1 /*
2 * Userspace test harness for load_unaligned_zeropad. Creates two
3 * pages and uses mprotect to prevent access to the second page and
4 * a SEGV handler that walks the exception tables and runs the fixup
5 * routine.
6 *
7 * The results are compared against a normal load that is that is
8 * performed while access to the second page is enabled via mprotect.
9 *
10 * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17
18 #include <stdlib.h>
19 #include <string.h>
20 #include <stdio.h>
21 #include <stdbool.h>
22 #include <signal.h>
23 #include <unistd.h>
24 #include <sys/mman.h>
25
26 #define FIXUP_SECTION ".ex_fixup"
27
28 static inline unsigned long __fls(unsigned long x);
29
30 #include "word-at-a-time.h"
31
32 #include "utils.h"
33
__fls(unsigned long x)34 static inline unsigned long __fls(unsigned long x)
35 {
36 int lz;
37
38 asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x));
39 return sizeof(unsigned long) - 1 - lz;
40 }
41
42 static int page_size;
43 static char *mem_region;
44
protect_region(void)45 static int protect_region(void)
46 {
47 if (mprotect(mem_region + page_size, page_size, PROT_NONE)) {
48 perror("mprotect");
49 return 1;
50 }
51
52 return 0;
53 }
54
unprotect_region(void)55 static int unprotect_region(void)
56 {
57 if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) {
58 perror("mprotect");
59 return 1;
60 }
61
62 return 0;
63 }
64
65 extern char __start___ex_table[];
66 extern char __stop___ex_table[];
67
68 struct extbl_entry {
69 int insn;
70 int fixup;
71 };
72
segv_handler(int signr,siginfo_t * info,void * ptr)73 static void segv_handler(int signr, siginfo_t *info, void *ptr)
74 {
75 ucontext_t *uc = (ucontext_t *)ptr;
76 unsigned long addr = (unsigned long)info->si_addr;
77 unsigned long *ip = &UCONTEXT_NIA(uc);
78 struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table;
79
80 while (entry < (struct extbl_entry *)__stop___ex_table) {
81 unsigned long insn, fixup;
82
83 insn = (unsigned long)&entry->insn + entry->insn;
84 fixup = (unsigned long)&entry->fixup + entry->fixup;
85
86 if (insn == *ip) {
87 *ip = fixup;
88 return;
89 }
90 }
91
92 printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
93 abort();
94 }
95
setup_segv_handler(void)96 static void setup_segv_handler(void)
97 {
98 struct sigaction action;
99
100 memset(&action, 0, sizeof(action));
101 action.sa_sigaction = segv_handler;
102 action.sa_flags = SA_SIGINFO;
103 sigaction(SIGSEGV, &action, NULL);
104 }
105
do_one_test(char * p,int page_offset)106 static int do_one_test(char *p, int page_offset)
107 {
108 unsigned long should;
109 unsigned long got;
110
111 FAIL_IF(unprotect_region());
112 should = *(unsigned long *)p;
113 FAIL_IF(protect_region());
114
115 got = load_unaligned_zeropad(p);
116
117 if (should != got) {
118 printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should);
119 return 1;
120 }
121
122 return 0;
123 }
124
test_body(void)125 static int test_body(void)
126 {
127 unsigned long i;
128
129 page_size = getpagesize();
130 mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
131 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
132
133 FAIL_IF(mem_region == MAP_FAILED);
134
135 for (i = 0; i < page_size; i++)
136 mem_region[i] = i;
137
138 memset(mem_region+page_size, 0, page_size);
139
140 setup_segv_handler();
141
142 for (i = 0; i < page_size; i++)
143 FAIL_IF(do_one_test(mem_region+i, i));
144
145 return 0;
146 }
147
main(void)148 int main(void)
149 {
150 return test_harness(test_body, "load_unaligned_zeropad");
151 }
152