1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * PPC64 code to handle Linux booting another kernel.
4 *
5 * Copyright (C) 2004-2005, IBM Corp.
6 *
7 * Created by: Milton D Miller II
8 */
9
10
11 #include <linux/kexec.h>
12 #include <linux/smp.h>
13 #include <linux/thread_info.h>
14 #include <linux/init_task.h>
15 #include <linux/errno.h>
16 #include <linux/kernel.h>
17 #include <linux/cpu.h>
18 #include <linux/hardirq.h>
19 #include <linux/of.h>
20 #include <linux/libfdt.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/setup.h>
31 #include <asm/smp.h>
32 #include <asm/hw_breakpoint.h>
33 #include <asm/svm.h>
34 #include <asm/ultravisor.h>
35 #include <asm/crashdump-ppc64.h>
36
machine_kexec_prepare(struct kimage * image)37 int machine_kexec_prepare(struct kimage *image)
38 {
39 int i;
40 unsigned long begin, end; /* limits of segment */
41 unsigned long low, high; /* limits of blocked memory range */
42 struct device_node *node;
43 const unsigned long *basep;
44 const unsigned int *sizep;
45
46 /*
47 * Since we use the kernel fault handlers and paging code to
48 * handle the virtual mode, we must make sure no destination
49 * overlaps kernel static data or bss.
50 */
51 for (i = 0; i < image->nr_segments; i++)
52 if (image->segment[i].mem < __pa(_end))
53 return -ETXTBSY;
54
55 /* We also should not overwrite the tce tables */
56 for_each_node_by_type(node, "pci") {
57 basep = of_get_property(node, "linux,tce-base", NULL);
58 sizep = of_get_property(node, "linux,tce-size", NULL);
59 if (basep == NULL || sizep == NULL)
60 continue;
61
62 low = *basep;
63 high = low + (*sizep);
64
65 for (i = 0; i < image->nr_segments; i++) {
66 begin = image->segment[i].mem;
67 end = begin + image->segment[i].memsz;
68
69 if ((begin < high) && (end > low)) {
70 of_node_put(node);
71 return -ETXTBSY;
72 }
73 }
74 }
75
76 return 0;
77 }
78
79 /* Called during kexec sequence with MMU off */
copy_segments(unsigned long ind)80 static notrace void copy_segments(unsigned long ind)
81 {
82 unsigned long entry;
83 unsigned long *ptr;
84 void *dest;
85 void *addr;
86
87 /*
88 * We rely on kexec_load to create a lists that properly
89 * initializes these pointers before they are used.
90 * We will still crash if the list is wrong, but at least
91 * the compiler will be quiet.
92 */
93 ptr = NULL;
94 dest = NULL;
95
96 for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
97 addr = __va(entry & PAGE_MASK);
98
99 switch (entry & IND_FLAGS) {
100 case IND_DESTINATION:
101 dest = addr;
102 break;
103 case IND_INDIRECTION:
104 ptr = addr;
105 break;
106 case IND_SOURCE:
107 copy_page(dest, addr);
108 dest += PAGE_SIZE;
109 }
110 }
111 }
112
113 /* Called during kexec sequence with MMU off */
kexec_copy_flush(struct kimage * image)114 notrace void kexec_copy_flush(struct kimage *image)
115 {
116 long i, nr_segments = image->nr_segments;
117 struct kexec_segment ranges[KEXEC_SEGMENT_MAX];
118
119 /* save the ranges on the stack to efficiently flush the icache */
120 memcpy(ranges, image->segment, sizeof(ranges));
121
122 /*
123 * After this call we may not use anything allocated in dynamic
124 * memory, including *image.
125 *
126 * Only globals and the stack are allowed.
127 */
128 copy_segments(image->head);
129
130 /*
131 * we need to clear the icache for all dest pages sometime,
132 * including ones that were in place on the original copy
133 */
134 for (i = 0; i < nr_segments; i++)
135 flush_icache_range((unsigned long)__va(ranges[i].mem),
136 (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
137 }
138
139 #ifdef CONFIG_SMP
140
141 static int kexec_all_irq_disabled = 0;
142
kexec_smp_down(void * arg)143 static void kexec_smp_down(void *arg)
144 {
145 local_irq_disable();
146 hard_irq_disable();
147
148 mb(); /* make sure our irqs are disabled before we say they are */
149 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
150 while(kexec_all_irq_disabled == 0)
151 cpu_relax();
152 mb(); /* make sure all irqs are disabled before this */
153 hw_breakpoint_disable();
154 /*
155 * Now every CPU has IRQs off, we can clear out any pending
156 * IPIs and be sure that no more will come in after this.
