1 /*
2  *  Copyright (C) 2001 Ben. Herrenschmidt (benh@kernel.crashing.org)
3  *
4  *  Modifications for ppc64:
5  *      Copyright (C) 2003 Dave Engebretsen <engebret@us.ibm.com>
6  *
7  *  Copyright 2008 Michael Ellerman, IBM Corporation.
8  *
9  *  This program is free software; you can redistribute it and/or
10  *  modify it under the terms of the GNU General Public License
11  *  as published by the Free Software Foundation; either version
12  *  2 of the License, or (at your option) any later version.
13  */
14 
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/string.h>
18 #include <linux/init.h>
19 #include <asm/cputable.h>
20 #include <asm/code-patching.h>
21 
22 
23 struct fixup_entry {
24 	unsigned long	mask;
25 	unsigned long	value;
26 	long		start_off;
27 	long		end_off;
28 	long		alt_start_off;
29 	long		alt_end_off;
30 };
31 
32 static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
33 {
34 	/*
35 	 * We store the offset to the code as a negative offset from
36 	 * the start of the alt_entry, to support the VDSO. This
37 	 * routine converts that back into an actual address.
38 	 */
39 	return (unsigned int *)((unsigned long)fcur + offset);
40 }
41 
42 static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
43 				 unsigned int *alt_start, unsigned int *alt_end)
44 {
45 	unsigned int instr;
46 
47 	instr = *src;
48 
49 	if (instr_is_relative_branch(*src)) {
50 		unsigned int *target = (unsigned int *)branch_target(src);
51 
52 		/* Branch within the section doesn't need translating */
53 		if (target < alt_start || target >= alt_end) {
54 			instr = translate_branch(dest, src);
55 			if (!instr)
56 				return 1;
57 		}
58 	}
59 
60 	patch_instruction(dest, instr);
61 
62 	return 0;
63 }
64 
65 static int patch_feature_section(unsigned long value, struct fixup_entry *fcur)
66 {
67 	unsigned int *start, *end, *alt_start, *alt_end, *src, *dest;
68 
69 	start = calc_addr(fcur, fcur->start_off);
70 	end = calc_addr(fcur, fcur->end_off);
71 	alt_start = calc_addr(fcur, fcur->alt_start_off);
72 	alt_end = calc_addr(fcur, fcur->alt_end_off);
73 
74 	if ((alt_end - alt_start) > (end - start))
75 		return 1;
76 
77 	if ((value & fcur->mask) == fcur->value)
78 		return 0;
79 
80 	src = alt_start;
81 	dest = start;
82 
83 	for (; src < alt_end; src++, dest++) {
84 		if (patch_alt_instruction(src, dest, alt_start, alt_end))
85 			return 1;
86 	}
87 
88 	for (; dest < end; dest++)
89 		patch_instruction(dest, PPC_INST_NOP);
90 
91 	return 0;
92 }
93 
94 void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
95 {
96 	struct fixup_entry *fcur, *fend;
97 
98 	fcur = fixup_start;
99 	fend = fixup_end;
100 
101 	for (; fcur < fend; fcur++) {
102 		if (patch_feature_section(value, fcur)) {
103 			WARN_ON(1);
104 			printk("Unable to patch feature section at %p - %p" \
105 				" with %p - %p\n",
106 				calc_addr(fcur, fcur->start_off),
107 				calc_addr(fcur, fcur->end_off),
108 				calc_addr(fcur, fcur->alt_start_off),
109 				calc_addr(fcur, fcur->alt_end_off));
110 		}
111 	}
112 }
113 
114 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
115 {
116 	long *start, *end;
117 	unsigned int *dest;
118 
119 	if (!(value & CPU_FTR_LWSYNC))
120 		return ;
121 
122 	start = fixup_start;
123 	end = fixup_end;
124 
125 	for (; start < end; start++) {
126 		dest = (void *)start + *start;
127 		patch_instruction(dest, PPC_INST_LWSYNC);
128 	}
129 }
130 
131 #ifdef CONFIG_FTR_FIXUP_SELFTEST
132 
133 #define check(x)	\
134 	if (!(x)) printk("feature-fixups: test failed at line %d\n", __LINE__);
135 
136 /* This must be after the text it fixes up, vmlinux.lds.S enforces that atm */
137 static struct fixup_entry fixup;
138 
139 static long calc_offset(struct fixup_entry *entry, unsigned int *p)
140 {
141 	return (unsigned long)p - (unsigned long)entry;
142 }
143 
144 void test_basic_patching(void)
145 {
146 	extern unsigned int ftr_fixup_test1;
147 	extern unsigned int end_ftr_fixup_test1;
148 	extern unsigned int ftr_fixup_test1_orig;
149 	extern unsigned int ftr_fixup_test1_expected;
150 	int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
151 
152 	fixup.value = fixup.mask = 8;
153 	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
154 	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
155 	fixup.alt_start_off = fixup.alt_end_off = 0;
156 
157 	/* Sanity check */
158 	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
159 
160 	/* Check we don't patch if the value matches */
161 	patch_feature_section(8, &fixup);
162 	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
163 
164 	/* Check we do patch if the value doesn't match */
165 	patch_feature_section(0, &fixup);
166 	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
167 
168 	/* Check we do patch if the mask doesn't match */
169 	memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
170 	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
171 	patch_feature_section(~8, &fixup);
172 	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
173 }
174 
175 static void test_alternative_patching(void)
176 {
177 	extern unsigned int ftr_fixup_test2;
178 	extern unsigned int end_ftr_fixup_test2;
179 	extern unsigned int ftr_fixup_test2_orig;
180 	extern unsigned int ftr_fixup_test2_alt;
181 	extern unsigned int ftr_fixup_test2_expected;
182 	int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
183 
184 	fixup.value = fixup.mask = 0xF;
185 	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
186 	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
187 	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
188 	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
189 
190 	/* Sanity check */
191 	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
192 
193 	/* Check we don't patch if the value matches */
194 	patch_feature_section(0xF, &fixup);
