1 /*
2  * Copyright IBM Corp.
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms of version 2.1 of the GNU Lesser General Public License
6  * as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it would be useful, but
9  * WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
11  *
12  */
13 
14 #include <assert.h>
15 #include <errno.h>
16 #include <fcntl.h>
17 #include <signal.h>
18 #include <stdarg.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <sys/mman.h>
23 #include <sys/ptrace.h>
24 #include <sys/syscall.h>
25 #include <ucontext.h>
26 #include <unistd.h>
27 
28 #include "utils.h"
29 
30 char *file_name;
31 
32 int in_test;
33 volatile int faulted;
34 volatile void *dar;
35 int errors;
36 
37 static void segv(int signum, siginfo_t *info, void *ctxt_v)
38 {
39 	ucontext_t *ctxt = (ucontext_t *)ctxt_v;
40 	struct pt_regs *regs = ctxt->uc_mcontext.regs;
41 
42 	if (!in_test) {
43 		fprintf(stderr, "Segfault outside of test !\n");
44 		exit(1);
45 	}
46 
47 	faulted = 1;
48 	dar = (void *)regs->dar;
49 	regs->nip += 4;
50 }
51 
52 static inline void do_read(const volatile void *addr)
53 {
54 	int ret;
55 
56 	asm volatile("lwz %0,0(%1); twi 0,%0,0; isync;\n"
57 		     : "=r" (ret) : "r" (addr) : "memory");
58 }
59 
60 static inline void do_write(const volatile void *addr)
61 {
62 	int val = 0x1234567;
63 
64 	asm volatile("stw %0,0(%1); sync; \n"
65 		     : : "r" (val), "r" (addr) : "memory");
66 }
67 
68 static inline void check_faulted(void *addr, long page, long subpage, int write)
69 {
70 	int want_fault = (subpage == ((page + 3) % 16));
71 
72 	if (write)
73 		want_fault |= (subpage == ((page + 1) % 16));
74 
75 	if (faulted != want_fault) {
76 		printf("Failed at %p (p=%ld,sp=%ld,w=%d), want=%s, got=%s !\n",
77 		       addr, page, subpage, write,
78 		       want_fault ? "fault" : "pass",
79 		       faulted ? "fault" : "pass");
80 		++errors;
81 	}
82 
83 	if (faulted) {
84 		if (dar != addr) {
85 			printf("Fault expected at %p and happened at %p !\n",
86 			       addr, dar);
87 		}
88 		faulted = 0;
89 		asm volatile("sync" : : : "memory");
90 	}
91 }
92 
93 static int run_test(void *addr, unsigned long size)
94 {
95 	unsigned int *map;
96 	long i, j, pages, err;
97 
98 	pages = size / 0x10000;
99 	map = malloc(pages * 4);
100 	assert(map);
101 
102 	/*
103 	 * for each page, mark subpage i % 16 read only and subpage
104 	 * (i + 3) % 16 inaccessible
105 	 */
106 	for (i = 0; i < pages; i++) {
107 		map[i] = (0x40000000 >> (((i + 1) * 2) % 32)) |
108 			(0xc0000000 >> (((i + 3) * 2) % 32));
109 	}
110 
111 	err = syscall(__NR_subpage_prot, addr, size, map);
112 	if (err) {
113 		perror("subpage_perm");
114 		return 1;
115 	}
116 	free(map);
117 
118 	in_test = 1;
119 	errors = 0;
120 	for (i = 0; i < pages; i++) {
121 		for (j = 0; j < 16; j++, addr += 0x1000) {
122 			do_read(addr);
123 			check_faulted(addr, i, j, 0);
124 			do_write(addr);
125 			check_faulted(addr, i, j, 1);
126 		}
127 	}
128 
129 	in_test = 0;
130 	if (errors) {
131 		printf("%d errors detected\n", errors);
132 		return 1;
133 	}
134 
135 	return 0;
136 }
137 
138 int test_anon(void)
139 {
140 	unsigned long align;
141 	struct sigaction act = {
142 		.sa_sigaction = segv,
143 		.sa_flags = SA_SIGINFO
144 	};
145 	void *mallocblock;
146 	unsigned long mallocsize;
147 
148 	if (getpagesize() != 0x10000) {
149 		fprintf(stderr, "Kernel page size must be 64K!\n");
150 		return 1;
151 	}
152 
153 	sigaction(SIGSEGV, &act, NULL);
154 
155 	mallocsize = 4 * 16 * 1024 * 1024;
156 
157 	FAIL_IF(posix_memalign(&mallocblock, 64 * 1024, mallocsize));
158 
159 	align = (unsigned long)mallocblock;
160 	if (align & 0xffff)
161 		align = (align | 0xffff) + 1;
162 
163 	mallocblock = (void *)align;
164 
165 	printf("allocated malloc block of 0x%lx bytes at %p\n",
166 	       mallocsize, mallocblock);
167 
168 	printf("testing malloc block...\n");
169 
170 	return run_test(mallocblock, mallocsize);
171 }
172 
173 int test_file(void)
174 {
175 	struct sigaction act = {
176 		.sa_sigaction = segv,
177 		.sa_flags = SA_SIGINFO
178 	};
179 	void *fileblock;
180 	off_t filesize;
181 	int fd;
182 
183 	fd = open(file_name, O_RDWR);
184 	if (fd == -1) {
185 		perror("failed to open file");
186 		return 1;
187 	}
188 	sigaction(SIGSEGV, &act, NULL);
189 
190 	filesize = lseek(fd, 0, SEEK_END);
191 	if (filesize & 0xffff)
192 		filesize &= ~0xfffful;
193 
194 	fileblock = mmap(NULL, filesize, PROT_READ | PROT_WRITE,
195 			 MAP_SHARED, fd, 0);
196 	if (fileblock == MAP_FAILED) {
197 		perror("failed to map file");
198 		return 1;
199 	}
200 	printf("allocated %s for 0x%lx bytes at %p\n",
201 	       file_name, filesize, fileblock);
202 
203 	printf("testing file map...\n");
204 
205 	return run_test(fileblock, filesize);
206 }
207 
208 int main(int argc, char *argv[])
209 {
210 	int rc;
211 
212 	rc = test_harness(test_anon, "subpage_prot_anon");
213 	if (rc)
214 		return rc;
215 
216 	if (argc > 1)
217 		file_name = argv[1];
218 	else
219 		file_name = "tempfile";
220 
221 	return test_harness(test_file, "subpage_prot_file");
222 }
223