xref: /netbsd-src/sys/arch/arm/vfp/vfp_init.c (revision f89f6560d453f5e37386cc7938c072d2f528b9fa)
1 /*      $NetBSD: vfp_init.c,v 1.47 2015/03/23 17:42:02 matt Exp $ */
2 
3 /*
4  * Copyright (c) 2008 ARM Ltd
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the company may not be used to endorse or promote
16  *    products derived from this software without specific prior written
17  *    permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR
20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY
23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
25  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/param.h>
33 #include <sys/types.h>
34 #include <sys/systm.h>
35 #include <sys/device.h>
36 #include <sys/proc.h>
37 #include <sys/cpu.h>
38 
39 #include <arm/locore.h>
40 #include <arm/pcb.h>
41 #include <arm/undefined.h>
42 #include <arm/vfpreg.h>
43 #include <arm/mcontext.h>
44 
45 #include <uvm/uvm_extern.h>		/* for pmap.h */
46 
47 #ifdef FPU_VFP
48 
49 #ifdef CPU_CORTEX
50 __asm(".fpu\tvfpv4");
51 #else
52 __asm(".fpu\tvfp");
53 #endif
54 
55 /* FLDMD <X>, {d0-d15} */
56 static inline void
57 load_vfpregs_lo(const uint64_t *p)
58 {
59 	__asm __volatile("vldmia %0, {d0-d15}" :: "r" (p) : "memory");
60 }
61 
62 /* FSTMD <X>, {d0-d15} */
63 static inline void
64 save_vfpregs_lo(uint64_t *p)
65 {
66 	__asm __volatile("vstmia %0, {d0-d15}" :: "r" (p) : "memory");
67 }
68 
69 #ifdef CPU_CORTEX
70 /* FLDMD <X>, {d16-d31} */
71 static inline void
72 load_vfpregs_hi(const uint64_t *p)
73 {
74 	__asm __volatile("vldmia\t%0, {d16-d31}" :: "r" (&p[16]) : "memory");
75 }
76 
77 /* FLDMD <X>, {d16-d31} */
78 static inline void
79 save_vfpregs_hi(uint64_t *p)
80 {
81 	__asm __volatile("vstmia\t%0, {d16-d31}" :: "r" (&p[16]) : "memory");
82 }
83 #endif
84 
85 static inline void
86 load_vfpregs(const struct vfpreg *fregs)
87 {
88 	load_vfpregs_lo(fregs->vfp_regs);
89 #ifdef CPU_CORTEX
90 #ifdef CPU_ARM11
91 	switch (curcpu()->ci_vfp_id) {
92 	case FPU_VFP_CORTEXA5:
93 	case FPU_VFP_CORTEXA7:
94 	case FPU_VFP_CORTEXA8:
95 	case FPU_VFP_CORTEXA9:
96 	case FPU_VFP_CORTEXA15:
97 	case FPU_VFP_CORTEXA15_QEMU:
98 #endif
99 		load_vfpregs_hi(fregs->vfp_regs);
100 #ifdef CPU_ARM11
101 		break;
102 	}
103 #endif
104 #endif
105 }
106 
107 static inline void
108 save_vfpregs(struct vfpreg *fregs)
109 {
110 	save_vfpregs_lo(fregs->vfp_regs);
111 #ifdef CPU_CORTEX
112 #ifdef CPU_ARM11
113 	switch (curcpu()->ci_vfp_id) {
114 	case FPU_VFP_CORTEXA5:
115 	case FPU_VFP_CORTEXA7:
116 	case FPU_VFP_CORTEXA8:
117 	case FPU_VFP_CORTEXA9:
118 	case FPU_VFP_CORTEXA15:
119 	case FPU_VFP_CORTEXA15_QEMU:
120 #endif
121 		save_vfpregs_hi(fregs->vfp_regs);
122 #ifdef CPU_ARM11
123 		break;
124 	}
125 #endif
126 #endif
127 }
128 
129 /* The real handler for VFP bounces.  */
130 static int vfp_handler(u_int, u_int, trapframe_t *, int);
131 #ifdef CPU_CORTEX
132 static int neon_handler(u_int, u_int, trapframe_t *, int);
133 #endif
134 
135 static void vfp_state_load(lwp_t *, u_int);
136 static void vfp_state_save(lwp_t *);
137 static void vfp_state_release(lwp_t *);
138 
139 const pcu_ops_t arm_vfp_ops = {
140 	.pcu_id = PCU_FPU,
141 	.pcu_state_save = vfp_state_save,
142 	.pcu_state_load = vfp_state_load,
143 	.pcu_state_release = vfp_state_release,
144 };
145 
146 /* determine what bits can be changed */
147 uint32_t vfp_fpscr_changable = VFP_FPSCR_CSUM;
148 /* default to run fast */
149 uint32_t vfp_fpscr_default = (VFP_FPSCR_DN | VFP_FPSCR_FZ | VFP_FPSCR_RN);
150 
151 /*
152  * Used to test for a VFP. The following function is installed as a coproc10
153  * handler on the undefined instruction vector and then we issue a VFP
154  * instruction. If undefined_test is non zero then the VFP did not handle
155  * the instruction so must be absent, or disabled.
