xref: /freebsd/sys/amd64/amd64/fpu.c (revision 4f29da19bd44f0e99f021510460a81bf754c21d2)
1 /*-
2  * Copyright (c) 1990 William Jolitz.
3  * Copyright (c) 1991 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 4. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  *	from: @(#)npx.c	7.2 (Berkeley) 5/12/91
31  */
32 
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/bus.h>
39 #include <sys/kernel.h>
40 #include <sys/lock.h>
41 #include <sys/malloc.h>
42 #include <sys/module.h>
43 #include <sys/mutex.h>
44 #include <sys/mutex.h>
45 #include <sys/proc.h>
46 #include <sys/sysctl.h>
47 #include <machine/bus.h>
48 #include <sys/rman.h>
49 #include <sys/signalvar.h>
50 
51 #include <machine/cputypes.h>
52 #include <machine/frame.h>
53 #include <machine/intr_machdep.h>
54 #include <machine/md_var.h>
55 #include <machine/pcb.h>
56 #include <machine/psl.h>
57 #include <machine/resource.h>
58 #include <machine/specialreg.h>
59 #include <machine/segments.h>
60 #include <machine/ucontext.h>
61 
62 /*
63  * Floating point support.
64  */
65 
66 #if defined(__GNUCLIKE_ASM) && !defined(lint)
67 
68 #define	fldcw(addr)		__asm("fldcw %0" : : "m" (*(addr)))
69 #define	fnclex()		__asm("fnclex")
70 #define	fninit()		__asm("fninit")
71 #define	fnstcw(addr)		__asm __volatile("fnstcw %0" : "=m" (*(addr)))
72 #define	fnstsw(addr)		__asm __volatile("fnstsw %0" : "=m" (*(addr)))
73 #define	fxrstor(addr)		__asm("fxrstor %0" : : "m" (*(addr)))
74 #define	fxsave(addr)		__asm __volatile("fxsave %0" : "=m" (*(addr)))
75 #define	ldmxcsr(r)		__asm __volatile("ldmxcsr %0" : : "m" (r))
76 #define	start_emulating()	__asm("smsw %%ax; orb %0,%%al; lmsw %%ax" \
77 				      : : "n" (CR0_TS) : "ax")
78 #define	stop_emulating()	__asm("clts")
79 
80 #else	/* !(__GNUCLIKE_ASM && !lint) */
81 
82 void	fldcw(caddr_t addr);
83 void	fnclex(void);
84 void	fninit(void);
85 void	fnstcw(caddr_t addr);
86 void	fnstsw(caddr_t addr);
87 void	fxsave(caddr_t addr);
88 void	fxrstor(caddr_t addr);
89 void	start_emulating(void);
90 void	stop_emulating(void);
91 
92 #endif	/* __GNUCLIKE_ASM && !lint */
93 
94 #define GET_FPU_CW(thread) ((thread)->td_pcb->pcb_save.sv_env.en_cw)
95 #define GET_FPU_SW(thread) ((thread)->td_pcb->pcb_save.sv_env.en_sw)
96 
97 typedef u_char bool_t;
98 
99 int	hw_float = 1;
100 SYSCTL_INT(_hw,HW_FLOATINGPT, floatingpoint,
101 	CTLFLAG_RD, &hw_float, 0,
102 	"Floatingpoint instructions executed in hardware");
103 
104 static	struct savefpu		fpu_cleanstate;
105 static	bool_t			fpu_cleanstate_ready;
106 
107 /*
108  * Initialize floating point unit.
109  */
110 void
111 fpuinit(void)
112 {
113 	register_t savecrit;
114 	u_int mxcsr;
115 	u_short control;
116 
117 	savecrit = intr_disable();
118 	PCPU_SET(fpcurthread, 0);
119 	stop_emulating();
120 	fninit();
121 	control = __INITIAL_FPUCW__;
122 	fldcw(&control);
123 	mxcsr = __INITIAL_MXCSR__;
124 	ldmxcsr(mxcsr);
125 	fxsave(&fpu_cleanstate);
126 	start_emulating();
127 	bzero(fpu_cleanstate.sv_fp, sizeof(fpu_cleanstate.sv_fp));
128 	bzero(fpu_cleanstate.sv_xmm, sizeof(fpu_cleanstate.sv_xmm));
129 	fpu_cleanstate_ready = 1;
130 	intr_restore(savecrit);
131 }
132 
133 /*
134  * Free coprocessor (if we have it).
