fprobe: Add a selftest for fprobe

Add a KUnit based selftest for fprobe interface.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/164735295554.1084943.18347620679928750960.stgit@devnote2
This commit is contained in:
Masami Hiramatsu 2022-03-15 23:02:35 +09:00 committed by Alexei Starovoitov
parent aba09b44a9
commit f4616fabab
3 changed files with 188 additions and 0 deletions

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@ -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

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@ -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

174
lib/test_fprobe.c Normal file
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@ -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");