1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * machine_kexec.c - handle transition of Linux booting another kernel
4 */
5
6 #include <linux/mm.h>
7 #include <linux/kexec.h>
8 #include <linux/delay.h>
9 #include <linux/reboot.h>
10 #include <linux/io.h>
11 #include <linux/irq.h>
12 #include <linux/memblock.h>
13 #include <linux/of_fdt.h>
14 #include <asm/mmu_context.h>
15 #include <asm/cacheflush.h>
16 #include <asm/kexec-internal.h>
17 #include <asm/fncpy.h>
18 #include <asm/mach-types.h>
19 #include <asm/smp_plat.h>
20 #include <asm/system_misc.h>
21 #include <asm/set_memory.h>
22
23 extern void relocate_new_kernel(void);
24 extern const unsigned int relocate_new_kernel_size;
25
26 static atomic_t waiting_for_crash_ipi;
27
28 /*
29 * Provide a dummy crash_notes definition while crash dump arrives to arm.
30 * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
31 */
32
33 int machine_kexec_prepare(struct kimage *image)
34 {
35 struct kexec_segment *current_segment;
36 __be32 header;
37 int i, err;
38
39 image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET
40 + KEXEC_ARM_ATAGS_OFFSET;
41
42 /*
43 * Validate that if the current HW supports SMP, then the SW supports
44 * and implements CPU hotplug for the current HW. If not, we won't be
45 * able to kexec reliably, so fail the prepare operation.
46 */
47 if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&
48 !platform_can_cpu_hotplug())
49 return -EINVAL;
50
51 /*
52 * No segment at default ATAGs address. try to locate
53 * a dtb using magic.
54 */
55 for (i = 0; i < image->nr_segments; i++) {
56 current_segment = &image->segment[i];
57
58 if (!memblock_is_region_memory(idmap_to_phys(current_segment->mem),
59 current_segment->memsz))
60 return -EINVAL;
61
62 err = get_user(header, (__be32*)current_segment->buf);
63 if (err)
64 return err;
65
66 if (header == cpu_to_be32(OF_DT_HEADER))
67 image->arch.kernel_r2 = current_segment->mem;
68 }
69 return 0;
70 }
71
72 void machine_kexec_cleanup(struct kimage *image)
73 {
74 }
75
76 static void machine_crash_nonpanic_core(void *unused)
77 {
78 struct pt_regs regs;
79
80 local_fiq_disable();
81
82 crash_setup_regs(®s, get_irq_regs());
83 printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
84 smp_processor_id());
85 crash_save_cpu(®s, smp_processor_id());
86 flush_cache_all();
87
88 set_cpu_online(smp_processor_id(), false);
89 atomic_dec(&waiting_for_crash_ipi);
90
91 while (1) {
92 cpu_relax();
93 wfe();
94 }
95 }
96
97 static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
98 CSD_INIT(machine_crash_nonpanic_core, NULL);
99
100 void crash_smp_send_stop(void)
101 {
102 static int cpus_stopped;
103 unsigned long msecs;
104 call_single_data_t *csd;
105 int cpu, this_cpu = raw_smp_processor_id();
106
107 if (cpus_stopped)
108 return;
109
110 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
111 for_each_online_cpu(cpu) {
112 if (cpu == this_cpu)
113 continue;
114
115 csd = &per_cpu(cpu_stop_csd, cpu);
116 smp_call_function_single_async(cpu, csd);
117 }
118
119 msecs = 1000; /* Wait at most a second for the other cpus to stop */
120 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
121 mdelay(1);
122 msecs--;
123 }
124 if (atomic_read(&waiting_for_crash_ipi) > 0)
125 pr_warn("Non-crashing CPUs did not react to IPI\n");
126
127 cpus_stopped = 1;
128 }
129
130 static void machine_kexec_mask_interrupts(void)
131 {
132 unsigned int i;
133 struct irq_desc *desc;
134
135 for_each_irq_desc(i, desc) {
136 struct irq_chip *chip;
137
138 chip = irq_desc_get_chip(desc);
139 if (!chip)
140 continue;
141
142 if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
143 chip->irq_eoi(&desc->irq_data);
144
145 if (chip->irq_mask)
146 chip->irq_mask(&desc->irq_data);
147
148 if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
149 chip->irq_disable(&desc->irq_data);
150 }
151 }
152
153 void machine_crash_shutdown(struct pt_regs *regs)
154 {
155 local_irq_disable();
156 crash_smp_send_stop();
157
158 crash_save_cpu(regs, smp_processor_id());
159 machine_kexec_mask_interrupts();
160
161 pr_info("Loading crashdump kernel...\n");
162 }
163
164 void machine_kexec(struct kimage *image)
165 {
166 unsigned long page_list, reboot_entry_phys;
167 struct kexec_relocate_data *data;
168 void (*reboot_entry)(void);
169 void *reboot_code_buffer;
170
171 /*
172 * This can only happen if machine_shutdown() failed to disable some
173 * CPU, and that can only happen if the checks in
174 * machine_kexec_prepare() were not correct. If this fails, we can't
175 * reliably kexec anyway, so BUG_ON is appropriate.
176 */
177 BUG_ON(num_online_cpus() > 1);
178
179 page_list = image->head & PAGE_MASK;
180
181 reboot_code_buffer = page_address(image->control_code_page);
182
183 /* copy our kernel relocation code to the control code page */
184 reboot_entry = fncpy(reboot_code_buffer,
185 &relocate_new_kernel,
186 relocate_new_kernel_size);
187
188 data = reboot_code_buffer + relocate_new_kernel_size;
189 data->kexec_start_address = image->start;
190 data->kexec_indirection_page = page_list;
191 data->kexec_mach_type = machine_arch_type;
192 data->kexec_r2 = image->arch.kernel_r2;
193
194 /* get the identity mapping physical address for the reboot code */
195 reboot_entry_phys = virt_to_idmap(reboot_entry);
196
197 pr_info("Bye!\n");
198
199 soft_restart(reboot_entry_phys);
200 }
201
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