Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
88df125f HC |
2 | /* |
3 | * Access kernel memory without faulting -- s390 specific implementation. | |
4 | * | |
3c1a3bce | 5 | * Copyright IBM Corp. 2009, 2015 |
88df125f HC |
6 | * |
7 | * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>, | |
8 | * | |
9 | */ | |
10 | ||
11 | #include <linux/uaccess.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/types.h> | |
14 | #include <linux/errno.h> | |
7f0bf656 | 15 | #include <linux/gfp.h> |
b2a68c23 | 16 | #include <linux/cpu.h> |
a0616cde | 17 | #include <asm/ctl_reg.h> |
63df41d6 | 18 | #include <asm/io.h> |
78c98f90 | 19 | #include <asm/stacktrace.h> |
88df125f | 20 | |
8a5d8473 | 21 | static notrace long s390_kernel_write_odd(void *dst, const void *src, size_t size) |
88df125f | 22 | { |
3c1a3bce HC |
23 | unsigned long aligned, offset, count; |
24 | char tmp[8]; | |
88df125f | 25 | |
3c1a3bce HC |
26 | aligned = (unsigned long) dst & ~7UL; |
27 | offset = (unsigned long) dst & 7UL; | |
28 | size = min(8UL - offset, size); | |
29 | count = size - 1; | |
88df125f HC |
30 | asm volatile( |
31 | " bras 1,0f\n" | |
3c1a3bce HC |
32 | " mvc 0(1,%4),0(%5)\n" |
33 | "0: mvc 0(8,%3),0(%0)\n" | |
34 | " ex %1,0(1)\n" | |
35 | " lg %1,0(%3)\n" | |
36 | " lra %0,0(%0)\n" | |
37 | " sturg %1,%0\n" | |
38 | : "+&a" (aligned), "+&a" (count), "=m" (tmp) | |
39 | : "a" (&tmp), "a" (&tmp[offset]), "a" (src) | |
40 | : "cc", "memory", "1"); | |
41 | return size; | |
88df125f HC |
42 | } |
43 | ||
8a5d8473 HC |
44 | /* |
45 | * s390_kernel_write - write to kernel memory bypassing DAT | |
46 | * @dst: destination address | |
47 | * @src: source address | |
48 | * @size: number of bytes to copy | |
49 | * | |
50 | * This function writes to kernel memory bypassing DAT and possible page table | |
51 | * write protection. It writes to the destination using the sturg instruction. | |
3c1a3bce HC |
52 | * Therefore we have a read-modify-write sequence: the function reads eight |
53 | * bytes from destination at an eight byte boundary, modifies the bytes | |
8a5d8473 | 54 | * requested and writes the result back in a loop. |
8a5d8473 | 55 | */ |
a646ef39 MS |
56 | static DEFINE_SPINLOCK(s390_kernel_write_lock); |
57 | ||
cb2cceae | 58 | notrace void *s390_kernel_write(void *dst, const void *src, size_t size) |
88df125f | 59 | { |
cb2cceae | 60 | void *tmp = dst; |
a646ef39 | 61 | unsigned long flags; |
3c1a3bce | 62 | long copied; |
88df125f | 63 | |
a646ef39 | 64 | spin_lock_irqsave(&s390_kernel_write_lock, flags); |
d6df52e9 VG |
65 | if (!(flags & PSW_MASK_DAT)) { |
66 | memcpy(dst, src, size); | |
67 | } else { | |
68 | while (size) { | |
69 | copied = s390_kernel_write_odd(tmp, src, size); | |
70 | tmp += copied; | |
71 | src += copied; | |
72 | size -= copied; | |
73 | } | |
88df125f | 74 | } |
a646ef39 | 75 | spin_unlock_irqrestore(&s390_kernel_write_lock, flags); |
cb2cceae JP |
76 | |
77 | return dst; | |
