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Linux-2.6.12-rc2
[mirror_ubuntu-artful-kernel.git] / arch / ppc / kernel / align.c
1 /*
2 * align.c - handle alignment exceptions for the Power PC.
3 *
4 * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
5 * Copyright (c) 1998-1999 TiVo, Inc.
6 * PowerPC 403GCX modifications.
7 * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
8 * PowerPC 403GCX/405GP modifications.
9 */
10 #include <linux/config.h>
11 #include <linux/kernel.h>
12 #include <linux/mm.h>
13 #include <asm/ptrace.h>
14 #include <asm/processor.h>
15 #include <asm/uaccess.h>
16 #include <asm/system.h>
17 #include <asm/cache.h>
18
19 struct aligninfo {
20 unsigned char len;
21 unsigned char flags;
22 };
23
24 #if defined(CONFIG_4xx) || defined(CONFIG_POWER4) || defined(CONFIG_BOOKE)
25 #define OPCD(inst) (((inst) & 0xFC000000) >> 26)
26 #define RS(inst) (((inst) & 0x03E00000) >> 21)
27 #define RA(inst) (((inst) & 0x001F0000) >> 16)
28 #define IS_XFORM(code) ((code) == 31)
29 #endif
30
31 #define INVALID { 0, 0 }
32
33 #define LD 1 /* load */
34 #define ST 2 /* store */
35 #define SE 4 /* sign-extend value */
36 #define F 8 /* to/from fp regs */
37 #define U 0x10 /* update index register */
38 #define M 0x20 /* multiple load/store */
39 #define S 0x40 /* single-precision fp, or byte-swap value */
40 #define SX 0x40 /* byte count in XER */
41 #define HARD 0x80 /* string, stwcx. */
42
43 #define DCBZ 0x5f /* 8xx/82xx dcbz faults when cache not enabled */
44
45 /*
46 * The PowerPC stores certain bits of the instruction that caused the
47 * alignment exception in the DSISR register. This array maps those
48 * bits to information about the operand length and what the
49 * instruction would do.
50 */
51 static struct aligninfo aligninfo[128] = {
52 { 4, LD }, /* 00 0 0000: lwz / lwarx */
53 INVALID, /* 00 0 0001 */
54 { 4, ST }, /* 00 0 0010: stw */
55 INVALID, /* 00 0 0011 */
56 { 2, LD }, /* 00 0 0100: lhz */
57 { 2, LD+SE }, /* 00 0 0101: lha */
58 { 2, ST }, /* 00 0 0110: sth */
59 { 4, LD+M }, /* 00 0 0111: lmw */
60 { 4, LD+F+S }, /* 00 0 1000: lfs */
61 { 8, LD+F }, /* 00 0 1001: lfd */
62 { 4, ST+F+S }, /* 00 0 1010: stfs */
63 { 8, ST+F }, /* 00 0 1011: stfd */
64 INVALID, /* 00 0 1100 */
65 INVALID, /* 00 0 1101: ld/ldu/lwa */
66 INVALID, /* 00 0 1110 */
67 INVALID, /* 00 0 1111: std/stdu */
68 { 4, LD+U }, /* 00 1 0000: lwzu */
69 INVALID, /* 00 1 0001 */
70 { 4, ST+U }, /* 00 1 0010: stwu */
71 INVALID, /* 00 1 0011 */
72 { 2, LD+U }, /* 00 1 0100: lhzu */
73 { 2, LD+SE+U }, /* 00 1 0101: lhau */
74 { 2, ST+U }, /* 00 1 0110: sthu */
75 { 4, ST+M }, /* 00 1 0111: stmw */
76 { 4, LD+F+S+U }, /* 00 1 1000: lfsu */
77 { 8, LD+F+U }, /* 00 1 1001: lfdu */
78 { 4, ST+F+S+U }, /* 00 1 1010: stfsu */
79 { 8, ST+F+U }, /* 00 1 1011: stfdu */