157 */
158 if (ppc_md.kexec_cpu_down)
159 ppc_md.kexec_cpu_down(0, 1);
160
161 reset_sprs();
162
163 kexec_smp_wait();
164 /* NOTREACHED */
165 }
166
kexec_prepare_cpus_wait(int wait_state)167 static void kexec_prepare_cpus_wait(int wait_state)
168 {
169 int my_cpu, i, notified=-1;
170
171 hw_breakpoint_disable();
172 my_cpu = get_cpu();
173 /* Make sure each CPU has at least made it to the state we need.
174 *
175 * FIXME: There is a (slim) chance of a problem if not all of the CPUs
176 * are correctly onlined. If somehow we start a CPU on boot with RTAS
177 * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
178 * time, the boot CPU will timeout. If it does eventually execute
179 * stuff, the secondary will start up (paca_ptrs[]->cpu_start was
180 * written) and get into a peculiar state.
181 * If the platform supports smp_ops->take_timebase(), the secondary CPU
182 * will probably be spinning in there. If not (i.e. pseries), the
183 * secondary will continue on and try to online itself/idle/etc. If it
184 * survives that, we need to find these
185 * possible-but-not-online-but-should-be CPUs and chaperone them into
186 * kexec_smp_wait().
187 */
188 for_each_online_cpu(i) {
189 if (i == my_cpu)
190 continue;
191
192 while (paca_ptrs[i]->kexec_state < wait_state) {
193 barrier();
194 if (i != notified) {
195 printk(KERN_INFO "kexec: waiting for cpu %d "
196 "(physical %d) to enter %i state\n",
197 i, paca_ptrs[i]->hw_cpu_id, wait_state);
198 notified = i;
199 }
200 }
201 }
202 mb();
203 }
204
205
206 /*
207 * The add_cpu() call in wake_offline_cpus() can fail as cpu_bootable()
208 * returns false for CPUs that fail the cpu_smt_thread_allowed() check
209 * or non primary threads if SMT is disabled. Re-enable SMT and set the
210 * number of SMT threads to threads per core.
211 */
kexec_smt_reenable(void)212 static void kexec_smt_reenable(void)
213 {
214 #if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
215 lock_device_hotplug();
216 cpu_smt_num_threads = threads_per_core;
217 cpu_smt_control = CPU_SMT_ENABLED;
218 unlock_device_hotplug();
219 #endif
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 */
wake_offline_cpus(void)232 static void wake_offline_cpus(void)
233 {
234 int cpu = 0;
235
236 kexec_smt_reenable();
237
238 for_each_present_cpu(cpu) {
239 if (!cpu_online(cpu)) {
240 printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
241 cpu);
242 WARN_ON(add_cpu(cpu));
243 }
244 }
245 }
246
kexec_prepare_cpus(void)247 static void kexec_prepare_cpus(void)
248 {
249 wake_offline_cpus();
250 smp_call_function(kexec_smp_down, NULL, /* wait */0);
251 local_irq_disable();
252 hard_irq_disable();
253
254 mb(); /* make sure IRQs are disabled before we say they are */
255 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
256
257 kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
258 /* we are sure every CPU has IRQs off at this point */
259 kexec_all_irq_disabled = 1;
260
261 /*
262 * Before removing MMU mappings make sure all CPUs have entered real
263 * mode:
264 */
265 kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
266
267 /* after we tell the others to go down */
268 if (ppc_md.kexec_cpu_down)
269 ppc_md.kexec_cpu_down(0, 0);
270
271 put_cpu();
272 }
273
274 #else /* ! SMP */
275
kexec_prepare_cpus(void)276 static void kexec_prepare_cpus(void)
277 {
278 /*
279 * move the secondarys to us so that we can copy
280 * the new kernel 0-0x100 safely
281 *
282 * do this if kexec in setup.c ?
283 *
284 * We need to release the cpus if we are ever going from an
285 * UP to an SMP kernel.
286 */
287 smp_release_cpus();
288 if (ppc_md.kexec_cpu_down)
289 ppc_md.kexec_cpu_down(0, 0);
290 local_irq_disable();
291 hard_irq_disable();
292 }
293
294 #endif /* SMP */
295
296 /*
297 * kexec thread structure and stack.
298 *
299 * We need to make sure that this is 16384-byte aligned due to the
300 * way process stacks are handled. It also must be statically allocated
301 * or allocated as part of the kimage, because everything else may be
302 * overwritten when we copy the kexec image. We piggyback on the
303 * "init_task" linker section here to statically allocate a stack.
304 *
305 * We could use a smaller stack if we don't care about anything using
306 * current, but that audit has not been performed.
307 */
308 static union thread_union kexec_stack = { };
309
310 /*
311 * For similar reasons to the stack above, the kexecing CPU needs to be on a
312 * static PACA; we switch to kexec_paca.