88df125f | 78 | } |
92fe3132 | 79 | |
13f9bae5 | 80 | static int __no_sanitize_address __memcpy_real(void *dest, void *src, size_t count) |
92fe3132 MH |
81 | { |
82 | register unsigned long _dest asm("2") = (unsigned long) dest; | |
83 | register unsigned long _len1 asm("3") = (unsigned long) count; | |
84 | register unsigned long _src asm("4") = (unsigned long) src; | |
85 | register unsigned long _len2 asm("5") = (unsigned long) count; | |
92fe3132 MH |
86 | int rc = -EFAULT; |
87 | ||
92fe3132 MH |
88 | asm volatile ( |
89 | "0: mvcle %1,%2,0x0\n" | |
90 | "1: jo 0b\n" | |
91 | " lhi %0,0x0\n" | |
92 | "2:\n" | |
93 | EX_TABLE(1b,2b) | |
94 | : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1), | |
95 | "+d" (_len2), "=m" (*((long *) dest)) | |
96 | : "m" (*((long *) src)) | |
97 | : "cc", "memory"); | |
b785e0d0 MH |
98 | return rc; |
99 | } | |
100 | ||
13f9bae5 VG |
101 | static unsigned long __no_sanitize_address _memcpy_real(unsigned long dest, |
102 | unsigned long src, | |
103 | unsigned long count) | |
b785e0d0 | 104 | { |
52499d93 | 105 | int irqs_disabled, rc; |
b785e0d0 | 106 | unsigned long flags; |
b785e0d0 MH |
107 | |
108 | if (!count) | |
109 | return 0; | |
13f9bae5 | 110 | flags = arch_local_irq_save(); |
52499d93 HC |
111 | irqs_disabled = arch_irqs_disabled_flags(flags); |
112 | if (!irqs_disabled) | |
113 | trace_hardirqs_off(); | |
13f9bae5 | 114 | __arch_local_irq_stnsm(0xf8); // disable DAT |
ce3dc447 | 115 | rc = __memcpy_real((void *) dest, (void *) src, (size_t) count); |
13f9bae5 VG |
116 | if (flags & PSW_MASK_DAT) |
117 | __arch_local_irq_stosm(0x04); // enable DAT | |
52499d93 | 118 | if (!irqs_disabled) |
0986d977 CB |
119 | trace_hardirqs_on(); |
120 | __arch_local_irq_ssm(flags); | |
92fe3132 MH |
121 | return rc; |
122 | } | |
7dd6b334 | 123 | |
ce3dc447 MS |
124 | /* |
125 | * Copy memory in real mode (kernel to kernel) | |
126 | */ | |
127 | int memcpy_real(void *dest, void *src, size_t count) | |
128 | { | |
7f28dad3 VG |
129 | int rc; |
130 | ||
131 | if (S390_lowcore.nodat_stack != 0) { | |
132 | preempt_disable(); | |
133 | rc = CALL_ON_STACK(_memcpy_real, S390_lowcore.nodat_stack, 3, | |
134 | dest, src, count); | |
135 | preempt_enable(); | |
136 | return rc; | |
137 | } | |
ce3dc447 MS |
138 | /* |
139 | * This is a really early memcpy_real call, the stacks are | |
140 | * not set up yet. Just call _memcpy_real on the early boot | |
141 | * stack | |
142 | */ | |
143 | return _memcpy_real((unsigned long) dest,(unsigned long) src, | |
144 | (unsigned long) count); | |
145 | } | |
146 | ||
7dd6b334 | 147 | /* |
73bf463e | 148 | * Copy memory in absolute mode (kernel to kernel) |
7dd6b334 | 149 | */ |
73bf463e | 150 | void memcpy_absolute(void *dest, void *src, size_t count) |
7dd6b334 | 151 | { |
73bf463e | 152 | unsigned long cr0, flags, prefix; |
7dd6b334 | 153 | |
73bf463e | 154 | flags = arch_local_irq_save(); |
7dd6b334 MH |
155 | __ctl_store(cr0, 0, 0); |
