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1/*
2 * Access kernel memory without faulting -- s390 specific implementation.
3 *
4 * Copyright IBM Corp. 2009
5 *
6 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
7 *
8 */
9
10#include <linux/uaccess.h>
11#include <linux/kernel.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <asm/system.h>
15
16/*
17 * This function writes to kernel memory bypassing DAT and possible
18 * write protection. It copies one to four bytes from src to dst
19 * using the stura instruction.
20 * Returns the number of bytes copied or -EFAULT.
21 */
22static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
23{
24 unsigned long count, aligned;
25 int offset, mask;
26 int rc = -EFAULT;
27
28 aligned = (unsigned long) dst & ~3UL;
29 offset = (unsigned long) dst & 3;
30 count = min_t(unsigned long, 4 - offset, size);
31 mask = (0xf << (4 - count)) & 0xf;
32 mask >>= offset;
33 asm volatile(
34 " bras 1,0f\n"
35 " icm 0,0,0(%3)\n"
36 "0: l 0,0(%1)\n"
37 " lra %1,0(%1)\n"
38 "1: ex %2,0(1)\n"
39 "2: stura 0,%1\n"
40 " la %0,0\n"
41 "3:\n"
42 EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
43 : "+d" (rc), "+a" (aligned)
44 : "a" (mask), "a" (src) : "cc", "memory", "0", "1");
45 return rc ? rc : count;
46}
47
48long probe_kernel_write(void *dst, const void *src, size_t size)
49{
50 long copied = 0;
51
52 while (size) {
53 copied = probe_kernel_write_odd(dst, src, size);
54 if (copied < 0)
55 break;
56 dst += copied;
57 src += copied;
58 size -= copied;
59 }
60 return copied < 0 ? -EFAULT : 0;
61}
62
63int memcpy_real(void *dest, void *src, size_t count)
64{
65 register unsigned long _dest asm("2") = (unsigned long) dest;
66 register unsigned long _len1 asm("3") = (unsigned long) count;
67 register unsigned long _src asm("4") = (unsigned long) src;
68 register unsigned long _len2 asm("5") = (unsigned long) count;
69 unsigned long flags;
70 int rc = -EFAULT;
71
72 if (!count)
73 return 0;
74 flags = __arch_local_irq_stnsm(0xf8UL);
75 asm volatile (
76 "0: mvcle %1,%2,0x0\n"
77 "1: jo 0b\n"
78 " lhi %0,0x0\n"
79 "2:\n"
80 EX_TABLE(1b,2b)
81 : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
82 "+d" (_len2), "=m" (*((long *) dest))
83 : "m" (*((long *) src))
84 : "cc", "memory");
85 arch_local_irq_restore(flags);
86 return rc;
87}
88
89/*
90 * Copy memory to absolute zero
91 */
92void copy_to_absolute_zero(void *dest, void *src, size_t count)
93{
94 unsigned long cr0;
95
96 BUG_ON((unsigned long) dest + count >= sizeof(struct _lowcore));
97 preempt_disable();
98 __ctl_store(cr0, 0, 0);
99 __ctl_clear_bit(0, 28); /* disable lowcore protection */
100 memcpy_real(dest + store_prefix(), src, count);
101 __ctl_load(cr0, 0, 0);
102 preempt_enable();
103}
1/*
2 * Access kernel memory without faulting -- s390 specific implementation.
3 *
4 * Copyright IBM Corp. 2009
5 *
6 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
7 *
8 */
9
10#include <linux/uaccess.h>
11#include <linux/kernel.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <linux/gfp.h>
15#include <linux/cpu.h>
16#include <asm/ctl_reg.h>
17#include <asm/io.h>
18
19/*
20 * This function writes to kernel memory bypassing DAT and possible
21 * write protection. It copies one to four bytes from src to dst
22 * using the stura instruction.
23 * Returns the number of bytes copied or -EFAULT.
