1#include <linux/module.h>
2#include <linux/sched.h>
3#include <linux/spinlock.h>
4#include <linux/list.h>
5#include <asm/alternative.h>
6#include <asm/sections.h>
7
8static int noreplace_smp = 0;
9static int smp_alt_once = 0;
10static int debug_alternative = 0;
11
12static int __init bootonly(char *str)
13{
14 smp_alt_once = 1;
15 return 1;
16}
17__setup("smp-alt-boot", bootonly);
18
19static int __init debug_alt(char *str)
20{
21 debug_alternative = 1;
22 return 1;
23}
24__setup("debug-alternative", debug_alt);
25
26static int __init setup_noreplace_smp(char *str)
27{
28 noreplace_smp = 1;
29 return 1;
30}
31__setup("noreplace-smp", setup_noreplace_smp);
32
33#ifdef CONFIG_PARAVIRT
34static int noreplace_paravirt = 0;
35
36static int __init setup_noreplace_paravirt(char *str)
37{
38 noreplace_paravirt = 1;
39 return 1;
40}
41__setup("noreplace-paravirt", setup_noreplace_paravirt);
42#endif
43
44#define DPRINTK(fmt, args...) if (debug_alternative) \
45 printk(KERN_DEBUG fmt, args)
46
47#ifdef GENERIC_NOP1
48
49
50
51asm("\t.data\nintelnops: "
52 GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6
53 GENERIC_NOP7 GENERIC_NOP8);
54extern unsigned char intelnops[];
55static unsigned char *intel_nops[ASM_NOP_MAX+1] = {
56 NULL,
57 intelnops,
58 intelnops + 1,
59 intelnops + 1 + 2,
60 intelnops + 1 + 2 + 3,
61 intelnops + 1 + 2 + 3 + 4,
62 intelnops + 1 + 2 + 3 + 4 + 5,
63 intelnops + 1 + 2 + 3 + 4 + 5 + 6,
64 intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
65};
66#endif
67
68#ifdef K8_NOP1
69asm("\t.data\nk8nops: "
70 K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6
71 K8_NOP7 K8_NOP8);
72extern unsigned char k8nops[];
73static unsigned char *k8_nops[ASM_NOP_MAX+1] = {
74 NULL,
75 k8nops,
76 k8nops + 1,
77 k8nops + 1 + 2,
78 k8nops + 1 + 2 + 3,
79 k8nops + 1 + 2 + 3 + 4,
80 k8nops + 1 + 2 + 3 + 4 + 5,
81 k8nops + 1 + 2 + 3 + 4 + 5 + 6,
82 k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
83};
84#endif
85
86#ifdef K7_NOP1
87asm("\t.data\nk7nops: "
88 K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6
89 K7_NOP7 K7_NOP8);
90extern unsigned char k7nops[];
91static unsigned char *k7_nops[ASM_NOP_MAX+1] = {
92 NULL,
93 k7nops,
94 k7nops + 1,
95 k7nops + 1 + 2,
96 k7nops + 1 + 2 + 3,
97 k7nops + 1 + 2 + 3 + 4,
98 k7nops + 1 + 2 + 3 + 4 + 5,
99 k7nops + 1 + 2 + 3 + 4 + 5 + 6,
100 k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
101};
102#endif
103
104#ifdef CONFIG_X86_64
105
106extern char __vsyscall_0;
107static inline unsigned char** find_nop_table(void)
108{
109 return k8_nops;
110}
111
112#else
113
114static struct nop {
115 int cpuid;
116 unsigned char **noptable;
117} noptypes[] = {
118 { X86_FEATURE_K8, k8_nops },
119 { X86_FEATURE_K7, k7_nops },
120 { -1, NULL }
121};
122
123static unsigned char** find_nop_table(void)
124{
125 unsigned char **noptable = intel_nops;
126 int i;
127
128 for (i = 0; noptypes[i].cpuid >= 0; i++) {
129 if (boot_cpu_has(noptypes[i].cpuid)) {
130 noptable = noptypes[i].noptable;
131 break;
132 }
133 }
134 return noptable;
135}
136
137#endif
138
139static void nop_out(void *insns, unsigned int len)
140{
