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Linux/arch/arm64/kernel/machine_kexec.c

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  1 /*
  2  * kexec for arm64
  3  *
  4  * Copyright (C) Linaro.
  5  * Copyright (C) Huawei Futurewei Technologies.
  6  *
  7  * This program is free software; you can redistribute it and/or modify
  8  * it under the terms of the GNU General Public License version 2 as
  9  * published by the Free Software Foundation.
 10  */
 11 
 12 #include <linux/interrupt.h>
 13 #include <linux/irq.h>
 14 #include <linux/kernel.h>
 15 #include <linux/kexec.h>
 16 #include <linux/page-flags.h>
 17 #include <linux/smp.h>
 18 
 19 #include <asm/cacheflush.h>
 20 #include <asm/cpu_ops.h>
 21 #include <asm/daifflags.h>
 22 #include <asm/memory.h>
 23 #include <asm/mmu.h>
 24 #include <asm/mmu_context.h>
 25 #include <asm/page.h>
 26 
 27 #include "cpu-reset.h"
 28 
 29 /* Global variables for the arm64_relocate_new_kernel routine. */
 30 extern const unsigned char arm64_relocate_new_kernel[];
 31 extern const unsigned long arm64_relocate_new_kernel_size;
 32 
 33 /**
 34  * kexec_image_info - For debugging output.
 35  */
 36 #define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
 37 static void _kexec_image_info(const char *func, int line,
 38         const struct kimage *kimage)
 39 {
 40         unsigned long i;
 41 
 42         pr_debug("%s:%d:\n", func, line);
 43         pr_debug("  kexec kimage info:\n");
 44         pr_debug("    type:        %d\n", kimage->type);
 45         pr_debug("    start:       %lx\n", kimage->start);
 46         pr_debug("    head:        %lx\n", kimage->head);
 47         pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
 48 
 49         for (i = 0; i < kimage->nr_segments; i++) {
 50                 pr_debug("      segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
 51                         i,
 52                         kimage->segment[i].mem,
 53                         kimage->segment[i].mem + kimage->segment[i].memsz,
 54                         kimage->segment[i].memsz,
 55                         kimage->segment[i].memsz /  PAGE_SIZE);
 56         }
 57 }
 58 
 59 void machine_kexec_cleanup(struct kimage *kimage)
 60 {
 61         /* Empty routine needed to avoid build errors. */
 62 }
 63 
 64 /**
 65  * machine_kexec_prepare - Prepare for a kexec reboot.
 66  *
 67  * Called from the core kexec code when a kernel image is loaded.
 68  * Forbid loading a kexec kernel if we have no way of hotplugging cpus or cpus
 69  * are stuck in the kernel. This avoids a panic once we hit machine_kexec().
 70  */
 71 int machine_kexec_prepare(struct kimage *kimage)
 72 {
 73         kexec_image_info(kimage);
 74 
 75         if (kimage->type != KEXEC_TYPE_CRASH && cpus_are_stuck_in_kernel()) {
 76                 pr_err("Can't kexec: CPUs are stuck in the kernel.\n");
 77                 return -EBUSY;
 78         }
 79 
 80         return 0;
 81 }
 82 
 83 /**
 84  * kexec_list_flush - Helper to flush the kimage list and source pages to PoC.
 85  */
 86 static void kexec_list_flush(struct kimage *kimage)
 87 {
 88         kimage_entry_t *entry;
 89 
 90         for (entry = &kimage->head; ; entry++) {
 91                 unsigned int flag;
 92                 void *addr;
 93 
 94                 /* flush the list entries. */
 95                 __flush_dcache_area(entry, sizeof(kimage_entry_t));
 96 
 97                 flag = *entry & IND_FLAGS;
 98                 if (flag == IND_DONE)
 99                         break;
100 
101                 addr = phys_to_virt(*entry & PAGE_MASK);
102 
103                 switch (flag) {
104                 case IND_INDIRECTION:
105                         /* Set entry point just before the new list page. */
106                         entry = (kimage_entry_t *)addr - 1;
107                         break;
108                 case IND_SOURCE:
109                         /* flush the source pages. */
110                         __flush_dcache_area(addr, PAGE_SIZE);
111                         break;
112                 case IND_DESTINATION:
113                         break;
114                 default:
115                         BUG();
116                 }
117         }
118 }
119 
120 /**
121  * kexec_segment_flush - Helper to flush the kimage segments to PoC.
