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1da177e4 LT |
1 | /* |
2 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) | |
3 | * | |
4 | * Floating-point emulation code | |
5 | * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2, or (at your option) | |
10 | * any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | */ | |
21 | /* | |
22 | * BEGIN_DESC | |
23 | * | |
24 | * File: | |
25 | * @(#) pa/fp/decode_exc.c $ Revision: $ | |
26 | * | |
27 | * Purpose: | |
28 | * <<please update with a synopsis of the functionality provided by this file>> | |
29 | * | |
30 | * External Interfaces: | |
31 | * <<the following list was autogenerated, please review>> | |
32 | * decode_fpu(Fpu_register, trap_counts) | |
33 | * | |
34 | * Internal Interfaces: | |
35 | * <<please update>> | |
36 | * | |
37 | * Theory: | |
38 | * <<please update with a overview of the operation of this file>> | |
39 | * | |
40 | * END_DESC | |
41 | */ | |
42 | ||
e9b26010 | 43 | #include <linux/kernel.h> |
1da177e4 LT |
44 | #include "float.h" |
45 | #include "sgl_float.h" | |
46 | #include "dbl_float.h" | |
47 | #include "cnv_float.h" | |
48 | /* #include "types.h" */ | |
49 | #include <asm/signal.h> | |
50 | #include <asm/siginfo.h> | |
51 | /* #include <machine/sys/mdep_private.h> */ | |
52 | ||
53 | #undef Fpustatus_register | |
54 | #define Fpustatus_register Fpu_register[0] | |
55 | ||
56 | /* General definitions */ | |
57 | #define DOESTRAP 1 | |
58 | #define NOTRAP 0 | |
497888cf | 59 | #define SIGNALCODE(signal, code) ((signal) << 24 | (code)) |
1da177e4 LT |
60 | #define copropbit 1<<31-2 /* bit position 2 */ |
61 | #define opclass 9 /* bits 21 & 22 */ | |
62 | #define fmt 11 /* bits 19 & 20 */ | |
63 | #define df 13 /* bits 17 & 18 */ | |
64 | #define twobits 3 /* mask low-order 2 bits */ | |
65 | #define fivebits 31 /* mask low-order 5 bits */ | |
66 | #define MAX_EXCP_REG 7 /* number of excpeption registers to check */ | |
67 | ||
68 | /* Exception register definitions */ | |
69 | #define Excp_type(index) Exceptiontype(Fpu_register[index]) | |
70 | #define Excp_instr(index) Instructionfield(Fpu_register[index]) | |
71 | #define Clear_excp_register(index) Allexception(Fpu_register[index]) = 0 | |
72 | #define Excp_format() \ | |
73 | (current_ir >> ((current_ir>>opclass & twobits)==1 ? df : fmt) & twobits) | |
74 | ||
75 | /* Miscellaneous definitions */ | |
76 | #define Fpu_sgl(index) Fpu_register[index*2] | |
77 | ||
78 | #define Fpu_dblp1(index) Fpu_register[index*2] | |
79 | #define Fpu_dblp2(index) Fpu_register[(index*2)+1] | |
80 | ||
81 | #define Fpu_quadp1(index) Fpu_register[index*2] | |
82 | #define Fpu_quadp2(index) Fpu_register[(index*2)+1] | |
83 | #define Fpu_quadp3(index) Fpu_register[(index*2)+2] | |
84 | #define Fpu_quadp4(index) Fpu_register[(index*2)+3] | |
85 | ||
86 | /* Single precision floating-point definitions */ | |
87 | #ifndef Sgl_decrement | |
88 | # define Sgl_decrement(sgl_value) Sall(sgl_value)-- | |
89 | #endif | |
90 | ||
91 | /* Double precision floating-point definitions */ | |
92 | #ifndef Dbl_decrement | |
93 | # define Dbl_decrement(dbl_valuep1,dbl_valuep2) \ | |
94 | if ((Dallp2(dbl_valuep2)--) == 0) Dallp1(dbl_valuep1)-- | |
95 | #endif | |
96 | ||
97 | ||
98 | #define update_trap_counts(Fpu_register, aflags, bflags, trap_counts) { \ | |
