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futex.c
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1 /* futex.c: futex operations
2  *
3  * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells ([email protected])
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/futex.h>
13 #include <linux/uaccess.h>
14 #include <asm/futex.h>
15 #include <asm/errno.h>
16 
17 /*
18  * the various futex operations; MMU fault checking is ignored under no-MMU
19  * conditions
20  */
21 static inline int atomic_futex_op_xchg_set(int oparg, u32 __user *uaddr, int *_oldval)
22 {
23  int oldval, ret;
24 
25  asm("0: \n"
26  " orcc gr0,gr0,gr0,icc3 \n" /* set ICC3.Z */
27  " ckeq icc3,cc7 \n"
28  "1: ld.p %M0,%1 \n" /* LD.P/ORCR must be atomic */
29  " orcr cc7,cc7,cc3 \n" /* set CC3 to true */
30  "2: cst.p %3,%M0 ,cc3,#1 \n"
31  " corcc gr29,gr29,gr0 ,cc3,#1 \n" /* clear ICC3.Z if store happens */
32  " beq icc3,#0,0b \n"
33  " setlos 0,%2 \n"
34  "3: \n"
35  ".subsection 2 \n"
36  "4: setlos %5,%2 \n"
37  " bra 3b \n"
38  ".previous \n"
39  ".section __ex_table,\"a\" \n"
40  " .balign 8 \n"
41  " .long 1b,4b \n"
42  " .long 2b,4b \n"
43  ".previous"
44  : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
45  : "3"(oparg), "i"(-EFAULT)
46  : "memory", "cc7", "cc3", "icc3"
47  );
48 
49  *_oldval = oldval;
50  return ret;
51 }
52 
53 static inline int atomic_futex_op_xchg_add(int oparg, u32 __user *uaddr, int *_oldval)
54 {
55  int oldval, ret;
56 
57  asm("0: \n"
58  " orcc gr0,gr0,gr0,icc3 \n" /* set ICC3.Z */
59  " ckeq icc3,cc7 \n"
60  "1: ld.p %M0,%1 \n" /* LD.P/ORCR must be atomic */
61  " orcr cc7,cc7,cc3 \n" /* set CC3 to true */
62  " add %1,%3,%3 \n"
63  "2: cst.p %3,%M0 ,cc3,#1 \n"
64  " corcc gr29,gr29,gr0 ,cc3,#1 \n" /* clear ICC3.Z if store happens */
65  " beq icc3,#0,0b \n"
66  " setlos 0,%2 \n"
67  "3: \n"
68  ".subsection 2 \n"
69  "4: setlos %5,%2 \n"
70  " bra 3b \n"
71  ".previous \n"
72  ".section __ex_table,\"a\" \n"
73  " .balign 8 \n"
74  " .long 1b,4b \n"
75  " .long 2b,4b \n"
76  ".previous"
77  : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
78  : "3"(oparg), "i"(-EFAULT)
79  : "memory", "cc7", "cc3", "icc3"
80  );
81 
82  *_oldval = oldval;
83  return ret;
84 }
85 
86 static inline int atomic_futex_op_xchg_or(int oparg, u32 __user *uaddr, int *_oldval)
87 {
88  int oldval, ret;
89 
90  asm("0: \n"
91  " orcc gr0,gr0,gr0,icc3 \n" /* set ICC3.Z */
92  " ckeq icc3,cc7 \n"
93  "1: ld.p %M0,%1 \n" /* LD.P/ORCR must be atomic */
94  " orcr cc7,cc7,cc3 \n" /* set CC3 to true */
95  " or %1,%3,%3 \n"
96  "2: cst.p %3,%M0 ,cc3,#1 \n"
97  " corcc gr29,gr29,gr0 ,cc3,#1 \n" /* clear ICC3.Z if store happens */
98  " beq icc3,#0,0b \n"
99  " setlos 0,%2 \n"
100  "3: \n"
101  ".subsection 2 \n"
102  "4: setlos %5,%2 \n"
103  " bra 3b \n"
104  ".previous \n"
105  ".section __ex_table,\"a\" \n"
106  " .balign 8 \n"
107  " .long 1b,4b \n"
108  " .long 2b,4b \n"
109  ".previous"
110  : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
111  : "3"(oparg), "i"(-EFAULT)
112  : "memory", "cc7", "cc3", "icc3"
113  );
114 
115  *_oldval = oldval;
116  return ret;
117 }
118 
119 static inline int atomic_futex_op_xchg_and(int oparg, u32 __user *uaddr, int *_oldval)
120 {
121  int oldval, ret;
122 
123  asm("0: \n"
124  " orcc gr0,gr0,gr0,icc3 \n" /* set ICC3.Z */
125  " ckeq icc3,cc7 \n"
