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
33static int page_size;
34static char *mem_region;
35
36static 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
46static 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
56extern char __start___ex_table[];
57extern 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
67static int segv_error;
68
69static 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
92static 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
102static 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
119static 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
144int main(void)
145{
146	return test_harness(test_body, "load_unaligned_zeropad");
147}
148