99 | aflags=(Fpu_register[0])>>27; /* assumes zero fill. 32 bit */ \ | |
100 | Fpu_register[0] |= bflags; \ | |
101 | } | |
102 | ||
103 | u_int | |
104 | decode_fpu(unsigned int Fpu_register[], unsigned int trap_counts[]) | |
105 | { | |
106 | unsigned int current_ir, excp; | |
107 | int target, exception_index = 1; | |
108 | boolean inexact; | |
109 | unsigned int aflags; | |
110 | unsigned int bflags; | |
111 | unsigned int excptype; | |
112 | ||
113 | ||
114 | /* Keep stats on how many floating point exceptions (based on type) | |
115 | * that happen. Want to keep this overhead low, but still provide | |
116 | * some information to the customer. All exits from this routine | |
117 | * need to restore Fpu_register[0] | |
118 | */ | |
119 | ||
120 | bflags=(Fpu_register[0] & 0xf8000000); | |
121 | Fpu_register[0] &= 0x07ffffff; | |
122 | ||
123 | /* exception_index is used to index the exception register queue. It | |
124 | * always points at the last register that contains a valid exception. A | |
125 | * zero value implies no exceptions (also the initialized value). Setting | |
126 | * the T-bit resets the exception_index to zero. | |
127 | */ | |
128 | ||
129 | /* | |
130 | * Check for reserved-op exception. A reserved-op exception does not | |
131 | * set any exception registers nor does it set the T-bit. If the T-bit | |
132 | * is not set then a reserved-op exception occurred. | |
133 | * | |
134 | * At some point, we may want to report reserved op exceptions as | |
135 | * illegal instructions. | |
136 | */ | |
137 | ||
138 | if (!Is_tbit_set()) { | |
139 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); | |
140 | return SIGNALCODE(SIGILL, ILL_COPROC); | |
141 | } | |
142 | ||
143 | /* | |
144 | * Is a coprocessor op. | |
145 | * | |
146 | * Now we need to determine what type of exception occurred. | |
147 | */ | |
148 | for (exception_index=1; exception_index<=MAX_EXCP_REG; exception_index++) { | |
149 | current_ir = Excp_instr(exception_index); | |
150 | /* | |
151 | * On PA89: there are 5 different unimplemented exception | |
152 | * codes: 0x1, 0x9, 0xb, 0x3, and 0x23. PA-RISC 2.0 adds | |
153 | * another, 0x2b. Only these have the low order bit set. | |
154 | */ | |
155 | excptype = Excp_type(exception_index); | |
156 | if (excptype & UNIMPLEMENTEDEXCEPTION) { | |
157 | /* | |
158 | * Clear T-bit and exception register so that | |
159 | * we can tell if a trap really occurs while | |
160 | * emulating the instruction. | |
161 | */ | |
162 | Clear_tbit(); | |
163 | Clear_excp_register(exception_index); | |
164 | /* | |
165 | * Now emulate this instruction. If a trap occurs, | |
166 | * fpudispatch will return a non-zero number | |
167 | */ | |
168 | excp = fpudispatch(current_ir,excptype,0,Fpu_register); | |
169 | /* accumulate the status flags, don't lose them as in hpux */ | |
170 | if (excp) { | |
171 | /* | |
172 | * We now need to make sure that the T-bit and the | |
173 | * exception register contain the correct values | |
174 | * before continuing. | |
175 | */ | |
176 | /* | |
177 | * Set t-bit since it might still be needed for a | |
178 | * subsequent real trap (I don't understand fully -PB) | |
179 | */ | |
180 | Set_tbit(); | |
181 | /* some of the following code uses | |
182 | * Excp_type(exception_index) so fix that up */ | |
