1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Userspace test harness for load_unaligned_zeropad. Creates two |
4 | * pages and uses mprotect to prevent access to the second page and |
5 | * a SEGV handler that walks the exception tables and runs the fixup |
6 | * routine. |
7 | * |
8 | * The results are compared against a normal load that is that is |
9 | * performed while access to the second page is enabled via mprotect. |
10 | * |
11 | * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM |
12 | */ |
13 | |
14 | #include <stdlib.h> |
15 | #include <string.h> |
16 | #include <stdio.h> |
17 | #include <stdbool.h> |
18 | #include <signal.h> |
19 | #include <unistd.h> |
20 | #include <sys/mman.h> |
21 | |
22 | #define FIXUP_SECTION ".ex_fixup" |
23 | |
24 | static inline unsigned long __fls(unsigned long x); |
25 | |
26 | #include "word-at-a-time.h" |
27 | |
28 | #include "utils.h" |
29 | |
30 | static inline unsigned long __fls(unsigned long x) |
31 | { |
32 | int lz; |
33 | |
34 | asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x)); |
35 | return sizeof(unsigned long) - 1 - lz; |
36 | } |
37 | |
38 | static int page_size; |
39 | static char *mem_region; |
40 | |
41 | static int protect_region(void) |
42 | { |
43 | if (mprotect(mem_region + page_size, page_size, PROT_NONE)) { |
44 | perror("mprotect" ); |
45 | return 1; |
46 | } |
47 | |
48 | return 0; |
49 | } |
50 | |
51 | static int unprotect_region(void) |
52 | { |
53 | if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) { |
54 | perror("mprotect" ); |
55 | return 1; |
56 | } |
57 | |
58 | return 0; |
59 | } |
60 | |
61 | extern char __start___ex_table[]; |
62 | extern char __stop___ex_table[]; |
63 | |
64 | struct extbl_entry { |
65 | int insn; |
66 | int fixup; |
67 | }; |
68 | |
69 | static void segv_handler(int signr, siginfo_t *info, void *ptr) |
70 | { |
71 | ucontext_t *uc = (ucontext_t *)ptr; |
72 | unsigned long addr = (unsigned long)info->si_addr; |
73 | unsigned long *ip = &UCONTEXT_NIA(uc); |
74 | struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table; |
75 | |
76 | while (entry < (struct extbl_entry *)__stop___ex_table) { |
77 | unsigned long insn, fixup; |
78 | |
79 | insn = (unsigned long)&entry->insn + entry->insn; |
80 | fixup = (unsigned long)&entry->fixup + entry->fixup; |
81 | |
82 | if (insn == *ip) { |
83 | *ip = fixup; |
84 | return; |
85 | } |
86 | } |
87 | |
88 | printf("No exception table match for NIA %lx ADDR %lx\n" , *ip, addr); |
89 | abort(); |
90 | } |
91 | |
92 | static void setup_segv_handler(void) |
93 | { |
94 | struct sigaction action; |
95 | |
96 | memset(&action, 0, sizeof(action)); |
97 | action.sa_sigaction = segv_handler; |
98 | action.sa_flags = SA_SIGINFO; |
99 | sigaction(SIGSEGV, &action, NULL); |
100 | } |
101 | |
102 | static int do_one_test(char *p, int page_offset) |
103 | { |
104 | unsigned long should; |
105 | unsigned long got; |
106 | |
107 | FAIL_IF(unprotect_region()); |
108 | should = *(unsigned long *)p; |
109 | FAIL_IF(protect_region()); |
110 | |
111 | got = load_unaligned_zeropad(addr: p); |
112 | |
113 | if (should != got) { |
114 | printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n" , page_offset, got, should); |
115 | return 1; |
116 | } |
117 | |
118 | return 0; |
119 | } |
120 | |
121 | static int test_body(void) |
122 | { |
123 | unsigned long i; |
124 | |
125 | page_size = getpagesize(); |
126 | mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, |
127 | MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); |
128 | |
129 | FAIL_IF(mem_region == MAP_FAILED); |
130 | |
131 | for (i = 0; i < page_size; i++) |
132 | mem_region[i] = i; |
133 | |
134 | memset(mem_region+page_size, 0, page_size); |
135 | |
136 | setup_segv_handler(); |
137 | |
138 | for (i = 0; i < page_size; i++) |
139 | FAIL_IF(do_one_test(p: mem_region+i, page_offset: i)); |
140 | |
141 | return 0; |
142 | } |
143 | |
144 | int main(void) |
145 | { |
146 | return test_harness(test_body, "load_unaligned_zeropad" ); |
147 | } |
148 | |