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 #include "word-at-a-time.h"
29 
30 #include "utils.h"
31 
32 
33 static int page_size;
34 static char *mem_region;
35 
36 static int protect_region(void)
37 {
38 	if (mprotect(mem_region + page_size, page_size, PROT_NONE)) {
39 		perror("mprotect");
40 		return 1;
41 	}
42 
43 	return 0;
44 }
45 
46 static int unprotect_region(void)
47 {
48 	if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) {
49 		perror("mprotect");
50 		return 1;
51 	}
52 
53 	return 0;
54 }
55 
56 extern char __start___ex_table[];
57 extern char __stop___ex_table[];
58 
59 #if defined(__powerpc64__)
60 #define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.gp_regs[PT_NIP]
61 #elif defined(__powerpc__)
62 #define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.uc_regs->gregs[PT_NIP]
63 #else
64 #error implement UCONTEXT_NIA
65 #endif
66 
67 static int segv_error;
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 	unsigned long *ex_p = (unsigned long *)__start___ex_table;
75 
76 	while (ex_p < (unsigned long *)__stop___ex_table) {
77 		unsigned long insn, fixup;
78 
79 		insn = *ex_p++;
80 		fixup = *ex_p++;
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 	segv_error++;
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(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 
116 	return 0;
117 }
118 
119 static int test_body(void)
120 {
121 	unsigned long i;
122 
123 	page_size = getpagesize();
124 	mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
125 		MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
126 
127 	FAIL_IF(mem_region == MAP_FAILED);
128 
129 	for (i = 0; i < page_size; i++)
130 		mem_region[i] = i;
131 
132 	memset(mem_region+page_size, 0, page_size);
133 
134 	setup_segv_handler();
135 
136 	for (i = 0; i < page_size; i++)
137 		FAIL_IF(do_one_test(mem_region+i, i));
138 
139 	FAIL_IF(segv_error);
140 
141 	return 0;
142 }
143 
144 int main(void)
145 {
146 	return test_harness(test_body, "load_unaligned_zeropad");
147 }
148