183 | Set_exceptiontype_and_instr_field(excp,current_ir, | |
184 | Fpu_register[exception_index]); | |
185 | if (excp == UNIMPLEMENTEDEXCEPTION) { | |
186 | /* | |
187 | * it is really unimplemented, so restore the | |
188 | * TIMEX extended unimplemented exception code | |
189 | */ | |
190 | excp = excptype; | |
191 | update_trap_counts(Fpu_register, aflags, bflags, | |
192 | trap_counts); | |
193 | return SIGNALCODE(SIGILL, ILL_COPROC); | |
194 | } | |
195 | /* some of the following code uses excptype, so | |
196 | * fix that up too */ | |
197 | excptype = excp; | |
198 | } | |
199 | /* handle exceptions other than the real UNIMPLIMENTED the | |
200 | * same way as if the hardware had caused them */ | |
201 | if (excp == NOEXCEPTION) | |
202 | /* For now use 'break', should technically be 'continue' */ | |
203 | break; | |
204 | } | |
205 | ||
206 | /* | |
207 | * In PA89, the underflow exception has been extended to encode | |
208 | * additional information. The exception looks like pp01x0, | |
209 | * where x is 1 if inexact and pp represent the inexact bit (I) | |
210 | * and the round away bit (RA) | |
211 | */ | |
212 | if (excptype & UNDERFLOWEXCEPTION) { | |
213 | /* check for underflow trap enabled */ | |
214 | if (Is_underflowtrap_enabled()) { | |
215 | update_trap_counts(Fpu_register, aflags, bflags, | |
216 | trap_counts); | |
217 | return SIGNALCODE(SIGFPE, FPE_FLTUND); | |
218 | } else { | |
219 | /* | |
220 | * Isn't a real trap; we need to | |
221 | * return the default value. | |
222 | */ | |
223 | target = current_ir & fivebits; | |
224 | #ifndef lint | |
225 | if (Ibit(Fpu_register[exception_index])) inexact = TRUE; | |
226 | else inexact = FALSE; | |
227 | #endif | |
228 | switch (Excp_format()) { | |
229 | case SGL: | |
230 | /* | |
231 | * If ra (round-away) is set, will | |
232 | * want to undo the rounding done | |
233 | * by the hardware. | |
234 | */ | |
235 | if (Rabit(Fpu_register[exception_index])) | |
236 | Sgl_decrement(Fpu_sgl(target)); | |
237 | ||
238 | /* now denormalize */ | |
239 | sgl_denormalize(&Fpu_sgl(target),&inexact,Rounding_mode()); | |
240 | break; | |
241 | case DBL: | |
242 | /* | |
243 | * If ra (round-away) is set, will | |
244 | * want to undo the rounding done | |
245 | * by the hardware. | |
246 | */ | |
247 | if (Rabit(Fpu_register[exception_index])) | |
248 | Dbl_decrement(Fpu_dblp1(target),Fpu_dblp2(target)); | |
249 | ||
250 | /* now denormalize */ | |
251 | dbl_denormalize(&Fpu_dblp1(target),&Fpu_dblp2(target), | |
252 | &inexact,Rounding_mode()); | |
253 | break; | |
254 | } | |
255 | if (inexact) Set_underflowflag(); | |
256 | /* | |
257 | * Underflow can generate an inexact | |
258 | * exception. If inexact trap is enabled, | |
259 | * want to do an inexact trap, otherwise | |
260 | * set inexact flag. | |
261 | */ | |
262 | if (inexact && Is_inexacttrap_enabled()) { | |
263 | /* | |
264 | * Set exception field of exception register | |
265 | * to inexact, parm field to zero. | |
266 | * Underflow bit should be cleared. | |
267 | */ | |
268 | Set_exceptiontype(Fpu_register[exception_index], | |
269 | INEXACTEXCEPTION); | |
270 | Set_parmfield(Fpu_register[exception_index],0); | |
271 | update_trap_counts(Fpu_register, aflags, bflags, | |
272 | trap_counts); | |
273 | return SIGNALCODE(SIGFPE, FPE_FLTRES); | |
