1 files changed, 186 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/uretprobe_stack.c b/tools/testing/selftests/bpf/prog_tests/uretprobe_stack.c
new file mode 100644
index 000000000000..6deb8d560ddd
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/uretprobe_stack.c
@@ -0,0 +1,186 @@
+// 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);
+}