selftests/bpf: add tests for sleepable (uk)probes

Add tests that ensure sleepable uprobe programs work correctly.
Add tests that ensure sleepable kprobe programs cannot attach.

Also add tests that attach both sleepable and non-sleepable
uprobe programs to the same location (i.e. same bpf_prog_array).
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Link: https://lore.kernel.org/r/c744e5bb7a5c0703f05444dc41f2522ba3579a48.1655248076.git.delyank@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -17,6 +17,14 @@ static void trigger_func2(void)
 	asm volatile ("");
 }
 
+/* attach point for byname sleepable uprobe */
+static void trigger_func3(void)
+{
+	asm volatile ("");
+}
+
+static char test_data[] = "test_data";
+
 void test_attach_probe(void)
 {
 	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
@@ -49,9 +57,17 @@ void test_attach_probe(void)
 	if (!ASSERT_GE(ref_ctr_offset, 0, "ref_ctr_offset"))
 		return;
 
-	skel = test_attach_probe__open_and_load();
+	skel = test_attach_probe__open();
 	if (!ASSERT_OK_PTR(skel, "skel_open"))
 		return;
+
+	/* sleepable kprobe test case needs flags set before loading */
+	if (!ASSERT_OK(bpf_program__set_flags(skel->progs.handle_kprobe_sleepable,
+		BPF_F_SLEEPABLE), "kprobe_sleepable_flags"))
+		goto cleanup;
+
+	if (!ASSERT_OK(test_attach_probe__load(skel), "skel_load"))
+		goto cleanup;
 	if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
 		goto cleanup;
 
@@ -151,6 +167,30 @@ void test_attach_probe(void)
 	if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname2, "attach_uretprobe_byname2"))
 		goto cleanup;
 
+	/* sleepable kprobes should not attach successfully */
+	skel->links.handle_kprobe_sleepable = bpf_program__attach(skel->progs.handle_kprobe_sleepable);
+	if (!ASSERT_ERR_PTR(skel->links.handle_kprobe_sleepable, "attach_kprobe_sleepable"))
+		goto cleanup;
+
+	/* test sleepable uprobe and uretprobe variants */
+	skel->links.handle_uprobe_byname3_sleepable = bpf_program__attach(skel->progs.handle_uprobe_byname3_sleepable);
+	if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname3_sleepable, "attach_uprobe_byname3_sleepable"))
+		goto cleanup;
+
+	skel->links.handle_uprobe_byname3 = bpf_program__attach(skel->progs.handle_uprobe_byname3);
+	if (!ASSERT_OK_PTR(skel->links.handle_uprobe_byname3, "attach_uprobe_byname3"))
+		goto cleanup;
+
+	skel->links.handle_uretprobe_byname3_sleepable = bpf_program__attach(skel->progs.handle_uretprobe_byname3_sleepable);
+	if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname3_sleepable, "attach_uretprobe_byname3_sleepable"))
+		goto cleanup;
+
+	skel->links.handle_uretprobe_byname3 = bpf_program__attach(skel->progs.handle_uretprobe_byname3);
+	if (!ASSERT_OK_PTR(skel->links.handle_uretprobe_byname3, "attach_uretprobe_byname3"))
+		goto cleanup;
+
+	skel->bss->user_ptr = test_data;
+
 	/* trigger & validate kprobe && kretprobe */
 	usleep(1);
 
@@ -164,6 +204,9 @@ void test_attach_probe(void)
 	/* trigger & validate uprobe attached by name */
 	trigger_func2();
 