156  */
157 
158 static int undefined_test;
159 
160 static int
161 vfp_test(u_int address, u_int insn, trapframe_t *frame, int fault_code)
162 {
163 
164 	frame->tf_pc += INSN_SIZE;
165 	++undefined_test;
166 	return 0;
167 }
168 
169 #else
170 /* determine what bits can be changed */
171 uint32_t vfp_fpscr_changable = VFP_FPSCR_CSUM|VFP_FPSCR_ESUM|VFP_FPSCR_RMODE;
172 #endif /* FPU_VFP */
173 
174 static int
175 vfp_fpscr_handler(u_int address, u_int insn, trapframe_t *frame, int fault_code)
176 {
177 	struct lwp * const l = curlwp;
178 	const u_int regno = (insn >> 12) & 0xf;
179 	/*
180 	 * Only match move to/from the FPSCR register and we
181 	 * can't be using the SP,LR,PC as a source.
182 	 */
183 	if ((insn & 0xffef0fff) != 0xeee10a10 || regno > 12)
184 		return 1;
185 
186 	struct pcb * const pcb = lwp_getpcb(l);
187 
188 #ifdef FPU_VFP
189 	/*
190 	 * If FPU is valid somewhere, let's just reenable VFP and
191 	 * retry the instruction (only safe thing to do since the
192 	 * pcb has a stale copy).
193 	 */
194 	if (pcb->pcb_vfp.vfp_fpexc & VFP_FPEXC_EN)
195 		return 1;
196 
197 	if (__predict_false(!vfp_used_p())) {
198 		pcb->pcb_vfp.vfp_fpscr = vfp_fpscr_default;
199 	}
200 #endif
201 
202 	/*
203 	 * We now know the pcb has the saved copy.
204 	 */
205 	register_t * const regp = &frame->tf_r0 + regno;
206 	if (insn & 0x00100000) {
207 		*regp = pcb->pcb_vfp.vfp_fpscr;
208 	} else {
209 		pcb->pcb_vfp.vfp_fpscr &= ~vfp_fpscr_changable;
210 		pcb->pcb_vfp.vfp_fpscr |= *regp & vfp_fpscr_changable;
211 	}
212 
213 	curcpu()->ci_vfp_evs[0].ev_count++;
214 
215 	frame->tf_pc += INSN_SIZE;
216 	return 0;
217 }
218 
219 #ifndef FPU_VFP
220 /*
221  * If we don't want VFP support, we still need to handle emulating VFP FPSCR
222  * instructions.
223  */
224 void
225 vfp_attach(struct cpu_info *ci)
226 {
227 	if (CPU_IS_PRIMARY(ci)) {
228 		install_coproc_handler(VFP_COPROC, vfp_fpscr_handler);
229 	}
230 	evcnt_attach_dynamic(&ci->ci_vfp_evs[0], EVCNT_TYPE_TRAP, NULL,
231 	    ci->ci_cpuname, "vfp fpscr traps");
232 }
233 
234 #else
235 void
236 vfp_attach(struct cpu_info *ci)
237 {
238 	const char *model = NULL;
239 
240 	if (CPU_ID_ARM11_P(ci->ci_arm_cpuid)
241 	    || CPU_ID_MV88SV58XX_P(ci->ci_arm_cpuid)
242 	    || CPU_ID_CORTEX_P(ci->ci_arm_cpuid)) {
243 #if 0
244 		const uint32_t nsacr = armreg_nsacr_read();
245 		const uint32_t nsacr_vfp = __BITS(VFP_COPROC,VFP_COPROC2);
246 		if ((nsacr & nsacr_vfp) != nsacr_vfp) {
247 			aprint_normal_dev(ci->ci_dev,
248 			    "VFP access denied (NSACR=%#x)\n", nsacr);
249 			install_coproc_handler(VFP_COPROC, vfp_fpscr_handler);
250 			ci->ci_vfp_id = 0;
251 			evcnt_attach_dynamic(&ci->ci_vfp_evs[0],
252 			    EVCNT_TYPE_TRAP, NULL, ci->ci_cpuname,
253 			    "vfp fpscr traps");
254 			return;
255 		}
256 #endif
257 		const uint32_t cpacr_vfp = CPACR_CPn(VFP_COPROC);
258 		const uint32_t cpacr_vfp2 = CPACR_CPn(VFP_COPROC2);
259 
260 		/*
261 		 * We first need to enable access to the coprocessors.
