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
20 #include <asm/page.h>
21 #include <asm/current.h>
22 #include <asm/machdep.h>
23 #include <asm/cacheflush.h>
24 #include <asm/firmware.h>
25 #include <asm/paca.h>
26 #include <asm/mmu.h>
27 #include <asm/sections.h> /* _end */
28 #include <asm/prom.h>
29 #include <asm/smp.h>
30 #include <asm/hw_breakpoint.h>
31 #include <asm/asm-prototypes.h>
32 #include <asm/svm.h>
33 #include <asm/ultravisor.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_ptrs[]->cpu_start was
172 * written) and get into a peculiar state.
173 * If the platform supports smp_ops->take_timebase(), the secondary CPU
174 * will probably be spinning in there. If not (i.e. pseries), the
175 * secondary will continue on and try to online itself/idle/etc. If it
176 * survives that, we need to find these
177 * possible-but-not-online-but-should-be CPUs and chaperone them into
178 * kexec_smp_wait().
179 */
180 for_each_online_cpu(i) {
181 if (i == my_cpu)
182 continue;
183
184 while (paca_ptrs[i]->kexec_state < wait_state) {
185 barrier();
186 if (i != notified) {
187 printk(KERN_INFO "kexec: waiting for cpu %d "
188 "(physical %d) to enter %i state\n",
189 i, paca_ptrs[i]->hw_cpu_id, wait_state);
190 notified = i;
191 }
192 }
193 }
194 mb();
195 }
196
197 /*
198 * We need to make sure each present CPU is online. The next kernel will scan
199 * the device tree and assume primary threads are online and query secondary
200 * threads via RTAS to online them if required. If we don't online primary
201 * threads, they will be stuck. However, we also online secondary threads as we
202 * may be using 'cede offline'. In this case RTAS doesn't see the secondary
203 * threads as offline -- and again, these CPUs will be stuck.
204 *
205 * So, we online all CPUs that should be running, including secondary threads.
206 */
207 static void wake_offline_cpus(void)
208 {
209 int cpu = 0;
210
211 for_each_present_cpu(cpu) {
212 if (!cpu_online(cpu)) {
213 printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
214 cpu);
215 WARN_ON(cpu_up(cpu));
216 }
217 }
218 }
219
220 static void kexec_prepare_cpus(void)
221 {
222 wake_offline_cpus();
223 smp_call_function(kexec_smp_down, NULL, /* wait */0);
224 local_irq_disable();
225 hard_irq_disable();
226
227 mb(); /* make sure IRQs are disabled before we say they are */
228 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
229
230 kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
231 /* we are sure every CPU has IRQs off at this point */
232 kexec_all_irq_disabled = 1;
233
234 /*
235 * Before removing MMU mappings make sure all CPUs have entered real
236 * mode:
237 */
238 kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
239
240 /* after we tell the others to go down */
241 if (ppc_md.kexec_cpu_down)
242 ppc_md.kexec_cpu_down(0, 0);
243
244 put_cpu();
245 }
246
247 #else /* ! SMP */
248
249 static void kexec_prepare_cpus(void)
250 {
251 /*
252 * move the secondarys to us so that we can copy
253 * the new kernel 0-0x100 safely
254 *
255 * do this if kexec in setup.c ?
256 *
257 * We need to release the cpus if we are ever going from an
258 * UP to an SMP kernel.
259 */
260 smp_release_cpus();
261 if (ppc_md.kexec_cpu_down)
262 ppc_md.kexec_cpu_down(0, 0);
263 local_irq_disable();
264 hard_irq_disable();
265 }
266
267 #endif /* SMP */
268
269 /*
270 * kexec thread structure and stack.
271 *
272 * We need to make sure that this is 16384-byte aligned due to the
273 * way process stacks are handled. It also must be statically allocated
274 * or allocated as part of the kimage, because everything else may be
275 * overwritten when we copy the kexec image. We piggyback on the
276 * "init_task" linker section here to statically allocate a stack.
277 *
278 * We could use a smaller stack if we don't care about anything using
279 * current, but that audit has not been performed.
280 */
281 static union thread_union kexec_stack __init_task_data =
282 { };
283
284 /*
285 * For similar reasons to the stack above, the kexecing CPU needs to be on a
286 * static PACA; we switch to kexec_paca.
