 = gettid();
>
> I hit a compilation failure here:
>
> /home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:75:14: error: call to undeclared function 'gettid'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> 75 | owner.pid = gettid();
> | ^
>
> If you looked at some other examples, the common usage is do 'syscall(SYS_gettid)'.
Not clear why this works for me but sure I'll change that.
>
> So the following patch should fix the compilation error:
>
> #include <sys/syscall.h>
> ...
> owner.pid = syscall(SYS_gettid);
> ...
>
> > + err = fcntl(perf_fd, F_SETOWN_EX, &owner);
> > + if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))
> > + goto cleanup;
> > +
> > + err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> > + if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))
> > + goto cleanup;
> > +
> > + test_function();
>
> As Andrii has mentioned in previous comments, we will have
> issue is RELEASE version of selftest is built
> RELEASE=1 make ...
>
> See https://lore.kernel.org/bpf/[email protected]
Not sure I follow this one. Are you saying adding asm volatile ("") in
test_function() is *not* sufficient?
- Kyle
>
> > +
> > +cleanup:
> > + if (perf_fd >= 0)
> > + close(perf_fd);
> > + if (ip)
> > + munmap(ip, page_size);
> > + if (skel)
> > + test_perf_skip__destroy(skel);
> > +
> > + signal(SIGIO, previous);
> > +}
> > 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..ef01a9161afe
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c
> > @@ -0,0 +1,23 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include "vmlinux.h"
> > +#include <bpf/bpf_helpers.h>
> > +#include <bpf/bpf_tracing.h>
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_ARRAY);
> > + __uint(max_entries, 1);
> > + __uint(map_flags, BPF_F_MMAPABLE);
> > + __type(key, uint32_t);
> > + __type(value, uintptr_t);
> > +} ip SEC(".maps");
> > +
> > +SEC("perf_event")
> > +int handler(struct bpf_perf_event_data *data)
> > +{
> > + const uint32_t index = 0;
> > + uintptr_t *v = bpf_map_lookup_elem(&ip, &index);
> > +
> > + return !(v && *v == PT_REGS_IP(&data->regs));
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
On Mon, Dec 4, 2023 at 2:14 PM Andrii Nakryiko
<[email protected]> wrote:
>
> On Mon, Dec 4, 2023 at 12:14 PM Kyle Huey <[email protected]> wrote:
> >
> > The test sets a hardware breakpoint and uses a bpf program to suppress the
> > I/O availability signal if the ip matches the expected value.
> >
> > Signed-off-by: Kyle Huey <[email protected]>
> > ---
> > .../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++
> > .../selftests/bpf/progs/test_perf_skip.c | 23 +++++
> > 2 files changed, 118 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..b269a31669b7
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
> > @@ -0,0 +1,95 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#define _GNU_SOURCE
> > +#include <test_progs.h>
> > +#include "test_perf_skip.skel.h"
> > +#include <linux/hw_breakpoint.h>
> > +#include <sys/mman.h>
> > +
> > +#define BPF_OBJECT "test_perf_skip.bpf.o"
>
> leftover?
Indeed. Fixed.
> > +
> > +static void handle_sig(int)
> > +{
> > + ASSERT_OK(1, "perf event not skipped");
> > +}
> > +
> > +static noinline int test_function(void)
> > +{
>
> please add
>
> asm volatile ("");
>
> here to prevent compiler from actually inlining at the call site
Ok.
> > + return 0;
> > +}
> > +
> > +void serial_test_perf_skip(void)
> > +{
> > + sighandler_t previous;
> > + int duration = 0;
> > + struct test_perf_skip *skel = NULL;
> > + int map_fd = -1;
> > + long page_size = sysconf(_SC_PAGE_SIZE);
> > + uintptr_t *ip = NULL;
> > + int prog_fd = -1;
> > + struct perf_event_attr attr = {0};
> > + int perf_fd = -1;
> > + struct f_owner_ex owner;
> > + int err;
> > +
> > + previous = signal(SIGIO, handle_sig);
> > +
> > + skel = test_perf_skip__open_and_load();
> > + if (!ASSERT_OK_PTR(skel, "skel_load"))
> > + goto cleanup;
> > +
> > + prog_fd = bpf_program__fd(skel->progs.handler);
> > + if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))
> > + goto cleanup;
> > +
> > + map_fd = bpf_map__fd(skel->maps.ip);
> > + if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))
> > + goto cleanup;
> > +
> > + ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
> > + if (!ASSERT_OK_PTR(ip, "mmap bpf map"))
> > + goto cleanup;
> > +
> > + *ip = (uintptr_t)test_function;
> > +
> > + 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;
> > +
> > + perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
> > + if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))
>
> please don't use CHECK() macro, stick to ASSERT_xxx()
Done.
> also, we are going to run all this on different hardware and VMs, see
> how we skip tests if hardware support is not there. See test__skip
> usage in prog_tests/perf_branches.c, as one example
Hmm I suppose it should be conditioned on CONFIG_HAVE_HW_BREAKPOINT.
> > + goto cleanup;
> > +
> > + err = fcntl(perf_fd, F_SETFL, O_ASYNC);
>
> I assume this is what will send SIGIO, right? Can you add a small
> comment explicitly saying this?
Done.
> > + if (!ASSERT_OK(err, "fcntl(F_SETFL, O_ASYNC)"))
> > + goto cleanup;
> > +
> > + owner.type = F_OWNER_TID;
> > + owner.pid = gettid();
> > + err = fcntl(perf_fd, F_SETOWN_EX, &owner);
> > + if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))
> > + goto cleanup;
> > +
> > + err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> > + if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))
> > + goto cleanup;
>
> we have a better way to do this, please use
> bpf_program__attach_perf_event() instead
Done.
> > +
> > + test_function();
> > +
> > +cleanup:
> > + if (perf_fd >= 0)
> > + close(perf_fd);
> > + if (ip)
> > + munmap(ip, page_size);
> > + if (skel)
> > + test_perf_skip__destroy(skel);
> > +
> > + signal(SIGIO, previous);
> > +}
> > 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..ef01a9161afe
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c
> > @@ -0,0 +1,23 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include "vmlinux.h"
> > +#include <bpf/bpf_helpers.h>
> > +#include <bpf/bpf_tracing.h>
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_ARRAY);
> > + __uint(max_entries, 1);
> > + __uint(map_flags, BPF_F_MMAPABLE);
> > + __type(key, uint32_t);
> > + __type(value, uintptr_t);
> > +} ip SEC(".maps");
>
> please use global variable:
>
> __u64 ip;
>
> and then access it from user-space side through skeleton
>
> skel->bss.ip = &test_function;
Done.
> > +
> > +SEC("perf_event")
> > +int handler(struct bpf_perf_event_data *data)
> > +{
> > + const uint32_t index = 0;
> > + uintptr_t *v = bpf_map_lookup_elem(&ip, &index);
> > +
> > + return !(v && *v == PT_REGS_IP(&data->regs));
>
> and so we the above global var suggestion this will be just:
>
> return ip == PT_REGS_IP(&data->regs);
>
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> > --
> > 2.34.1
> >
- Kyle