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
37int 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, name: "linux,tce-base", NULL);
58 sizep = of_get_property(node, name: "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 */
80static 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(to: dest, from: addr);
108 dest += PAGE_SIZE;
109 }
110 }
111}
112
113/* Called during kexec sequence with MMU off */
114notrace 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(ind: 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(start: (unsigned long)__va(ranges[i].mem),
136 end: (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
137}
138
139#ifdef CONFIG_SMP
140
141static int kexec_all_irq_disabled = 0;
142
143static 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
167static 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 * We need to make sure each present CPU is online. The next kernel will scan
207 * the device tree and assume primary threads are online and query secondary
208 * threads via RTAS to online them if required. If we don't online primary
209 * threads, they will be stuck. However, we also online secondary threads as we
210 * may be using 'cede offline'. In this case RTAS doesn't see the secondary
211 * threads as offline -- and again, these CPUs will be stuck.
212 *
213 * So, we online all CPUs that should be running, including secondary threads.
214 */
215static void wake_offline_cpus(void)
216{
217 int cpu = 0;
218
219 for_each_present_cpu(cpu) {
220 if (!cpu_online(cpu)) {
221 printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
222 cpu);
223 WARN_ON(add_cpu(cpu));
224 }
225 }
226}
227
228static void kexec_prepare_cpus(void)
229{
230 wake_offline_cpus();
231 smp_call_function(func: kexec_smp_down, NULL, /* wait */0);
232 local_irq_disable();
233 hard_irq_disable();
234
235 mb(); /* make sure IRQs are disabled before we say they are */
236 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
237
238 kexec_prepare_cpus_wait(wait_state: KEXEC_STATE_IRQS_OFF);
239 /* we are sure every CPU has IRQs off at this point */
240 kexec_all_irq_disabled = 1;
241
242 /*
243 * Before removing MMU mappings make sure all CPUs have entered real
244 * mode:
245 */
246 kexec_prepare_cpus_wait(wait_state: KEXEC_STATE_REAL_MODE);
247
248 /* after we tell the others to go down */
249 if (ppc_md.kexec_cpu_down)
250 ppc_md.kexec_cpu_down(0, 0);
251
252 put_cpu();
253}
254
255#else /* ! SMP */
256
257static void kexec_prepare_cpus(void)
258{
259 /*
260 * move the secondarys to us so that we can copy
261 * the new kernel 0-0x100 safely
262 *
263 * do this if kexec in setup.c ?
264 *
265 * We need to release the cpus if we are ever going from an
266 * UP to an SMP kernel.
267 */
268 smp_release_cpus();
269 if (ppc_md.kexec_cpu_down)
270 ppc_md.kexec_cpu_down(0, 0);
271 local_irq_disable();
272 hard_irq_disable();
273}
274
275#endif /* SMP */
276
277/*
278 * kexec thread structure and stack.
279 *
280 * We need to make sure that this is 16384-byte aligned due to the
281 * way process stacks are handled. It also must be statically allocated
282 * or allocated as part of the kimage, because everything else may be
283 * overwritten when we copy the kexec image. We piggyback on the
284 * "init_task" linker section here to statically allocate a stack.
285 *
286 * We could use a smaller stack if we don't care about anything using
287 * current, but that audit has not been performed.
288 */
289static union thread_union kexec_stack = { };
290
291/*
292 * For similar reasons to the stack above, the kexecing CPU needs to be on a
293 * static PACA; we switch to kexec_paca.
294 */
295static struct paca_struct kexec_paca;
296
297/* Our assembly helper, in misc_64.S */
298extern void kexec_sequence(void *newstack, unsigned long start,
299 void *image, void *control,
300 void (*clear_all)(void),
301 bool copy_with_mmu_off) __noreturn;
302
303/* too late to fail here */
304void default_machine_kexec(struct kimage *image)
305{
306 bool copy_with_mmu_off;
307
308 /* prepare control code if any */
309
310 /*
311 * If the kexec boot is the normal one, need to shutdown other cpus
312 * into our wait loop and quiesce interrupts.
313 * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
314 * stopping other CPUs and collecting their pt_regs is done before
315 * using debugger IPI.
