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