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 */
 24static struct os_info os_info __page_aligned_data;
 25
 26/*
 27 * Compute checksum over OS info structure
 28 */
 29u32 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 */
 38void 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 */
 48void 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 */
 59void __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
 75static struct os_info *os_info_old;
 76
 77/*
 78 * Allocate and copy OS info entry from oldmem
 79 */
 80static 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;
110fail_free:
111	kfree(buf);
112fail:
113	os_info_old->entry[nr].addr = 0;
114out:
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 */
122static 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;
153fail_free:
154	kfree(os_info_old);
155fail:
156	os_info_init = 1;
157	os_info_old = NULL;
158}
159
160/*
161 * Return pointer to os infor entry and its size
162 */
163void *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