316 */
317
318 if (!kdump_in_progress())
319 kexec_prepare_cpus();
320
321#ifdef CONFIG_PPC_PSERIES
322 /*
323 * This must be done after other CPUs have shut down, otherwise they
324 * could execute the 'scv' instruction, which is not supported with
325 * reloc disabled (see configure_exceptions()).
326 */
327 if (firmware_has_feature(FW_FEATURE_SET_MODE))
328 pseries_disable_reloc_on_exc();
329#endif
330
331 printk("kexec: Starting switchover sequence.\n");
332
333 /* switch to a staticly allocated stack. Based on irq stack code.
334 * We setup preempt_count to avoid using VMX in memcpy.
335 * XXX: the task struct will likely be invalid once we do the copy!
336 */
337 current_thread_info()->flags = 0;
338 current_thread_info()->preempt_count = HARDIRQ_OFFSET;
339
340 /* We need a static PACA, too; copy this CPU's PACA over and switch to
341 * it. Also poison per_cpu_offset and NULL lppaca to catch anyone using
342 * non-static data.
343 */
344 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
345 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
346#ifdef CONFIG_PPC_PSERIES
347 kexec_paca.lppaca_ptr = NULL;
348#endif
349
350 if (is_secure_guest() && !(image->preserve_context ||
351 image->type == KEXEC_TYPE_CRASH)) {
352 uv_unshare_all_pages();
353 printk("kexec: Unshared all shared pages.\n");
354 }
355
356 paca_ptrs[kexec_paca.paca_index] = &kexec_paca;
357
358 setup_paca(&kexec_paca);
359
360 /*
361 * The lppaca should be unregistered at this point so the HV won't
362 * touch it. In the case of a crash, none of the lppacas are
363 * unregistered so there is not much we can do about it here.
364 */
365
366 /*
367 * On Book3S, the copy must happen with the MMU off if we are either
368 * using Radix page tables or we are not in an LPAR since we can
369 * overwrite the page tables while copying.
370 *
371 * In an LPAR, we keep the MMU on otherwise we can't access beyond
372 * the RMA. On BookE there is no real MMU off mode, so we have to
373 * keep it enabled as well (but then we have bolted TLB entries).
374 */
375#ifdef CONFIG_PPC_BOOK3E_64
376 copy_with_mmu_off = false;
377#else
378 copy_with_mmu_off = radix_enabled() ||
379 !(firmware_has_feature(FW_FEATURE_LPAR) ||
380 firmware_has_feature(FW_FEATURE_PS3_LV1));
381#endif
382
383 /* Some things are best done in assembly. Finding globals with
384 * a toc is easier in C, so pass in what we can.
385 */
386 kexec_sequence(newstack: &kexec_stack, start: image->start, image,
387 page_address(image->control_code_page),
388 clear_all: mmu_cleanup_all, copy_with_mmu_off);
389 /* NOTREACHED */
390}
391
392#ifdef CONFIG_PPC_64S_HASH_MMU
393/* Values we need to export to the second kernel via the device tree. */
394static __be64 htab_base;
395static __be64 htab_size;
396
397static struct property htab_base_prop = {
398 .name = "linux,htab-base",
399 .length = sizeof(unsigned long),
400 .value = &htab_base,
401};
402
403static struct property htab_size_prop = {
404 .name = "linux,htab-size",
405 .length = sizeof(unsigned long),
406 .value = &htab_size,
407};
408
409static int __init export_htab_values(void)
410{
411 struct device_node *node;
412
413 /* On machines with no htab htab_address is NULL */
414 if (!htab_address)
415 return -ENODEV;
416
417 node = of_find_node_by_path("/chosen");
418 if (!node)
419 return -ENODEV;
420
421 /* remove any stale properties so ours can be found */
422 of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
423 of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
424
425 htab_base = cpu_to_be64(__pa(htab_address));
426 of_add_property(node, &htab_base_prop);
427 htab_size = cpu_to_be64(htab_size_bytes);
428 of_add_property(node, &htab_size_prop);
429
430 of_node_put(node);
431 return 0;
432}
433late_initcall(export_htab_values);
434#endif /* CONFIG_PPC_64S_HASH_MMU */
435
436#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP)
437/**
438 * add_node_props - Reads node properties from device node structure and add
439 * them to fdt.
