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linux-stable/tools/testing/selftests/bpf/prog_tests/usdt.c

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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#define _SDT_HAS_SEMAPHORES 1
#include "../sdt.h"
#include "test_usdt.skel.h"
#include "test_urandom_usdt.skel.h"
int lets_test_this(int);
static volatile int idx = 2;
static volatile __u64 bla = 0xFEDCBA9876543210ULL;
static volatile short nums[] = {-1, -2, -3, };
static volatile struct {
int x;
signed char y;
} t1 = { 1, -127 };
#define SEC(name) __attribute__((section(name), used))
unsigned short test_usdt0_semaphore SEC(".probes");
unsigned short test_usdt3_semaphore SEC(".probes");
unsigned short test_usdt12_semaphore SEC(".probes");
static void __always_inline trigger_func(int x) {
long y = 42;
if (test_usdt0_semaphore)
STAP_PROBE(test, usdt0);
if (test_usdt3_semaphore)
STAP_PROBE3(test, usdt3, x, y, &bla);
if (test_usdt12_semaphore) {
STAP_PROBE12(test, usdt12,
x, x + 1, y, x + y, 5,
y / 7, bla, &bla, -9, nums[x],
nums[idx], t1.y);
}
}
static void subtest_basic_usdt(void)
{
LIBBPF_OPTS(bpf_usdt_opts, opts);
struct test_usdt *skel;
struct test_usdt__bss *bss;
int err;
skel = test_usdt__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
bss = skel->bss;
bss->my_pid = getpid();
err = test_usdt__attach(skel);
if (!ASSERT_OK(err, "skel_attach"))
goto cleanup;
/* usdt0 won't be auto-attached */
opts.usdt_cookie = 0xcafedeadbeeffeed;
skel->links.usdt0 = bpf_program__attach_usdt(skel->progs.usdt0,
0 /*self*/, "/proc/self/exe",
"test", "usdt0", &opts);
if (!ASSERT_OK_PTR(skel->links.usdt0, "usdt0_link"))
goto cleanup;
trigger_func(1);
ASSERT_EQ(bss->usdt0_called, 1, "usdt0_called");
ASSERT_EQ(bss->usdt3_called, 1, "usdt3_called");
ASSERT_EQ(bss->usdt12_called, 1, "usdt12_called");
ASSERT_EQ(bss->usdt0_cookie, 0xcafedeadbeeffeed, "usdt0_cookie");
ASSERT_EQ(bss->usdt0_arg_cnt, 0, "usdt0_arg_cnt");
ASSERT_EQ(bss->usdt0_arg_ret, -ENOENT, "usdt0_arg_ret");
/* auto-attached usdt3 gets default zero cookie value */
ASSERT_EQ(bss->usdt3_cookie, 0, "usdt3_cookie");
ASSERT_EQ(bss->usdt3_arg_cnt, 3, "usdt3_arg_cnt");
ASSERT_EQ(bss->usdt3_arg_rets[0], 0, "usdt3_arg1_ret");
ASSERT_EQ(bss->usdt3_arg_rets[1], 0, "usdt3_arg2_ret");
ASSERT_EQ(bss->usdt3_arg_rets[2], 0, "usdt3_arg3_ret");
ASSERT_EQ(bss->usdt3_args[0], 1, "usdt3_arg1");
ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2");
ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3");
/* auto-attached usdt12 gets default zero cookie value */
ASSERT_EQ(bss->usdt12_cookie, 0, "usdt12_cookie");
ASSERT_EQ(bss->usdt12_arg_cnt, 12, "usdt12_arg_cnt");
ASSERT_EQ(bss->usdt12_args[0], 1, "usdt12_arg1");
ASSERT_EQ(bss->usdt12_args[1], 1 + 1, "usdt12_arg2");
ASSERT_EQ(bss->usdt12_args[2], 42, "usdt12_arg3");
ASSERT_EQ(bss->usdt12_args[3], 42 + 1, "usdt12_arg4");
ASSERT_EQ(bss->usdt12_args[4], 5, "usdt12_arg5");
ASSERT_EQ(bss->usdt12_args[5], 42 / 7, "usdt12_arg6");
ASSERT_EQ(bss->usdt12_args[6], bla, "usdt12_arg7");
ASSERT_EQ(bss->usdt12_args[7], (uintptr_t)&bla, "usdt12_arg8");
ASSERT_EQ(bss->usdt12_args[8], -9, "usdt12_arg9");
ASSERT_EQ(bss->usdt12_args[9], nums[1], "usdt12_arg10");
ASSERT_EQ(bss->usdt12_args[10], nums[idx], "usdt12_arg11");
ASSERT_EQ(bss->usdt12_args[11], t1.y, "usdt12_arg12");
/* trigger_func() is marked __always_inline, so USDT invocations will be
* inlined in two different places, meaning that each USDT will have
* at least 2 different places to be attached to. This verifies that
* bpf_program__attach_usdt() handles this properly and attaches to
* all possible places of USDT invocation.
