1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * machine_kexec.c for kexec
4  *
5  * Copyright (C) 2022 Loongson Technology Corporation Limited
6  */
7 #include <linux/compiler.h>
8 #include <linux/cpu.h>
9 #include <linux/kexec.h>
10 #include <linux/crash_dump.h>
11 #include <linux/delay.h>
12 #include <linux/irq.h>
13 #include <linux/libfdt.h>
14 #include <linux/mm.h>
15 #include <linux/of_fdt.h>
16 #include <linux/reboot.h>
17 #include <linux/sched.h>
18 #include <linux/sched/task_stack.h>
19 
20 #include <asm/bootinfo.h>
21 #include <asm/cacheflush.h>
22 #include <asm/page.h>
23 
24 /* 0x100000 ~ 0x200000 is safe */
25 #define KEXEC_CONTROL_CODE	TO_CACHE(0x100000UL)
26 #define KEXEC_CMDLINE_ADDR	TO_CACHE(0x108000UL)
27 
28 static unsigned long reboot_code_buffer;
29 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
30 
31 #ifdef CONFIG_SMP
32 static void (*relocated_kexec_smp_wait)(void *);
33 atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
34 #endif
35 
36 static unsigned long efi_boot;
37 static unsigned long cmdline_ptr;
38 static unsigned long systable_ptr;
39 static unsigned long start_addr;
40 static unsigned long first_ind_entry;
41 
42 static void kexec_image_info(const struct kimage *kimage)
43 {
44 	unsigned long i;
45 
46 	pr_debug("kexec kimage info:\n");
47 	pr_debug("\ttype:        %d\n", kimage->type);
48 	pr_debug("\tstart:       %lx\n", kimage->start);
49 	pr_debug("\thead:        %lx\n", kimage->head);
50 	pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
51 
52 	for (i = 0; i < kimage->nr_segments; i++) {
53 		pr_debug("\t    segment[%lu]: %016lx - %016lx", i,
54 			kimage->segment[i].mem,
55 			kimage->segment[i].mem + kimage->segment[i].memsz);
56 		pr_debug("\t\t0x%lx bytes, %lu pages\n",
57 			(unsigned long)kimage->segment[i].memsz,
58 			(unsigned long)kimage->segment[i].memsz /  PAGE_SIZE);
59 	}
60 }
61 
62 int machine_kexec_prepare(struct kimage *kimage)
63 {
64 	int i;
65 	char *bootloader = "kexec";
66 	void *cmdline_ptr = (void *)KEXEC_CMDLINE_ADDR;
67 
68 	kexec_image_info(kimage);
69 
70 	kimage->arch.efi_boot = fw_arg0;
71 	kimage->arch.systable_ptr = fw_arg2;
72 
73 	/* Find the command line */
74 	for (i = 0; i < kimage->nr_segments; i++) {
75 		if (!strncmp(bootloader, (char __user *)kimage->segment[i].buf, strlen(bootloader))) {
76 			if (!copy_from_user(cmdline_ptr, kimage->segment[i].buf, COMMAND_LINE_SIZE))
77 				kimage->arch.cmdline_ptr = (unsigned long)cmdline_ptr;
78 			break;
79 		}
80 	}
81 
82 	if (!kimage->arch.cmdline_ptr) {
83 		pr_err("Command line not included in the provided image\n");
84 		return -EINVAL;
85 	}
86 
87 	/* kexec/kdump need a safe page to save reboot_code_buffer */
88 	kimage->control_code_page = virt_to_page((void *)KEXEC_CONTROL_CODE);
89 
90 	reboot_code_buffer = (unsigned long)page_address(kimage->control_code_page);
91 	memcpy((void *)reboot_code_buffer, relocate_new_kernel, relocate_new_kernel_size);
92 
93 #ifdef CONFIG_SMP
94 	/* All secondary cpus now may jump to kexec_smp_wait cycle */
95 	relocated_kexec_smp_wait = reboot_code_buffer + (void *)(kexec_smp_wait - relocate_new_kernel);
96 #endif
97 
98 	return 0;
99 }
100 
101 void machine_kexec_cleanup(struct kimage *kimage)
102 {
103 }
104 
105 void kexec_reboot(void)
106 {
107 	do_kexec_t do_kexec = NULL;
108 
109 	/*
110 	 * We know we were online, and there will be no incoming IPIs at
111 	 * this point. Mark online again before rebooting so that the crash
112 	 * analysis tool will see us correctly.
113 	 */
114 	set_cpu_online(smp_processor_id(), true);
115 
116 	/* Ensure remote CPUs observe that we're online before rebooting. */
117 	smp_mb__after_atomic();
118 
119 	/*
120 	 * Make sure we get correct instructions written by the
121 	 * machine_kexec_prepare() CPU.
