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 
segv(int signum,siginfo_t * info,void * ctxt_v)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 
do_read(const volatile void * addr)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 
do_write(const volatile void * addr)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 
check_faulted(void * addr,long page,long subpage,int write)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 
run_test(void * addr,unsigned long size)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 
syscall_available(void)138 static int syscall_available(void)
139 {
140 	int rc;
141 
142 	errno = 0;
143 	rc = syscall(__NR_subpage_prot, 0, 0, 0);
144 
145 	return rc == 0 || (errno != ENOENT && errno != ENOSYS);
146 }
147 
test_anon(void)148 int test_anon(void)
149 {
150 	unsigned long align;
151 	struct sigaction act = {
152 		.sa_sigaction = segv,
153 		.sa_flags = SA_SIGINFO
154 	};
155 	void *mallocblock;
156 	unsigned long mallocsize;
157 
158 	SKIP_IF(!syscall_available());
159 
160 	if (getpagesize() != 0x10000) {
161 		fprintf(stderr, "Kernel page size must be 64K!\n");
162 		return 1;
163 	}
164 
165 	sigaction(SIGSEGV, &act, NULL);
166 
167 	mallocsize = 4 * 16 * 1024 * 1024;
168 
169 	FAIL_IF(posix_memalign(&mallocblock, 64 * 1024, mallocsize));
170 
171 	align = (unsigned long)mallocblock;
172 	if (align & 0xffff)
173 		align = (align | 0xffff) + 1;
174 
175 	mallocblock = (void *)align;
176 
177 	printf("allocated malloc block of 0x%lx bytes at %p\n",
178 	       mallocsize, mallocblock);
179 
180 	printf("testing malloc block...\n");
181 
182 	return run_test(mallocblock, mallocsize);
183 }
184 
test_file(void)185 int test_file(void)
186 {
187 	struct sigaction act = {
188 		.sa_sigaction = segv,
189 		.sa_flags = SA_SIGINFO
190 	};
191 	void *fileblock;
192 	off_t filesize;
193 	int fd;
194 
195 	SKIP_IF(!syscall_available());
196 
197 	fd = open(file_name, O_RDWR);
198 	if (fd == -1) {
199 		perror("failed to open file");
200 		return 1;
201 	}
202 	sigaction(SIGSEGV, &act, NULL);
203 
204 	filesize = lseek(fd, 0, SEEK_END);
205 	if (filesize & 0xffff)
206 		filesize &= ~0xfffful;
207 
208 	fileblock = mmap(NULL, filesize, PROT_READ | PROT_WRITE,
209 			 MAP_SHARED, fd, 0);
210 	if (fileblock == MAP_FAILED) {
211 		perror("failed to map file");
212 		return 1;
213 	}
214 	printf("allocated %s for 0x%lx bytes at %p\n",
215 	       file_name, filesize, fileblock);
216 
217 	printf("testing file map...\n");
218 
219 	return run_test(fileblock, filesize);
220 }
221 
main(int argc,char * argv[])222 int main(int argc, char *argv[])
223 {
224 	int rc;
225 
226 	rc = test_harness(test_anon, "subpage_prot_anon");
227 	if (rc)
228 		return rc;
229 
230 	if (argc > 1)
231 		file_name = argv[1];
232 	else
233 		file_name = "tempfile";
234 
235 	return test_harness(test_file, "subpage_prot_file");
236 }
237