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Linux/arch/powerpc/kernel/machine_kexec_64.c

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  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/paca.h>
 27 #include <asm/mmu.h>
 28 #include <asm/sections.h>       /* _end */
 29 #include <asm/prom.h>
 30 #include <asm/smp.h>
 31 #include <asm/hw_breakpoint.h>
 32 
 33 int default_machine_kexec_prepare(struct kimage *image)
 34 {
 35         int i;
 36         unsigned long begin, end;       /* limits of segment */
 37         unsigned long low, high;        /* limits of blocked memory range */
 38         struct device_node *node;
 39         const unsigned long *basep;
 40         const unsigned int *sizep;
 41 
 42         if (!ppc_md.hpte_clear_all)
 43                 return -ENOENT;
 44 
 45         /*
 46          * Since we use the kernel fault handlers and paging code to
 47          * handle the virtual mode, we must make sure no destination
 48          * overlaps kernel static data or bss.
 49          */
 50         for (i = 0; i < image->nr_segments; i++)
 51                 if (image->segment[i].mem < __pa(_end))
 52                         return -ETXTBSY;
 53 
 54         /*
 55          * For non-LPAR, we absolutely can not overwrite the mmu hash
 56          * table, since we are still using the bolted entries in it to
 57          * do the copy.  Check that here.
 58          *
 59          * It is safe if the end is below the start of the blocked
 60          * region (end <= low), or if the beginning is after the
 61          * end of the blocked region (begin >= high).  Use the
 62          * boolean identity !(a || b)  === (!a && !b).
 63          */
 64         if (htab_address) {
 65                 low = __pa(htab_address);
 66                 high = low + htab_size_bytes;
 67 
 68                 for (i = 0; i < image->nr_segments; i++) {
 69                         begin = image->segment[i].mem;
 70                         end = begin + image->segment[i].memsz;
 71 
 72                         if ((begin < high) && (end > low))
 73                                 return -ETXTBSY;
 74                 }
 75         }
 76 
 77         /* We also should not overwrite the tce tables */
 78         for_each_node_by_type(node, "pci") {
 79                 basep = of_get_property(node, "linux,tce-base", NULL);
 80                 sizep = of_get_property(node, "linux,tce-size", NULL);
 81                 if (basep == NULL || sizep == NULL)
 82                         continue;
 83 
 84                 low = *basep;
 85                 high = low + (*sizep);
 86 
 87                 for (i = 0; i < image->nr_segments; i++) {
 88                         begin = image->segment[i].mem;
 89                         end = begin + image->segment[i].memsz;
 90 
 91                         if ((begin < high) && (end > low))
 92                                 return -ETXTBSY;
 93                 }
 94         }
 95 
 96         return 0;
 97 }
 98 
 99 #define IND_FLAGS (IND_DESTINATION | IND_INDIRECTION | IND_DONE | IND_SOURCE)
100 
101 static void copy_segments(unsigned long ind)
102 {
103         unsigned long entry;
104         unsigned long *ptr;
105         void *dest;
106         void *addr;
107 
108         /*
109          * We rely on kexec_load to create a lists that properly
110          * initializes these pointers before they are used.
111          * We will still crash if the list is wrong, but at least
112          * the compiler will be quiet.
113          */
114         ptr = NULL;
115         dest = NULL;
116 
117         for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
118                 addr = __va(entry & PAGE_MASK);
119 
120                 switch (entry & IND_FLAGS) {
121                 case IND_DESTINATION:
122                         dest = addr;
123                         break;
124                 case IND_INDIRECTION:
125                         ptr = addr;
126                         break;
127                 case IND_SOURCE:
128                         copy_page(dest, addr);
129                         dest += PAGE_SIZE;
130                 }
131         }
132 }
133 
134 void kexec_copy_flush(struct kimage *image)
135 {
136         long i, nr_segments = image->nr_segments;
137         struct  kexec_segment ranges[KEXEC_SEGMENT_MAX];
138 
139         /* save the ranges on the stack to efficiently flush the icache */
140         memcpy(ranges, image->segment, sizeof(ranges));
141 
142         /*
143          * After this call we may not use anything allocated in dynamic
144          * memory, including *image.
145          *
146          * Only globals and the stack are allowed.
