xref: /openbmc/linux/arch/s390/kernel/os_info.c (revision a2818ee4)
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/lowcore.h>
17 #include <asm/os_info.h>
18 
19 /*
20  * OS info structure has to be page aligned
21  */
22 static struct os_info os_info __page_aligned_data;
23 
24 /*
25  * Compute checksum over OS info structure
26  */
27 u32 os_info_csum(struct os_info *os_info)
28 {
29 	int size = sizeof(*os_info) - offsetof(struct os_info, version_major);
30 	return (__force u32)csum_partial(&os_info->version_major, size, 0);
31 }
32 
33 /*
34  * Add crashkernel info to OS info and update checksum
35  */
36 void os_info_crashkernel_add(unsigned long base, unsigned long size)
37 {
38 	os_info.crashkernel_addr = (u64)(unsigned long)base;
39 	os_info.crashkernel_size = (u64)(unsigned long)size;
40 	os_info.csum = os_info_csum(&os_info);
41 }
42 
43 /*
44  * Add OS info entry and update checksum
45  */
46 void os_info_entry_add(int nr, void *ptr, u64 size)
47 {
48 	os_info.entry[nr].addr = (u64)(unsigned long)ptr;
49 	os_info.entry[nr].size = size;
50 	os_info.entry[nr].csum = (__force u32)csum_partial(ptr, size, 0);
51 	os_info.csum = os_info_csum(&os_info);
52 }
53 
54 /*
55  * Initialize OS info struture and set lowcore pointer
56  */
57 void __init os_info_init(void)
58 {
59 	void *ptr = &os_info;
60 
61 	os_info.version_major = OS_INFO_VERSION_MAJOR;
62 	os_info.version_minor = OS_INFO_VERSION_MINOR;
63 	os_info.magic = OS_INFO_MAGIC;
64 	os_info.csum = os_info_csum(&os_info);
65 	mem_assign_absolute(S390_lowcore.os_info, (unsigned long) ptr);
66 }
67 
68 #ifdef CONFIG_CRASH_DUMP
69 
70 static struct os_info *os_info_old;
71 
72 /*
73  * Allocate and copy OS info entry from oldmem
74  */
75 static void os_info_old_alloc(int nr, int align)
76 {
77 	unsigned long addr, size = 0;
78 	char *buf, *buf_align, *msg;
79 	u32 csum;
80 
81 	addr = os_info_old->entry[nr].addr;
82 	if (!addr) {
83 		msg = "not available";
84 		goto fail;
85 	}
86 	size = os_info_old->entry[nr].size;
87 	buf = kmalloc(size + align - 1, GFP_KERNEL);
88 	if (!buf) {
89 		msg = "alloc failed";
90 		goto fail;
91 	}
92 	buf_align = PTR_ALIGN(buf, align);
93 	if (copy_oldmem_kernel(buf_align, (void *) addr, size)) {
94 		msg = "copy failed";
95 		goto fail_free;
96 	}
97 	csum = (__force u32)csum_partial(buf_align, size, 0);
98 	if (csum != os_info_old->entry[nr].csum) {
99 		msg = "checksum failed";
100 		goto fail_free;
101 	}
102 	os_info_old->entry[nr].addr = (u64)(unsigned long)buf_align;
103 	msg = "copied";
104 	goto out;
105 fail_free:
106 	kfree(buf);
107 fail:
108 	os_info_old->entry[nr].addr = 0;
109 out:
110 	pr_info("entry %i: %s (addr=0x%lx size=%lu)\n",
111 		nr, msg, addr, size);
112 }
113 
114 /*
115  * Initialize os info and os info entries from oldmem
116  */
117 static void os_info_old_init(void)
118 {
119 	static int os_info_init;
120 	unsigned long addr;
121 
122 	if (os_info_init)
123 		return;
124 	if (!OLDMEM_BASE)
125 		goto fail;
126 	if (copy_oldmem_kernel(&addr, &S390_lowcore.os_info, sizeof(addr)))
127 		goto fail;
128 	if (addr == 0 || addr % PAGE_SIZE)
129 		goto fail;
130 	os_info_old = kzalloc(sizeof(*os_info_old), GFP_KERNEL);
131 	if (!os_info_old)
132 		goto fail;
133 	if (copy_oldmem_kernel(os_info_old, (void *) addr,
134 			       sizeof(*os_info_old)))
135 		goto fail_free;
136 	if (os_info_old->magic != OS_INFO_MAGIC)
137 		goto fail_free;
138 	if (os_info_old->csum != os_info_csum(os_info_old))
139 		goto fail_free;
140 	if (os_info_old->version_major > OS_INFO_VERSION_MAJOR)
141 		goto fail_free;
142 	os_info_old_alloc(OS_INFO_VMCOREINFO, 1);
143 	os_info_old_alloc(OS_INFO_REIPL_BLOCK, 1);
144 	pr_info("crashkernel: addr=0x%lx size=%lu\n",
145 		(unsigned long) os_info_old->crashkernel_addr,
146 		(unsigned long) os_info_old->crashkernel_size);
147 	os_info_init = 1;
148 	return;
149 fail_free:
150 	kfree(os_info_old);
151 fail:
152 	os_info_init = 1;
153 	os_info_old = NULL;
154 }
155 
156 /*
157  * Return pointer to os infor entry and its size
158  */
159 void *os_info_old_entry(int nr, unsigned long *size)
160 {
161 	os_info_old_init();
162 
163 	if (!os_info_old)
164 		return NULL;
165 	if (!os_info_old->entry[nr].addr)
166 		return NULL;
167 	*size = (unsigned long) os_info_old->entry[nr].size;
168 	return (void *)(unsigned long)os_info_old->entry[nr].addr;
169 }
170 #endif
171