1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2019 FORTH-ICS/CARV
4  *  Nick Kossifidis <mick@ics.forth.gr>
5  */
6 
7 #include <linux/kexec.h>
8 #include <asm/kexec.h>		/* For riscv_kexec_* symbol defines */
9 #include <linux/smp.h>		/* For smp_send_stop () */
10 #include <asm/cacheflush.h>	/* For local_flush_icache_all() */
11 #include <asm/barrier.h>	/* For smp_wmb() */
12 #include <asm/page.h>		/* For PAGE_MASK */
13 #include <linux/libfdt.h>	/* For fdt_check_header() */
14 #include <asm/set_memory.h>	/* For set_memory_x() */
15 #include <linux/compiler.h>	/* For unreachable() */
16 #include <linux/cpu.h>		/* For cpu_down() */
17 #include <linux/reboot.h>
18 
19 /*
20  * kexec_image_info - Print received image details
21  */
22 static void
23 kexec_image_info(const struct kimage *image)
24 {
25 	unsigned long i;
26 
27 	pr_debug("Kexec image info:\n");
28 	pr_debug("\ttype:        %d\n", image->type);
29 	pr_debug("\tstart:       %lx\n", image->start);
30 	pr_debug("\thead:        %lx\n", image->head);
31 	pr_debug("\tnr_segments: %lu\n", image->nr_segments);
32 
33 	for (i = 0; i < image->nr_segments; i++) {
34 		pr_debug("\t    segment[%lu]: %016lx - %016lx", i,
35 			image->segment[i].mem,
36 			image->segment[i].mem + image->segment[i].memsz);
37 		pr_debug("\t\t0x%lx bytes, %lu pages\n",
38 			(unsigned long) image->segment[i].memsz,
39 			(unsigned long) image->segment[i].memsz /  PAGE_SIZE);
40 	}
41 }
42 
43 /*
44  * machine_kexec_prepare - Initialize kexec
45  *
46  * This function is called from do_kexec_load, when the user has
47  * provided us with an image to be loaded. Its goal is to validate
48  * the image and prepare the control code buffer as needed.
49  * Note that kimage_alloc_init has already been called and the
50  * control buffer has already been allocated.
51  */
52 int
53 machine_kexec_prepare(struct kimage *image)
54 {
55 	struct kimage_arch *internal = &image->arch;
56 	struct fdt_header fdt = {0};
57 	void *control_code_buffer = NULL;
58 	unsigned int control_code_buffer_sz = 0;
59 	int i = 0;
60 
61 	kexec_image_info(image);
62 
63 	/* Find the Flattened Device Tree and save its physical address */
64 	for (i = 0; i < image->nr_segments; i++) {
65 		if (image->segment[i].memsz <= sizeof(fdt))
66 			continue;
67 
68 		if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt)))
69 			continue;
70 
71 		if (fdt_check_header(&fdt))
72 			continue;
73 
74 		internal->fdt_addr = (unsigned long) image->segment[i].mem;
75 		break;
76 	}
77 
78 	if (!internal->fdt_addr) {
79 		pr_err("Device tree not included in the provided image\n");
80 		return -EINVAL;
81 	}
82 
83 	/* Copy the assembler code for relocation to the control page */
84 	if (image->type != KEXEC_TYPE_CRASH) {
85 		control_code_buffer = page_address(image->control_code_page);
86 		control_code_buffer_sz = page_size(image->control_code_page);
87 
88 		if (unlikely(riscv_kexec_relocate_size > control_code_buffer_sz)) {
89 			pr_err("Relocation code doesn't fit within a control page\n");
90 			return -EINVAL;
91 		}
92 
93 		memcpy(control_code_buffer, riscv_kexec_relocate,
94 			riscv_kexec_relocate_size);
95 
96 		/* Mark the control page executable */
97 		set_memory_x((unsigned long) control_code_buffer, 1);
98 	}
99 
100 	return 0;
101 }
102 
103 
104 /*
105  * machine_kexec_cleanup - Cleanup any leftovers from
106  *			   machine_kexec_prepare
107  *
108  * This function is called by kimage_free to handle any arch-specific
109  * allocations done on machine_kexec_prepare. Since we didn't do any
110  * allocations there, this is just an empty function. Note that the
111  * control buffer is freed by kimage_free.
112  */
113 void
114 machine_kexec_cleanup(struct kimage *image)
115 {
116 }
117 
118 
119 /*
120  * machine_shutdown - Prepare for a kexec reboot
121  *
122  * This function is called by kernel_kexec just before machine_kexec
123  * below. Its goal is to prepare the rest of the system (the other
124  * harts and possibly devices etc) for a kexec reboot.
125  */
126 void machine_shutdown(void)
127 {
128 	/*
129 	 * No more interrupts on this hart
130 	 * until we are back up.
131 	 */
132 	local_irq_disable();
133 
134 #if defined(CONFIG_HOTPLUG_CPU)
135 	smp_shutdown_nonboot_cpus(smp_processor_id());
136 #endif
137 }
138 
139 /*
140  * machine_crash_shutdown - Prepare to kexec after a kernel crash
141  *
142  * This function is called by crash_kexec just before machine_kexec
143  * below and its goal is similar to machine_shutdown, but in case of
144  * a kernel crash. Since we don't handle such cases yet, this function
145  * is empty.
146  */
147 void
148 machine_crash_shutdown(struct pt_regs *regs)
149 {
150 	crash_save_cpu(regs, smp_processor_id());
151 	machine_shutdown();
152 	pr_info("Starting crashdump kernel...\n");
153 }
154 
155 /*
156  * machine_kexec - Jump to the loaded kimage
157  *
158  * This function is called by kernel_kexec which is called by the
159  * reboot system call when the reboot cmd is LINUX_REBOOT_CMD_KEXEC,
160  * or by crash_kernel which is called by the kernel's arch-specific
161  * trap handler in case of a kernel panic. It's the final stage of
162  * the kexec process where the pre-loaded kimage is ready to be
163  * executed. We assume at this point that all other harts are
164  * suspended and this hart will be the new boot hart.
165  */
166 void __noreturn
167 machine_kexec(struct kimage *image)
168 {
169 	struct kimage_arch *internal = &image->arch;
170 	unsigned long jump_addr = (unsigned long) image->start;
171 	unsigned long first_ind_entry = (unsigned long) &image->head;
172 	unsigned long this_cpu_id = smp_processor_id();
173 	unsigned long this_hart_id = cpuid_to_hartid_map(this_cpu_id);
174 	unsigned long fdt_addr = internal->fdt_addr;
175 	void *control_code_buffer = page_address(image->control_code_page);
176 	riscv_kexec_method kexec_method = NULL;
177 
178 	if (image->type != KEXEC_TYPE_CRASH)
179 		kexec_method = control_code_buffer;
180 	else
181 		kexec_method = (riscv_kexec_method) &riscv_kexec_norelocate;
182 
183 	pr_notice("Will call new kernel at %08lx from hart id %lx\n",
184 		  jump_addr, this_hart_id);
185 	pr_notice("FDT image at %08lx\n", fdt_addr);
186 
187 	/* Make sure the relocation code is visible to the hart */
188 	local_flush_icache_all();
189 
190 	/* Jump to the relocation code */
191 	pr_notice("Bye...\n");
192 	kexec_method(first_ind_entry, jump_addr, fdt_addr,
193 		     this_hart_id, kernel_map.va_pa_offset);
194 	unreachable();
195 }
196