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
23extern void relocate_new_kernel(void);
24extern const unsigned int relocate_new_kernel_size;
25
26static 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
33int 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
72void machine_kexec_cleanup(struct kimage *image)
73{
74}
75
76static void machine_crash_nonpanic_core(void *unused)
77{
78	struct pt_regs regs;
79
80	local_fiq_disable();
81
82	crash_setup_regs(&regs, 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(&regs, 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
97static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
98	CSD_INIT(machine_crash_nonpanic_core, NULL);
99
100void 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
130static 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
153void 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
164void 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