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
__fls(unsigned long x)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
protect_region(void)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
unprotect_region(void)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
segv_handler(int signr,siginfo_t * info,void * ptr)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
setup_segv_handler(void)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
do_one_test(char * p,int page_offset)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(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
test_body(void)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(mem_region+i, i));
140
141 return 0;
142 }
143
main(void)144 int main(void)
145 {
146 return test_harness(test_body, "load_unaligned_zeropad");
147 }
148