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tools/bpf: add a test for bpf_get_stack with raw tracepoint prog

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The test attached a raw_tracepoint program to raw_syscalls/sys_enter.
It tested to get stack for user space, kernel space and user
space with build_id request. It also tested to get user
and kernel stack into the same buffer with back-to-back
bpf_get_stack helper calls.

If jit is not enabled, the user space application will check
to ensure that the kernel function for raw_tracepoint
___bpf_prog_run is part of the stack.

If jit is enabled, we did not have a reliable way to
verify the kernel stack, so just assume the kernel stack
is good when the kernel stack size is greater than 0.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song
2018-04-28 22:28:15 -07:00
committed by Alexei Starovoitov
parent 2abe611c5f
commit 173965fbfb
3 changed files with 266 additions and 12 deletions
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172
tools/testing/selftests/bpf/test_progs.c
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@@ -38,8 +38,10 @@ typedef __u16 __sum16;
#include "bpf_util.h"
#include "bpf_endian.h"
#include "bpf_rlimit.h"
#include "trace_helpers.h"
static int error_cnt, pass_cnt;
static bool jit_enabled;
#define MAGIC_BYTES 123
@@ -391,13 +393,30 @@ static inline __u64 ptr_to_u64(const void *ptr)
return (__u64) (unsigned long) ptr;
}
static bool is_jit_enabled(void)
{
const char *jit_sysctl = "/proc/sys/net/core/bpf_jit_enable";
bool enabled = false;
int sysctl_fd;
sysctl_fd = open(jit_sysctl, 0, O_RDONLY);
if (sysctl_fd != -1) {
char tmpc;
if (read(sysctl_fd, &tmpc, sizeof(tmpc)) == 1)
enabled = (tmpc != '0');
close(sysctl_fd);
}
return enabled;
}
static void test_bpf_obj_id(void)
{
const __u64 array_magic_value = 0xfaceb00c;
const __u32 array_key = 0;
const int nr_iters = 2;
const char *file = "./test_obj_id.o";
const char *jit_sysctl = "/proc/sys/net/core/bpf_jit_enable";
const char *expected_prog_name = "test_obj_id";
const char *expected_map_name = "test_map_id";
const __u64 nsec_per_sec = 1000000000;
@@ -414,20 +433,11 @@ static void test_bpf_obj_id(void)
char jited_insns[128], xlated_insns[128], zeros[128];
__u32 i, next_id, info_len, nr_id_found, duration = 0;
struct timespec real_time_ts, boot_time_ts;
int sysctl_fd, jit_enabled = 0, err = 0;
int err = 0;
__u64 array_value;
uid_t my_uid = getuid();
time_t now, load_time;
sysctl_fd = open(jit_sysctl, 0, O_RDONLY);
if (sysctl_fd != -1) {
char tmpc;
if (read(sysctl_fd, &tmpc, sizeof(tmpc)) == 1)
jit_enabled = (tmpc != '0');
close(sysctl_fd);
}
err = bpf_prog_get_fd_by_id(0);
CHECK(err >= 0 || errno != ENOENT,
"get-fd-by-notexist-prog-id", "err %d errno %d\n", err, errno);
@@ -1204,8 +1214,147 @@ out:
return;
}
#define MAX_CNT_RAWTP 10ull
#define MAX_STACK_RAWTP 100
struct get_stack_trace_t {
int pid;
int kern_stack_size;
int user_stack_size;
int user_stack_buildid_size;
__u64 kern_stack[MAX_STACK_RAWTP];
__u64 user_stack[MAX_STACK_RAWTP];
struct bpf_stack_build_id user_stack_buildid[MAX_STACK_RAWTP];
};
static int get_stack_print_output(void *data, int size)
{
bool good_kern_stack = false, good_user_stack = false;
const char *nonjit_func = "___bpf_prog_run";
struct get_stack_trace_t *e = data;
