powerpc/kexec: Add to and tidy debug/comments in machine_kexec64.c
[linux-block.git] / arch / powerpc / kernel / machine_kexec_64.c
CommitLineData
fce0d574 1/*
3d1229d6 2 * PPC64 code to handle Linux booting another kernel.
fce0d574
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3 *
4 * Copyright (C) 2004-2005, IBM Corp.
5 *
6 * Created by: Milton D Miller II
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 */
11
12
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13#include <linux/kexec.h>
14#include <linux/smp.h>
15#include <linux/thread_info.h>
d200c922 16#include <linux/init_task.h>
fce0d574 17#include <linux/errno.h>
e2f7f737 18#include <linux/kernel.h>
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19
20#include <asm/page.h>
21#include <asm/current.h>
22#include <asm/machdep.h>
23#include <asm/cacheflush.h>
24#include <asm/paca.h>
25#include <asm/mmu.h>
26#include <asm/sections.h> /* _end */
27#include <asm/prom.h>
2249ca9d 28#include <asm/smp.h>
5aae8a53 29#include <asm/hw_breakpoint.h>
fce0d574 30
3d1229d6 31int default_machine_kexec_prepare(struct kimage *image)
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32{
33 int i;
34 unsigned long begin, end; /* limits of segment */
35 unsigned long low, high; /* limits of blocked memory range */
36 struct device_node *node;
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37 const unsigned long *basep;
38 const unsigned int *sizep;
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39
40 if (!ppc_md.hpte_clear_all)
41 return -ENOENT;
42
43 /*
44 * Since we use the kernel fault handlers and paging code to
45 * handle the virtual mode, we must make sure no destination
46 * overlaps kernel static data or bss.
47 */
72414d3f 48 for (i = 0; i < image->nr_segments; i++)
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49 if (image->segment[i].mem < __pa(_end))
50 return -ETXTBSY;
51
52 /*
53 * For non-LPAR, we absolutely can not overwrite the mmu hash
54 * table, since we are still using the bolted entries in it to
55 * do the copy. Check that here.
56 *
57 * It is safe if the end is below the start of the blocked
58 * region (end <= low), or if the beginning is after the
59 * end of the blocked region (begin >= high). Use the
60 * boolean identity !(a || b) === (!a && !b).
61 */
62 if (htab_address) {
63 low = __pa(htab_address);
337a7128 64 high = low + htab_size_bytes;
fce0d574 65
72414d3f 66 for (i = 0; i < image->nr_segments; i++) {
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67 begin = image->segment[i].mem;
68 end = begin + image->segment[i].memsz;
69
70 if ((begin < high) && (end > low))
71 return -ETXTBSY;
72 }
73 }
74
75 /* We also should not overwrite the tce tables */
76 for (node = of_find_node_by_type(NULL, "pci"); node != NULL;
77 node = of_find_node_by_type(node, "pci")) {
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78 basep = of_get_property(node, "linux,tce-base", NULL);
79 sizep = of_get_property(node, "linux,tce-size", NULL);
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80 if (basep == NULL || sizep == NULL)
81 continue;
82
83 low = *basep;
84 high = low + (*sizep);
85
72414d3f 86 for (i = 0; i < image->nr_segments; i++) {
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87 begin = image->segment[i].mem;
88 end = begin + image->segment[i].memsz;
89
90 if ((begin < high) && (end > low))
91 return -ETXTBSY;
92 }
93 }
94
95 return 0;
96}
97
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98#define IND_FLAGS (IND_DESTINATION | IND_INDIRECTION | IND_DONE | IND_SOURCE)
99
100static void copy_segments(unsigned long ind)
101{
102 unsigned long entry;
103 unsigned long *ptr;
104 void *dest;
105 void *addr;
106
107 /*
108 * We rely on kexec_load to create a lists that properly
109 * initializes these pointers before they are used.
110 * We will still crash if the list is wrong, but at least
111 * the compiler will be quiet.