135  */
136 void
137 fpuexit(struct thread *td)
138 {
139 	register_t savecrit;
140 
141 	savecrit = intr_disable();
142 	if (curthread == PCPU_GET(fpcurthread)) {
143 		stop_emulating();
144 		fxsave(&PCPU_GET(curpcb)->pcb_save);
145 		start_emulating();
146 		PCPU_SET(fpcurthread, 0);
147 	}
148 	intr_restore(savecrit);
149 }
150 
151 int
152 fpuformat()
153 {
154 
155 	return (_MC_FPFMT_XMM);
156 }
157 
158 /*
159  * The following mechanism is used to ensure that the FPE_... value
160  * that is passed as a trapcode to the signal handler of the user
161  * process does not have more than one bit set.
162  *
163  * Multiple bits may be set if the user process modifies the control
164  * word while a status word bit is already set.  While this is a sign
165  * of bad coding, we have no choise than to narrow them down to one
166  * bit, since we must not send a trapcode that is not exactly one of
167  * the FPE_ macros.
168  *
169  * The mechanism has a static table with 127 entries.  Each combination
170  * of the 7 FPU status word exception bits directly translates to a
171  * position in this table, where a single FPE_... value is stored.
172  * This FPE_... value stored there is considered the "most important"
173  * of the exception bits and will be sent as the signal code.  The
174  * precedence of the bits is based upon Intel Document "Numerical
175  * Applications", Chapter "Special Computational Situations".
176  *
177  * The macro to choose one of these values does these steps: 1) Throw
178  * away status word bits that cannot be masked.  2) Throw away the bits
179  * currently masked in the control word, assuming the user isn't
180  * interested in them anymore.  3) Reinsert status word bit 7 (stack
181  * fault) if it is set, which cannot be masked but must be presered.
182  * 4) Use the remaining bits to point into the trapcode table.
183  *
184  * The 6 maskable bits in order of their preference, as stated in the
185  * above referenced Intel manual:
186  * 1  Invalid operation (FP_X_INV)
187  * 1a   Stack underflow
188  * 1b   Stack overflow
189  * 1c   Operand of unsupported format
190  * 1d   SNaN operand.
191  * 2  QNaN operand (not an exception, irrelavant here)
192  * 3  Any other invalid-operation not mentioned above or zero divide
193  *      (FP_X_INV, FP_X_DZ)
194  * 4  Denormal operand (FP_X_DNML)
195  * 5  Numeric over/underflow (FP_X_OFL, FP_X_UFL)
196  * 6  Inexact result (FP_X_IMP)
197  */
198 static char fpetable[128] = {
199 	0,
200 	FPE_FLTINV,	/*  1 - INV */
201 	FPE_FLTUND,	/*  2 - DNML */
202 	FPE_FLTINV,	/*  3 - INV | DNML */
203 	FPE_FLTDIV,	/*  4 - DZ */
204 	FPE_FLTINV,	/*  5 - INV | DZ */
205 	FPE_FLTDIV,	/*  6 - DNML | DZ */
206 	FPE_FLTINV,	/*  7 - INV | DNML | DZ */
207 	FPE_FLTOVF,	/*  8 - OFL */
208 	FPE_FLTINV,	/*  9 - INV | OFL */
209 	FPE_FLTUND,	/*  A - DNML | OFL */
