1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Load ELF vmlinux file for the kexec_file_load syscall.
4 *
5 * Copyright (C) 2021 Huawei Technologies Co, Ltd.
6 *
7 * Author: Liao Chang (liaochang1@huawei.com)
8 *
9 * Based on kexec-tools' kexec-elf-riscv.c, heavily modified
10 * for kernel.
11 */
12
13 #define pr_fmt(fmt) "kexec_image: " fmt
14
15 #include <linux/elf.h>
16 #include <linux/kexec.h>
17 #include <linux/slab.h>
18 #include <linux/of.h>
19 #include <linux/libfdt.h>
20 #include <linux/types.h>
21 #include <linux/memblock.h>
22 #include <asm/setup.h>
23
riscv_kexec_elf_load(struct kimage * image,struct elfhdr * ehdr,struct kexec_elf_info * elf_info,unsigned long old_pbase,unsigned long new_pbase)24 static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
25 struct kexec_elf_info *elf_info, unsigned long old_pbase,
26 unsigned long new_pbase)
27 {
28 int i;
29 int ret = 0;
30 size_t size;
31 struct kexec_buf kbuf;
32 const struct elf_phdr *phdr;
33
34 kbuf.image = image;
35
36 for (i = 0; i < ehdr->e_phnum; i++) {
37 phdr = &elf_info->proghdrs[i];
38 if (phdr->p_type != PT_LOAD)
39 continue;
40
41 size = phdr->p_filesz;
42 if (size > phdr->p_memsz)
43 size = phdr->p_memsz;
44
45 kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
46 kbuf.bufsz = size;
47 kbuf.buf_align = phdr->p_align;
48 kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
49 kbuf.memsz = phdr->p_memsz;
50 kbuf.top_down = false;
51 ret = kexec_add_buffer(&kbuf);
52 if (ret)
53 break;
54 }
55
56 return ret;
57 }
58
59 /*
60 * Go through the available phsyical memory regions and find one that hold
61 * an image of the specified size.
62 */
elf_find_pbase(struct kimage * image,unsigned long kernel_len,struct elfhdr * ehdr,struct kexec_elf_info * elf_info,unsigned long * old_pbase,unsigned long * new_pbase)63 static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
64 struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
65 unsigned long *old_pbase, unsigned long *new_pbase)
66 {
67 int i;
68 int ret;
69 struct kexec_buf kbuf;
70 const struct elf_phdr *phdr;
71 unsigned long lowest_paddr = ULONG_MAX;
72 unsigned long lowest_vaddr = ULONG_MAX;
73
74 for (i = 0; i < ehdr->e_phnum; i++) {
75 phdr = &elf_info->proghdrs[i];
76 if (phdr->p_type != PT_LOAD)
77 continue;
78
79 if (lowest_paddr > phdr->p_paddr)
80 lowest_paddr = phdr->p_paddr;
81
82 if (lowest_vaddr > phdr->p_vaddr)
83 lowest_vaddr = phdr->p_vaddr;
84 }
85
86 kbuf.image = image;
87 kbuf.buf_min = lowest_paddr;
88 kbuf.buf_max = ULONG_MAX;
89
90 /*
91 * Current riscv boot protocol requires 2MB alignment for
92 * RV64 and 4MB alignment for RV32
93 *
94 */
95 kbuf.buf_align = PMD_SIZE;
96 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
97 kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
98 kbuf.top_down = false;
99 ret = arch_kexec_locate_mem_hole(&kbuf);
100 if (!ret) {
101 *old_pbase = lowest_paddr;
102 *new_pbase = kbuf.mem;
103 image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
104 }
105 return ret;
106 }
107
elf_kexec_load(struct kimage * image,char * kernel_buf,unsigned long kernel_len,char * initrd,unsigned long initrd_len,char * cmdline,unsigned long cmdline_len)108 static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
109 unsigned long kernel_len, char *initrd,
110 unsigned long initrd_len, char *cmdline,
111 unsigned long cmdline_len)
112 {
113 int ret;
114 unsigned long old_kernel_pbase = ULONG_MAX;
115 unsigned long new_kernel_pbase = 0UL;
116 struct elfhdr ehdr;
117 struct kexec_elf_info elf_info;
118
119 ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
120 if (ret)
121 return ERR_PTR(ret);
122
123 ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
124 &old_kernel_pbase, &new_kernel_pbase);
125 if (ret)
126 goto out;
127
128 /* Add the kernel binary to the image */
129 ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
130 old_kernel_pbase, new_kernel_pbase);
131 if (ret)
132 goto out;
133
134 ret = load_extra_segments(image, image->start, kernel_len,
135 initrd, initrd_len, cmdline, cmdline_len);
136 out:
137 kexec_free_elf_info(&elf_info);
138 return ret ? ERR_PTR(ret) : NULL;
139 }
140
141 const struct kexec_file_ops elf_kexec_ops = {
142 .probe = kexec_elf_probe,
143 .load = elf_kexec_load,
144 };
145