126  "1: ld.p %M0,%1 \n" /* LD.P/ORCR must be atomic */
127  " orcr cc7,cc7,cc3 \n" /* set CC3 to true */
128  " and %1,%3,%3 \n"
129  "2: cst.p %3,%M0 ,cc3,#1 \n"
130  " corcc gr29,gr29,gr0 ,cc3,#1 \n" /* clear ICC3.Z if store happens */
131  " beq icc3,#0,0b \n"
132  " setlos 0,%2 \n"
133  "3: \n"
134  ".subsection 2 \n"
135  "4: setlos %5,%2 \n"
136  " bra 3b \n"
137  ".previous \n"
138  ".section __ex_table,\"a\" \n"
139  " .balign 8 \n"
140  " .long 1b,4b \n"
141  " .long 2b,4b \n"
142  ".previous"
143  : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
144  : "3"(oparg), "i"(-EFAULT)
145  : "memory", "cc7", "cc3", "icc3"
146  );
147 
148  *_oldval = oldval;
149  return ret;
150 }
151 
152 static inline int atomic_futex_op_xchg_xor(int oparg, u32 __user *uaddr, int *_oldval)
153 {
154  int oldval, ret;
155 
156  asm("0: \n"
157  " orcc gr0,gr0,gr0,icc3 \n" /* set ICC3.Z */
158  " ckeq icc3,cc7 \n"
159  "1: ld.p %M0,%1 \n" /* LD.P/ORCR must be atomic */
160  " orcr cc7,cc7,cc3 \n" /* set CC3 to true */
161  " xor %1,%3,%3 \n"
162  "2: cst.p %3,%M0 ,cc3,#1 \n"
163  " corcc gr29,gr29,gr0 ,cc3,#1 \n" /* clear ICC3.Z if store happens */
164  " beq icc3,#0,0b \n"
165  " setlos 0,%2 \n"
166  "3: \n"
167  ".subsection 2 \n"
168  "4: setlos %5,%2 \n"
169  " bra 3b \n"
170  ".previous \n"
171  ".section __ex_table,\"a\" \n"
172  " .balign 8 \n"
173  " .long 1b,4b \n"
174  " .long 2b,4b \n"
175  ".previous"
176  : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
177  : "3"(oparg), "i"(-EFAULT)
178  : "memory", "cc7", "cc3", "icc3"
179  );
180 
181  *_oldval = oldval;
182  return ret;
183 }
184 
185 /*****************************************************************************/
186 /*
187  * do the futex operations
188  */
189 int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
190 {
191  int op = (encoded_op >> 28) & 7;
192  int cmp = (encoded_op >> 24) & 15;
193  int oparg = (encoded_op << 8) >> 20;
194  int cmparg = (encoded_op << 20) >> 20;
195  int oldval = 0, ret;
196 
197  if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
198  oparg = 1 << oparg;
199 
200  if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
201  return -EFAULT;
202 
203  pagefault_disable();
204 
205  switch (op) {
206  case FUTEX_OP_SET:
207  ret = atomic_futex_op_xchg_set(oparg, uaddr, &oldval);
208  break;
209  case FUTEX_OP_ADD:
210  ret = atomic_futex_op_xchg_add(oparg, uaddr, &oldval);
211  break;
212  case FUTEX_OP_OR:
213  ret = atomic_futex_op_xchg_or(oparg, uaddr, &oldval);
214  break;
215  case FUTEX_OP_ANDN:
216  ret = atomic_futex_op_xchg_and(~oparg, uaddr, &oldval);
217  break;
218  case FUTEX_OP_XOR:
219  ret = atomic_futex_op_xchg_xor(oparg, uaddr, &oldval);
220  break;
221  default:
222  ret = -ENOSYS;
223  break;
224  }
225 
226  pagefault_enable();
227 
228  if (!ret) {
229  switch (cmp) {
230  case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
231  case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
232  case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
233  case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
234  case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
235  case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
236  default: ret = -ENOSYS; break;
237  }
238  }
239 
240  return ret;
241 
242 } /* end futex_atomic_op_inuser() */
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