313 */
314 static struct paca_struct kexec_paca;
315
316 /* Our assembly helper, in misc_64.S */
317 extern void kexec_sequence(void *newstack, unsigned long start,
318 void *image, void *control,
319 void (*clear_all)(void),
320 bool copy_with_mmu_off) __noreturn;
321
322 /* too late to fail here */
default_machine_kexec(struct kimage * image)323 void default_machine_kexec(struct kimage *image)
324 {
325 bool copy_with_mmu_off;
326
327 /* prepare control code if any */
328
329 /*
330 * If the kexec boot is the normal one, need to shutdown other cpus
331 * into our wait loop and quiesce interrupts.
332 * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
333 * stopping other CPUs and collecting their pt_regs is done before
334 * using debugger IPI.
335 */
336
337 if (!kdump_in_progress())
338 kexec_prepare_cpus();
339
340 #ifdef CONFIG_PPC_PSERIES
341 /*
342 * This must be done after other CPUs have shut down, otherwise they
343 * could execute the 'scv' instruction, which is not supported with
344 * reloc disabled (see configure_exceptions()).
345 */
346 if (firmware_has_feature(FW_FEATURE_SET_MODE))
347 pseries_disable_reloc_on_exc();
348 #endif
349
350 printk("kexec: Starting switchover sequence.\n");
351
352 /* switch to a staticly allocated stack. Based on irq stack code.
353 * We setup preempt_count to avoid using VMX in memcpy.
354 * XXX: the task struct will likely be invalid once we do the copy!
355 */
356 current_thread_info()->flags = 0;
357 current_thread_info()->preempt_count = HARDIRQ_OFFSET;
358
359 /* We need a static PACA, too; copy this CPU's PACA over and switch to
360 * it. Also poison per_cpu_offset and NULL lppaca to catch anyone using
361 * non-static data.
362 */
363 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
364 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
365 #ifdef CONFIG_PPC_PSERIES
366 kexec_paca.lppaca_ptr = NULL;
367 #endif
368
369 if (is_secure_guest() && !(image->preserve_context ||
370 image->type == KEXEC_TYPE_CRASH)) {
371 uv_unshare_all_pages();
372 printk("kexec: Unshared all shared pages.\n");
373 }
374
375 paca_ptrs[kexec_paca.paca_index] = &kexec_paca;
376
377 setup_paca(&kexec_paca);
378
379 /*
380 * The lppaca should be unregistered at this point so the HV won't
381 * touch it. In the case of a crash, none of the lppacas are
382 * unregistered so there is not much we can do about it here.
383 */
384
385 /*
386 * On Book3S, the copy must happen with the MMU off if we are either
387 * using Radix page tables or we are not in an LPAR since we can
388 * overwrite the page tables while copying.
389 *
390 * In an LPAR, we keep the MMU on otherwise we can't access beyond
391 * the RMA. On BookE there is no real MMU off mode, so we have to
392 * keep it enabled as well (but then we have bolted TLB entries).
393 */
394 #ifdef CONFIG_PPC_BOOK3E_64
395 copy_with_mmu_off = false;
396 #else
397 copy_with_mmu_off = radix_enabled() ||
398 !(firmware_has_feature(FW_FEATURE_LPAR) ||
399 firmware_has_feature(FW_FEATURE_PS3_LV1));
400 #endif
401
402 /* Some things are best done in assembly. Finding globals with
403 * a toc is easier in C, so pass in what we can.
404 */
405 kexec_sequence(&kexec_stack, image->start, image,
406 page_address(image->control_code_page),
407 mmu_cleanup_all, copy_with_mmu_off);
408 /* NOTREACHED */
409 }
410
411 #ifdef CONFIG_PPC_64S_HASH_MMU
412 /* Values we need to export to the second kernel via the device tree. */
413 static __be64 htab_base;
414 static __be64 htab_size;
415
416 static struct property htab_base_prop = {
417 .name = "linux,htab-base",
418 .length = sizeof(unsigned long),
419 .value = &htab_base,
420 };
421
422 static struct property htab_size_prop = {
423 .name = "linux,htab-size",
424 .length = sizeof(unsigned long),
425 .value = &htab_size,
426 };
427
export_htab_values(void)428 static int __init export_htab_values(void)
429 {
430 struct device_node *node;
431
432 /* On machines with no htab htab_address is NULL */
433 if (!htab_address)
434 return -ENODEV;
435
436 node = of_find_node_by_path("/chosen");
437 if (!node)
438 return -ENODEV;
439
440 /* remove any stale properties so ours can be found */
441 of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
442 of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
443
444 htab_base = cpu_to_be64(__pa(htab_address));
445 of_add_property(node, &htab_base_prop);
446 htab_size = cpu_to_be64(htab_size_bytes);
447 of_add_property(node, &htab_size_prop);
448
449 of_node_put(node);
450 return 0;
451 }
452 late_initcall(export_htab_values);
453 #endif /* CONFIG_PPC_64S_HASH_MMU */
454
455 #if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP)
456 /**
457 * add_node_props - Reads node properties from device node structure and add
458 * them to fdt.
