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
28static inline unsigned long __fls(unsigned long x);
29
30#include "word-at-a-time.h"
31
32#include "utils.h"
33
34static 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
42static int page_size;
43static char *mem_region;
44
45static 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
55static 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
65extern char __start___ex_table[];
66extern char __stop___ex_table[];
67
68#if defined(__powerpc64__)
69#define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.gp_regs[PT_NIP]
70#elif defined(__powerpc__)
71#define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.uc_regs->gregs[PT_NIP]
72#else
73#error implement UCONTEXT_NIA
74#endif
75
76static int segv_error;
77
78static void segv_handler(int signr, siginfo_t *info, void *ptr)
79{
80	ucontext_t *uc = (ucontext_t *)ptr;
81	unsigned long addr = (unsigned long)info->si_addr;
82	unsigned long *ip = &UCONTEXT_NIA(uc);
83	unsigned long *ex_p = (unsigned long *)__start___ex_table;
84
85	while (ex_p < (unsigned long *)__stop___ex_table) {
86		unsigned long insn, fixup;
87
88		insn = *ex_p++;
89		fixup = *ex_p++;
90
91		if (insn == *ip) {
92			*ip = fixup;
93			return;
94		}
95	}
96
97	printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
98	segv_error++;
99}
100
101static void setup_segv_handler(void)
102{
103	struct sigaction action;
104
105	memset(&action, 0, sizeof(action));
106	action.sa_sigaction = segv_handler;
107	action.sa_flags = SA_SIGINFO;
108	sigaction(SIGSEGV, &action, NULL);
109}
110
111static int do_one_test(char *p, int page_offset)
112{
113	unsigned long should;
114	unsigned long got;
115
116	FAIL_IF(unprotect_region());
117	should = *(unsigned long *)p;
118	FAIL_IF(protect_region());
119
120	got = load_unaligned_zeropad(p);
121
122	if (should != got)
123		printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should);
124
125	return 0;
126}
127
128static int test_body(void)
129{
130	unsigned long i;
131
132	page_size = getpagesize();
133	mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
134		MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
135
136	FAIL_IF(mem_region == MAP_FAILED);
137
138	for (i = 0; i < page_size; i++)
139		mem_region[i] = i;
140
141	memset(mem_region+page_size, 0, page_size);
142
143	setup_segv_handler();
144
145	for (i = 0; i < page_size; i++)
146		FAIL_IF(do_one_test(mem_region+i, i));
147
148	FAIL_IF(segv_error);
149
150	return 0;
151}
152
153int main(void)
154{
155	return test_harness(test_body, "load_unaligned_zeropad");
156}
157