147          */
148         copy_segments(image->head);
149 
150         /*
151          * we need to clear the icache for all dest pages sometime,
152          * including ones that were in place on the original copy
153          */
154         for (i = 0; i < nr_segments; i++)
155                 flush_icache_range((unsigned long)__va(ranges[i].mem),
156                         (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
157 }
158 
159 #ifdef CONFIG_SMP
160 
161 static int kexec_all_irq_disabled = 0;
162 
163 static void kexec_smp_down(void *arg)
164 {
165         local_irq_disable();
166         hard_irq_disable();
167 
168         mb(); /* make sure our irqs are disabled before we say they are */
169         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
170         while(kexec_all_irq_disabled == 0)
171                 cpu_relax();
172         mb(); /* make sure all irqs are disabled before this */
173         hw_breakpoint_disable();
174         /*
175          * Now every CPU has IRQs off, we can clear out any pending
176          * IPIs and be sure that no more will come in after this.
177          */
178         if (ppc_md.kexec_cpu_down)
179                 ppc_md.kexec_cpu_down(0, 1);
180 
181         kexec_smp_wait();
182         /* NOTREACHED */
183 }
184 
185 static void kexec_prepare_cpus_wait(int wait_state)
186 {
187         int my_cpu, i, notified=-1;
188 
189         hw_breakpoint_disable();
190         my_cpu = get_cpu();
191         /* Make sure each CPU has at least made it to the state we need.
192          *
193          * FIXME: There is a (slim) chance of a problem if not all of the CPUs
194          * are correctly onlined.  If somehow we start a CPU on boot with RTAS
195          * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
196          * time, the boot CPU will timeout.  If it does eventually execute
197          * stuff, the secondary will start up (paca[].cpu_start was written) and
198          * get into a peculiar state.  If the platform supports
199          * smp_ops->take_timebase(), the secondary CPU will probably be spinning
200          * in there.  If not (i.e. pseries), the secondary will continue on and
201          * try to online itself/idle/etc. If it survives that, we need to find
202          * these possible-but-not-online-but-should-be CPUs and chaperone them
203          * into kexec_smp_wait().
204          */
205         for_each_online_cpu(i) {
206                 if (i == my_cpu)
207                         continue;
208 
209                 while (paca[i].kexec_state < wait_state) {
210                         barrier();
211                         if (i != notified) {
212                                 printk(KERN_INFO "kexec: waiting for cpu %d "
213                                        "(physical %d) to enter %i state\n",
214                                        i, paca[i].hw_cpu_id, wait_state);
215                                 notified = i;
216                         }
217                 }
218         }
219         mb();
220 }
221 
222 /*
223  * We need to make sure each present CPU is online.  The next kernel will scan
224  * the device tree and assume primary threads are online and query secondary
225  * threads via RTAS to online them if required.  If we don't online primary
226  * threads, they will be stuck.  However, we also online secondary threads as we
227  * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
228  * threads as offline -- and again, these CPUs will be stuck.
229  *
230  * So, we online all CPUs that should be running, including secondary threads.
231  */
232 static void wake_offline_cpus(void)
233 {
234         int cpu = 0;
235 
236         for_each_present_cpu(cpu) {
237                 if (!cpu_online(cpu)) {
238                         printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
239                                cpu);
240                         cpu_up(cpu);
241                 }
242         }
243 }
244 
245 static void kexec_prepare_cpus(void)
246 {
247         wake_offline_cpus();
248         smp_call_function(kexec_smp_down, NULL, /* wait */0);
249         local_irq_disable();
250         hard_irq_disable();
251 
252         mb(); /* make sure IRQs are disabled before we say they are */
253         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
254 
255         kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
256         /* we are sure every CPU has IRQs off at this point */
257         kexec_all_irq_disabled = 1;
258 
259         /* after we tell the others to go down */
260         if (ppc_md.kexec_cpu_down)
261                 ppc_md.kexec_cpu_down(0, 0);
262 
263         /*
264          * Before removing MMU mappings make sure all CPUs have entered real
265          * mode:
266          */
267         kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
268 
269         put_cpu();
270 }
271 
272 #else /* ! SMP */
273 
274 static void kexec_prepare_cpus(void)
275 {
276         /*
277          * move the secondarys to us so that we can copy
278          * the new kernel 0-0x100 safely
279          *
280          * do this if kexec in setup.c ?
281          *
282          * We need to release the cpus if we are ever going from an
283          * UP to an SMP kernel.
