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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/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 
 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 
 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 
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 
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 
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  */
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 
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 
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 */
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_BOOK3S_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 
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_BOOK3S_64 */
406 

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