141 unsigned char **noptable = find_nop_table();
142
143 while (len > 0) {
144 unsigned int noplen = len;
145 if (noplen > ASM_NOP_MAX)
146 noplen = ASM_NOP_MAX;
147 memcpy(insns, noptable[noplen], noplen);
148 insns += noplen;
149 len -= noplen;
150 }
151}
152
153extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
154extern u8 *__smp_locks[], *__smp_locks_end[];
155
156
157
158
159
160
161
162void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
163{
164 struct alt_instr *a;
165 u8 *instr;
166 int diff;
167
168 DPRINTK("%s: alt table %p -> %p\n", __FUNCTION__, start, end);
169 for (a = start; a < end; a++) {
170 BUG_ON(a->replacementlen > a->instrlen);
171 if (!boot_cpu_has(a->cpuid))
172 continue;
173 instr = a->instr;
174#ifdef CONFIG_X86_64
175
176 if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) {
177 instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));
178 DPRINTK("%s: vsyscall fixup: %p => %p\n",
179 __FUNCTION__, a->instr, instr);
180 }
181#endif
182 memcpy(instr, a->replacement, a->replacementlen);
183 diff = a->instrlen - a->replacementlen;
184 nop_out(instr + a->replacementlen, diff);
185 }
186}
187
188#ifdef CONFIG_SMP
189
190static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
191{
192 u8 **ptr;
193
194 for (ptr = start; ptr < end; ptr++) {
195 if (*ptr < text)
196 continue;
197 if (*ptr > text_end)
198 continue;
199 **ptr = 0xf0;
200 };
201}
202
203static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
204{
205 u8 **ptr;
206
207 if (noreplace_smp)
208 return;
209
210 for (ptr = start; ptr < end; ptr++) {
211 if (*ptr < text)
212 continue;
213 if (*ptr > text_end)
214 continue;
215 nop_out(*ptr, 1);
216 };
217}
218
219struct smp_alt_module {
220
221 struct module *mod;
222 char *name;
223
224
225 u8 **locks;
226 u8 **locks_end;
227
228
229 u8 *text;
230 u8 *text_end;
231
232 struct list_head next;
233};
234static LIST_HEAD(smp_alt_modules);
235static DEFINE_SPINLOCK(smp_alt);
236
237void alternatives_smp_module_add(struct module *mod, char *name,
238 void *locks, void *locks_end,
239 void *text, void *text_end)
240{
241 struct smp_alt_module *smp;
242 unsigned long flags;
243
244 if (noreplace_smp)
245 return;
246
247 if (smp_alt_once) {
248 if (boot_cpu_has(X86_FEATURE_UP))
249 alternatives_smp_unlock(locks, locks_end,
250 text, text_end);
251 return;
252 }
253
254 smp = kzalloc(sizeof(*smp), GFP_KERNEL);
255 if (NULL == smp)
256 return;
257
258 smp->mod = mod;
259 smp->name = name;
260 smp->locks = locks;
261 smp->locks_end = locks_end;
262 smp->text = text;
263 smp->text_end = text_end;
264 DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n",
265 __FUNCTION__, smp->locks, smp->locks_end,
266 smp->text, smp->text_end, smp->name);
267
268 spin_lock_irqsave(&smp_alt, flags);
269 list_add_tail(&smp->next, &smp_alt_modules);
270 if (boot_cpu_has(X86_FEATURE_UP))
271 alternatives_smp_unlock(smp->locks, smp->locks_end,
272 smp->text, smp->text_end);
273 spin_unlock_irqrestore(&smp_alt, flags);
274}
275
276void alternatives_smp_module_del(struct module *mod)
277{
278 struct smp_alt_module *item;
279 unsigned long flags;
280
281 if (smp_alt_once || noreplace_smp)