284          */
285         smp_release_cpus();
286         if (ppc_md.kexec_cpu_down)
287                 ppc_md.kexec_cpu_down(0, 0);
288         local_irq_disable();
289         hard_irq_disable();
290 }
291 
292 #endif /* SMP */
293 
294 /*
295  * kexec thread structure and stack.
296  *
297  * We need to make sure that this is 16384-byte aligned due to the
298  * way process stacks are handled.  It also must be statically allocated
299  * or allocated as part of the kimage, because everything else may be
300  * overwritten when we copy the kexec image.  We piggyback on the
301  * "init_task" linker section here to statically allocate a stack.
302  *
303  * We could use a smaller stack if we don't care about anything using
304  * current, but that audit has not been performed.
305  */
306 static union thread_union kexec_stack __init_task_data =
307         { };
308 
309 /*
310  * For similar reasons to the stack above, the kexecing CPU needs to be on a
311  * static PACA; we switch to kexec_paca.
312  */
313 struct paca_struct kexec_paca;
314 
315 /* Our assembly helper, in kexec_stub.S */
316 extern void kexec_sequence(void *newstack, unsigned long start,
317                            void *image, void *control,
318                            void (*clear_all)(void)) __noreturn;
319 
320 /* too late to fail here */
321 void default_machine_kexec(struct kimage *image)
322 {
323         /* prepare control code if any */
324 
325         /*
326         * If the kexec boot is the normal one, need to shutdown other cpus
327         * into our wait loop and quiesce interrupts.
328         * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
329         * stopping other CPUs and collecting their pt_regs is done before
330         * using debugger IPI.
331         */
332 
333         if (crashing_cpu == -1)
334                 kexec_prepare_cpus();
335 
336         pr_debug("kexec: Starting switchover sequence.\n");
337 
338         /* switch to a staticly allocated stack.  Based on irq stack code.
339          * We setup preempt_count to avoid using VMX in memcpy.
340          * XXX: the task struct will likely be invalid once we do the copy!
341          */
342         kexec_stack.thread_info.task = current_thread_info()->task;
343         kexec_stack.thread_info.flags = 0;
344         kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
345         kexec_stack.thread_info.cpu = current_thread_info()->cpu;
346 
347         /* We need a static PACA, too; copy this CPU's PACA over and switch to
348          * it.  Also poison per_cpu_offset to catch anyone using non-static
349          * data.
350          */
351         memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
352         kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
353         paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
354                 kexec_paca.paca_index;
355         setup_paca(&kexec_paca);
356 
357         /* XXX: If anyone does 'dynamic lppacas' this will also need to be
358          * switched to a static version!
359          */
360 
361         /* Some things are best done in assembly.  Finding globals with
362          * a toc is easier in C, so pass in what we can.
363          */
364         kexec_sequence(&kexec_stack, image->start, image,
365                         page_address(image->control_code_page),
366                         ppc_md.hpte_clear_all);
367         /* NOTREACHED */
368 }
369 
370 /* Values we need to export to the second kernel via the device tree. */
371 static unsigned long htab_base;
372 
373 static struct property htab_base_prop = {
374         .name = "linux,htab-base",
375         .length = sizeof(unsigned long),
376         .value = &htab_base,
377 };
378 
379 static struct property htab_size_prop = {
380         .name = "linux,htab-size",
381         .length = sizeof(unsigned long),
382         .value = &htab_size_bytes,
383 };
384 
385 static int __init export_htab_values(void)
386 {
387         struct device_node *node;
388         struct property *prop;
389 
390         /* On machines with no htab htab_address is NULL */
391         if (!htab_address)
392                 return -ENODEV;
393 
394         node = of_find_node_by_path("/chosen");
395         if (!node)
396                 return -ENODEV;
397 
398         /* remove any stale propertys so ours can be found */
399         prop = of_find_property(node, htab_base_prop.name, NULL);
400         if (prop)
401                 of_remove_property(node, prop);
402         prop = of_find_property(node, htab_size_prop.name, NULL);
403         if (prop)
404                 of_remove_property(node, prop);
405 
406         htab_base = __pa(htab_address);
407         of_add_property(node, &htab_base_prop);
408         of_add_property(node, &htab_size_prop);
409 
410         of_node_put(node);
411         return 0;
412 }
413 late_initcall(export_htab_values);
414 

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