210 	FPE_FLTINV,	/*  B - INV | DNML | OFL */
211 	FPE_FLTDIV,	/*  C - DZ | OFL */
212 	FPE_FLTINV,	/*  D - INV | DZ | OFL */
213 	FPE_FLTDIV,	/*  E - DNML | DZ | OFL */
214 	FPE_FLTINV,	/*  F - INV | DNML | DZ | OFL */
215 	FPE_FLTUND,	/* 10 - UFL */
216 	FPE_FLTINV,	/* 11 - INV | UFL */
217 	FPE_FLTUND,	/* 12 - DNML | UFL */
218 	FPE_FLTINV,	/* 13 - INV | DNML | UFL */
219 	FPE_FLTDIV,	/* 14 - DZ | UFL */
220 	FPE_FLTINV,	/* 15 - INV | DZ | UFL */
221 	FPE_FLTDIV,	/* 16 - DNML | DZ | UFL */
222 	FPE_FLTINV,	/* 17 - INV | DNML | DZ | UFL */
223 	FPE_FLTOVF,	/* 18 - OFL | UFL */
224 	FPE_FLTINV,	/* 19 - INV | OFL | UFL */
225 	FPE_FLTUND,	/* 1A - DNML | OFL | UFL */
226 	FPE_FLTINV,	/* 1B - INV | DNML | OFL | UFL */
227 	FPE_FLTDIV,	/* 1C - DZ | OFL | UFL */
228 	FPE_FLTINV,	/* 1D - INV | DZ | OFL | UFL */
229 	FPE_FLTDIV,	/* 1E - DNML | DZ | OFL | UFL */
230 	FPE_FLTINV,	/* 1F - INV | DNML | DZ | OFL | UFL */
231 	FPE_FLTRES,	/* 20 - IMP */
232 	FPE_FLTINV,	/* 21 - INV | IMP */
233 	FPE_FLTUND,	/* 22 - DNML | IMP */
234 	FPE_FLTINV,	/* 23 - INV | DNML | IMP */
235 	FPE_FLTDIV,	/* 24 - DZ | IMP */
236 	FPE_FLTINV,	/* 25 - INV | DZ | IMP */
237 	FPE_FLTDIV,	/* 26 - DNML | DZ | IMP */
238 	FPE_FLTINV,	/* 27 - INV | DNML | DZ | IMP */
239 	FPE_FLTOVF,	/* 28 - OFL | IMP */
240 	FPE_FLTINV,	/* 29 - INV | OFL | IMP */
241 	FPE_FLTUND,	/* 2A - DNML | OFL | IMP */
242 	FPE_FLTINV,	/* 2B - INV | DNML | OFL | IMP */
243 	FPE_FLTDIV,	/* 2C - DZ | OFL | IMP */
244 	FPE_FLTINV,	/* 2D - INV | DZ | OFL | IMP */
245 	FPE_FLTDIV,	/* 2E - DNML | DZ | OFL | IMP */
246 	FPE_FLTINV,	/* 2F - INV | DNML | DZ | OFL | IMP */
247 	FPE_FLTUND,	/* 30 - UFL | IMP */
248 	FPE_FLTINV,	/* 31 - INV | UFL | IMP */
249 	FPE_FLTUND,	/* 32 - DNML | UFL | IMP */
250 	FPE_FLTINV,	/* 33 - INV | DNML | UFL | IMP */
251 	FPE_FLTDIV,	/* 34 - DZ | UFL | IMP */
252 	FPE_FLTINV,	/* 35 - INV | DZ | UFL | IMP */
253 	FPE_FLTDIV,	/* 36 - DNML | DZ | UFL | IMP */
254 	FPE_FLTINV,	/* 37 - INV | DNML | DZ | UFL | IMP */
255 	FPE_FLTOVF,	/* 38 - OFL | UFL | IMP */
256 	FPE_FLTINV,	/* 39 - INV | OFL | UFL | IMP */
257 	FPE_FLTUND,	/* 3A - DNML | OFL | UFL | IMP */
258 	FPE_FLTINV,	/* 3B - INV | DNML | OFL | UFL | IMP */
259 	FPE_FLTDIV,	/* 3C - DZ | OFL | UFL | IMP */
260 	FPE_FLTINV,	/* 3D - INV | DZ | OFL | UFL | IMP */
261 	FPE_FLTDIV,	/* 3E - DNML | DZ | OFL | UFL | IMP */
262 	FPE_FLTINV,	/* 3F - INV | DNML | DZ | OFL | UFL | IMP */
263 	FPE_FLTSUB,	/* 40 - STK */
264 	FPE_FLTSUB,	/* 41 - INV | STK */
265 	FPE_FLTUND,	/* 42 - DNML | STK */
266 	FPE_FLTSUB,	/* 43 - INV | DNML | STK */
267 	FPE_FLTDIV,	/* 44 - DZ | STK */
268 	FPE_FLTSUB,	/* 45 - INV | DZ | STK */
269 	FPE_FLTDIV,	/* 46 - DNML | DZ | STK */
270 	FPE_FLTSUB,	/* 47 - INV | DNML | DZ | STK */
271 	FPE_FLTOVF,	/* 48 - OFL | STK */
272 	FPE_FLTSUB,	/* 49 - INV | OFL | STK */
273 	FPE_FLTUND,	/* 4A - DNML | OFL | STK */