80 INVALID, /* 00 1 1100 */
81 INVALID, /* 00 1 1101 */
82 INVALID, /* 00 1 1110 */
83 INVALID, /* 00 1 1111 */
84 INVALID, /* 01 0 0000: ldx */
85 INVALID, /* 01 0 0001 */
86 INVALID, /* 01 0 0010: stdx */
87 INVALID, /* 01 0 0011 */
88 INVALID, /* 01 0 0100 */
89 INVALID, /* 01 0 0101: lwax */
90 INVALID, /* 01 0 0110 */
91 INVALID, /* 01 0 0111 */
92 { 4, LD+M+HARD+SX }, /* 01 0 1000: lswx */
93 { 4, LD+M+HARD }, /* 01 0 1001: lswi */
94 { 4, ST+M+HARD+SX }, /* 01 0 1010: stswx */
95 { 4, ST+M+HARD }, /* 01 0 1011: stswi */
96 INVALID, /* 01 0 1100 */
97 INVALID, /* 01 0 1101 */
98 INVALID, /* 01 0 1110 */
99 INVALID, /* 01 0 1111 */
100 INVALID, /* 01 1 0000: ldux */
101 INVALID, /* 01 1 0001 */
102 INVALID, /* 01 1 0010: stdux */
103 INVALID, /* 01 1 0011 */
104 INVALID, /* 01 1 0100 */
105 INVALID, /* 01 1 0101: lwaux */
106 INVALID, /* 01 1 0110 */
107 INVALID, /* 01 1 0111 */
108 INVALID, /* 01 1 1000 */
109 INVALID, /* 01 1 1001 */
110 INVALID, /* 01 1 1010 */
111 INVALID, /* 01 1 1011 */
112 INVALID, /* 01 1 1100 */
113 INVALID, /* 01 1 1101 */
114 INVALID, /* 01 1 1110 */
115 INVALID, /* 01 1 1111 */
116 INVALID, /* 10 0 0000 */
117 INVALID, /* 10 0 0001 */
118 { 0, ST+HARD }, /* 10 0 0010: stwcx. */
119 INVALID, /* 10 0 0011 */
120 INVALID, /* 10 0 0100 */
121 INVALID, /* 10 0 0101 */
122 INVALID, /* 10 0 0110 */
123 INVALID, /* 10 0 0111 */
124 { 4, LD+S }, /* 10 0 1000: lwbrx */
125 INVALID, /* 10 0 1001 */
126 { 4, ST+S }, /* 10 0 1010: stwbrx */
127 INVALID, /* 10 0 1011 */
128 { 2, LD+S }, /* 10 0 1100: lhbrx */
129 INVALID, /* 10 0 1101 */
130 { 2, ST+S }, /* 10 0 1110: sthbrx */
131 INVALID, /* 10 0 1111 */
132 INVALID, /* 10 1 0000 */
133 INVALID, /* 10 1 0001 */
134 INVALID, /* 10 1 0010 */
135 INVALID, /* 10 1 0011 */
136 INVALID, /* 10 1 0100 */
137 INVALID, /* 10 1 0101 */
138 INVALID, /* 10 1 0110 */
139 INVALID, /* 10 1 0111 */
140 INVALID, /* 10 1 1000 */
141 INVALID, /* 10 1 1001 */
142 INVALID, /* 10 1 1010 */
143 INVALID, /* 10 1 1011 */
144 INVALID, /* 10 1 1100 */
145 INVALID, /* 10 1 1101 */
146 INVALID, /* 10 1 1110 */
147 { 0, ST+HARD }, /* 10 1 1111: dcbz */
148 { 4, LD }, /* 11 0 0000: lwzx */
149 INVALID, /* 11 0 0001 */
150 { 4, ST }, /* 11 0 0010: stwx */
151 INVALID, /* 11 0 0011 */
152 { 2, LD }, /* 11 0 0100: lhzx */
153 { 2, LD+SE }, /* 11 0 0101: lhax */
154 { 2, ST }, /* 11 0 0110: sthx */
155 INVALID, /* 11 0 0111 */
156 { 4, LD+F+S }, /* 11 0 1000: lfsx */
157 { 8, LD+F }, /* 11 0 1001: lfdx */
158 { 4, ST+F+S }, /* 11 0 1010: stfsx */
159 { 8, ST+F }, /* 11 0 1011: stfdx */
160 INVALID, /* 11 0 1100 */
161 INVALID, /* 11 0 1101: lmd */
162 INVALID, /* 11 0 1110 */
163 INVALID, /* 11 0 1111: stmd */
164 { 4, LD+U }, /* 11 1 0000: lwzux */
165 INVALID, /* 11 1 0001 */
