| 1 | |
| 2 | * kexec.c - kexec_load system call
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| 3 | * Copyright (C) 2002-2004 Eric Biederman <[email protected]>
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| 4 | *
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| 5 | * This source code is licensed under the GNU General Public License,
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| 6 | * Version 2. See the file COPYING for more details.
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| 7 |
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| 8 |
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| 9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 10 |
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| 11 | #include <linux/capability.h>
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| 12 | #include <linux/mm.h>
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| 13 | #include <linux/file.h>
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| 14 | #include <linux/kexec.h>
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| 15 | #include <linux/mutex.h>
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| 16 | #include <linux/list.h>
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| 17 | #include <linux/syscalls.h>
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| 18 | #include <linux/vmalloc.h>
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| 19 | #include <linux/slab.h>
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| 20 |
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| 21 | #include "kexec_internal.h"
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| 22 |
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| 23 | static int copy_user_segment_list(struct kimage *image,
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| 24 | unsigned long nr_segments,
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| 25 | struct kexec_segment __user *segments)
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| 26 | {
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| 27 | int ret;
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| 28 | size_t segment_bytes;
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| 29 |
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| 30 |
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| 31 | image->nr_segments = nr_segments;
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| 32 | segment_bytes = nr_segments * sizeof(*segments);
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| 33 | ret = copy_from_user(image->segment, segments, segment_bytes);
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| 34 | if (ret)
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| 35 | ret = -EFAULT;
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| 36 |
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| 37 | return ret;
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| 38 | }
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| 39 |
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| 40 | static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
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| 41 | unsigned long nr_segments,
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| 42 | struct kexec_segment __user *segments,
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| 43 | unsigned long flags)
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| 44 | {
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| 45 | int ret;
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| 46 | struct kimage *image;
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| 47 | bool kexec_on_panic = flags & KEXEC_ON_CRASH;
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| 48 |
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| 49 | if (kexec_on_panic) {
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| 50 |
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| 51 | if ((entry < phys_to_boot_phys(crashk_res.start)) ||
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| 52 | (entry > phys_to_boot_phys(crashk_res.end)))
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| 53 | return -EADDRNOTAVAIL;
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| 54 | }
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| 55 |
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| 56 |
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| 57 | image = do_kimage_alloc_init();
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| 58 | if (!image)
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| 59 | return -ENOMEM;
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| 60 |
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| 61 | image->start = entry;
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| 62 |
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| 63 | ret = copy_user_segment_list(image, nr_segments, segments);
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| 64 | if (ret)
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| 65 | goto out_free_image;
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| 66 |
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| 67 | if (kexec_on_panic) {
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| 68 |
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| 69 | image->control_page = crashk_res.start;
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| 70 | image->type = KEXEC_TYPE_CRASH;
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| 71 | }
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| 72 |
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| 73 | ret = sanity_check_segment_list(image);
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| 74 | if (ret)
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| 75 | goto out_free_image;
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| 76 |
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| 77 | |
| 78 | * Find a location for the control code buffer, and add it
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| 79 | * the vector of segments so that it's pages will also be
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| 80 | * counted as destination pages.
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| 81 |
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| 82 | ret = -ENOMEM;
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| 83 | image->control_code_page = kimage_alloc_control_pages(image,
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| 84 | get_order(KEXEC_CONTROL_PAGE_SIZE));
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| 85 | if (!image->control_code_page) {
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| 86 | pr_err("Could not allocate control_code_buffer\n");
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| 87 | goto out_free_image;
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| 88 | }
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| 89 |
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| 90 | if (!kexec_on_panic) {
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| 91 | image->swap_page = kimage_alloc_control_pages(image, 0);
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| 92 | if (!image->swap_page) {
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| 93 | pr_err("Could not allocate swap buffer\n");
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| 94 | goto out_free_control_pages;
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| 95 | }
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| 96 | }
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| 97 |
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| 98 | *rimage = image;
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| 99 | return 0;
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| 100 | out_free_control_pages:
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| 101 | kimage_free_page_list(&image->control_pages);
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| 102 | out_free_image:
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| 103 | kfree(image);
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| 104 | return ret;
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| 105 | }
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| 106 |
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| 107 | static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
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| 108 | struct kexec_segment __user *segments, unsigned long flags)
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| 109 | {
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| 110 | struct kimage **dest_image, *image;
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| 111 | unsigned long i;
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| 112 | int ret;
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| 113 |
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| 114 | if (flags & KEXEC_ON_CRASH) {
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| 115 | dest_image = &kexec_crash_image;
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| 116 | if (kexec_crash_image)
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| 117 | arch_kexec_unprotect_crashkres();
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| 118 | } else {
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| 119 | dest_image = &kexec_image;
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| 120 | }
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| 121 |
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| 122 | if (nr_segments == 0) {
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| 123 |
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| 124 | kimage_free(xchg(dest_image, NULL));
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| 125 | return 0;
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| 126 | }
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| 127 | if (flags & KEXEC_ON_CRASH) {
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| 128 | |
| 129 | * Loading another kernel to switch to if this one
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| 130 | * crashes. Free any current crash dump kernel before
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| 131 | * we corrupt it.