459 * @fdt: Flattened device tree of the kernel
460 * @node_offset: offset of the node to add a property at
461 * @dn: device node pointer
462 *
463 * Returns 0 on success, negative errno on error.
464 */
add_node_props(void * fdt,int node_offset,const struct device_node * dn)465 static int add_node_props(void *fdt, int node_offset, const struct device_node *dn)
466 {
467 int ret = 0;
468 struct property *pp;
469
470 if (!dn)
471 return -EINVAL;
472
473 for_each_property_of_node(dn, pp) {
474 ret = fdt_setprop(fdt, node_offset, pp->name, pp->value, pp->length);
475 if (ret < 0) {
476 pr_err("Unable to add %s property: %s\n", pp->name, fdt_strerror(ret));
477 return ret;
478 }
479 }
480 return ret;
481 }
482
483 /**
484 * update_cpus_node - Update cpus node of flattened device tree using of_root
485 * device node.
486 * @fdt: Flattened device tree of the kernel.
487 *
488 * Returns 0 on success, negative errno on error.
489 *
490 * Note: expecting no subnodes under /cpus/<node> with device_type == "cpu".
491 * If this changes, update this function to include them.
492 */
update_cpus_node(void * fdt)493 int update_cpus_node(void *fdt)
494 {
495 int prev_node_offset;
496 const char *device_type;
497 const struct fdt_property *prop;
498 struct device_node *cpus_node, *dn;
499 int cpus_offset, cpus_subnode_offset, ret = 0;
500
501 cpus_offset = fdt_path_offset(fdt, "/cpus");
502 if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
503 pr_err("Malformed device tree: error reading /cpus node: %s\n",
504 fdt_strerror(cpus_offset));
505 return cpus_offset;
506 }
507
508 prev_node_offset = cpus_offset;
509 /* Delete sub-nodes of /cpus node with device_type == "cpu" */
510 for (cpus_subnode_offset = fdt_first_subnode(fdt, cpus_offset); cpus_subnode_offset >= 0;) {
511 /* Ignore nodes that do not have a device_type property or device_type != "cpu" */
512 prop = fdt_get_property(fdt, cpus_subnode_offset, "device_type", NULL);
513 if (!prop || strcmp(prop->data, "cpu")) {
514 prev_node_offset = cpus_subnode_offset;
515 goto next_node;
516 }
517
518 ret = fdt_del_node(fdt, cpus_subnode_offset);
519 if (ret < 0) {
520 pr_err("Failed to delete a cpus sub-node: %s\n", fdt_strerror(ret));
521 return ret;
522 }
523 next_node:
524 if (prev_node_offset == cpus_offset)
525 cpus_subnode_offset = fdt_first_subnode(fdt, cpus_offset);
526 else
527 cpus_subnode_offset = fdt_next_subnode(fdt, prev_node_offset);
528 }
529
530 cpus_node = of_find_node_by_path("/cpus");
531 /* Fail here to avoid kexec/kdump kernel boot hung */
532 if (!cpus_node) {
533 pr_err("No /cpus node found\n");
534 return -EINVAL;
535 }
536
537 /* Add all /cpus sub-nodes of device_type == "cpu" to FDT */
538 for_each_child_of_node(cpus_node, dn) {
539 /* Ignore device nodes that do not have a device_type property
540 * or device_type != "cpu".
541 */
542 device_type = of_get_property(dn, "device_type", NULL);
543 if (!device_type || strcmp(device_type, "cpu"))
544 continue;
545
546 cpus_subnode_offset = fdt_add_subnode(fdt, cpus_offset, dn->full_name);
547 if (cpus_subnode_offset < 0) {
548 pr_err("Unable to add %s subnode: %s\n", dn->full_name,
549 fdt_strerror(cpus_subnode_offset));
550 ret = cpus_subnode_offset;
551 goto out;
552 }
553
554 ret = add_node_props(fdt, cpus_subnode_offset, dn);
555 if (ret < 0)
556 goto out;
557 }
558 out:
559 of_node_put(cpus_node);
560 of_node_put(dn);
561 return ret;
562 }
563 #endif /* CONFIG_KEXEC_FILE || CONFIG_CRASH_DUMP */
564