122  */
123 static void kexec_segment_flush(const struct kimage *kimage)
124 {
125         unsigned long i;
126 
127         pr_debug("%s:\n", __func__);
128 
129         for (i = 0; i < kimage->nr_segments; i++) {
130                 pr_debug("  segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
131                         i,
132                         kimage->segment[i].mem,
133                         kimage->segment[i].mem + kimage->segment[i].memsz,
134                         kimage->segment[i].memsz,
135                         kimage->segment[i].memsz /  PAGE_SIZE);
136 
137                 __flush_dcache_area(phys_to_virt(kimage->segment[i].mem),
138                         kimage->segment[i].memsz);
139         }
140 }
141 
142 /**
143  * machine_kexec - Do the kexec reboot.
144  *
145  * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC.
146  */
147 void machine_kexec(struct kimage *kimage)
148 {
149         phys_addr_t reboot_code_buffer_phys;
150         void *reboot_code_buffer;
151         bool in_kexec_crash = (kimage == kexec_crash_image);
152         bool stuck_cpus = cpus_are_stuck_in_kernel();
153 
154         /*
155          * New cpus may have become stuck_in_kernel after we loaded the image.
156          */
157         BUG_ON(!in_kexec_crash && (stuck_cpus || (num_online_cpus() > 1)));
158         WARN(in_kexec_crash && (stuck_cpus || smp_crash_stop_failed()),
159                 "Some CPUs may be stale, kdump will be unreliable.\n");
160 
161         reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
162         reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
163 
164         kexec_image_info(kimage);
165 
166         pr_debug("%s:%d: control_code_page:        %p\n", __func__, __LINE__,
167                 kimage->control_code_page);
168         pr_debug("%s:%d: reboot_code_buffer_phys:  %pa\n", __func__, __LINE__,
169                 &reboot_code_buffer_phys);
170         pr_debug("%s:%d: reboot_code_buffer:       %p\n", __func__, __LINE__,
171                 reboot_code_buffer);
172         pr_debug("%s:%d: relocate_new_kernel:      %p\n", __func__, __LINE__,
173                 arm64_relocate_new_kernel);
174         pr_debug("%s:%d: relocate_new_kernel_size: 0x%lx(%lu) bytes\n",
175                 __func__, __LINE__, arm64_relocate_new_kernel_size,
176                 arm64_relocate_new_kernel_size);
177 
178         /*
179          * Copy arm64_relocate_new_kernel to the reboot_code_buffer for use
180          * after the kernel is shut down.
181          */
182         memcpy(reboot_code_buffer, arm64_relocate_new_kernel,
183                 arm64_relocate_new_kernel_size);
184 
185         /* Flush the reboot_code_buffer in preparation for its execution. */
186         __flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
187 
188         /*
189          * Although we've killed off the secondary CPUs, we don't update
190          * the online mask if we're handling a crash kernel and consequently
191          * need to avoid flush_icache_range(), which will attempt to IPI
192          * the offline CPUs. Therefore, we must use the __* variant here.
193          */
194         __flush_icache_range((uintptr_t)reboot_code_buffer,
195                              arm64_relocate_new_kernel_size);
196 
197         /* Flush the kimage list and its buffers. */
198         kexec_list_flush(kimage);
199 
200         /* Flush the new image if already in place. */
201         if ((kimage != kexec_crash_image) && (kimage->head & IND_DONE))
202                 kexec_segment_flush(kimage);
203 
204         pr_info("Bye!\n");
205 
206         local_daif_mask();
207 
208         /*
209          * cpu_soft_restart will shutdown the MMU, disable data caches, then
210          * transfer control to the reboot_code_buffer which contains a copy of
211          * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel
212          * uses physical addressing to relocate the new image to its final
213          * position and transfers control to the image entry point when the
214          * relocation is complete.