195 	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
196 
197 	/* Check we do patch if the value doesn't match */
198 	patch_feature_section(0, &fixup);
199 	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
200 
201 	/* Check we do patch if the mask doesn't match */
202 	memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
203 	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
204 	patch_feature_section(~0xF, &fixup);
205 	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
206 }
207 
208 static void test_alternative_case_too_big(void)
209 {
210 	extern unsigned int ftr_fixup_test3;
211 	extern unsigned int end_ftr_fixup_test3;
212 	extern unsigned int ftr_fixup_test3_orig;
213 	extern unsigned int ftr_fixup_test3_alt;
214 	int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
215 
216 	fixup.value = fixup.mask = 0xC;
217 	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
218 	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
219 	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
220 	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
221 
222 	/* Sanity check */
223 	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
224 
225 	/* Expect nothing to be patched, and the error returned to us */
226 	check(patch_feature_section(0xF, &fixup) == 1);
227 	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
228 	check(patch_feature_section(0, &fixup) == 1);
229 	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
230 	check(patch_feature_section(~0xF, &fixup) == 1);
231 	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
232 }
233 
234 static void test_alternative_case_too_small(void)
235 {
236 	extern unsigned int ftr_fixup_test4;
237 	extern unsigned int end_ftr_fixup_test4;
238 	extern unsigned int ftr_fixup_test4_orig;
239 	extern unsigned int ftr_fixup_test4_alt;
240 	extern unsigned int ftr_fixup_test4_expected;
241 	int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
242 	unsigned long flag;
243 
244 	/* Check a high-bit flag */
245 	flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
246 	fixup.value = fixup.mask = flag;
247 	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
248 	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
249 	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
250 	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
251 
252 	/* Sanity check */
253 	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
254 
255 	/* Check we don't patch if the value matches */
256 	patch_feature_section(flag, &fixup);
257 	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
258 
259 	/* Check we do patch if the value doesn't match */
260 	patch_feature_section(0, &fixup);
261 	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
262 
263 	/* Check we do patch if the mask doesn't match */
264 	memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
265 	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
266 	patch_feature_section(~flag, &fixup);
267 	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
268 }
269 
270 static void test_alternative_case_with_branch(void)
271 {
272 	extern unsigned int ftr_fixup_test5;
273 	extern unsigned int end_ftr_fixup_test5;
274 	extern unsigned int ftr_fixup_test5_expected;
275 	int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
276 
277 	check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
278 }
279 
280 static void test_alternative_case_with_external_branch(void)
281 {
282 	extern unsigned int ftr_fixup_test6;
283 	extern unsigned int end_ftr_fixup_test6;
284 	extern unsigned int ftr_fixup_test6_expected;
285 	int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
286 
287 	check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
288 }
289 
290 static void test_cpu_macros(void)
291 {
292 	extern u8 ftr_fixup_test_FTR_macros;
293 	extern u8 ftr_fixup_test_FTR_macros_expected;
294 	unsigned long size = &ftr_fixup_test_FTR_macros_expected -
295 			     &ftr_fixup_test_FTR_macros;
296 
297 	/* The fixups have already been done for us during boot */
298 	check(memcmp(&ftr_fixup_test_FTR_macros,
299 		     &ftr_fixup_test_FTR_macros_expected, size) == 0);
300 }
301 
302 static void test_fw_macros(void)
303 {
304 #ifdef CONFIG_PPC64
305 	extern u8 ftr_fixup_test_FW_FTR_macros;
306 	extern u8 ftr_fixup_test_FW_FTR_macros_expected;
307 	unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
308 			     &ftr_fixup_test_FW_FTR_macros;
309 
310 	/* The fixups have already been done for us during boot */
311 	check(memcmp(&ftr_fixup_test_FW_FTR_macros,
312 		     &ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
313 #endif
314 }
315 
316 static void test_lwsync_macros(void)
317 {
318 	extern u8 lwsync_fixup_test;
319 	extern u8 end_lwsync_fixup_test;
320 	extern u8 lwsync_fixup_test_expected_LWSYNC;
321 	extern u8 lwsync_fixup_test_expected_SYNC;
322 	unsigned long size = &end_lwsync_fixup_test -
323 			     &lwsync_fixup_test;
324 
325 	/* The fixups have already been done for us during boot */
326 	if (cur_cpu_spec->cpu_features & CPU_FTR_LWSYNC) {
327 		check(memcmp(&lwsync_fixup_test,
328 			     &lwsync_fixup_test_expected_LWSYNC, size) == 0);
329 	} else {
330 		check(memcmp(&lwsync_fixup_test,
331 			     &lwsync_fixup_test_expected_SYNC, size) == 0);
332 	}
333 }
334 
335 static int __init test_feature_fixups(void)
336 {
337 	printk(KERN_DEBUG "Running feature fixup self-tests ...\n");
338 
339 	test_basic_patching();
340 	test_alternative_patching();
341 	test_alternative_case_too_big();
342 	test_alternative_case_too_small();
343 	test_alternative_case_with_branch();
344 	test_alternative_case_with_external_branch();
345 	test_cpu_macros();
346 	test_fw_macros();
347 	test_lwsync_macros();
348 
349 	return 0;
350 }
351 late_initcall(test_feature_fixups);
352 
353 #endif /* CONFIG_FTR_FIXUP_SELFTEST */
354