1 /*
2 * PPC64 code to handle Linux booting another kernel.
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
13 #include <linux/kexec.h>
14 #include <linux/smp.h>
15 #include <linux/thread_info.h>
16 #include <linux/init_task.h>
17 #include <linux/errno.h>
18 #include <linux/kernel.h>
19 #include <linux/cpu.h>
20 #include <linux/hardirq.h>
21
22 #include <asm/page.h>
23 #include <asm/current.h>
24 #include <asm/machdep.h>
25 #include <asm/cacheflush.h>
26 #include <asm/firmware.h>
27 #include <asm/paca.h>
28 #include <asm/mmu.h>
29 #include <asm/sections.h> /* _end */
30 #include <asm/prom.h>
31 #include <asm/smp.h>
32 #include <asm/hw_breakpoint.h>
33 #include <asm/asm-prototypes.h>
34
default_machine_kexec_prepare(struct kimage * image)35 int default_machine_kexec_prepare(struct kimage *image)
36 {
37 int i;
38 unsigned long begin, end; /* limits of segment */
39 unsigned long low, high; /* limits of blocked memory range */
40 struct device_node *node;
41 const unsigned long *basep;
42 const unsigned int *sizep;
43
44 /*
45 * Since we use the kernel fault handlers and paging code to
46 * handle the virtual mode, we must make sure no destination
47 * overlaps kernel static data or bss.
48 */
49 for (i = 0; i < image->nr_segments; i++)
50 if (image->segment[i].mem < __pa(_end))
51 return -ETXTBSY;
52
53 /* We also should not overwrite the tce tables */
54 for_each_node_by_type(node, "pci") {
55 basep = of_get_property(node, "linux,tce-base", NULL);
56 sizep = of_get_property(node, "linux,tce-size", NULL);
57 if (basep == NULL || sizep == NULL)
58 continue;
59
60 low = *basep;
61 high = low + (*sizep);
62
63 for (i = 0; i < image->nr_segments; i++) {
64 begin = image->segment[i].mem;
65 end = begin + image->segment[i].memsz;
66
67 if ((begin < high) && (end > low))
68 return -ETXTBSY;
69 }
70 }
71
72 return 0;
73 }
74
copy_segments(unsigned long ind)75 static void copy_segments(unsigned long ind)
76 {
77 unsigned long entry;
78 unsigned long *ptr;
79 void *dest;
80 void *addr;
81
82 /*
83 * We rely on kexec_load to create a lists that properly
84 * initializes these pointers before they are used.
85 * We will still crash if the list is wrong, but at least
86 * the compiler will be quiet.
87 */
88 ptr = NULL;
89 dest = NULL;
90
91 for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
92 addr = __va(entry & PAGE_MASK);
93
94 switch (entry & IND_FLAGS) {
95 case IND_DESTINATION:
96 dest = addr;
97 break;
98 case IND_INDIRECTION:
99 ptr = addr;
100 break;
101 case IND_SOURCE:
102 copy_page(dest, addr);
103 dest += PAGE_SIZE;
104 }
105 }
106 }
107
kexec_copy_flush(struct kimage * image)108 void kexec_copy_flush(struct kimage *image)
109 {
110 long i, nr_segments = image->nr_segments;
111 struct kexec_segment ranges[KEXEC_SEGMENT_MAX];
112
113 /* save the ranges on the stack to efficiently flush the icache */
114 memcpy(ranges, image->segment, sizeof(ranges));
115
116 /*
117 * After this call we may not use anything allocated in dynamic
118 * memory, including *image.
119 *
120 * Only globals and the stack are allowed.
121 */
122 copy_segments(image->head);
123
124 /*
125 * we need to clear the icache for all dest pages sometime,
126 * including ones that were in place on the original copy
127 */
128 for (i = 0; i < nr_segments; i++)
129 flush_icache_range((unsigned long)__va(ranges[i].mem),
130 (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
131 }
132
133 #ifdef CONFIG_SMP
134
135 static int kexec_all_irq_disabled = 0;
136
kexec_smp_down(void * arg)137 static void kexec_smp_down(void *arg)
138 {
139 local_irq_disable();
140 hard_irq_disable();
141
142 mb(); /* make sure our irqs are disabled before we say they are */
143 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
144 while(kexec_all_irq_disabled == 0)
145 cpu_relax();
146 mb(); /* make sure all irqs are disabled before this */
147 hw_breakpoint_disable();
148 /*
149 * Now every CPU has IRQs off, we can clear out any pending
150 * IPIs and be sure that no more will come in after this.