215          */
216 
217         cpu_soft_restart(reboot_code_buffer_phys, kimage->head, kimage->start, 0);
218 
219         BUG(); /* Should never get here. */
220 }
221 
222 static void machine_kexec_mask_interrupts(void)
223 {
224         unsigned int i;
225         struct irq_desc *desc;
226 
227         for_each_irq_desc(i, desc) {
228                 struct irq_chip *chip;
229                 int ret;
230 
231                 chip = irq_desc_get_chip(desc);
232                 if (!chip)
233                         continue;
234 
235                 /*
236                  * First try to remove the active state. If this
237                  * fails, try to EOI the interrupt.
238                  */
239                 ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);
240 
241                 if (ret && irqd_irq_inprogress(&desc->irq_data) &&
242                     chip->irq_eoi)
243                         chip->irq_eoi(&desc->irq_data);
244 
245                 if (chip->irq_mask)
246                         chip->irq_mask(&desc->irq_data);
247 
248                 if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
249                         chip->irq_disable(&desc->irq_data);
250         }
251 }
252 
253 /**
254  * machine_crash_shutdown - shutdown non-crashing cpus and save registers
255  */
256 void machine_crash_shutdown(struct pt_regs *regs)
257 {
258         local_irq_disable();
259 
260         /* shutdown non-crashing cpus */
261         crash_smp_send_stop();
262 
263         /* for crashing cpu */
264         crash_save_cpu(regs, smp_processor_id());
265         machine_kexec_mask_interrupts();
266 
267         pr_info("Starting crashdump kernel...\n");
268 }
269 
270 void arch_kexec_protect_crashkres(void)
271 {
272         int i;
273 
274         kexec_segment_flush(kexec_crash_image);
275 
276         for (i = 0; i < kexec_crash_image->nr_segments; i++)
277                 set_memory_valid(
278                         __phys_to_virt(kexec_crash_image->segment[i].mem),
279                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 0);
280 }
281 
282 void arch_kexec_unprotect_crashkres(void)
283 {
284         int i;
285 
286         for (i = 0; i < kexec_crash_image->nr_segments; i++)
287                 set_memory_valid(
288                         __phys_to_virt(kexec_crash_image->segment[i].mem),
289                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 1);
290 }
291 
292 #ifdef CONFIG_HIBERNATION
293 /*
294  * To preserve the crash dump kernel image, the relevant memory segments
295  * should be mapped again around the hibernation.
296  */
297 void crash_prepare_suspend(void)
298 {
299         if (kexec_crash_image)
300                 arch_kexec_unprotect_crashkres();
301 }
302 
303 void crash_post_resume(void)
304 {
305         if (kexec_crash_image)
306                 arch_kexec_protect_crashkres();
307 }
308 
309 /*
310  * crash_is_nosave
311  *
312  * Return true only if a page is part of reserved memory for crash dump kernel,
313  * but does not hold any data of loaded kernel image.
314  *
315  * Note that all the pages in crash dump kernel memory have been initially
316  * marked as Reserved in kexec_reserve_crashkres_pages().
317  *
318  * In hibernation, the pages which are Reserved and yet "nosave" are excluded
319  * from the hibernation iamge. crash_is_nosave() does thich check for crash
320  * dump kernel and will reduce the total size of hibernation image.
321  */
322 
323 bool crash_is_nosave(unsigned long pfn)
324 {
325         int i;
326         phys_addr_t addr;
327 
328         if (!crashk_res.end)
329                 return false;
330 
331         /* in reserved memory? */
332         addr = __pfn_to_phys(pfn);
333         if ((addr < crashk_res.start) || (crashk_res.end < addr))
334                 return false;
335 
336         if (!kexec_crash_image)
337                 return true;
338 
339         /* not part of loaded kernel image? */
340         for (i = 0; i < kexec_crash_image->nr_segments; i++)
341                 if (addr >= kexec_crash_image->segment[i].mem &&
342                                 addr < (kexec_crash_image->segment[i].mem +
343                                         kexec_crash_image->segment[i].memsz))
344                         return false;
345 
346         return true;
347 }
348 
349 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
350 {
351         unsigned long addr;
352         struct page *page;
353 
354         for (addr = begin; addr < end; addr += PAGE_SIZE) {
355                 page = phys_to_page(addr);
356                 ClearPageReserved(page);
357                 free_reserved_page(page);
358         }
359 }
360 #endif /* CONFIG_HIBERNATION */
361 

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