274 	FPE_FLTSUB,	/* 4B - INV | DNML | OFL | STK */
275 	FPE_FLTDIV,	/* 4C - DZ | OFL | STK */
276 	FPE_FLTSUB,	/* 4D - INV | DZ | OFL | STK */
277 	FPE_FLTDIV,	/* 4E - DNML | DZ | OFL | STK */
278 	FPE_FLTSUB,	/* 4F - INV | DNML | DZ | OFL | STK */
279 	FPE_FLTUND,	/* 50 - UFL | STK */
280 	FPE_FLTSUB,	/* 51 - INV | UFL | STK */
281 	FPE_FLTUND,	/* 52 - DNML | UFL | STK */
282 	FPE_FLTSUB,	/* 53 - INV | DNML | UFL | STK */
283 	FPE_FLTDIV,	/* 54 - DZ | UFL | STK */
284 	FPE_FLTSUB,	/* 55 - INV | DZ | UFL | STK */
285 	FPE_FLTDIV,	/* 56 - DNML | DZ | UFL | STK */
286 	FPE_FLTSUB,	/* 57 - INV | DNML | DZ | UFL | STK */
287 	FPE_FLTOVF,	/* 58 - OFL | UFL | STK */
288 	FPE_FLTSUB,	/* 59 - INV | OFL | UFL | STK */
289 	FPE_FLTUND,	/* 5A - DNML | OFL | UFL | STK */
290 	FPE_FLTSUB,	/* 5B - INV | DNML | OFL | UFL | STK */
291 	FPE_FLTDIV,	/* 5C - DZ | OFL | UFL | STK */
292 	FPE_FLTSUB,	/* 5D - INV | DZ | OFL | UFL | STK */
293 	FPE_FLTDIV,	/* 5E - DNML | DZ | OFL | UFL | STK */
294 	FPE_FLTSUB,	/* 5F - INV | DNML | DZ | OFL | UFL | STK */
295 	FPE_FLTRES,	/* 60 - IMP | STK */
296 	FPE_FLTSUB,	/* 61 - INV | IMP | STK */
297 	FPE_FLTUND,	/* 62 - DNML | IMP | STK */
298 	FPE_FLTSUB,	/* 63 - INV | DNML | IMP | STK */
299 	FPE_FLTDIV,	/* 64 - DZ | IMP | STK */
300 	FPE_FLTSUB,	/* 65 - INV | DZ | IMP | STK */
301 	FPE_FLTDIV,	/* 66 - DNML | DZ | IMP | STK */
302 	FPE_FLTSUB,	/* 67 - INV | DNML | DZ | IMP | STK */
303 	FPE_FLTOVF,	/* 68 - OFL | IMP | STK */
304 	FPE_FLTSUB,	/* 69 - INV | OFL | IMP | STK */
305 	FPE_FLTUND,	/* 6A - DNML | OFL | IMP | STK */
306 	FPE_FLTSUB,	/* 6B - INV | DNML | OFL | IMP | STK */
307 	FPE_FLTDIV,	/* 6C - DZ | OFL | IMP | STK */
308 	FPE_FLTSUB,	/* 6D - INV | DZ | OFL | IMP | STK */
309 	FPE_FLTDIV,	/* 6E - DNML | DZ | OFL | IMP | STK */
310 	FPE_FLTSUB,	/* 6F - INV | DNML | DZ | OFL | IMP | STK */
311 	FPE_FLTUND,	/* 70 - UFL | IMP | STK */
312 	FPE_FLTSUB,	/* 71 - INV | UFL | IMP | STK */
313 	FPE_FLTUND,	/* 72 - DNML | UFL | IMP | STK */
314 	FPE_FLTSUB,	/* 73 - INV | DNML | UFL | IMP | STK */
315 	FPE_FLTDIV,	/* 74 - DZ | UFL | IMP | STK */
316 	FPE_FLTSUB,	/* 75 - INV | DZ | UFL | IMP | STK */
317 	FPE_FLTDIV,	/* 76 - DNML | DZ | UFL | IMP | STK */
318 	FPE_FLTSUB,	/* 77 - INV | DNML | DZ | UFL | IMP | STK */
319 	FPE_FLTOVF,	/* 78 - OFL | UFL | IMP | STK */
320 	FPE_FLTSUB,	/* 79 - INV | OFL | UFL | IMP | STK */
321 	FPE_FLTUND,	/* 7A - DNML | OFL | UFL | IMP | STK */
322 	FPE_FLTSUB,	/* 7B - INV | DNML | OFL | UFL | IMP | STK */
323 	FPE_FLTDIV,	/* 7C - DZ | OFL | UFL | IMP | STK */
324 	FPE_FLTSUB,	/* 7D - INV | DZ | OFL | UFL | IMP | STK */
325 	FPE_FLTDIV,	/* 7E - DNML | DZ | OFL | UFL | IMP | STK */
326 	FPE_FLTSUB,	/* 7F - INV | DNML | DZ | OFL | UFL | IMP | STK */
327 };
328 
329 /*
330  * Preserve the FP status word, clear FP exceptions, then generate a SIGFPE.
