// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#include "uretprobe_stack.skel.h"
#include "../sdt.h"
/* We set up target_1() -> target_2() -> target_3() -> target_4() -> USDT()
* call chain, each being traced by our BPF program. On entry or return from
* each target_*() we are capturing user stack trace and recording it in
* global variable, so that user space part of the test can validate it.
*
* Note, we put each target function into a custom section to get those
* __start_XXX/__stop_XXX symbols, generated by linker for us, which allow us
* to know address range of those functions
*/
__attribute__((section("uprobe__target_4")))
__weak int target_4(void)
{
STAP_PROBE1(uretprobe_stack, target, 42);
return 42;
}
extern const void *__start_uprobe__target_4;
extern const void *__stop_uprobe__target_4;
__attribute__((section("uprobe__target_3")))
__weak int target_3(void)
{
return target_4();
}
extern const void *__start_uprobe__target_3;
extern const void *__stop_uprobe__target_3;
__attribute__((section("uprobe__target_2")))
__weak int target_2(void)
{
return target_3();
}
extern const void *__start_uprobe__target_2;
extern const void *__stop_uprobe__target_2;
__attribute__((section("uprobe__target_1")))
__weak int target_1(int depth)
{
if (depth < 1)
return 1 + target_1(depth + 1);
else
return target_2();
}
extern const void *__start_uprobe__target_1;
extern const void *__stop_uprobe__target_1;
extern const void *__start_uretprobe_stack_sec;
extern const void *__stop_uretprobe_stack_sec;
struct range {
long start;
long stop;
};
static struct range targets[] = {
{}, /* we want target_1 to map to target[1], so need 1-based indexing */
{ (long)&__start_uprobe__target_1, (long)&__stop_uprobe__target_1 },
{ (long)&__start_uprobe__target_2, (long)&__stop_uprobe__target_2 },
{ (long)&__start_uprobe__target_3, (long)&__stop_uprobe__target_3 },
{ (long)&__start_uprobe__target_4, (long)&__stop_uprobe__target_4 },
};
static struct range caller = {
(long)&__start_uretprobe_stack_sec,
(long)&__stop_uretprobe_stack_sec,
};
static void validate_stack(__u64 *ips, int stack_len, int cnt, ...)
{
int i, j;
va_list args;
if (!ASSERT_GT(stack_len, 0, "stack_len"))
return;
stack_len /= 8;
/* check if we have enough entries to satisfy test expectations */
if (!ASSERT_GE(stack_len, cnt, "stack_len2"))
return;
if (env.verbosity >= VERBOSE_NORMAL) {
printf("caller: %#lx - %#lx\n", caller.start, caller.stop);
for (i = 1; i < ARRAY_SIZE(targets); i++)
printf("target_%d: %#lx - %#lx\n", i, targets[i].start, targets[i].stop);
for (i = 0; i < stack_len; i++) {
for (j = 1; j < ARRAY_SIZE(targets); j++) {
if (ips[i] >= targets[j].start && ips[i] < targets[j].stop)
break;
}
if (j < ARRAY_SIZE(targets)) { /* found target match */
printf("ENTRY #%d: %#lx (in target_%d)\n", i, (long)ips[i], j);
} else if (ips[i] >= caller.start && ips[i] < caller.stop) {
printf("ENTRY #%d: %#lx (in caller)\n", i, (long)ips[i]);
} else {
printf("ENTRY #%d: %#lx\n", i, (long)ips[i]);
}
}
}
va_start(args, cnt);
for (i = cnt - 1; i >= 0; i--) {
/* most recent entry is the deepest target function */
const struct range *t = va_arg(args, const struct range *);
ASSERT_GE(ips[i], t->start, "addr_start");
ASSERT_LT(ips[i], t->stop, "addr_stop");
}
va_end(args);
}
/* __weak prevents inlining */
__attribute__((section("uretprobe_stack_sec")))
__weak void test_uretprobe_stack(void)
{
LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
struct uretprobe_stack *skel;
int err;
skel = uretprobe_stack__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
err = uretprobe_stack__attach(skel);
if (!ASSERT_OK(err, "skel_attach"))
goto cleanup;
/* trigger */
ASSERT_EQ(target_1(0), 42 + 1, "trigger_return");
/*
* Stacks captured on ENTRY uprobes
*/
/* (uprobe 1) target_1 in stack trace*/
validate_stack(skel->bss->entry_stack1, skel->bss->entry1_len,
2, &caller, &targets[1]);
/* (uprobe 1, recursed) */
validate_stack(skel->bss->entry_stack1_recur, skel->bss->entry1_recur_len,
3, &caller, &targets[1], &targets[1]);
/* (uprobe 2) caller -> target_1 -> target_1 -> target_2 */
validate_stack(skel->bss->entry_stack2, skel->bss->entry2_len,
4, &caller, &targets[1], &targets[1], &targets[2]);
/* (uprobe 3) */
validate_stack(skel->bss->entry_stack3, skel->bss->entry3_len,
5, &caller, &targets[1], &targets[1], &targets[2], &targets[3]);
/* (uprobe 4) caller -> target_1 -> target_1 -> target_2 -> target_3 -> target_4 */
validate_stack(skel->bss->entry_stack4, skel->bss->entry4_len,
6, &caller, &targets[1], &targets[1], &targets[2], &targets[3], &targets[4]);
/* (USDT): full caller -> target_1 -> target_1 -> target_2 (uretprobed)
* -> target_3 -> target_4 (uretprobes) chain
*/
validate_stack(skel->bss->usdt_stack, skel->bss->usdt_len,
6, &caller, &targets[1], &targets[1], &targets[2], &targets[3], &targets[4]);
/*
* Now stacks captured on the way out in EXIT uprobes
*/
/* (uretprobe 4) everything up to target_4, but excluding it */
validate_stack(skel->bss->exit_stack4, skel->bss->exit4_len,
5, &caller, &targets[1], &targets[1], &targets[2], &targets[3]);
/* we didn't install uretprobes on target_2 and target_3 */
/* (uretprobe 1, recur) first target_1 call only */
validate_stack(skel->bss->exit_stack1_recur, skel->bss->exit1_recur_len,
2, &caller, &targets[1]);
/* (uretprobe 1) just a caller in the stack trace */
validate_stack(skel->bss->exit_stack1, skel->bss->exit1_len,
1, &caller);
cleanup:
uretprobe_stack__destroy(skel);
}
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