166 { 4, ST+U }, /* 11 1 0010: stwux */
167 INVALID, /* 11 1 0011 */
168 { 2, LD+U }, /* 11 1 0100: lhzux */
169 { 2, LD+SE+U }, /* 11 1 0101: lhaux */
170 { 2, ST+U }, /* 11 1 0110: sthux */
171 INVALID, /* 11 1 0111 */
172 { 4, LD+F+S+U }, /* 11 1 1000: lfsux */
173 { 8, LD+F+U }, /* 11 1 1001: lfdux */
174 { 4, ST+F+S+U }, /* 11 1 1010: stfsux */
175 { 8, ST+F+U }, /* 11 1 1011: stfdux */
176 INVALID, /* 11 1 1100 */
177 INVALID, /* 11 1 1101 */
178 INVALID, /* 11 1 1110 */
179 INVALID, /* 11 1 1111 */
180 };
181
182 #define SWAP(a, b) (t = (a), (a) = (b), (b) = t)
183
184 int
185 fix_alignment(struct pt_regs *regs)
186 {
187 int instr, nb, flags;
188 #if defined(CONFIG_4xx) || defined(CONFIG_POWER4) || defined(CONFIG_BOOKE)
189 int opcode, f1, f2, f3;
190 #endif
191 int i, t;
192 int reg, areg;
193 int offset, nb0;
194 unsigned char __user *addr;
195 unsigned char *rptr;
196 union {
197 long l;
198 float f;
199 double d;
200 unsigned char v[8];
201 } data;
202
203 CHECK_FULL_REGS(regs);
204
205 #if defined(CONFIG_4xx) || defined(CONFIG_POWER4) || defined(CONFIG_BOOKE)
206 /* The 4xx-family & Book-E processors have no DSISR register,
207 * so we emulate it.
208 * The POWER4 has a DSISR register but doesn't set it on
209 * an alignment fault. -- paulus
210 */
211
212 if (__get_user(instr, (unsigned int __user *) regs->nip))
213 return 0;
214 opcode = OPCD(instr);
215 reg = RS(instr);
216 areg = RA(instr);
217
218 if (!IS_XFORM(opcode)) {
219 f1 = 0;
220 f2 = (instr & 0x04000000) >> 26;
221 f3 = (instr & 0x78000000) >> 27;
222 } else {
223 f1 = (instr & 0x00000006) >> 1;
224 f2 = (instr & 0x00000040) >> 6;
225 f3 = (instr & 0x00000780) >> 7;
226 }
227
228 instr = ((f1 << 5) | (f2 << 4) | f3);
229 #else
230 reg = (regs->dsisr >> 5) & 0x1f; /* source/dest register */
231 areg = regs->dsisr & 0x1f; /* register to update */
232 instr = (regs->dsisr >> 10) & 0x7f;
233 #endif
234
235 nb = aligninfo[instr].len;
236 if (nb == 0) {
237 long __user *p;
238 int i;
239
240 if (instr != DCBZ)
241 return 0; /* too hard or invalid instruction */
242 /*
243 * The dcbz (data cache block zero) instruction
244 * gives an alignment fault if used on non-cacheable
245 * memory. We handle the fault mainly for the
246 * case when we are running with the cache disabled
247 * for debugging.
248 */
249 p = (long __user *) (regs->dar & -L1_CACHE_BYTES);
250 if (user_mode(regs)
251 && !access_ok(VERIFY_WRITE, p, L1_CACHE_BYTES))
252 return -EFAULT;
253 for (i = 0; i < L1_CACHE_BYTES / sizeof(long); ++i)
254 if (__put_user(0, p+i))
255 return -EFAULT;
256 return 1;
257 }
258
259 flags = aligninfo[instr].flags;
260 if ((flags & (LD|ST)) == 0)
261 return 0;
262
263 /* For the 4xx-family & Book-E processors, the 'dar' field of the
264 * pt_regs structure is overloaded and is really from the DEAR.