331  *
332  * Clearing exceptions is necessary mainly to avoid IRQ13 bugs.  We now
333  * depend on longjmp() restoring a usable state.  Restoring the state
334  * or examining it might fail if we didn't clear exceptions.
335  *
336  * The error code chosen will be one of the FPE_... macros. It will be
337  * sent as the second argument to old BSD-style signal handlers and as
338  * "siginfo_t->si_code" (second argument) to SA_SIGINFO signal handlers.
339  *
340  * XXX the FP state is not preserved across signal handlers.  So signal
341  * handlers cannot afford to do FP unless they preserve the state or
342  * longjmp() out.  Both preserving the state and longjmp()ing may be
343  * destroyed by IRQ13 bugs.  Clearing FP exceptions is not an acceptable
344  * solution for signals other than SIGFPE.
345  */
346 int
347 fputrap()
348 {
349 	register_t savecrit;
350 	u_short control, status;
351 
352 	savecrit = intr_disable();
353 
354 	/*
355 	 * Interrupt handling (for another interrupt) may have pushed the
356 	 * state to memory.  Fetch the relevant parts of the state from
357 	 * wherever they are.
358 	 */
359 	if (PCPU_GET(fpcurthread) != curthread) {
360 		control = GET_FPU_CW(curthread);
361 		status = GET_FPU_SW(curthread);
362 	} else {
363 		fnstcw(&control);
364 		fnstsw(&status);
365 	}
366 
367 	if (PCPU_GET(fpcurthread) == curthread)
368 		fnclex();
369 	intr_restore(savecrit);
370 	return (fpetable[status & ((~control & 0x3f) | 0x40)]);
371 }
372 
373 /*
374  * Implement device not available (DNA) exception
375  *
376  * It would be better to switch FP context here (if curthread != fpcurthread)
377  * and not necessarily for every context switch, but it is too hard to
378  * access foreign pcb's.
379  */
380 
381 static int err_count = 0;
382 
383 int
384 fpudna()
385 {
386 	struct pcb *pcb;
387 	register_t s;
388 
389 	if (PCPU_GET(fpcurthread) == curthread) {
390 		printf("fpudna: fpcurthread == curthread %d times\n",
391 		    ++err_count);
392 		stop_emulating();
393 		return (1);
394 	}
395 	if (PCPU_GET(fpcurthread) != NULL) {
396 		printf("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
397 		       PCPU_GET(fpcurthread),
398 		       PCPU_GET(fpcurthread)->td_proc->p_pid,
399 		       curthread, curthread->td_proc->p_pid);
400 		panic("fpudna");
401 	}
402 	s = intr_disable();
403 	stop_emulating();
404 	/*
405 	 * Record new context early in case frstor causes a trap.
406 	 */
407 	PCPU_SET(fpcurthread, curthread);
408 	pcb = PCPU_GET(curpcb);
409 
410 	if ((pcb->pcb_flags & PCB_FPUINITDONE) == 0) {
411 		/*
412 		 * This is the first time this thread has used the FPU,
413 		 * explicitly load sanitized registers.