282 return;
283
284 spin_lock_irqsave(&smp_alt, flags);
285 list_for_each_entry(item, &smp_alt_modules, next) {
286 if (mod != item->mod)
287 continue;
288 list_del(&item->next);
289 spin_unlock_irqrestore(&smp_alt, flags);
290 DPRINTK("%s: %s\n", __FUNCTION__, item->name);
291 kfree(item);
292 return;
293 }
294 spin_unlock_irqrestore(&smp_alt, flags);
295}
296
297void alternatives_smp_switch(int smp)
298{
299 struct smp_alt_module *mod;
300 unsigned long flags;
301
302#ifdef CONFIG_LOCKDEP
303
304
305
306
307
308 printk("lockdep: not fixing up alternatives.\n");
309 return;
310#endif
311
312 if (noreplace_smp || smp_alt_once)
313 return;
314 BUG_ON(!smp && (num_online_cpus() > 1));
315
316 spin_lock_irqsave(&smp_alt, flags);
317 if (smp) {
318 printk(KERN_INFO "SMP alternatives: switching to SMP code\n");
319 clear_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
320 clear_bit(X86_FEATURE_UP, cpu_data[0].x86_capability);
321 list_for_each_entry(mod, &smp_alt_modules, next)
322 alternatives_smp_lock(mod->locks, mod->locks_end,
323 mod->text, mod->text_end);
324 } else {
325 printk(KERN_INFO "SMP alternatives: switching to UP code\n");
326 set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
327 set_bit(X86_FEATURE_UP, cpu_data[0].x86_capability);
328 list_for_each_entry(mod, &smp_alt_modules, next)
329 alternatives_smp_unlock(mod->locks, mod->locks_end,
330 mod->text, mod->text_end);
331 }
332 spin_unlock_irqrestore(&smp_alt, flags);
333}
334
335#endif
336
337#ifdef CONFIG_PARAVIRT
338void apply_paravirt(struct paravirt_patch_site *start,
339 struct paravirt_patch_site *end)
340{
341 struct paravirt_patch_site *p;
342
343 if (noreplace_paravirt)
344 return;
345
346 for (p = start; p < end; p++) {
347 unsigned int used;
348
349 used = paravirt_ops.patch(p->instrtype, p->clobbers, p->instr,
350 p->len);
351
352 BUG_ON(used > p->len);
353
354
355 nop_out(p->instr + used, p->len - used);
356 }
357
358
359
360 sync_core();
361}
362extern struct paravirt_patch_site __start_parainstructions[],
363 __stop_parainstructions[];
364#endif
365
366void __init alternative_instructions(void)
367{
368 unsigned long flags;
369
370 local_irq_save(flags);
371 apply_alternatives(__alt_instructions, __alt_instructions_end);
372
373
374
375
376#ifdef CONFIG_HOTPLUG_CPU
377 if (num_possible_cpus() < 2)
378 smp_alt_once = 1;
379#else
380 smp_alt_once = 1;
381#endif
382
383#ifdef CONFIG_SMP
384 if (smp_alt_once) {
385 if (1 == num_possible_cpus()) {
386 printk(KERN_INFO "SMP alternatives: switching to UP code\n");
387 set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
388 set_bit(X86_FEATURE_UP, cpu_data[0].x86_capability);
389 alternatives_smp_unlock(__smp_locks, __smp_locks_end,
390 _text, _etext);
391 }
392 free_init_pages("SMP alternatives",
393 (unsigned long)__smp_locks,
394 (unsigned long)__smp_locks_end);
395 } else {
396 alternatives_smp_module_add(NULL, "core kernel",
397 __smp_locks, __smp_locks_end,
398 _text, _etext);
399 alternatives_smp_switch(0);
400 }
401#endif
402 apply_paravirt(__parainstructions, __parainstructions_end);
403 local_irq_restore(flags);
404}
405