265 */
266
267 addr = (unsigned char __user *)regs->dar;
268
269 if (flags & M) {
270 /* lmw, stmw, lswi/x, stswi/x */
271 nb0 = 0;
272 if (flags & HARD) {
273 if (flags & SX) {
274 nb = regs->xer & 127;
275 if (nb == 0)
276 return 1;
277 } else {
278 if (__get_user(instr,
279 (unsigned int __user *)regs->nip))
280 return 0;
281 nb = (instr >> 11) & 0x1f;
282 if (nb == 0)
283 nb = 32;
284 }
285 if (nb + reg * 4 > 128) {
286 nb0 = nb + reg * 4 - 128;
287 nb = 128 - reg * 4;
288 }
289 } else {
290 /* lwm, stmw */
291 nb = (32 - reg) * 4;
292 }
293 rptr = (unsigned char *) &regs->gpr[reg];
294 if (flags & LD) {
295 for (i = 0; i < nb; ++i)
296 if (__get_user(rptr[i], addr+i))
297 return -EFAULT;
298 if (nb0 > 0) {
299 rptr = (unsigned char *) &regs->gpr[0];
300 addr += nb;
301 for (i = 0; i < nb0; ++i)
302 if (__get_user(rptr[i], addr+i))
303 return -EFAULT;
304 }
305 for (; (i & 3) != 0; ++i)
306 rptr[i] = 0;
307 } else {
308 for (i = 0; i < nb; ++i)
309 if (__put_user(rptr[i], addr+i))
310 return -EFAULT;
311 if (nb0 > 0) {
312 rptr = (unsigned char *) &regs->gpr[0];
313 addr += nb;
314 for (i = 0; i < nb0; ++i)
315 if (__put_user(rptr[i], addr+i))
316 return -EFAULT;
317 }
318 }
319 return 1;
320 }
321
322 offset = 0;
323 if (nb < 4) {
324 /* read/write the least significant bits */
325 data.l = 0;
326 offset = 4 - nb;
327 }
328
329 /* Verify the address of the operand */
330 if (user_mode(regs)) {
331 if (!access_ok((flags & ST? VERIFY_WRITE: VERIFY_READ), addr, nb))
332 return -EFAULT; /* bad address */
333 }
334
335 if (flags & F) {
336 preempt_disable();
337 if (regs->msr & MSR_FP)
338 giveup_fpu(current);
339 preempt_enable();
340 }
341
342 /* If we read the operand, copy it in, else get register values */
343 if (flags & LD) {
344 for (i = 0; i < nb; ++i)
345 if (__get_user(data.v[offset+i], addr+i))
346 return -EFAULT;
347 } else if (flags & F) {
348 data.d = current->thread.fpr[reg];
349 } else {
350 data.l = regs->gpr[reg];
351 }
352
353 switch (flags & ~U) {
354 case LD+SE: /* sign extend */
355 if (data.v[2] >= 0x80)
356 data.v[0] = data.v[1] = -1;
357 break;
358
359 case LD+S: /* byte-swap */
360 case ST+S:
361 if (nb == 2) {
362 SWAP(data.v[2], data.v[3]);
363 } else {
364 SWAP(data.v[0], data.v[3]);
365 SWAP(data.v[1], data.v[2]);
366 }
367 break;
368
369 /* Single-precision FP load and store require conversions... */
370 case LD+F+S:
371 preempt_disable();
372 enable_kernel_fp();
373 cvt_fd(&data.f, &data.d, &current->thread.fpscr);
374 preempt_enable();
375 break;
376 case ST+F+S:
377 preempt_disable();
378 enable_kernel_fp();
379 cvt_df(&data.d, &data.f, &current->thread.fpscr);
380 preempt_enable();
381 break;
382 }
383
384 if (flags & ST) {
385 for (i = 0; i < nb; ++i)
386 if (__put_user(data.v[offset+i], addr+i))
387 return -EFAULT;
388 } else if (flags & F) {
389 current->thread.fpr[reg] = data.d;
390 } else {
391 regs->gpr[reg] = data.l;
392 }
393
394 if (flags & U)
395 regs->gpr[areg] = regs->dar;
396
397 return 1;
398 }
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