selftests/bpf: Add uprobe/usdt syscall tests

Adding tests for optimized uprobe/usdt probes.

Checking that we get expected trampoline and attached bpf programs
get executed properly.

Signed-off-by: Jiri Olsa <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Acked-by: Andrii Nakryiko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c

···
 #include <asm/ptrace.h>
 #include <linux/compiler.h>
 #include <linux/stringify.h>
+#include <linux/kernel.h>
 #include <sys/wait.h>
 #include <sys/syscall.h>
 #include <sys/prctl.h>
 #include <asm/prctl.h>
 #include "uprobe_syscall.skel.h"
 #include "uprobe_syscall_executed.skel.h"
+
+#define USDT_NOP .byte 0x0f, 0x1f, 0x44, 0x00, 0x00
+#include "usdt.h"
+
+#pragma GCC diagnostic ignored "-Wattributes"
 
 __naked unsigned long uretprobe_regs_trigger(void)
 {
···
 	close(go[0]);
 }
 
+#define TRAMP "[uprobes-trampoline]"
+
+__attribute__((aligned(16)))
+__nocf_check __weak __naked void uprobe_test(void)
+{
+	asm volatile ("					\n"
+		".byte 0x0f, 0x1f, 0x44, 0x00, 0x00	\n"
+		"ret					\n"
+	);
+}
+
+__attribute__((aligned(16)))
+__nocf_check __weak void usdt_test(void)
+{
+	USDT(optimized_uprobe, usdt);
+}
+
+static int find_uprobes_trampoline(void *tramp_addr)
+{
+	void *start, *end;
+	char line[128];
+	int ret = -1;
+	FILE *maps;
+
+	maps = fopen("/proc/self/maps", "r");
+	if (!maps) {
+		fprintf(stderr, "cannot open maps\n");
+		return -1;
+	}
+
+	while (fgets(line, sizeof(line), maps)) {
+		int m = -1;
+
+		/* We care only about private r-x mappings. */
+		if (sscanf(line, "%p-%p r-xp %*x %*x:%*x %*u %n", &start, &end, &m) != 2)
+			continue;
+		if (m < 0)
+			continue;
+		if (!strncmp(&line[m], TRAMP, sizeof(TRAMP)-1) && (start == tramp_addr)) {
+			ret = 0;
+			break;
+		}
+	}
+
+	fclose(maps);
+	return ret;
+}
+
+static unsigned char nop5[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
+
+static void *find_nop5(void *fn)
+{
+	int i;
+
+	for (i = 0; i < 10; i++) {
+		if (!memcmp(nop5, fn + i, 5))
+			return fn + i;
+	}
+	return NULL;
+}
+
+typedef void (__attribute__((nocf_check)) *trigger_t)(void);
+
+static bool shstk_is_enabled;
+
+static void *check_attach(struct uprobe_syscall_executed *skel, trigger_t trigger,
+			  void *addr, int executed)
+{
+	struct __arch_relative_insn {
+		__u8 op;
+		__s32 raddr;
+	} __packed *call;
+	void *tramp = NULL;
+	__u8 *bp;
+
+	/* Uprobe gets optimized after first trigger, so let's press twice. */
+	trigger();
+	trigger();
+
+	/* Make sure bpf program got executed.. */
+	ASSERT_EQ(skel->bss->executed, executed, "executed");
+
+	if (shstk_is_enabled) {
+		/* .. and check optimization is disabled under shadow stack. */
+		bp = (__u8 *) addr;
+		ASSERT_EQ(*bp, 0xcc, "int3");
+	} else {
+		/* .. and check the trampoline is as expected. */
+		call = (struct __arch_relative_insn *) addr;
+		tramp = (void *) (call + 1) + call->raddr;
+		ASSERT_EQ(call->op, 0xe8, "call");
+		ASSERT_OK(find_uprobes_trampoline(tramp), "uprobes_trampoline");
+	}
+
+	return tramp;
+}
+
+static void check_detach(void *addr, void *tramp)
+{
+	/* [uprobes_trampoline] stays after detach */
+	ASSERT_OK(!shstk_is_enabled && find_uprobes_trampoline(tramp), "uprobes_trampoline");
+	ASSERT_OK(memcmp(addr, nop5, 5), "nop5");
+}
+
+static void check(struct uprobe_syscall_executed *skel, struct bpf_link *link,
+		  trigger_t trigger, void *addr, int executed)
+{
+	void *tramp;
+
+	tramp = check_attach(skel, trigger, addr, executed);
+	bpf_link__destroy(link);
+	check_detach(addr, tramp);
+}
+
+static void test_uprobe_legacy(void)
+{
+	struct uprobe_syscall_executed *skel = NULL;
+	LIBBPF_OPTS(bpf_uprobe_opts, opts,
+		.retprobe = true,
+	);
+	struct bpf_link *link;
+	unsigned long offset;
+
+	offset = get_uprobe_offset(&uprobe_test);
+	if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+		goto cleanup;
+
+	/* uprobe */
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		return;
+
+	skel->bss->pid = getpid();
+
+	link = bpf_program__attach_uprobe_opts(skel->progs.test_uprobe,
+				0, "/proc/self/exe", offset, NULL);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_opts"))
+		goto cleanup;
+
+	check(skel, link, uprobe_test, uprobe_test, 2);
+
+	/* uretprobe */
+	skel->bss->executed = 0;
+
+	link = bpf_program__attach_uprobe_opts(skel->progs.test_uretprobe,
+				0, "/proc/self/exe", offset, &opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_opts"))
+		goto cleanup;
+
+	check(skel, link, uprobe_test, uprobe_test, 2);
+
+cleanup:
+	uprobe_syscall_executed__destroy(skel);
+}
+
+static void test_uprobe_multi(void)
+{
+	struct uprobe_syscall_executed *skel = NULL;
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
+	struct bpf_link *link;
+	unsigned long offset;
+
+	offset = get_uprobe_offset(&uprobe_test);
+	if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+		goto cleanup;
+
+	opts.offsets = &offset;
+	opts.cnt = 1;
+
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		return;
+
+	skel->bss->pid = getpid();
+
+	/* uprobe.multi */
+	link = bpf_program__attach_uprobe_multi(skel->progs.test_uprobe_multi,
+				0, "/proc/self/exe", NULL, &opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	check(skel, link, uprobe_test, uprobe_test, 2);
+
+	/* uretprobe.multi */
+	skel->bss->executed = 0;
+	opts.retprobe = true;
+	link = bpf_program__attach_uprobe_multi(skel->progs.test_uretprobe_multi,
+				0, "/proc/self/exe", NULL, &opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	check(skel, link, uprobe_test, uprobe_test, 2);
+
+cleanup:
+	uprobe_syscall_executed__destroy(skel);
+}
+
+static void test_uprobe_session(void)
+{
+	struct uprobe_syscall_executed *skel = NULL;
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
+		.session = true,
+	);
+	struct bpf_link *link;
+	unsigned long offset;
+
+	offset = get_uprobe_offset(&uprobe_test);
+	if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+		goto cleanup;
+
+	opts.offsets = &offset;
+	opts.cnt = 1;
+
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		return;
+
+	skel->bss->pid = getpid();
+
+	link = bpf_program__attach_uprobe_multi(skel->progs.test_uprobe_session,
+				0, "/proc/self/exe", NULL, &opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	check(skel, link, uprobe_test, uprobe_test, 4);
+
+cleanup:
+	uprobe_syscall_executed__destroy(skel);
+}
+
+static void test_uprobe_usdt(void)
+{
+	struct uprobe_syscall_executed *skel;
+	struct bpf_link *link;
+	void *addr;
+
+	errno = 0;
+	addr = find_nop5(usdt_test);
+	if (!ASSERT_OK_PTR(addr, "find_nop5"))
+		return;
+
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		return;
+
+	skel->bss->pid = getpid();
+
+	link = bpf_program__attach_usdt(skel->progs.test_usdt,
+				-1 /* all PIDs */, "/proc/self/exe",
+				"optimized_uprobe", "usdt", NULL);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_usdt"))
+		goto cleanup;
+
+	check(skel, link, usdt_test, addr, 2);
+
+cleanup:
+	uprobe_syscall_executed__destroy(skel);
+}
+
 /*
  * Borrowed from tools/testing/selftests/x86/test_shadow_stack.c.
  *
···
 		return;
 	}
 
