1 #include <darwintest.h>
2 #include <stdio.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <sys/mman.h>
6 #include <mach/machine/vm_param.h>
7
8 static inline unsigned char *
get_guarded_page(void)9 get_guarded_page(void)
10 {
11 unsigned char *p = mmap(NULL, 3 * PAGE_SIZE, PROT_NONE, MAP_SHARED | MAP_ANON, 0, 0);
12 p += PAGE_SIZE;
13 mprotect(p, PAGE_SIZE, PROT_READ | PROT_WRITE);
14 return p;
15 }
16
17 static inline void
free_guarded_page(unsigned char * p)18 free_guarded_page(unsigned char *p)
19 {
20 munmap(p - PAGE_SIZE, 3 * PAGE_SIZE);
21 }
22
23 /* memcmp_zero_ptr_aligned() checks string s of n bytes contains all zeros.
24 * Address and size of the string s must be pointer-aligned.
25 * Return 0 if true, 1 otherwise. Also return 0 if n is 0.
26 */
27 extern int
28 memcmp_zero_ptr_aligned(const void *s, size_t n);
29
30 T_DECL(memcmp_zero, "memcmp_zero")
31 {
32 // the assembly version is for the kernel and doesn't support arm64_32
33 #if defined(__arm64__) && __LP64__
34 unsigned char *buffer = get_guarded_page();
35 unsigned char *right = buffer + PAGE_SIZE - 512;
36 const int ptr_size = sizeof(buffer);
37
38 for (size_t i = 0; i < 256; i += ptr_size) {
39 for (size_t j = i; j < 256; ++j) {
40 for (size_t k = 0; k < 256; ++k) {
41 if (k < i) {
42 buffer[k] = (unsigned char)rand();
43 } else if (k < j) {
44 buffer[k] = '\0';
45 } else if (k == j) {
46 do {
47 buffer[k] = (unsigned char)rand();
48 } while (!buffer[k]);
49 } else {
50 buffer[k] = '\0';
51 }
52 }
53 for (size_t m = 0; m < 128; m += ptr_size) {
54 int result = memcmp_zero_ptr_aligned(&buffer[i], m);
55 int ref = j - i < m ? 1 : 0;
56 T_QUIET; T_ASSERT_EQ(result, ref, "expected %d, saw %d\n"
57 "memcmp_zero_ptr_aligned(buf[%zd], %zd)\n",
58 ref, result, i, m);
59 }
60
61
62 for (size_t k = 0; k < 256; ++k) {
63 if (k < i) {
64 right[k] = (unsigned char)rand();
65 } else if (k < j) {
66 right[k] = '\0';
67 } else if (k == j) {
68 do {
69 right[k] = (unsigned char)rand();
70 } while (!right[k]);
71 } else {
72 right[k] = '\0';
73 }
74 }
75 for (size_t m = 0; m < 256; m += ptr_size) {
76 int result = memcmp_zero_ptr_aligned(&right[i], m);
77 int ref = j - i < m ? 1 : 0;
78 T_QUIET; T_ASSERT_EQ(result, ref, "expected %d, saw %d\n"
79 "memcmp_zero_ptr_aligned(buf[%zd], %zd)\n",
80 ref, result, i, m);
81 }
82 }
83 }
84
85 T_PASS("success");
86
87 free_guarded_page(buffer);
88 #else
89 T_SKIP("no optimized version to test");
90 #endif
91 }
92