112 */
113 ptr = NULL;
114 dest = NULL;
115
116 for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
117 addr = __va(entry & PAGE_MASK);
118
119 switch (entry & IND_FLAGS) {
120 case IND_DESTINATION:
121 dest = addr;
122 break;
123 case IND_INDIRECTION:
124 ptr = addr;
125 break;
126 case IND_SOURCE:
127 copy_page(dest, addr);
128 dest += PAGE_SIZE;
129 }
130 }
131}
132
133void kexec_copy_flush(struct kimage *image)
134{
135 long i, nr_segments = image->nr_segments;
136 struct kexec_segment ranges[KEXEC_SEGMENT_MAX];
137
138 /* save the ranges on the stack to efficiently flush the icache */
139 memcpy(ranges, image->segment, sizeof(ranges));
140
141 /*
142 * After this call we may not use anything allocated in dynamic
143 * memory, including *image.
144 *
145 * Only globals and the stack are allowed.
146 */
147 copy_segments(image->head);
148
149 /*
150 * we need to clear the icache for all dest pages sometime,
151 * including ones that were in place on the original copy
152 */
153 for (i = 0; i < nr_segments; i++)
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154 flush_icache_range((unsigned long)__va(ranges[i].mem),
155 (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
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156}
157
158#ifdef CONFIG_SMP
159
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160static int kexec_all_irq_disabled = 0;
161
1c21a293 162static void kexec_smp_down(void *arg)
fce0d574 163{
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164 local_irq_disable();
165 mb(); /* make sure our irqs are disabled before we say they are */
166 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
167 while(kexec_all_irq_disabled == 0)
168 cpu_relax();
169 mb(); /* make sure all irqs are disabled before this */
5aae8a53 170 hw_breakpoint_disable();
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171 /*
172 * Now every CPU has IRQs off, we can clear out any pending
173 * IPIs and be sure that no more will come in after this.
174 */
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175 if (ppc_md.kexec_cpu_down)
176 ppc_md.kexec_cpu_down(0, 1);
fce0d574 177
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178 kexec_smp_wait();
179 /* NOTREACHED */
180}
181
1fc711f7 182static void kexec_prepare_cpus_wait(int wait_state)
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183{
184 int my_cpu, i, notified=-1;
185
5aae8a53 186 hw_breakpoint_disable();
fce0d574 187 my_cpu = get_cpu();
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188 /* Make sure each CPU has at least made it to the state we need.
189 *
190 * FIXME: There is a (slim) chance of a problem if not all of the CPUs
191 * are correctly onlined. If somehow we start a CPU on boot with RTAS
192 * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
193 * time, the boot CPU will timeout. If it does eventually execute
194 * stuff, the secondary will start up (paca[].cpu_start was written) and
195 * get into a peculiar state. If the platform supports
196 * smp_ops->take_timebase(), the secondary CPU will probably be spinning
197 * in there. If not (i.e. pseries), the secondary will continue on and
198 * try to online itself/idle/etc. If it survives that, we need to find
199 * these possible-but-not-online-but-should-be CPUs and chaperone them
200 * into kexec_smp_wait().
201 */
b636f137 202 for_each_online_cpu(i) {
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203 if (i == my_cpu)
204 continue;
205
1fc711f7 206 while (paca[i].kexec_state < wait_state) {
b3ca8093 207 barrier();
fce0d574 208 if (i != notified) {
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209 printk(KERN_INFO "kexec: waiting for cpu %d "
210 "(physical %d) to enter %i state\n",
211 i, paca[i].hw_cpu_id, wait_state);
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212 notified = i;
213 }
214 }
215 }
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216 mb();
217}
218
219static void kexec_prepare_cpus(void)
220{
221
222 smp_call_function(kexec_smp_down, NULL, /* wait */0);
223 local_irq_disable();
224 mb(); /* make sure IRQs are disabled before we say they are */
225 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
226
227 kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
228 /* we are sure every CPU has IRQs off at this point */
229 kexec_all_irq_disabled = 1;
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230
231 /* after we tell the others to go down */
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232 if (ppc_md.kexec_cpu_down)
233 ppc_md.kexec_cpu_down(0, 0);
fce0d574 234
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235 /*
236 * Before removing MMU mappings make sure all CPUs have entered real
237 * mode:
238 */
1fc711f7 239 kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
fce0d574 240
1fc711f7 241 put_cpu();
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242}
243
244#else /* ! SMP */
245
246static void kexec_prepare_cpus(void)
247{
248 /*
249 * move the secondarys to us so that we can copy
250 * the new kernel 0-0x100 safely
251 *
252 * do this if kexec in setup.c ?