-	/* Run all of the uretprobe tests. */
+	/* Run all the tests with shadow stack in place. */
+	shstk_is_enabled = true;
+
 	test_uretprobe_regs_equal();
 	test_uretprobe_regs_change();
 	test_uretprobe_syscall_call();
+
+	test_uprobe_legacy();
+	test_uprobe_multi();
+	test_uprobe_session();
+	test_uprobe_usdt();
+
+	shstk_is_enabled = false;
 
 	ARCH_PRCTL(ARCH_SHSTK_DISABLE, ARCH_SHSTK_SHSTK);
 }
···
 		test_uretprobe_syscall_call();
 	if (test__start_subtest("uretprobe_shadow_stack"))
 		test_uretprobe_shadow_stack();
+	if (test__start_subtest("uprobe_legacy"))
+		test_uprobe_legacy();
+	if (test__start_subtest("uprobe_multi"))
+		test_uprobe_multi();
+	if (test__start_subtest("uprobe_session"))
+		test_uprobe_session();
+	if (test__start_subtest("uprobe_usdt"))
+		test_uprobe_usdt();
 }
 #else
 static void __test_uprobe_syscall(void)

tools/testing/selftests/bpf/progs/uprobe_syscall_executed.c

···
 // SPDX-License-Identifier: GPL-2.0
 #include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/usdt.bpf.h>
 #include <string.h>
 
 struct pt_regs regs;
···
 int executed = 0;
 int pid;
 
+SEC("uprobe")
+int BPF_UPROBE(test_uprobe)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	executed++;
+	return 0;
+}
+
+SEC("uretprobe")
+int BPF_URETPROBE(test_uretprobe)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	executed++;
+	return 0;
+}
+
+SEC("uprobe.multi")
+int test_uprobe_multi(struct pt_regs *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	executed++;
+	return 0;
+}
+
 SEC("uretprobe.multi")
 int test_uretprobe_multi(struct pt_regs *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	executed++;
+	return 0;
+}
+
+SEC("uprobe.session")
+int test_uprobe_session(struct pt_regs *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	executed++;
+	return 0;
+}
+
+SEC("usdt")
+int test_usdt(struct pt_regs *ctx)
 {
 	if (bpf_get_current_pid_tgid() >> 32 != pid)
 		return 0;