122 	 */
123 	__asm__ __volatile__ ("\tibar 0\n"::);
124 
125 #ifdef CONFIG_SMP
126 	/* All secondary cpus go to kexec_smp_wait */
127 	if (smp_processor_id() > 0) {
128 		relocated_kexec_smp_wait(NULL);
129 		unreachable();
130 	}
131 #endif
132 
133 	do_kexec = (void *)reboot_code_buffer;
134 	do_kexec(efi_boot, cmdline_ptr, systable_ptr, start_addr, first_ind_entry);
135 
136 	unreachable();
137 }
138 
139 
140 #ifdef CONFIG_SMP
141 static void kexec_shutdown_secondary(void *regs)
142 {
143 	int cpu = smp_processor_id();
144 
145 	if (!cpu_online(cpu))
146 		return;
147 
148 	/* We won't be sent IPIs any more. */
149 	set_cpu_online(cpu, false);
150 
151 	local_irq_disable();
152 	while (!atomic_read(&kexec_ready_to_reboot))
153 		cpu_relax();
154 
155 	kexec_reboot();
156 }
157 
158 static void crash_shutdown_secondary(void *passed_regs)
159 {
160 	int cpu = smp_processor_id();
161 	struct pt_regs *regs = passed_regs;
162 
163 	/*
164 	 * If we are passed registers, use those. Otherwise get the
165 	 * regs from the last interrupt, which should be correct, as
166 	 * we are in an interrupt. But if the regs are not there,
167 	 * pull them from the top of the stack. They are probably
168 	 * wrong, but we need something to keep from crashing again.
169 	 */
170 	if (!regs)
171 		regs = get_irq_regs();
172 	if (!regs)
173 		regs = task_pt_regs(current);
174 
175 	if (!cpu_online(cpu))
176 		return;
177 
178 	/* We won't be sent IPIs any more. */
179 	set_cpu_online(cpu, false);
180 
181 	local_irq_disable();
182 	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
183 		crash_save_cpu(regs, cpu);
184 	cpumask_set_cpu(cpu, &cpus_in_crash);
185 
186 	while (!atomic_read(&kexec_ready_to_reboot))
187 		cpu_relax();
188 
189 	kexec_reboot();
190 }
191 
192 void crash_smp_send_stop(void)
193 {
194 	unsigned int ncpus;
195 	unsigned long timeout;
196 	static int cpus_stopped;
197 
198 	/*
199 	 * This function can be called twice in panic path, but obviously
200 	 * we should execute this only once.
201 	 */
202 	if (cpus_stopped)
203 		return;
204 
205 	cpus_stopped = 1;
206 
207 	 /* Excluding the panic cpu */
208 	ncpus = num_online_cpus() - 1;
209 
210 	smp_call_function(crash_shutdown_secondary, NULL, 0);
211 	smp_wmb();
212 
213 	/*
214 	 * The crash CPU sends an IPI and wait for other CPUs to
215 	 * respond. Delay of at least 10 seconds.
216 	 */
217 	timeout = MSEC_PER_SEC * 10;
218 	pr_emerg("Sending IPI to other cpus...\n");
219 	while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) {
220 		mdelay(1);
221 		cpu_relax();
222 	}
223 }
224 #endif /* defined(CONFIG_SMP) */
225 
226 void machine_shutdown(void)
227 {
228 	int cpu;
229 
230 	/* All CPUs go to reboot_code_buffer */
231 	for_each_possible_cpu(cpu)
232 		if (!cpu_online(cpu))
233 			cpu_device_up(get_cpu_device(cpu));
234 
235 #ifdef CONFIG_SMP
236 	smp_call_function(kexec_shutdown_secondary, NULL, 0);
237 #endif
238 }
239 
240 void machine_crash_shutdown(struct pt_regs *regs)
241 {
242 	int crashing_cpu;
243 
244 	local_irq_disable();
245 
246 	crashing_cpu = smp_processor_id();
247 	crash_save_cpu(regs, crashing_cpu);
248 
249 #ifdef CONFIG_SMP
250 	crash_smp_send_stop();
251 #endif
252 	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
253 
254 	pr_info("Starting crashdump kernel...\n");
255 }
256 
257 void machine_kexec(struct kimage *image)
258 {
259 	unsigned long entry, *ptr;
260 	struct kimage_arch *internal = &image->arch;
261 
262 	efi_boot = internal->efi_boot;
263 	cmdline_ptr = internal->cmdline_ptr;
264 	systable_ptr = internal->systable_ptr;
265 
266 	start_addr = (unsigned long)phys_to_virt(image->start);
267 
268 	first_ind_entry = (image->type == KEXEC_TYPE_DEFAULT) ?
269 		(unsigned long)phys_to_virt(image->head & PAGE_MASK) : 0;
270 
271 	/*
272 	 * The generic kexec code builds a page list with physical
273 	 * addresses. they are directly accessible through XKPRANGE
274 	 * hence the phys_to_virt() call.
275 	 */
276 	for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
277 	     ptr = (entry & IND_INDIRECTION) ?
278 	       phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
279 		if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
280 		    *ptr & IND_DESTINATION)
281 			*ptr = (unsigned long) phys_to_virt(*ptr);
282 	}
283 
284 	/* Mark offline before disabling local irq. */
285 	set_cpu_online(smp_processor_id(), false);
286 
287 	/* We do not want to be bothered. */
288 	local_irq_disable();
289 
290 	pr_notice("EFI boot flag 0x%lx\n", efi_boot);
291 	pr_notice("Command line at 0x%lx\n", cmdline_ptr);
292 	pr_notice("System table at 0x%lx\n", systable_ptr);
293 	pr_notice("We will call new kernel at 0x%lx\n", start_addr);
294 	pr_notice("Bye ...\n");
295 
296 	/* Make reboot code buffer available to the boot CPU. */
297 	flush_cache_all();
298 
299 #ifdef CONFIG_SMP
300 	atomic_set(&kexec_ready_to_reboot, 1);
301 #endif
302 
303 	kexec_reboot();
304 }
305