*/
trigger_func(2);
ASSERT_EQ(bss->usdt0_called, 2, "usdt0_called");
ASSERT_EQ(bss->usdt3_called, 2, "usdt3_called");
ASSERT_EQ(bss->usdt12_called, 2, "usdt12_called");
/* only check values that depend on trigger_func()'s input value */
ASSERT_EQ(bss->usdt3_args[0], 2, "usdt3_arg1");
ASSERT_EQ(bss->usdt12_args[0], 2, "usdt12_arg1");
ASSERT_EQ(bss->usdt12_args[1], 2 + 1, "usdt12_arg2");
ASSERT_EQ(bss->usdt12_args[3], 42 + 2, "usdt12_arg4");
ASSERT_EQ(bss->usdt12_args[9], nums[2], "usdt12_arg10");
/* detach and re-attach usdt3 */
bpf_link__destroy(skel->links.usdt3);
opts.usdt_cookie = 0xBADC00C51E;
skel->links.usdt3 = bpf_program__attach_usdt(skel->progs.usdt3, -1 /* any pid */,
"/proc/self/exe", "test", "usdt3", &opts);
if (!ASSERT_OK_PTR(skel->links.usdt3, "usdt3_reattach"))
goto cleanup;
trigger_func(3);
ASSERT_EQ(bss->usdt3_called, 3, "usdt3_called");
/* this time usdt3 has custom cookie */
ASSERT_EQ(bss->usdt3_cookie, 0xBADC00C51E, "usdt3_cookie");
ASSERT_EQ(bss->usdt3_arg_cnt, 3, "usdt3_arg_cnt");
ASSERT_EQ(bss->usdt3_arg_rets[0], 0, "usdt3_arg1_ret");
ASSERT_EQ(bss->usdt3_arg_rets[1], 0, "usdt3_arg2_ret");
ASSERT_EQ(bss->usdt3_arg_rets[2], 0, "usdt3_arg3_ret");
ASSERT_EQ(bss->usdt3_args[0], 3, "usdt3_arg1");
ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2");
ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3");
cleanup:
test_usdt__destroy(skel);
}
unsigned short test_usdt_100_semaphore SEC(".probes");
unsigned short test_usdt_300_semaphore SEC(".probes");
unsigned short test_usdt_400_semaphore SEC(".probes");
#define R10(F, X) F(X+0); F(X+1);F(X+2); F(X+3); F(X+4); \
F(X+5); F(X+6); F(X+7); F(X+8); F(X+9);
#define R100(F, X) R10(F,X+ 0);R10(F,X+10);R10(F,X+20);R10(F,X+30);R10(F,X+40); \
R10(F,X+50);R10(F,X+60);R10(F,X+70);R10(F,X+80);R10(F,X+90);
/* carefully control that we get exactly 100 inlines by preventing inlining */
static void __always_inline f100(int x)
{
STAP_PROBE1(test, usdt_100, x);
}
__weak void trigger_100_usdts(void)
{
R100(f100, 0);
}
/* we shouldn't be able to attach to test:usdt2_300 USDT as we don't have as
* many slots for specs. It's important that each STAP_PROBE2() invocation
* (after untolling) gets different arg spec due to compiler inlining i as
* a constant
*/
static void __always_inline f300(int x)
{
STAP_PROBE1(test, usdt_300, x);
}
__weak void trigger_300_usdts(void)
{
R100(f300, 0);
R100(f300, 100);
R100(f300, 200);
}
static void __always_inline f400(int x __attribute__((unused)))
{
STAP_PROBE1(test, usdt_400, 400);
}
/* this time we have 400 different USDT call sites, but they have uniform
* argument location, so libbpf's spec string deduplication logic should keep