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253 *
254 * We need to release the cpus if we are ever going from an
255 * UP to an SMP kernel.
fce0d574 256 */
75eedfed 257 smp_release_cpus();
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258 if (ppc_md.kexec_cpu_down)
259 ppc_md.kexec_cpu_down(0, 0);
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260 local_irq_disable();
261}
262
263#endif /* SMP */
264
265/*
266 * kexec thread structure and stack.
267 *
268 * We need to make sure that this is 16384-byte aligned due to the
269 * way process stacks are handled. It also must be statically allocated
270 * or allocated as part of the kimage, because everything else may be
271 * overwritten when we copy the kexec image. We piggyback on the
272 * "init_task" linker section here to statically allocate a stack.
273 *
274 * We could use a smaller stack if we don't care about anything using
275 * current, but that audit has not been performed.
276 */
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277static union thread_union kexec_stack __init_task_data =
278 { };
fce0d574 279
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280/*
281 * For similar reasons to the stack above, the kexecing CPU needs to be on a
282 * static PACA; we switch to kexec_paca.
283 */
284struct paca_struct kexec_paca;
285
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286/* Our assembly helper, in kexec_stub.S */
287extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
72414d3f 288 void *image, void *control,
1767c8f3 289 void (*clear_all)(void)) ATTRIB_NORET;
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290
291/* too late to fail here */
3d1229d6 292void default_machine_kexec(struct kimage *image)
fce0d574 293{
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294 /* prepare control code if any */
295
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296 /*
297 * If the kexec boot is the normal one, need to shutdown other cpus
298 * into our wait loop and quiesce interrupts.
299 * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
300 * stopping other CPUs and collecting their pt_regs is done before
301 * using debugger IPI.
302 */
303
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304 if (crashing_cpu == -1)
305 kexec_prepare_cpus();
fce0d574 306
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307 pr_debug("kexec: Starting switchover sequence.\n");
308
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309 /* switch to a staticly allocated stack. Based on irq stack code.
310 * XXX: the task struct will likely be invalid once we do the copy!
311 */
312 kexec_stack.thread_info.task = current_thread_info()->task;
313 kexec_stack.thread_info.flags = 0;
314
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315 /* We need a static PACA, too; copy this CPU's PACA over and switch to
316 * it. Also poison per_cpu_offset to catch anyone using non-static
317 * data.
318 */
319 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
320 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
321 paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
322 kexec_paca.paca_index;
323 setup_paca(&kexec_paca);
324
325 /* XXX: If anyone does 'dynamic lppacas' this will also need to be
326 * switched to a static version!
327 */
328
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329 /* Some things are best done in assembly. Finding globals with
330 * a toc is easier in C, so pass in what we can.
331 */
332 kexec_sequence(&kexec_stack, image->start, image,
333 page_address(image->control_code_page),
1767c8f3 334 ppc_md.hpte_clear_all);
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335 /* NOTREACHED */
336}
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337
338/* Values we need to export to the second kernel via the device tree. */
2e8e4f5b 339static unsigned long htab_base;
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340
341static struct property htab_base_prop = {
342 .name = "linux,htab-base",
343 .length = sizeof(unsigned long),
1a38147e 344 .value = &htab_base,
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345};
346
347static struct property htab_size_prop = {
348 .name = "linux,htab-size",
349 .length = sizeof(unsigned long),
1a38147e 350 .value = &htab_size_bytes,
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351};
352
6f29c329 353static int __init export_htab_values(void)
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354{
355 struct device_node *node;
ed7b2144 356 struct property *prop;
593e537b 357
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358 /* On machines with no htab htab_address is NULL */
359 if (!htab_address)
6f29c329 360 return -ENODEV;
2e8e4f5b 361
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362 node = of_find_node_by_path("/chosen");
363 if (!node)
6f29c329 364 return -ENODEV;
593e537b 365
ed7b2144 366 /* remove any stale propertys so ours can be found */
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367 prop = of_find_property(node, htab_base_prop.name, NULL);
368 if (prop)
369 prom_remove_property(node, prop);
370 prop = of_find_property(node, htab_size_prop.name, NULL);
371 if (prop)
372 prom_remove_property(node, prop);
373
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374 htab_base = __pa(htab_address);
375 prom_add_property(node, &htab_base_prop);
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376 prom_add_property(node, &htab_size_prop);
377
593e537b 378 of_node_put(node);
aa98c50d 379 return 0;
35dd5432 380}
6f29c329 381late_initcall(export_htab_values);