Merge branch 'fprobe: Introduce fprobe function entry/exit probe'

Masami Hiramatsu says:

====================

Hi,

Here is the 12th version of fprobe. This version fixes a possible gcc-11 issue which
was reported as kretprobes on arm issue, and also I updated the fprobe document.

The previous version (v11) is here[1];

[1] https://lore.kernel.org/all/164701432038.268462.3329725152949938527.stgit@devnote2/T/#u

This series introduces the fprobe, the function entry/exit probe
with multiple probe point support for x86, arm64 and powerpc64le.
This also introduces the rethook for hooking function return as same as
the kretprobe does. This abstraction will help us to generalize the fgraph
tracer, because we can just switch to it from the rethook in fprobe,
depending on the kernel configuration.

The patch [1/12] is from Jiri's series[2].

[2] https://lore.kernel.org/all/20220104080943.113249-1-jolsa@kernel.org/T/#u

And the patch [9/10] adds the FPROBE_FL_KPROBE_SHARED flag for the case
if user wants to share the same code (or share a same resource) on the
fprobe and the kprobes.

I forcibly updated my kprobes/fprobe branch, you can pull this series
from:

 https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git kprobes/fprobe

Thank you,
---

Jiri Olsa (1):
      ftrace: Add ftrace_set_filter_ips function
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

3 files changed, 188 insertions, 0 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 72ca4684beda..b0bf0d224b2c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2118,6 +2118,18 @@ config KPROBES_SANITY_TEST
 
 	  Say N if you are unsure.
 
+config FPROBE_SANITY_TEST
+	bool "Self test for fprobe"
+	depends on DEBUG_KERNEL
+	depends on FPROBE
+	depends on KUNIT=y
+	help
+	  This option will enable testing the fprobe when the system boot.
+	  A series of tests are made to verify that the fprobe is functioning
+	  properly.
+
+	  Say N if you are unsure.
+
 config BACKTRACE_SELF_TEST
 	tristate "Self test for the backtrace code"
 	depends on DEBUG_KERNEL
diff --git a/lib/Makefile b/lib/Makefile
index 300f569c626b..154008764b16 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -103,6 +103,8 @@ obj-$(CONFIG_TEST_HMM) += test_hmm.o
 obj-$(CONFIG_TEST_FREE_PAGES) += test_free_pages.o
 obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
 obj-$(CONFIG_TEST_REF_TRACKER) += test_ref_tracker.o
+CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
+obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
 #
 # CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns
 # off the generation of FPU/SSE* instructions for kernel proper but FPU_FLAGS
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
new file mode 100644
index 000000000000..ed70637a2ffa
--- /dev/null
+++ b/lib/test_fprobe.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * test_fprobe.c - simple sanity test for fprobe
+ */
+
+#include <linux/kernel.h>
+#include <linux/fprobe.h>
+#include <linux/random.h>
+#include <kunit/test.h>
+
+#define div_factor 3
+
+static struct kunit *current_test;
+
+static u32 rand1, entry_val, exit_val;
+
+/* Use indirect calls to avoid inlining the target functions */
+static u32 (*target)(u32 value);
+static u32 (*target2)(u32 value);
+static unsigned long target_ip;
+static unsigned long target2_ip;
+
+static noinline u32 fprobe_selftest_target(u32 value)
+{
+	return (value / div_factor);
+}
+
+static noinline u32 fprobe_selftest_target2(u32 value)
+{
+	return (value / div_factor) + 1;
+}
+
+static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+{
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
+	if (ip != target_ip)
+		KUNIT_EXPECT_EQ(current_test, ip, target2_ip);
+	entry_val = (rand1 / div_factor);
+}
+
+static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+{
+	unsigned long ret = regs_return_value(regs);
+
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	if (ip != target_ip) {
+		KUNIT_EXPECT_EQ(current_test, ip, target2_ip);
+		KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1);
+	} else
+		KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor));
+	KUNIT_EXPECT_EQ(current_test, entry_val, (rand1 / div_factor));
+	exit_val = entry_val + div_factor;
+}
+
+/* Test entry only (no rethook) */
+static void test_fprobe_entry(struct kunit *test)
+{
+	struct fprobe fp_entry = {
+		.entry_handler = fp_entry_handler,
+	};
+
+	current_test = test;
+
+	/* Before register, unregister should be failed. */
+	KUNIT_EXPECT_NE(test, 0, unregister_fprobe(&fp_entry));
+	KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp_entry, "fprobe_selftest_target*", NULL));
+
+	entry_val = 0;
+	exit_val = 0;
+	target(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, 0, exit_val);
+
+	entry_val = 0;
+	exit_val = 0;
+	target2(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, 0, exit_val);
+
+	KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp_entry));
+}
+
+static void test_fprobe(struct kunit *test)
+{
+	struct fprobe fp = {
+		.entry_handler = fp_entry_handler,
+		.exit_handler = fp_exit_handler,
+	};
+
+	current_test = test;
+	KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target*", NULL));
+
+	entry_val = 0;
+	exit_val = 0;
+	target(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
+
+	entry_val = 0;
+	exit_val = 0;
+	target2(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
+
+	KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
+}
+
+static void test_fprobe_syms(struct kunit *test)
+{
+	static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_target2"};
+	struct fprobe fp = {
+		.entry_handler = fp_entry_handler,
+		.exit_handler = fp_exit_handler,
+	};
+
+	current_test = test;
+	KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2));
+
+	entry_val = 0;
+	exit_val = 0;
+	target(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
+
+	entry_val = 0;
+	exit_val = 0;
+	target2(rand1);
+	KUNIT_EXPECT_NE(test, 0, entry_val);
+	KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
+
+	KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
+}
+
+static unsigned long get_ftrace_location(void *func)
+{
+	unsigned long size, addr = (unsigned long)func;
+
+	if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size)
+		return 0;
+
+	return ftrace_location_range(addr, addr + size - 1);
+}
+
+static int fprobe_test_init(struct kunit *test)
+{
+	do {
+		rand1 = prandom_u32();
+	} while (rand1 <= div_factor);
+
+	target = fprobe_selftest_target;
+	target2 = fprobe_selftest_target2;
+	target_ip = get_ftrace_location(target);
+	target2_ip = get_ftrace_location(target2);
+
+	return 0;
+}
+
+static struct kunit_case fprobe_testcases[] = {
+	KUNIT_CASE(test_fprobe_entry),
+	KUNIT_CASE(test_fprobe),
+	KUNIT_CASE(test_fprobe_syms),
+	{}
+};
+
+static struct kunit_suite fprobe_test_suite = {
+	.name = "fprobe_test",
+	.init = fprobe_test_init,
+	.test_cases = fprobe_testcases,
+};
+
+kunit_test_suites(&fprobe_test_suite);
+
+MODULE_LICENSE("GPL");