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| 132 |
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| 133 | kimage_free(xchg(&kexec_crash_image, NULL));
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| 134 | }
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| 135 |
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| 136 | ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
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| 137 | if (ret)
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| 138 | return ret;
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| 139 |
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| 140 | if (flags & KEXEC_PRESERVE_CONTEXT)
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| 141 | image->preserve_context = 1;
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| 142 |
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| 143 | ret = machine_kexec_prepare(image);
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| 144 | if (ret)
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| 145 | goto out;
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| 146 |
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| 147 | |
| 148 | * Some architecture(like S390) may touch the crash memory before
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| 149 | * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
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| 150 |
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| 151 | ret = kimage_crash_copy_vmcoreinfo(image);
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| 152 | if (ret)
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| 153 | goto out;
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| 154 |
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| 155 | for (i = 0; i < nr_segments; i++) {
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| 156 | ret = kimage_load_segment(image, &image->segment[i]);
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| 157 | if (ret)
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| 158 | goto out;
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| 159 | }
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| 160 |
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| 161 | kimage_terminate(image);
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| 162 |
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| 163 |
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| 164 | image = xchg(dest_image, image);
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| 165 |
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| 166 | out:
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| 167 | if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
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| 168 | arch_kexec_protect_crashkres();
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| 169 |
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| 170 | kimage_free(image);
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| 171 | return ret;
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| 172 | }
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| 173 |
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| 174 | |
| 175 | * Exec Kernel system call: for obvious reasons only root may call it.
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| 176 | *
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| 177 | * This call breaks up into three pieces.
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| 178 | * - A generic part which loads the new kernel from the current
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| 179 | * address space, and very carefully places the data in the
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| 180 | * allocated pages.
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| 181 | *
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| 182 | * - A generic part that interacts with the kernel and tells all of
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| 183 | * the devices to shut down. Preventing on-going dmas, and placing
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| 184 | * the devices in a consistent state so a later kernel can
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| 185 | * reinitialize them.
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| 186 | *
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| 187 | * - A machine specific part that includes the syscall number
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| 188 | * and then copies the image to it's final destination. And
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| 189 | * jumps into the image at entry.
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| 190 | *
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| 191 | * kexec does not sync, or unmount filesystems so if you need
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| 192 | * that to happen you need to do that yourself.
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| 193 |
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| 194 |
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| 195 | static inline int kexec_load_check(unsigned long nr_segments,
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| 196 | unsigned long flags)
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| 197 | {
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| 198 |
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| 199 | if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
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| 200 | return -EPERM;
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| 201 |
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| 202 | |
| 203 | * Verify we have a legal set of flags
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| 204 | * This leaves us room for future extensions.
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| 205 |
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| 206 | if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
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| 207 | return -EINVAL;
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| 208 |
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| 209 | |
| 210 | * of segments passed to kexec_load.
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| 211 |
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| 212 | if (nr_segments > KEXEC_SEGMENT_MAX)
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| 213 | return -EINVAL;
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| 214 |
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| 215 | return 0;
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| 216 | }
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| 217 |
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| 218 | SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
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| 219 | struct kexec_segment __user *, segments, unsigned long, flags)
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| 220 | {
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| 221 | int result;
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| 222 |
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| 223 | result = kexec_load_check(nr_segments, flags);
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| 224 | if (result)
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| 225 | return result;
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| 226 |
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| 227 |
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| 228 | if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
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| 229 | ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
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| 230 | return -EINVAL;
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| 231 |
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| 232 | |
| 233 | * region when loading crash kernels we need a mutex here to
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| 234 | * prevent multiple crash kernels from attempting to load
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| 235 | * simultaneously, and to prevent a crash kernel from loading
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| 236 | * over the top of a in use crash kernel.
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| 237 | *
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| 238 | * KISS: always take the mutex.
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| 239 |
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| 240 | if (!mutex_trylock(&kexec_mutex))
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| 241 | return -EBUSY;
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| 242 |
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| 243 | result = do_kexec_load(entry, nr_segments, segments, flags);
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| 244 |
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| 245 | mutex_unlock(&kexec_mutex);
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| 246 |
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| 247 | return result;
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| 248 | }
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| 249 |
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| 250 | #ifdef CONFIG_COMPAT
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| 251 | COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
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| 252 | compat_ulong_t, nr_segments,
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| 253 | struct compat_kexec_segment __user *, segments,
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| 254 | compat_ulong_t, flags)
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| 255 | {
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| 256 | struct compat_kexec_segment in;
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| 257 | struct kexec_segment out, __user *ksegments;
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| 258 | unsigned long i, result;
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| 259 |
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| 260 | result = kexec_load_check(nr_segments, flags);
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| 261 | if (result)
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| 262 | return result;
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| 263 |
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| 264 | |
| 265 | * architecture to do anything.
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| 266 |
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| 267 | if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
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| 268 | return -EINVAL;
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| 269 |
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| 270 | ksegments = compat_alloc_user_space(nr_segments * sizeof(out));
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| 271 | for (i = 0; i < nr_segments; i++) {
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| 272 | result = copy_from_user(&in, &segments[i], sizeof(in));
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| 273 | if (result)
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| 274 | return -EFAULT;
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| 275 |
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| 276 | out.buf = compat_ptr(in.buf);
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| 277 | out.bufsz = in.bufsz;
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| 278 | out.mem = in.mem;
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| 279 | out.memsz = in.memsz;
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| 280 |
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| 281 | result = copy_to_user(&ksegments[i], &out, sizeof(out));
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| 282 | if (result)
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| 283 | return -EFAULT;
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| 284 | }
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| 285 |
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| 286 | |
| 287 | * region when loading crash kernels we need a mutex here to
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| 288 | * prevent multiple crash kernels from attempting to load
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| 289 | * simultaneously, and to prevent a crash kernel from loading
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| 290 | * over the top of a in use crash kernel.
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| 291 | *
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| 292 | * KISS: always take the mutex.
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| 293 |
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| 294 | if (!mutex_trylock(&kexec_mutex))
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| 295 | return -EBUSY;
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| 296 |
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| 297 | result = do_kexec_load(entry, nr_segments, ksegments, flags);
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| 298 |
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| 299 | mutex_unlock(&kexec_mutex);
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| 300 |
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| 301 | return result;
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| 302 | }
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| 303 | #endif
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