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test_kprobes: Add recursed kprobe test case 

Add a recursed kprobe test case to the KUnit test module for kprobes.
This will probe a function which is called from the pre_handler and
post_handler itself. If the kprobe is correctly implemented, the recursed
kprobe handlers will be skipped and the number of skipped kprobe will
be counted on kprobe::nmissed.

Link: https://lore.kernel.org/all/167414238758.2301956.258548940194352895.stgit@devnote3/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-02-21 08:52:42 +09:00
parent 8478cca1e3
commit 1fcd09fd4f
1 changed files with 37 additions and 2 deletions
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39
lib/test_kprobes.c
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@ -14,6 +14,7 @@
static u32 rand1, preh_val, posth_val;
static u32 (*target)(u32 value);
static u32 (*recursed_target)(u32 value);
static u32 (*target2)(u32 value);
static struct kunit *current_test;
@ -27,18 +28,27 @@ static noinline u32 kprobe_target(u32 value)
return (value / div_factor);
}
static noinline u32 kprobe_recursed_target(u32 value)
{
return (value / div_factor);
}
static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
preh_val = (rand1 / div_factor);
preh_val = recursed_target(rand1);
return 0;
}
static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
u32 expval = recursed_target(rand1);
KUNIT_EXPECT_FALSE(current_test, preemptible());
KUNIT_EXPECT_EQ(current_test, preh_val, (rand1 / div_factor));
KUNIT_EXPECT_EQ(current_test, preh_val, expval);
posth_val = preh_val + div_factor;
}
@ -136,6 +146,29 @@ static void test_kprobes(struct kunit *test)
unregister_kprobes(kps, 2);
}
static struct kprobe kp_missed = {
.symbol_name = "kprobe_recursed_target",
.pre_handler = kp_pre_handler,
.post_handler = kp_post_handler,
};
static void test_kprobe_missed(struct kunit *test)
{
current_test = test;
preh_val = 0;
posth_val = 0;
KUNIT_EXPECT_EQ(test, 0, register_kprobe(&kp_missed));
recursed_target(rand1);
KUNIT_EXPECT_EQ(test, 2, kp_missed.nmissed);
KUNIT_EXPECT_NE(test, 0, preh_val);
KUNIT_EXPECT_NE(test, 0, posth_val);
unregister_kprobe(&kp_missed);
}
#ifdef CONFIG_KRETPROBES
static u32 krph_val;
@ -336,6 +369,7 @@ static int kprobes_test_init(struct kunit *test)
{
target = kprobe_target;
target2 = kprobe_target2;
recursed_target = kprobe_recursed_target;
stacktrace_target = kprobe_stacktrace_target;
internal_target = kprobe_stacktrace_internal_target;
stacktrace_driver = kprobe_stacktrace_driver;
@ -346,6 +380,7 @@ static int kprobes_test_init(struct kunit *test)
static struct kunit_case kprobes_testcases[] = {
KUNIT_CASE(test_kprobe),
KUNIT_CASE(test_kprobes),
KUNIT_CASE(test_kprobe_missed),
#ifdef CONFIG_KRETPROBES
KUNIT_CASE(test_kretprobe),
KUNIT_CASE(test_kretprobes),