24 */
25static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
26{
27 unsigned long count, aligned;
28 int offset, mask;
29 int rc = -EFAULT;
30
31 aligned = (unsigned long) dst & ~3UL;
32 offset = (unsigned long) dst & 3;
33 count = min_t(unsigned long, 4 - offset, size);
34 mask = (0xf << (4 - count)) & 0xf;
35 mask >>= offset;
36 asm volatile(
37 " bras 1,0f\n"
38 " icm 0,0,0(%3)\n"
39 "0: l 0,0(%1)\n"
40 " lra %1,0(%1)\n"
41 "1: ex %2,0(1)\n"
42 "2: stura 0,%1\n"
43 " la %0,0\n"
44 "3:\n"
45 EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
46 : "+d" (rc), "+a" (aligned)
47 : "a" (mask), "a" (src) : "cc", "memory", "0", "1");
48 return rc ? rc : count;
49}
50
51long probe_kernel_write(void *dst, const void *src, size_t size)
52{
53 long copied = 0;
54
55 while (size) {
56 copied = probe_kernel_write_odd(dst, src, size);
57 if (copied < 0)
58 break;
59 dst += copied;
60 src += copied;
61 size -= copied;
62 }
63 return copied < 0 ? -EFAULT : 0;
64}
65
66static int __memcpy_real(void *dest, void *src, size_t count)
67{
68 register unsigned long _dest asm("2") = (unsigned long) dest;
69 register unsigned long _len1 asm("3") = (unsigned long) count;
70 register unsigned long _src asm("4") = (unsigned long) src;
71 register unsigned long _len2 asm("5") = (unsigned long) count;
72 int rc = -EFAULT;
73
74 asm volatile (
75 "0: mvcle %1,%2,0x0\n"
76 "1: jo 0b\n"
77 " lhi %0,0x0\n"
78 "2:\n"
79 EX_TABLE(1b,2b)
80 : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
81 "+d" (_len2), "=m" (*((long *) dest))
82 : "m" (*((long *) src))
83 : "cc", "memory");
84 return rc;
85}
86
87/*
88 * Copy memory in real mode (kernel to kernel)
89 */
90int memcpy_real(void *dest, void *src, size_t count)
91{
92 unsigned long flags;
93 int rc;
94
95 if (!count)
96 return 0;
97 local_irq_save(flags);
98 __arch_local_irq_stnsm(0xfbUL);
99 rc = __memcpy_real(dest, src, count);
100 local_irq_restore(flags);
101 return rc;
102}
103
104/*
105 * Copy memory in absolute mode (kernel to kernel)
106 */
107void memcpy_absolute(void *dest, void *src, size_t count)
108{
109 unsigned long cr0, flags, prefix;
110
111 flags = arch_local_irq_save();
112 __ctl_store(cr0, 0, 0);
113 __ctl_clear_bit(0, 28); /* disable lowcore protection */
114 prefix = store_prefix();
115 if (prefix) {
116 local_mcck_disable();
117 set_prefix(0);
118 memcpy(dest, src, count);
119 set_prefix(prefix);
120 local_mcck_enable();
121 } else {
122 memcpy(dest, src, count);
123 }
124 __ctl_load(cr0, 0, 0);
125 arch_local_irq_restore(flags);
126}
127
128/*
129 * Copy memory from kernel (real) to user (virtual)
130 */
131int copy_to_user_real(void __user *dest, void *src, unsigned long count)
132{
133 int offs = 0, size, rc;
134 char *buf;
135
136 buf = (char *) __get_free_page(GFP_KERNEL);
137 if (!buf)
138 return -ENOMEM;
139 rc = -EFAULT;
140 while (offs < count) {
141 size = min(PAGE_SIZE, count - offs);
142 if (memcpy_real(buf, src + offs, size))
143 goto out;
144 if (copy_to_user(dest + offs, buf, size))
145 goto out;
146 offs += size;
147 }
148 rc = 0;
149out:
150 free_page((unsigned long) buf);
151 return rc;
152}
153
154/*
155 * Check if physical address is within prefix or zero page
156 */
157static int is_swapped(unsigned long addr)
158{
159 unsigned long lc;
160 int cpu;
161
162 if (addr < sizeof(struct _lowcore))
163 return 1;
164 for_each_online_cpu(cpu) {
165 lc = (unsigned long) lowcore_ptr[cpu];
166 if (addr > lc + sizeof(struct _lowcore) - 1 || addr < lc)
167 continue;
168 return 1;
169 }
170 return 0;
171}
172
173/*
174 * Convert a physical pointer for /dev/mem access
175 *
176 * For swapped prefix pages a new buffer is returned that contains a copy of
177 * the absolute memory. The buffer size is maximum one page large.
178 */
179void *xlate_dev_mem_ptr(unsigned long addr)
180{
181 void *bounce = (void *) addr;
182 unsigned long size;
183
184 get_online_cpus();
185 preempt_disable();
186 if (is_swapped(addr)) {
187 size = PAGE_SIZE - (addr & ~PAGE_MASK);
188 bounce = (void *) __get_free_page(GFP_ATOMIC);
189 if (bounce)
190 memcpy_absolute(bounce, (void *) addr, size);
191 }
192 preempt_enable();
193 put_online_cpus();
194 return bounce;
195}
196
197/*
198 * Free converted buffer for /dev/mem access (if necessary)
199 */
200void unxlate_dev_mem_ptr(unsigned long addr, void *buf)
201{
202 if ((void *) addr != buf)
203 free_page((unsigned long) buf);
204}