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88df125f HC |
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> | |
7f0bf656 | 14 | #include <linux/gfp.h> |
b2a68c23 | 15 | #include <linux/cpu.h> |
a0616cde | 16 | #include <asm/ctl_reg.h> |
63df41d6 | 17 | #include <asm/io.h> |
88df125f HC |
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 | */ | |
f29c5041 | 25 | static long probe_kernel_write_odd(void *dst, const void *src, size_t size) |
88df125f HC |
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 | ||
f29c5041 | 51 | long probe_kernel_write(void *dst, const void *src, size_t size) |
88df125f HC |
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 | } | |
92fe3132 | 65 | |
b785e0d0 | 66 | static int __memcpy_real(void *dest, void *src, size_t count) |
92fe3132 MH |
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; | |
92fe3132 MH |
72 | int rc = -EFAULT; |
73 | ||
92fe3132 MH |
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"); | |
b785e0d0 MH |
84 | return rc; |
85 | } | |
86 | ||
87 | /* | |
88 | * Copy memory in real mode (kernel to kernel) | |
89 | */ | |
90 | int 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); | |
92fe3132 MH |
101 | return rc; |
102 | } | |
7dd6b334 MH |
103 | |
104 | /* | |
73bf463e | 105 | * Copy memory in absolute mode (kernel to kernel) |
7dd6b334 | 106 | */ |
73bf463e | 107 | void memcpy_absolute(void *dest, void *src, size_t count) |
7dd6b334 | 108 | { |
73bf463e | 109 | unsigned long cr0, flags, prefix; |
7dd6b334 | 110 | |
73bf463e | 111 | flags = arch_local_irq_save(); |
7dd6b334 MH |
112 | __ctl_store(cr0, 0, 0); |
113 | __ctl_clear_bit(0, 28); /* disable lowcore protection */ | |
73bf463e MH |
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 | } | |
7dd6b334 | 124 | __ctl_load(cr0, 0, 0); |
73bf463e | 125 | arch_local_irq_restore(flags); |
7dd6b334 | 126 | } |
7f0bf656 MH |
127 | |
128 | /* | |
129 | * Copy memory from kernel (real) to user (virtual) | |
130 | */ | |
211deca6 | 131 | int copy_to_user_real(void __user *dest, void *src, unsigned long count) |
7f0bf656 MH |
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; | |
149 | out: | |
150 | free_page((unsigned long) buf); | |
151 | return rc; | |
152 | } | |
153 | ||
b2a68c23 MH |
154 | /* |
155 | * Check if physical address is within prefix or zero page | |
156 | */ | |
157 | static 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 | ||
b2a68c23 MH |
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 | */ | |
179 | void *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) | |
73bf463e | 190 | memcpy_absolute(bounce, (void *) addr, size); |
b2a68c23 MH |
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 | */ | |
200 | void unxlate_dev_mem_ptr(unsigned long addr, void *buf) | |
201 | { | |
202 | if ((void *) addr != buf) | |
203 | free_page((unsigned long) buf); | |
204 | } |