274 | } | |
275 | else { | |
276 | /* | |
277 | * Exception register needs to be cleared. | |
278 | * Inexact flag needs to be set if inexact. | |
279 | */ | |
280 | Clear_excp_register(exception_index); | |
281 | if (inexact) Set_inexactflag(); | |
282 | } | |
283 | } | |
284 | continue; | |
285 | } | |
286 | switch(Excp_type(exception_index)) { | |
287 | case OVERFLOWEXCEPTION: | |
288 | case OVERFLOWEXCEPTION | INEXACTEXCEPTION: | |
289 | /* check for overflow trap enabled */ | |
290 | update_trap_counts(Fpu_register, aflags, bflags, | |
291 | trap_counts); | |
292 | if (Is_overflowtrap_enabled()) { | |
293 | update_trap_counts(Fpu_register, aflags, bflags, | |
294 | trap_counts); | |
295 | return SIGNALCODE(SIGFPE, FPE_FLTOVF); | |
296 | } else { | |
297 | /* | |
298 | * Isn't a real trap; we need to | |
299 | * return the default value. | |
300 | */ | |
301 | target = current_ir & fivebits; | |
302 | switch (Excp_format()) { | |
303 | case SGL: | |
304 | Sgl_setoverflow(Fpu_sgl(target)); | |
305 | break; | |
306 | case DBL: | |
307 | Dbl_setoverflow(Fpu_dblp1(target),Fpu_dblp2(target)); | |
308 | break; | |
309 | } | |
310 | Set_overflowflag(); | |
311 | /* | |
312 | * Overflow always generates an inexact | |
313 | * exception. If inexact trap is enabled, | |
314 | * want to do an inexact trap, otherwise | |
315 | * set inexact flag. | |
316 | */ | |
317 | if (Is_inexacttrap_enabled()) { | |
318 | /* | |
319 | * Set exception field of exception | |
320 | * register to inexact. Overflow | |
321 | * bit should be cleared. | |
322 | */ | |
323 | Set_exceptiontype(Fpu_register[exception_index], | |
324 | INEXACTEXCEPTION); | |
325 | update_trap_counts(Fpu_register, aflags, bflags, | |
326 | trap_counts); | |
327 | return SIGNALCODE(SIGFPE, FPE_FLTRES); | |
328 | } | |
329 | else { | |
330 | /* | |
331 | * Exception register needs to be cleared. | |
332 | * Inexact flag needs to be set. | |
333 | */ | |
334 | Clear_excp_register(exception_index); | |
335 | Set_inexactflag(); | |
336 | } | |
337 | } | |
338 | break; | |
339 | case INVALIDEXCEPTION: | |
370361f8 | 340 | case OPC_2E_INVALIDEXCEPTION: |
1da177e4 LT |
341 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); |
342 | return SIGNALCODE(SIGFPE, FPE_FLTINV); | |
343 | case DIVISIONBYZEROEXCEPTION: | |
344 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); | |
550f0d92 | 345 | Clear_excp_register(exception_index); |
1da177e4 LT |
346 | return SIGNALCODE(SIGFPE, FPE_FLTDIV); |
347 | case INEXACTEXCEPTION: | |
348 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); | |
349 | return SIGNALCODE(SIGFPE, FPE_FLTRES); | |
350 | default: | |
351 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); | |
352 | printk("%s(%d) Unknown FPU exception 0x%x\n", __FILE__, | |
353 | __LINE__, Excp_type(exception_index)); | |
354 | return SIGNALCODE(SIGILL, ILL_COPROC); | |
355 | case NOEXCEPTION: /* no exception */ | |
356 | /* | |
357 | * Clear exception register in case | |
358 | * other fields are non-zero. | |
359 | */ | |
360 | Clear_excp_register(exception_index); | |
361 | break; | |
362 | } | |
363 | } | |
364 | /* | |
365 | * No real exceptions occurred. | |
366 | */ | |
367 | Clear_tbit(); | |
368 | update_trap_counts(Fpu_register, aflags, bflags, trap_counts); | |
369 | return(NOTRAP); | |
370 | } |