151 */
152 if (ppc_md.kexec_cpu_down)
153 ppc_md.kexec_cpu_down(0, 1);
154
155 kexec_smp_wait();
156 /* NOTREACHED */
157 }
158
kexec_prepare_cpus_wait(int wait_state)159 static void kexec_prepare_cpus_wait(int wait_state)
160 {
161 int my_cpu, i, notified=-1;
162
163 hw_breakpoint_disable();
164 my_cpu = get_cpu();
165 /* Make sure each CPU has at least made it to the state we need.
166 *
167 * FIXME: There is a (slim) chance of a problem if not all of the CPUs
168 * are correctly onlined. If somehow we start a CPU on boot with RTAS
169 * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
170 * time, the boot CPU will timeout. If it does eventually execute
171 * stuff, the secondary will start up (paca[].cpu_start was written) and
172 * get into a peculiar state. If the platform supports
173 * smp_ops->take_timebase(), the secondary CPU will probably be spinning
174 * in there. If not (i.e. pseries), the secondary will continue on and
175 * try to online itself/idle/etc. If it survives that, we need to find
176 * these possible-but-not-online-but-should-be CPUs and chaperone them
177 * into kexec_smp_wait().
178 */
179 for_each_online_cpu(i) {
180 if (i == my_cpu)
181 continue;
182
183 while (paca[i].kexec_state < wait_state) {
184 barrier();
185 if (i != notified) {
186 printk(KERN_INFO "kexec: waiting for cpu %d "
187 "(physical %d) to enter %i state\n",
188 i, paca[i].hw_cpu_id, wait_state);
189 notified = i;
190 }
191 }
192 }
193 mb();
194 }
195
196 /*
197 * We need to make sure each present CPU is online. The next kernel will scan
198 * the device tree and assume primary threads are online and query secondary
199 * threads via RTAS to online them if required. If we don't online primary
200 * threads, they will be stuck. However, we also online secondary threads as we
201 * may be using 'cede offline'. In this case RTAS doesn't see the secondary
202 * threads as offline -- and again, these CPUs will be stuck.
203 *
204 * So, we online all CPUs that should be running, including secondary threads.
205 */
wake_offline_cpus(void)206 static void wake_offline_cpus(void)
207 {
208 int cpu = 0;
209
210 for_each_present_cpu(cpu) {
211 if (!cpu_online(cpu)) {
212 printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
213 cpu);
214 WARN_ON(cpu_up(cpu));
215 }
216 }
217 }
218
kexec_prepare_cpus(void)219 static void kexec_prepare_cpus(void)
220 {
221 wake_offline_cpus();
222 smp_call_function(kexec_smp_down, NULL, /* wait */0);
223 local_irq_disable();
224 hard_irq_disable();
225
226 mb(); /* make sure IRQs are disabled before we say they are */
227 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
228
229 kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
230 /* we are sure every CPU has IRQs off at this point */
231 kexec_all_irq_disabled = 1;
232
233 /* after we tell the others to go down */
234 if (ppc_md.kexec_cpu_down)
235 ppc_md.kexec_cpu_down(0, 0);
236
237 /*
238 * Before removing MMU mappings make sure all CPUs have entered real
239 * mode:
240 */
241 kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
242
243 put_cpu();
244 }
245
246 #else /* ! SMP */
247
kexec_prepare_cpus(void)248 static void kexec_prepare_cpus(void)
249 {
250 /*
251 * move the secondarys to us so that we can copy
252 * the new kernel 0-0x100 safely
253 *
254 * do this if kexec in setup.c ?
255 *
256 * We need to release the cpus if we are ever going from an
257 * UP to an SMP kernel.
258 */
259 smp_release_cpus();
260 if (ppc_md.kexec_cpu_down)
261 ppc_md.kexec_cpu_down(0, 0);
262 local_irq_disable();
263 hard_irq_disable();
264 }
265
266 #endif /* SMP */
267
268 /*
269 * kexec thread structure and stack.
270 *
271 * We need to make sure that this is 16384-byte aligned due to the
272 * way process stacks are handled. It also must be statically allocated
273 * or allocated as part of the kimage, because everything else may be
274 * overwritten when we copy the kexec image. We piggyback on the
275 * "init_task" linker section here to statically allocate a stack.
276 *
277 * We could use a smaller stack if we don't care about anything using
278 * current, but that audit has not been performed.