* spec count use very small and so we should be able to attach to all 400
* call sites
*/
__weak void trigger_400_usdts(void)
{
R100(f400, 0);
R100(f400, 100);
R100(f400, 200);
R100(f400, 300);
}
static void subtest_multispec_usdt(void)
{
LIBBPF_OPTS(bpf_usdt_opts, opts);
struct test_usdt *skel;
struct test_usdt__bss *bss;
int err, i;
skel = test_usdt__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
bss = skel->bss;
bss->my_pid = getpid();
err = test_usdt__attach(skel);
if (!ASSERT_OK(err, "skel_attach"))
goto cleanup;
/* usdt_100 is auto-attached and there are 100 inlined call sites,
* let's validate that all of them are properly attached to and
* handled from BPF side
*/
trigger_100_usdts();
ASSERT_EQ(bss->usdt_100_called, 100, "usdt_100_called");
ASSERT_EQ(bss->usdt_100_sum, 99 * 100 / 2, "usdt_100_sum");
/* Stress test free spec ID tracking. By default libbpf allows up to
* 256 specs to be used, so if we don't return free spec IDs back
* after few detachments and re-attachments we should run out of
* available spec IDs.
*/
for (i = 0; i < 2; i++) {
bpf_link__destroy(skel->links.usdt_100);
skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1,
"/proc/self/exe",
"test", "usdt_100", NULL);
if (!ASSERT_OK_PTR(skel->links.usdt_100, "usdt_100_reattach"))
goto cleanup;
bss->usdt_100_sum = 0;
trigger_100_usdts();
ASSERT_EQ(bss->usdt_100_called, (i + 1) * 100 + 100, "usdt_100_called");
ASSERT_EQ(bss->usdt_100_sum, 99 * 100 / 2, "usdt_100_sum");
}
/* Now let's step it up and try to attach USDT that requires more than
* 256 attach points with different specs for each.
* Note that we need trigger_300_usdts() only to actually have 300
* USDT call sites, we are not going to actually trace them.
*/
trigger_300_usdts();
/* we'll reuse usdt_100 BPF program for usdt_300 test */
bpf_link__destroy(skel->links.usdt_100);
skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1, "/proc/self/exe",
"test", "usdt_300", NULL);
err = -errno;
if (!ASSERT_ERR_PTR(skel->links.usdt_100, "usdt_300_bad_attach"))
goto cleanup;
ASSERT_EQ(err, -E2BIG, "usdt_300_attach_err");
/* let's check that there are no "dangling" BPF programs attached due
* to partial success of the above test:usdt_300 attachment
*/
bss->usdt_100_called = 0;
bss->usdt_100_sum = 0;
f300(777); /* this is 301st instance of usdt_300 */
ASSERT_EQ(bss->usdt_100_called, 0, "usdt_301_called");
ASSERT_EQ(bss->usdt_100_sum, 0, "usdt_301_sum");
/* This time we have USDT with 400 inlined invocations, but arg specs
* should be the same across all sites, so libbpf will only need to
* use one spec and thus we'll be able to attach 400 uprobes
* successfully.
*
* Again, we are reusing usdt_100 BPF program.