414 		 */
415 		fxrstor(&fpu_cleanstate);
416 		pcb->pcb_flags |= PCB_FPUINITDONE;
417 	} else
418 		fxrstor(&pcb->pcb_save);
419 	intr_restore(s);
420 
421 	return (1);
422 }
423 
424 /*
425  * This should be called with interrupts disabled and only when the owning
426  * FPU thread is non-null.
427  */
428 void
429 fpudrop()
430 {
431 	struct thread *td;
432 
433 	td = PCPU_GET(fpcurthread);
434 	PCPU_SET(fpcurthread, NULL);
435 	td->td_pcb->pcb_flags &= ~PCB_FPUINITDONE;
436 	start_emulating();
437 }
438 
439 /*
440  * Get the state of the FPU without dropping ownership (if possible).
441  * It returns the FPU ownership status.
442  */
443 int
444 fpugetregs(struct thread *td, struct savefpu *addr)
445 {
446 	register_t s;
447 
448 	if ((td->td_pcb->pcb_flags & PCB_FPUINITDONE) == 0) {
449 		if (fpu_cleanstate_ready)
450 			bcopy(&fpu_cleanstate, addr, sizeof(fpu_cleanstate));
451 		else
452 			bzero(addr, sizeof(*addr));
453 		return (_MC_FPOWNED_NONE);
454 	}
455 	s = intr_disable();
456 	if (td == PCPU_GET(fpcurthread)) {
457 		fxsave(addr);
458 		intr_restore(s);
459 		return (_MC_FPOWNED_FPU);
460 	} else {
461 		intr_restore(s);
462 		bcopy(&td->td_pcb->pcb_save, addr, sizeof(*addr));
463 		return (_MC_FPOWNED_PCB);
464 	}
465 }
466 
467 /*
468  * Set the state of the FPU.
469  */
470 void
471 fpusetregs(struct thread *td, struct savefpu *addr)
472 {
473 	register_t s;
474 
475 	s = intr_disable();
476 	if (td == PCPU_GET(fpcurthread)) {
477 		fxrstor(addr);
478 		intr_restore(s);
479 	} else {
480 		intr_restore(s);
481 		bcopy(addr, &td->td_pcb->pcb_save, sizeof(*addr));
482 	}
483 	curthread->td_pcb->pcb_flags |= PCB_FPUINITDONE;
484 }
485 
486 /*
487  * This really sucks.  We want the acpi version only, but it requires
488  * the isa_if.h file in order to get the definitions.
489  */
490 #include "opt_isa.h"
491 #ifdef DEV_ISA
492 #include <isa/isavar.h>
493 /*
494  * This sucks up the legacy ISA support assignments from PNPBIOS/ACPI.
495  */
496 static struct isa_pnp_id fpupnp_ids[] = {
497 	{ 0x040cd041, "Legacy ISA coprocessor support" }, /* PNP0C04 */
498 	{ 0 }
499 };
500 
501 static int
502 fpupnp_probe(device_t dev)
503 {
504 	int result;
505 
506 	result = ISA_PNP_PROBE(device_get_parent(dev), dev, fpupnp_ids);
507 	if (result <= 0)
508 		device_quiet(dev);
509 	return (result);
510 }
511 
512 static int
513 fpupnp_attach(device_t dev)
514 {
515 
516 	return (0);
517 }
518 
519 static device_method_t fpupnp_methods[] = {
520 	/* Device interface */
521 	DEVMETHOD(device_probe,		fpupnp_probe),
522 	DEVMETHOD(device_attach,	fpupnp_attach),
523 	DEVMETHOD(device_detach,	bus_generic_detach),
524 	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
525 	DEVMETHOD(device_suspend,	bus_generic_suspend),
526 	DEVMETHOD(device_resume,	bus_generic_resume),
527 
528 	{ 0, 0 }
529 };
530 
531 static driver_t fpupnp_driver = {
532 	"fpupnp",
533 	fpupnp_methods,
534 	1,			/* no softc */
535 };
536 
537 static devclass_t fpupnp_devclass;
538 
539 DRIVER_MODULE(fpupnp, acpi, fpupnp_driver, fpupnp_devclass, 0, 0);
540 #endif	/* DEV_ISA */
541