279 */
280 static union thread_union kexec_stack __init_task_data =
281 { };
282
283 /*
284 * For similar reasons to the stack above, the kexecing CPU needs to be on a
285 * static PACA; we switch to kexec_paca.
286 */
287 struct paca_struct kexec_paca;
288
289 /* Our assembly helper, in misc_64.S */
290 extern void kexec_sequence(void *newstack, unsigned long start,
291 void *image, void *control,
292 void (*clear_all)(void),
293 bool copy_with_mmu_off) __noreturn;
294
295 /* too late to fail here */
default_machine_kexec(struct kimage * image)296 void default_machine_kexec(struct kimage *image)
297 {
298 bool copy_with_mmu_off;
299
300 /* prepare control code if any */
301
302 /*
303 * If the kexec boot is the normal one, need to shutdown other cpus
304 * into our wait loop and quiesce interrupts.
305 * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
306 * stopping other CPUs and collecting their pt_regs is done before
307 * using debugger IPI.
308 */
309
310 if (!kdump_in_progress())
311 kexec_prepare_cpus();
312
313 printk("kexec: Starting switchover sequence.\n");
314
315 /* switch to a staticly allocated stack. Based on irq stack code.
316 * We setup preempt_count to avoid using VMX in memcpy.
317 * XXX: the task struct will likely be invalid once we do the copy!
318 */
319 kexec_stack.thread_info.task = current_thread_info()->task;
320 kexec_stack.thread_info.flags = 0;
321 kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
322 kexec_stack.thread_info.cpu = current_thread_info()->cpu;
323
324 /* We need a static PACA, too; copy this CPU's PACA over and switch to
325 * it. Also poison per_cpu_offset to catch anyone using non-static
326 * data.
327 */
328 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
329 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
330 paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
331 kexec_paca.paca_index;
332 setup_paca(&kexec_paca);
333
334 /* XXX: If anyone does 'dynamic lppacas' this will also need to be
335 * switched to a static version!
336 */
337 /*
338 * On Book3S, the copy must happen with the MMU off if we are either
339 * using Radix page tables or we are not in an LPAR since we can
340 * overwrite the page tables while copying.
341 *
342 * In an LPAR, we keep the MMU on otherwise we can't access beyond
343 * the RMA. On BookE there is no real MMU off mode, so we have to
344 * keep it enabled as well (but then we have bolted TLB entries).
345 */
346 #ifdef CONFIG_PPC_BOOK3E
347 copy_with_mmu_off = false;
348 #else
349 copy_with_mmu_off = radix_enabled() ||
350 !(firmware_has_feature(FW_FEATURE_LPAR) ||
351 firmware_has_feature(FW_FEATURE_PS3_LV1));
352 #endif
353
354 /* Some things are best done in assembly. Finding globals with
355 * a toc is easier in C, so pass in what we can.
356 */
357 kexec_sequence(&kexec_stack, image->start, image,
358 page_address(image->control_code_page),
359 mmu_cleanup_all, copy_with_mmu_off);
360 /* NOTREACHED */
361 }
362
363 #ifdef CONFIG_PPC_STD_MMU_64
364 /* Values we need to export to the second kernel via the device tree. */
365 static unsigned long htab_base;
366 static unsigned long htab_size;
367
368 static struct property htab_base_prop = {
369 .name = "linux,htab-base",
370 .length = sizeof(unsigned long),
371 .value = &htab_base,
372 };
373
374 static struct property htab_size_prop = {
375 .name = "linux,htab-size",
376 .length = sizeof(unsigned long),
377 .value = &htab_size,
378 };
379
export_htab_values(void)380 static int __init export_htab_values(void)
381 {
382 struct device_node *node;
383
384 /* On machines with no htab htab_address is NULL */
385 if (!htab_address)
386 return -ENODEV;
387
388 node = of_find_node_by_path("/chosen");
389 if (!node)
390 return -ENODEV;
391
392 /* remove any stale propertys so ours can be found */
393 of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
394 of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
395
396 htab_base = cpu_to_be64(__pa(htab_address));
397 of_add_property(node, &htab_base_prop);
398 htab_size = cpu_to_be64(htab_size_bytes);
399 of_add_property(node, &htab_size_prop);
400
401 of_node_put(node);
402 return 0;
403 }
404 late_initcall(export_htab_values);
405 #endif /* CONFIG_PPC_STD_MMU_64 */
406