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uaccess_mvcos.c
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1 /*
2  * Optimized user space space access functions based on mvcos.
3  *
4  * Copyright IBM Corp. 2006
5  * Author(s): Martin Schwidefsky ([email protected]),
6  * Gerald Schaefer ([email protected])
7  */
8 
9 #include <linux/errno.h>
10 #include <linux/mm.h>
11 #include <asm/uaccess.h>
12 #include <asm/futex.h>
13 #include "uaccess.h"
14 
15 #ifndef CONFIG_64BIT
16 #define AHI "ahi"
17 #define ALR "alr"
18 #define CLR "clr"
19 #define LHI "lhi"
20 #define SLR "slr"
21 #else
22 #define AHI "aghi"
23 #define ALR "algr"
24 #define CLR "clgr"
25 #define LHI "lghi"
26 #define SLR "slgr"
27 #endif
28 
29 static size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x)
30 {
31  register unsigned long reg0 asm("0") = 0x81UL;
32  unsigned long tmp1, tmp2;
33 
34  tmp1 = -4096UL;
35  asm volatile(
36  "0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
37  "9: jz 7f\n"
38  "1:"ALR" %0,%3\n"
39  " "SLR" %1,%3\n"
40  " "SLR" %2,%3\n"
41  " j 0b\n"
42  "2: la %4,4095(%1)\n"/* %4 = ptr + 4095 */
43  " nr %4,%3\n" /* %4 = (ptr + 4095) & -4096 */
44  " "SLR" %4,%1\n"
45  " "CLR" %0,%4\n" /* copy crosses next page boundary? */
46  " jnh 4f\n"
47  "3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
48  "10:"SLR" %0,%4\n"
49  " "ALR" %2,%4\n"
50  "4:"LHI" %4,-1\n"
51  " "ALR" %4,%0\n" /* copy remaining size, subtract 1 */
52  " bras %3,6f\n" /* memset loop */
53  " xc 0(1,%2),0(%2)\n"
54  "5: xc 0(256,%2),0(%2)\n"
55  " la %2,256(%2)\n"
56  "6:"AHI" %4,-256\n"
57  " jnm 5b\n"
58  " ex %4,0(%3)\n"
59  " j 8f\n"
60  "7:"SLR" %0,%0\n"
61  "8: \n"
62  EX_TABLE(0b,2b) EX_TABLE(3b,4b) EX_TABLE(9b,2b) EX_TABLE(10b,4b)
63  : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
64  : "d" (reg0) : "cc", "memory");
65  return size;
66 }
67 
68 static size_t copy_from_user_mvcos_check(size_t size, const void __user *ptr, void *x)
69 {
70  if (size <= 256)
71  return copy_from_user_std(size, ptr, x);
72  return copy_from_user_mvcos(size, ptr, x);
73 }
74 
75 static size_t copy_to_user_mvcos(size_t size, void __user *ptr, const void *x)
76 {
77  register unsigned long reg0 asm("0") = 0x810000UL;
78  unsigned long tmp1, tmp2;
79 
80  tmp1 = -4096UL;
81  asm volatile(
82  "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
83  "6: jz 4f\n"
84  "1:"ALR" %0,%3\n"
85  " "SLR" %1,%3\n"
86  " "SLR" %2,%3\n"
87  " j 0b\n"
88  "2: la %4,4095(%1)\n"/* %4 = ptr + 4095 */
89  " nr %4,%3\n" /* %4 = (ptr + 4095) & -4096 */
90  " "SLR" %4,%1\n"
91  " "CLR" %0,%4\n" /* copy crosses next page boundary? */
92  " jnh 5f\n"
93  "3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
94  "7:"SLR" %0,%4\n"
95  " j 5f\n"
96  "4:"SLR" %0,%0\n"
97  "5: \n"
98  EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
99  : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
100  : "d" (reg0) : "cc", "memory");
101  return size;
102 }
103 
104 static size_t copy_to_user_mvcos_check(size_t size, void __user *ptr,
105  const void *x)
106 {
107  if (size <= 256)
108  return copy_to_user_std(size, ptr, x);
109  return copy_to_user_mvcos(size, ptr, x);
110 }
111 
112 static size_t copy_in_user_mvcos(size_t size, void __user *to,
113  const void __user *from)
114 {
115  register unsigned long reg0 asm("0") = 0x810081UL;