287 */
288 struct paca_struct kexec_paca;
289
290 /* Our assembly helper, in misc_64.S */
291 extern void kexec_sequence(void *newstack, unsigned long start,
292 void *image, void *control,
293 void (*clear_all)(void),
294 bool copy_with_mmu_off) __noreturn;
295
296 /* too late to fail here */
297 void default_machine_kexec(struct kimage *image)
298 {
299 bool copy_with_mmu_off;
300
301 /* prepare control code if any */
302
303 /*
304 * If the kexec boot is the normal one, need to shutdown other cpus
305 * into our wait loop and quiesce interrupts.
306 * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
307 * stopping other CPUs and collecting their pt_regs is done before
308 * using debugger IPI.
309 */
310
311 if (!kdump_in_progress())
312 kexec_prepare_cpus();
313
314 printk("kexec: Starting switchover sequence.\n");
315
316 /* switch to a staticly allocated stack. Based on irq stack code.
317 * We setup preempt_count to avoid using VMX in memcpy.
318 * XXX: the task struct will likely be invalid once we do the copy!
319 */
320 current_thread_info()->flags = 0;
321 current_thread_info()->preempt_count = HARDIRQ_OFFSET;
322
323 /* We need a static PACA, too; copy this CPU's PACA over and switch to
324 * it. Also poison per_cpu_offset and NULL lppaca to catch anyone using
325 * non-static data.
326 */
327 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
328 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
329 #ifdef CONFIG_PPC_PSERIES
330 kexec_paca.lppaca_ptr = NULL;
331 #endif
332
333 if (is_secure_guest() && !(image->preserve_context ||
334 image->type == KEXEC_TYPE_CRASH)) {
335 uv_unshare_all_pages();
336 printk("kexec: Unshared all shared pages.\n");
337 }
338
339 paca_ptrs[kexec_paca.paca_index] = &kexec_paca;
340
341 setup_paca(&kexec_paca);
342
343 /*
344 * The lppaca should be unregistered at this point so the HV won't
345 * touch it. In the case of a crash, none of the lppacas are
346 * unregistered so there is not much we can do about it here.
347 */
348
349 /*
350 * On Book3S, the copy must happen with the MMU off if we are either
351 * using Radix page tables or we are not in an LPAR since we can
352 * overwrite the page tables while copying.
353 *
354 * In an LPAR, we keep the MMU on otherwise we can't access beyond
355 * the RMA. On BookE there is no real MMU off mode, so we have to
356 * keep it enabled as well (but then we have bolted TLB entries).
357 */
358 #ifdef CONFIG_PPC_BOOK3E
359 copy_with_mmu_off = false;
360 #else
361 copy_with_mmu_off = radix_enabled() ||
362 !(firmware_has_feature(FW_FEATURE_LPAR) ||
363 firmware_has_feature(FW_FEATURE_PS3_LV1));
364 #endif
365
366 /* Some things are best done in assembly. Finding globals with
367 * a toc is easier in C, so pass in what we can.
368 */
369 kexec_sequence(&kexec_stack, image->start, image,
370 page_address(image->control_code_page),
371 mmu_cleanup_all, copy_with_mmu_off);
372 /* NOTREACHED */
373 }
374
375 #ifdef CONFIG_PPC_BOOK3S_64
376 /* Values we need to export to the second kernel via the device tree. */
377 static unsigned long htab_base;
378 static unsigned long htab_size;
379
380 static struct property htab_base_prop = {
381 .name = "linux,htab-base",
382 .length = sizeof(unsigned long),
383 .value = &htab_base,
384 };
385
386 static struct property htab_size_prop = {
387 .name = "linux,htab-size",
388 .length = sizeof(unsigned long),
389 .value = &htab_size,
390 };
391
392 static int __init export_htab_values(void)
393 {
394 struct device_node *node;
395
396 /* On machines with no htab htab_address is NULL */
397 if (!htab_address)
398 return -ENODEV;
399
400 node = of_find_node_by_path("/chosen");
401 if (!node)
402 return -ENODEV;
403
404 /* remove any stale propertys so ours can be found */
405 of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
406 of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
407
408 htab_base = cpu_to_be64(__pa(htab_address));
409 of_add_property(node, &htab_base_prop);
410 htab_size = cpu_to_be64(htab_size_bytes);
411 of_add_property(node, &htab_size_prop);
412
413 of_node_put(node);
414 return 0;
415 }
416 late_initcall(export_htab_values);
417 #endif /* CONFIG_PPC_BOOK3S_64 */