*/
skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1,
"/proc/self/exe",
"test", "usdt_400", NULL);
if (!ASSERT_OK_PTR(skel->links.usdt_100, "usdt_400_attach"))
goto cleanup;
trigger_400_usdts();
ASSERT_EQ(bss->usdt_100_called, 400, "usdt_400_called");
ASSERT_EQ(bss->usdt_100_sum, 400 * 400, "usdt_400_sum");
cleanup:
test_usdt__destroy(skel);
}
static FILE *urand_spawn(int *pid)
{
FILE *f;
/* urandom_read's stdout is wired into f */
f = popen("./urandom_read 1 report-pid", "r");
if (!f)
return NULL;
if (fscanf(f, "%d", pid) != 1) {
pclose(f);
return NULL;
}
return f;
}
static int urand_trigger(FILE **urand_pipe)
{
int exit_code;
/* pclose() waits for child process to exit and returns their exit code */
exit_code = pclose(*urand_pipe);
*urand_pipe = NULL;
return exit_code;
}
static void subtest_urandom_usdt(bool auto_attach)
{
struct test_urandom_usdt *skel;
struct test_urandom_usdt__bss *bss;
struct bpf_link *l;
FILE *urand_pipe = NULL;
int err, urand_pid = 0;
skel = test_urandom_usdt__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
urand_pipe = urand_spawn(&urand_pid);
if (!ASSERT_OK_PTR(urand_pipe, "urand_spawn"))
goto cleanup;
bss = skel->bss;
bss->urand_pid = urand_pid;
if (auto_attach) {
err = test_urandom_usdt__attach(skel);
if (!ASSERT_OK(err, "skel_auto_attach"))
goto cleanup;
} else {
l = bpf_program__attach_usdt(skel->progs.urand_read_without_sema,
urand_pid, "./urandom_read",
"urand", "read_without_sema", NULL);
if (!ASSERT_OK_PTR(l, "urand_without_sema_attach"))
goto cleanup;
skel->links.urand_read_without_sema = l;
l = bpf_program__attach_usdt(skel->progs.urand_read_with_sema,
urand_pid, "./urandom_read",
"urand", "read_with_sema", NULL);
if (!ASSERT_OK_PTR(l, "urand_with_sema_attach"))
goto cleanup;
skel->links.urand_read_with_sema = l;
l = bpf_program__attach_usdt(skel->progs.urandlib_read_without_sema,
urand_pid, "./liburandom_read.so",
"urandlib", "read_without_sema", NULL);
if (!ASSERT_OK_PTR(l, "urandlib_without_sema_attach"))
goto cleanup;
skel->links.urandlib_read_without_sema = l;
l = bpf_program__attach_usdt(skel->progs.urandlib_read_with_sema,
urand_pid, "./liburandom_read.so",
"urandlib", "read_with_sema", NULL);
if (!ASSERT_OK_PTR(l, "urandlib_with_sema_attach"))
goto cleanup;
skel->links.urandlib_read_with_sema = l;
}
/* trigger urandom_read USDTs */
ASSERT_OK(urand_trigger(&urand_pipe), "urand_exit_code");
ASSERT_EQ(bss->urand_read_without_sema_call_cnt, 1, "urand_wo_sema_cnt");
ASSERT_EQ(bss->urand_read_without_sema_buf_sz_sum, 256, "urand_wo_sema_sum");
ASSERT_EQ(bss->urand_read_with_sema_call_cnt, 1, "urand_w_sema_cnt");
ASSERT_EQ(bss->urand_read_with_sema_buf_sz_sum, 256, "urand_w_sema_sum");
ASSERT_EQ(bss->urandlib_read_without_sema_call_cnt, 1, "urandlib_wo_sema_cnt");
ASSERT_EQ(bss->urandlib_read_without_sema_buf_sz_sum, 256, "urandlib_wo_sema_sum");
ASSERT_EQ(bss->urandlib_read_with_sema_call_cnt, 1, "urandlib_w_sema_cnt");
ASSERT_EQ(bss->urandlib_read_with_sema_buf_sz_sum, 256, "urandlib_w_sema_sum");
cleanup:
if (urand_pipe)
pclose(urand_pipe);
test_urandom_usdt__destroy(skel);
}
void test_usdt(void)
{
if (test__start_subtest("basic"))
subtest_basic_usdt();
if (test__start_subtest("multispec"))
subtest_multispec_usdt();
if (test__start_subtest("urand_auto_attach"))
subtest_urandom_usdt(true /* auto_attach */);
if (test__start_subtest("urand_pid_attach"))
subtest_urandom_usdt(false /* auto_attach */);
}
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