116  unsigned long tmp1, tmp2;
117 
118  tmp1 = -4096UL;
119  /* FIXME: copy with reduced length. */
120  asm volatile(
121  "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
122  " jz 2f\n"
123  "1:"ALR" %0,%3\n"
124  " "SLR" %1,%3\n"
125  " "SLR" %2,%3\n"
126  " j 0b\n"
127  "2:"SLR" %0,%0\n"
128  "3: \n"
129  EX_TABLE(0b,3b)
130  : "+a" (size), "+a" (to), "+a" (from), "+a" (tmp1), "=a" (tmp2)
131  : "d" (reg0) : "cc", "memory");
132  return size;
133 }
134 
135 static size_t clear_user_mvcos(size_t size, void __user *to)
136 {
137  register unsigned long reg0 asm("0") = 0x810000UL;
138  unsigned long tmp1, tmp2;
139 
140  tmp1 = -4096UL;
141  asm volatile(
142  "0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"
143  " jz 4f\n"
144  "1:"ALR" %0,%2\n"
145  " "SLR" %1,%2\n"
146  " j 0b\n"
147  "2: la %3,4095(%1)\n"/* %4 = to + 4095 */
148  " nr %3,%2\n" /* %4 = (to + 4095) & -4096 */
149  " "SLR" %3,%1\n"
150  " "CLR" %0,%3\n" /* copy crosses next page boundary? */
151  " jnh 5f\n"
152  "3: .insn ss,0xc80000000000,0(%3,%1),0(%4),0\n"
153  " "SLR" %0,%3\n"
154  " j 5f\n"
155  "4:"SLR" %0,%0\n"
156  "5: \n"
157  EX_TABLE(0b,2b) EX_TABLE(3b,5b)
158  : "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
159  : "a" (empty_zero_page), "d" (reg0) : "cc", "memory");
160  return size;
161 }
162 
163 static size_t strnlen_user_mvcos(size_t count, const char __user *src)
164 {
165  char buf[256];
166  int rc;
167  size_t done, len, len_str;
168 
169  done = 0;
170  do {
171  len = min(count - done, (size_t) 256);
172  rc = uaccess.copy_from_user(len, src + done, buf);
173  if (unlikely(rc == len))
174  return 0;
175  len -= rc;
176  len_str = strnlen(buf, len);
177  done += len_str;
178  } while ((len_str == len) && (done < count));
179  return done + 1;
180 }
181 
182 static size_t strncpy_from_user_mvcos(size_t count, const char __user *src,
183  char *dst)
184 {
185  int rc;
186  size_t done, len, len_str;
187 
188  done = 0;
189  do {
190  len = min(count - done, (size_t) 4096);
191  rc = uaccess.copy_from_user(len, src + done, dst);
192  if (unlikely(rc == len))
193  return -EFAULT;
194  len -= rc;
195  len_str = strnlen(dst, len);
196  done += len_str;
197  } while ((len_str == len) && (done < count));
198  return done;
199 }
200 
201 struct uaccess_ops uaccess_mvcos = {
202  .copy_from_user = copy_from_user_mvcos_check,
203  .copy_from_user_small = copy_from_user_std,
204  .copy_to_user = copy_to_user_mvcos_check,
205  .copy_to_user_small = copy_to_user_std,
206  .copy_in_user = copy_in_user_mvcos,
207  .clear_user = clear_user_mvcos,
208  .strnlen_user = strnlen_user_std,
209  .strncpy_from_user = strncpy_from_user_std,
210  .futex_atomic_op = futex_atomic_op_std,
211  .futex_atomic_cmpxchg = futex_atomic_cmpxchg_std,
212 };
213 
214 struct uaccess_ops uaccess_mvcos_switch = {
215  .copy_from_user = copy_from_user_mvcos,
216  .copy_from_user_small = copy_from_user_mvcos,
217  .copy_to_user = copy_to_user_mvcos,
218  .copy_to_user_small = copy_to_user_mvcos,
219  .copy_in_user = copy_in_user_mvcos,
220  .clear_user = clear_user_mvcos,
221  .strnlen_user = strnlen_user_mvcos,
222  .strncpy_from_user = strncpy_from_user_mvcos,
223  .futex_atomic_op = futex_atomic_op_pt,
224  .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
225 };
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