int i, num_stack;
static __u64 cnt;
struct ksym *ks;
cnt++;
if (size < sizeof(struct get_stack_trace_t)) {
__u64 *raw_data = data;
bool found = false;
num_stack = size / sizeof(__u64);
/* If jit is enabled, we do not have a good way to
* verify the sanity of the kernel stack. So we
* just assume it is good if the stack is not empty.
* This could be improved in the future.
*/
if (jit_enabled) {
found = num_stack > 0;
} else {
for (i = 0; i < num_stack; i++) {
ks = ksym_search(raw_data[i]);
if (strcmp(ks->name, nonjit_func) == 0) {
found = true;
break;
}
}
}
if (found) {
good_kern_stack = true;
good_user_stack = true;
}
} else {
num_stack = e->kern_stack_size / sizeof(__u64);
if (jit_enabled) {
good_kern_stack = num_stack > 0;
} else {
for (i = 0; i < num_stack; i++) {
ks = ksym_search(e->kern_stack[i]);
if (strcmp(ks->name, nonjit_func) == 0) {
good_kern_stack = true;
break;
}
}
}
if (e->user_stack_size > 0 && e->user_stack_buildid_size > 0)
good_user_stack = true;
}
if (!good_kern_stack || !good_user_stack)
return PERF_EVENT_ERROR;
if (cnt == MAX_CNT_RAWTP)
return PERF_EVENT_DONE;
return PERF_EVENT_CONT;
}
static void test_get_stack_raw_tp(void)
{
const char *file = "./test_get_stack_rawtp.o";
int i, efd, err, prog_fd, pmu_fd, perfmap_fd;
struct perf_event_attr attr = {};
struct timespec tv = {0, 10};
__u32 key = 0, duration = 0;
struct bpf_object *obj;
err = bpf_prog_load(file, BPF_PROG_TYPE_RAW_TRACEPOINT, &obj, &prog_fd);
if (CHECK(err, "prog_load raw tp", "err %d errno %d\n", err, errno))
return;
efd = bpf_raw_tracepoint_open("sys_enter", prog_fd);
if (CHECK(efd < 0, "raw_tp_open", "err %d errno %d\n", efd, errno))
goto close_prog;
perfmap_fd = bpf_find_map(__func__, obj, "perfmap");
if (CHECK(perfmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
perfmap_fd, errno))
goto close_prog;
err = load_kallsyms();
if (CHECK(err < 0, "load_kallsyms", "err %d errno %d\n", err, errno))
goto close_prog;
attr.sample_type = PERF_SAMPLE_RAW;
attr.type = PERF_TYPE_SOFTWARE;
attr.config = PERF_COUNT_SW_BPF_OUTPUT;
pmu_fd = syscall(__NR_perf_event_open, &attr, getpid()/*pid*/, -1/*cpu*/,
-1/*group_fd*/, 0);
if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", pmu_fd,
errno))
goto close_prog;
err = bpf_map_update_elem(perfmap_fd, &key, &pmu_fd, BPF_ANY);
if (CHECK(err < 0, "bpf_map_update_elem", "err %d errno %d\n", err,
errno))
goto close_prog;
err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
if (CHECK(err < 0, "ioctl PERF_EVENT_IOC_ENABLE", "err %d errno %d\n",
err, errno))
goto close_prog;
err = perf_event_mmap(pmu_fd);
if (CHECK(err < 0, "perf_event_mmap", "err %d errno %d\n", err, errno))
goto close_prog;
/* trigger some syscall action */
for (i = 0; i < MAX_CNT_RAWTP; i++)
nanosleep(&tv, NULL);
err = perf_event_poller(pmu_fd, get_stack_print_output);
if (CHECK(err < 0, "perf_event_poller", "err %d errno %d\n", err, errno))
goto close_prog;
goto close_prog_noerr;
close_prog:
error_cnt++;
close_prog_noerr:
bpf_object__close(obj);
}
int main(void)
{
jit_enabled = is_jit_enabled();
test_pkt_access();
test_xdp();
test_xdp_adjust_tail();
@@ -1219,6 +1368,7 @@ int main(void)
test_stacktrace_map();
test_stacktrace_build_id();
test_stacktrace_map_raw_tp();
test_get_stack_raw_tp();
printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;