440 * @fdt: Flattened device tree of the kernel
441 * @node_offset: offset of the node to add a property at
442 * @dn: device node pointer
443 *
444 * Returns 0 on success, negative errno on error.
445 */
446static int add_node_props(void *fdt, int node_offset, const struct device_node *dn)
447{
448 int ret = 0;
449 struct property *pp;
450
451 if (!dn)
452 return -EINVAL;
453
454 for_each_property_of_node(dn, pp) {
455 ret = fdt_setprop(fdt, nodeoffset: node_offset, name: pp->name, val: pp->value, len: pp->length);
456 if (ret < 0) {
457 pr_err("Unable to add %s property: %s\n", pp->name, fdt_strerror(ret));
458 return ret;
459 }
460 }
461 return ret;
462}
463
464/**
465 * update_cpus_node - Update cpus node of flattened device tree using of_root
466 * device node.
467 * @fdt: Flattened device tree of the kernel.
468 *
469 * Returns 0 on success, negative errno on error.
470 *
471 * Note: expecting no subnodes under /cpus/<node> with device_type == "cpu".
472 * If this changes, update this function to include them.
473 */
474int update_cpus_node(void *fdt)
475{
476 int prev_node_offset;
477 const char *device_type;
478 const struct fdt_property *prop;
479 struct device_node *cpus_node, *dn;
480 int cpus_offset, cpus_subnode_offset, ret = 0;
481
482 cpus_offset = fdt_path_offset(fdt, path: "/cpus");
483 if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
484 pr_err("Malformed device tree: error reading /cpus node: %s\n",
485 fdt_strerror(cpus_offset));
486 return cpus_offset;
487 }
488
489 prev_node_offset = cpus_offset;
490 /* Delete sub-nodes of /cpus node with device_type == "cpu" */
491 for (cpus_subnode_offset = fdt_first_subnode(fdt, offset: cpus_offset); cpus_subnode_offset >= 0;) {
492 /* Ignore nodes that do not have a device_type property or device_type != "cpu" */
493 prop = fdt_get_property(fdt, nodeoffset: cpus_subnode_offset, name: "device_type", NULL);
494 if (!prop || strcmp(prop->data, "cpu")) {
495 prev_node_offset = cpus_subnode_offset;
496 goto next_node;
497 }
498
499 ret = fdt_del_node(fdt, nodeoffset: cpus_subnode_offset);
500 if (ret < 0) {
501 pr_err("Failed to delete a cpus sub-node: %s\n", fdt_strerror(ret));
502 return ret;
503 }
504next_node:
505 if (prev_node_offset == cpus_offset)
506 cpus_subnode_offset = fdt_first_subnode(fdt, offset: cpus_offset);
507 else
508 cpus_subnode_offset = fdt_next_subnode(fdt, offset: prev_node_offset);
509 }
510
511 cpus_node = of_find_node_by_path(path: "/cpus");
512 /* Fail here to avoid kexec/kdump kernel boot hung */
513 if (!cpus_node) {
514 pr_err("No /cpus node found\n");
515 return -EINVAL;
516 }
517
518 /* Add all /cpus sub-nodes of device_type == "cpu" to FDT */
519 for_each_child_of_node(cpus_node, dn) {
520 /* Ignore device nodes that do not have a device_type property
521 * or device_type != "cpu".
522 */
523 device_type = of_get_property(node: dn, name: "device_type", NULL);
524 if (!device_type || strcmp(device_type, "cpu"))
525 continue;
526
527 cpus_subnode_offset = fdt_add_subnode(fdt, parentoffset: cpus_offset, name: dn->full_name);
528 if (cpus_subnode_offset < 0) {
529 pr_err("Unable to add %s subnode: %s\n", dn->full_name,
530 fdt_strerror(cpus_subnode_offset));
531 ret = cpus_subnode_offset;
532 goto out;
533 }
534
535 ret = add_node_props(fdt, node_offset: cpus_subnode_offset, dn);
536 if (ret < 0)
537 goto out;
538 }
539out:
540 of_node_put(node: cpus_node);
541 of_node_put(node: dn);
542 return ret;
543}
544#endif /* CONFIG_KEXEC_FILE || CONFIG_CRASH_DUMP */
545

source code of linux/arch/powerpc/kexec/core_64.c