lib/test_fprobe.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * test_fprobe.c - simple sanity test for fprobe
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/fprobe.h>
   8 #include <linux/random.h>
   9 #include <kunit/test.h>
  10
  11 #define div_factor 3
  12
  13 static struct kunit *current_test;
  14
  15 static u32 rand1, entry_val, exit_val;
  16
  17 /* Use indirect calls to avoid inlining the target functions */
  18 static u32 (*target)(u32 value);
  19 static u32 (*target2)(u32 value);
  20 static unsigned long target_ip;
  21 static unsigned long target2_ip;
  22
  23 static noinline u32 fprobe_selftest_target(u32 value)
  24 {
  25         return (value / div_factor);
  26 }
  27
  28 static noinline u32 fprobe_selftest_target2(u32 value)
  29 {
  30         return (value / div_factor) + 1;
  31 }
  32
  33 static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
  34 {
  35         KUNIT_EXPECT_FALSE(current_test, preemptible());
  36         /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
  37         if (ip != target_ip)
  38                 KUNIT_EXPECT_EQ(current_test, ip, target2_ip);
  39         entry_val = (rand1 / div_factor);
  40 }
  41
  42 static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
  43 {
  44         unsigned long ret = regs_return_value(regs);
  45
  46         KUNIT_EXPECT_FALSE(current_test, preemptible());
  47         if (ip != target_ip) {
  48                 KUNIT_EXPECT_EQ(current_test, ip, target2_ip);
  49                 KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1);
  50         } else
  51                 KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor));
  52         KUNIT_EXPECT_EQ(current_test, entry_val, (rand1 / div_factor));
  53         exit_val = entry_val + div_factor;
  54 }
  55
  56 /* Test entry only (no rethook) */
  57 static void test_fprobe_entry(struct kunit *test)
  58 {
  59         struct fprobe fp_entry = {
  60                 .entry_handler = fp_entry_handler,
  61         };
  62
  63         current_test = test;
  64
  65         /* Before register, unregister should be failed. */
  66         KUNIT_EXPECT_NE(test, 0, unregister_fprobe(&fp_entry));
  67         KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp_entry, "fprobe_selftest_target*", NULL));
  68
  69         entry_val = 0;
  70         exit_val = 0;
  71         target(rand1);
  72         KUNIT_EXPECT_NE(test, 0, entry_val);
  73         KUNIT_EXPECT_EQ(test, 0, exit_val);
  74
  75         entry_val = 0;
  76         exit_val = 0;
  77         target2(rand1);
  78         KUNIT_EXPECT_NE(test, 0, entry_val);
  79         KUNIT_EXPECT_EQ(test, 0, exit_val);
  80
  81         KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp_entry));
  82 }
  83
  84 static void test_fprobe(struct kunit *test)
  85 {
  86         struct fprobe fp = {
  87                 .entry_handler = fp_entry_handler,
  88                 .exit_handler = fp_exit_handler,
  89         };
  90
  91         current_test = test;
  92         KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target*", NULL));
  93
  94         entry_val = 0;
  95         exit_val = 0;
  96         target(rand1);
  97         KUNIT_EXPECT_NE(test, 0, entry_val);
  98         KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
  99
 100         entry_val = 0;
 101         exit_val = 0;
 102         target2(rand1);
 103         KUNIT_EXPECT_NE(test, 0, entry_val);
 104         KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
 105
 106         KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
 107 }
 108
 109 static void test_fprobe_syms(struct kunit *test)
 110 {
 111         static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_target2"};
 112         struct fprobe fp = {
 113                 .entry_handler = fp_entry_handler,
 114                 .exit_handler = fp_exit_handler,
 115         };
 116
 117         current_test = test;
 118         KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2));
 119
 120         entry_val = 0;
 121         exit_val = 0;
 122         target(rand1);
 123         KUNIT_EXPECT_NE(test, 0, entry_val);
 124         KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
 125
 126         entry_val = 0;
 127         exit_val = 0;
 128         target2(rand1);
 129         KUNIT_EXPECT_NE(test, 0, entry_val);
 130         KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val);
 131
 132         KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
 133 }
 134
 135 static unsigned long get_ftrace_location(void *func)
 136 {
 137         unsigned long size, addr = (unsigned long)func;
 138
 139         if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size)
 140                 return 0;
 141
 142         return ftrace_location_range(addr, addr + size - 1);
 143 }
 144
 145 static int fprobe_test_init(struct kunit *test)
 146 {
 147         do {
 148                 rand1 = prandom_u32();
 149         } while (rand1 <= div_factor);
 150
 151         target = fprobe_selftest_target;
 152         target2 = fprobe_selftest_target2;
 153         target_ip = get_ftrace_location(target);
 154         target2_ip = get_ftrace_location(target2);
 155
 156         return 0;
 157 }
 158
 159 static struct kunit_case fprobe_testcases[] = {
 160         KUNIT_CASE(test_fprobe_entry),
 161         KUNIT_CASE(test_fprobe),
 162         KUNIT_CASE(test_fprobe_syms),
 163         {}
 164 };
 165
 166 static struct kunit_suite fprobe_test_suite = {
 167         .name = "fprobe_test",
 168         .init = fprobe_test_init,
 169         .test_cases = fprobe_testcases,
 170 };
 171
 172 kunit_test_suites(&fprobe_test_suite);
 173
 174 MODULE_LICENSE("GPL");