156 | __ctl_clear_bit(0, 28); /* disable lowcore protection */ | |
73bf463e MH |
157 | prefix = store_prefix(); |
158 | if (prefix) { | |
159 | local_mcck_disable(); | |
160 | set_prefix(0); | |
161 | memcpy(dest, src, count); | |
162 | set_prefix(prefix); | |
163 | local_mcck_enable(); | |
164 | } else { | |
165 | memcpy(dest, src, count); | |
166 | } | |
7dd6b334 | 167 | __ctl_load(cr0, 0, 0); |
73bf463e | 168 | arch_local_irq_restore(flags); |
7dd6b334 | 169 | } |
7f0bf656 MH |
170 | |
171 | /* | |
172 | * Copy memory from kernel (real) to user (virtual) | |
173 | */ | |
211deca6 | 174 | int copy_to_user_real(void __user *dest, void *src, unsigned long count) |
7f0bf656 MH |
175 | { |
176 | int offs = 0, size, rc; | |
177 | char *buf; | |
178 | ||
179 | buf = (char *) __get_free_page(GFP_KERNEL); | |
180 | if (!buf) | |
181 | return -ENOMEM; | |
182 | rc = -EFAULT; | |
183 | while (offs < count) { | |
184 | size = min(PAGE_SIZE, count - offs); | |
185 | if (memcpy_real(buf, src + offs, size)) | |
186 | goto out; | |
187 | if (copy_to_user(dest + offs, buf, size)) | |
188 | goto out; | |
189 | offs += size; | |
190 | } | |
191 | rc = 0; | |
192 | out: | |
193 | free_page((unsigned long) buf); | |
194 | return rc; | |
195 | } | |
196 | ||
b2a68c23 MH |
197 | /* |
198 | * Check if physical address is within prefix or zero page | |
199 | */ | |
200 | static int is_swapped(unsigned long addr) | |
201 | { | |
202 | unsigned long lc; | |
203 | int cpu; | |
204 | ||
c667aeac | 205 | if (addr < sizeof(struct lowcore)) |
b2a68c23 MH |
206 | return 1; |
207 | for_each_online_cpu(cpu) { | |
208 | lc = (unsigned long) lowcore_ptr[cpu]; | |
c667aeac | 209 | if (addr > lc + sizeof(struct lowcore) - 1 || addr < lc) |
b2a68c23 MH |
210 | continue; |
211 | return 1; | |
212 | } | |
213 | return 0; | |
214 | } | |
215 | ||
b2a68c23 MH |
216 | /* |
217 | * Convert a physical pointer for /dev/mem access | |
218 | * | |
219 | * For swapped prefix pages a new buffer is returned that contains a copy of | |
220 | * the absolute memory. The buffer size is maximum one page large. | |
221 | */ | |
4707a341 | 222 | void *xlate_dev_mem_ptr(phys_addr_t addr) |
b2a68c23 MH |
223 | { |
224 | void *bounce = (void *) addr; | |
225 | unsigned long size; | |
226 | ||
227 | get_online_cpus(); | |
228 | preempt_disable(); | |
229 | if (is_swapped(addr)) { | |
230 | size = PAGE_SIZE - (addr & ~PAGE_MASK); | |
231 | bounce = (void *) __get_free_page(GFP_ATOMIC); | |
232 | if (bounce) | |
73bf463e | 233 | memcpy_absolute(bounce, (void *) addr, size); |
b2a68c23 MH |
234 | } |
235 | preempt_enable(); | |
236 | put_online_cpus(); | |
237 | return bounce; | |
238 | } | |
239 | ||
240 | /* | |
241 | * Free converted buffer for /dev/mem access (if necessary) | |
242 | */ | |
4707a341 | 243 | void unxlate_dev_mem_ptr(phys_addr_t addr, void *buf) |
b2a68c23 MH |
244 | { |
245 | if ((void *) addr != buf) | |
246 | free_page((unsigned long) buf); | |
247 | } |