+	/* trigger & validate sleepable uprobe attached by name */
+	trigger_func3();
+
 	ASSERT_EQ(skel->bss->kprobe_res, 1, "check_kprobe_res");
 	ASSERT_EQ(skel->bss->kprobe2_res, 11, "check_kprobe_auto_res");
 	ASSERT_EQ(skel->bss->kretprobe_res, 2, "check_kretprobe_res");
@@ -174,6 +217,10 @@ void test_attach_probe(void)
 	ASSERT_EQ(skel->bss->uretprobe_byname_res, 6, "check_uretprobe_byname_res");
 	ASSERT_EQ(skel->bss->uprobe_byname2_res, 7, "check_uprobe_byname2_res");
 	ASSERT_EQ(skel->bss->uretprobe_byname2_res, 8, "check_uretprobe_byname2_res");
+	ASSERT_EQ(skel->bss->uprobe_byname3_sleepable_res, 9, "check_uprobe_byname3_sleepable_res");
+	ASSERT_EQ(skel->bss->uprobe_byname3_res, 10, "check_uprobe_byname3_res");
+	ASSERT_EQ(skel->bss->uretprobe_byname3_sleepable_res, 11, "check_uretprobe_byname3_sleepable_res");
+	ASSERT_EQ(skel->bss->uretprobe_byname3_res, 12, "check_uretprobe_byname3_res");
 
 cleanup:
 	test_attach_probe__destroy(skel);

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

@@ -5,6 +5,7 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
+#include <stdbool.h>
 #include "bpf_misc.h"
 
 int kprobe_res = 0;
@@ -17,6 +18,11 @@ int uprobe_byname_res = 0;
 int uretprobe_byname_res = 0;
 int uprobe_byname2_res = 0;
 int uretprobe_byname2_res = 0;
+int uprobe_byname3_sleepable_res = 0;
+int uprobe_byname3_res = 0;
+int uretprobe_byname3_sleepable_res = 0;
+int uretprobe_byname3_res = 0;
+void *user_ptr = 0;
 
 SEC("kprobe")
 int handle_kprobe(struct pt_regs *ctx)
@@ -32,6 +38,17 @@ int BPF_KPROBE(handle_kprobe_auto)
 	return 0;
 }
 
+/**
+ * This program will be manually made sleepable on the userspace side
+ * and should thus be unattachable.
+ */
+SEC("kprobe/" SYS_PREFIX "sys_nanosleep")
+int handle_kprobe_sleepable(struct pt_regs *ctx)
+{
+	kprobe_res = 2;
+	return 0;
+}
+
 SEC("kretprobe")
 int handle_kretprobe(struct pt_regs *ctx)
 {
@@ -93,4 +110,47 @@ int handle_uretprobe_byname2(struct pt_regs *ctx)
 	return 0;
 }
 
+static __always_inline bool verify_sleepable_user_copy(void)
+{
+	char data[9];
+
+	bpf_copy_from_user(data, sizeof(data), user_ptr);
+	return bpf_strncmp(data, sizeof(data), "test_data") == 0;
+}
+
+SEC("uprobe.s//proc/self/exe:trigger_func3")
+int handle_uprobe_byname3_sleepable(struct pt_regs *ctx)
+{
+	if (verify_sleepable_user_copy())
+		uprobe_byname3_sleepable_res = 9;
+	return 0;
+}
+
+/**
+ * same target as the uprobe.s above to force sleepable and non-sleepable
+ * programs in the same bpf_prog_array
+ */
+SEC("uprobe//proc/self/exe:trigger_func3")
+int handle_uprobe_byname3(struct pt_regs *ctx)
+{
+	uprobe_byname3_res = 10;
+	return 0;
+}
+
+SEC("uretprobe.s//proc/self/exe:trigger_func3")
+int handle_uretprobe_byname3_sleepable(struct pt_regs *ctx)
+{
+	if (verify_sleepable_user_copy())
+		uretprobe_byname3_sleepable_res = 11;
+	return 0;
+}
+
+SEC("uretprobe//proc/self/exe:trigger_func3")
+int handle_uretprobe_byname3(struct pt_regs *ctx)
+{
+	uretprobe_byname3_res = 12;
+	return 0;
+}
+
+
 char _license[] SEC("license") = "GPL";