1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * OS info memory interface
4  *
5  * Copyright IBM Corp. 2012
6  * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
7  */
8 
9 #define KMSG_COMPONENT "os_info"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11 
12 #include <linux/crash_dump.h>
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <asm/checksum.h>
16 #include <asm/abs_lowcore.h>
17 #include <asm/os_info.h>
18 #include <asm/maccess.h>
19 #include <asm/asm-offsets.h>
20 
21 /*
22  * OS info structure has to be page aligned
23  */
24 static struct os_info os_info __page_aligned_data;
25 
26 /*
27  * Compute checksum over OS info structure
28  */
os_info_csum(struct os_info * os_info)29 u32 os_info_csum(struct os_info *os_info)
30 {
31 	int size = sizeof(*os_info) - offsetof(struct os_info, version_major);
32 	return (__force u32)csum_partial(&os_info->version_major, size, 0);
33 }
34 
35 /*
36  * Add crashkernel info to OS info and update checksum
37  */
os_info_crashkernel_add(unsigned long base,unsigned long size)38 void os_info_crashkernel_add(unsigned long base, unsigned long size)
39 {
40 	os_info.crashkernel_addr = (u64)(unsigned long)base;
41 	os_info.crashkernel_size = (u64)(unsigned long)size;
42 	os_info.csum = os_info_csum(&os_info);
43 }
44 
45 /*
46  * Add OS info entry and update checksum
47  */
os_info_entry_add(int nr,void * ptr,u64 size)48 void os_info_entry_add(int nr, void *ptr, u64 size)
49 {
50 	os_info.entry[nr].addr = __pa(ptr);
51 	os_info.entry[nr].size = size;
52 	os_info.entry[nr].csum = (__force u32)csum_partial(ptr, size, 0);
53 	os_info.csum = os_info_csum(&os_info);
54 }
55 
56 /*
57  * Initialize OS info structure and set lowcore pointer
58  */
os_info_init(void)59 void __init os_info_init(void)
60 {
61 	struct lowcore *abs_lc;
62 	unsigned long flags;
63 
64 	os_info.version_major = OS_INFO_VERSION_MAJOR;
65 	os_info.version_minor = OS_INFO_VERSION_MINOR;
66 	os_info.magic = OS_INFO_MAGIC;
67 	os_info.csum = os_info_csum(&os_info);
68 	abs_lc = get_abs_lowcore(&flags);
69 	abs_lc->os_info = __pa(&os_info);
70 	put_abs_lowcore(abs_lc, flags);
71 }
72 
73 #ifdef CONFIG_CRASH_DUMP
74 
75 static struct os_info *os_info_old;
76 
77 /*
78  * Allocate and copy OS info entry from oldmem
79  */
os_info_old_alloc(int nr,int align)80 static void os_info_old_alloc(int nr, int align)
81 {
82 	unsigned long addr, size = 0;
83 	char *buf, *buf_align, *msg;
84 	u32 csum;
85 
86 	addr = os_info_old->entry[nr].addr;
87 	if (!addr) {
88 		msg = "not available";
89 		goto fail;
90 	}
91 	size = os_info_old->entry[nr].size;
92 	buf = kmalloc(size + align - 1, GFP_KERNEL);
93 	if (!buf) {
94 		msg = "alloc failed";
95 		goto fail;
96 	}
97 	buf_align = PTR_ALIGN(buf, align);
98 	if (copy_oldmem_kernel(buf_align, addr, size)) {
99 		msg = "copy failed";
100 		goto fail_free;
101 	}
102 	csum = (__force u32)csum_partial(buf_align, size, 0);
103 	if (csum != os_info_old->entry[nr].csum) {
104 		msg = "checksum failed";
105 		goto fail_free;
106 	}
107 	os_info_old->entry[nr].addr = (u64)(unsigned long)buf_align;
108 	msg = "copied";
109 	goto out;
110 fail_free:
111 	kfree(buf);
112 fail:
113 	os_info_old->entry[nr].addr = 0;
114 out:
115 	pr_info("entry %i: %s (addr=0x%lx size=%lu)\n",
116 		nr, msg, addr, size);
117 }
118 
119 /*
120  * Initialize os info and os info entries from oldmem
121  */
os_info_old_init(void)122 static void os_info_old_init(void)
123 {
124 	static int os_info_init;
125 	unsigned long addr;
126 
127 	if (os_info_init)
128 		return;
129 	if (!oldmem_data.start)
130 		goto fail;
131 	if (copy_oldmem_kernel(&addr, __LC_OS_INFO, sizeof(addr)))
132 		goto fail;
133 	if (addr == 0 || addr % PAGE_SIZE)
134 		goto fail;
135 	os_info_old = kzalloc(sizeof(*os_info_old), GFP_KERNEL);
136 	if (!os_info_old)
137 		goto fail;
138 	if (copy_oldmem_kernel(os_info_old, addr, sizeof(*os_info_old)))
139 		goto fail_free;
140 	if (os_info_old->magic != OS_INFO_MAGIC)
141 		goto fail_free;
142 	if (os_info_old->csum != os_info_csum(os_info_old))
143 		goto fail_free;
144 	if (os_info_old->version_major > OS_INFO_VERSION_MAJOR)
145 		goto fail_free;
146 	os_info_old_alloc(OS_INFO_VMCOREINFO, 1);
147 	os_info_old_alloc(OS_INFO_REIPL_BLOCK, 1);
148 	pr_info("crashkernel: addr=0x%lx size=%lu\n",
149 		(unsigned long) os_info_old->crashkernel_addr,
150 		(unsigned long) os_info_old->crashkernel_size);
151 	os_info_init = 1;
152 	return;
153 fail_free:
154 	kfree(os_info_old);
155 fail:
156 	os_info_init = 1;
157 	os_info_old = NULL;
158 }
159 
160 /*
161  * Return pointer to os infor entry and its size
162  */
os_info_old_entry(int nr,unsigned long * size)163 void *os_info_old_entry(int nr, unsigned long *size)
164 {
165 	os_info_old_init();
166 
167 	if (!os_info_old)
168 		return NULL;
169 	if (!os_info_old->entry[nr].addr)
170 		return NULL;
171 	*size = (unsigned long) os_info_old->entry[nr].size;
172 	return (void *)(unsigned long)os_info_old->entry[nr].addr;
173 }
174 #endif
175