262 		 */
263 		uint32_t cpacr = armreg_cpacr_read();
264 		cpacr |= __SHIFTIN(CPACR_ALL, cpacr_vfp);
265 		cpacr |= __SHIFTIN(CPACR_ALL, cpacr_vfp2);
266 		armreg_cpacr_write(cpacr);
267 
268 		/*
269 		 * If we could enable them, then they exist.
270 		 */
271 		cpacr = armreg_cpacr_read();
272 		bool vfp_p = __SHIFTOUT(cpacr, cpacr_vfp2) == CPACR_ALL
273 		    && __SHIFTOUT(cpacr, cpacr_vfp) == CPACR_ALL;
274 		if (!vfp_p) {
275 			aprint_normal_dev(ci->ci_dev,
276 			    "VFP access denied (CPACR=%#x)\n", cpacr);
277 			install_coproc_handler(VFP_COPROC, vfp_fpscr_handler);
278 			ci->ci_vfp_id = 0;
279 			evcnt_attach_dynamic(&ci->ci_vfp_evs[0],
280 			    EVCNT_TYPE_TRAP, NULL, ci->ci_cpuname,
281 			    "vfp fpscr traps");
282 			return;
283 		}
284 	}
285 
286 	void *uh = install_coproc_handler(VFP_COPROC, vfp_test);
287 
288 	undefined_test = 0;
289 
290 	const uint32_t fpsid = armreg_fpsid_read();
291 
292 	remove_coproc_handler(uh);
293 
294 	if (undefined_test != 0) {
295 		aprint_normal_dev(ci->ci_dev, "No VFP detected\n");
296 		install_coproc_handler(VFP_COPROC, vfp_fpscr_handler);
297 		ci->ci_vfp_id = 0;
298 		return;
299 	}
300 
301 	ci->ci_vfp_id = fpsid;
302 	switch (fpsid & ~ VFP_FPSID_REV_MSK) {
303 	case FPU_VFP10_ARM10E:
304 		model = "VFP10 R1";
305 		break;
306 	case FPU_VFP11_ARM11:
307 		model = "VFP11";
308 		break;
309 	case FPU_VFP_MV88SV58XX:
310 		model = "VFP3";
311 		break;
312 	case FPU_VFP_CORTEXA5:
313 	case FPU_VFP_CORTEXA7:
314 	case FPU_VFP_CORTEXA8:
315 	case FPU_VFP_CORTEXA9:
316 	case FPU_VFP_CORTEXA15:
317 	case FPU_VFP_CORTEXA15_QEMU:
318 		if (armreg_cpacr_read() & CPACR_V7_ASEDIS) {
319 			model = "VFP 4.0+";
320 		} else {
321 			model = "NEON MPE (VFP 3.0+)";
322 			cpu_neon_present = 1;
323 		}
324 		break;
325 	default:
326 		aprint_normal_dev(ci->ci_dev, "unrecognized VFP version %#x\n",
327 		    fpsid);
328 		install_coproc_handler(VFP_COPROC, vfp_fpscr_handler);
329 		vfp_fpscr_changable = VFP_FPSCR_CSUM|VFP_FPSCR_ESUM
330 		    |VFP_FPSCR_RMODE;
331 		vfp_fpscr_default = 0;
332 		return;
333 	}
334 
335 	cpu_fpu_present = 1;
336 	cpu_media_and_vfp_features[0] = armreg_mvfr0_read();
337 	cpu_media_and_vfp_features[1] = armreg_mvfr1_read();
338 	if (fpsid != 0) {
339 		uint32_t f0 = armreg_mvfr0_read();
340 		uint32_t f1 = armreg_mvfr1_read();
341 		aprint_normal("vfp%d at %s: %s%s%s%s%s\n",
342 		    device_unit(ci->ci_dev),
343 		    device_xname(ci->ci_dev),
344 		    model,
345 		    ((f0 & ARM_MVFR0_ROUNDING_MASK) ? ", rounding" : ""),
346 		    ((f0 & ARM_MVFR0_EXCEPT_MASK) ? ", exceptions" : ""),
347 		    ((f1 & ARM_MVFR1_D_NAN_MASK) ? ", NaN propagation" : ""),
348 		    ((f1 & ARM_MVFR1_FTZ_MASK) ? ", denormals" : ""));
349 		aprint_verbose("vfp%d: mvfr: [0]=%#x [1]=%#x\n",
350 		    device_unit(ci->ci_dev), f0, f1);
351 		if (CPU_IS_PRIMARY(ci)) {
352 			if (f0 & ARM_MVFR0_ROUNDING_MASK) {
353 				vfp_fpscr_changable |= VFP_FPSCR_RMODE;
354 			}
355 			if (f1 & ARM_MVFR0_EXCEPT_MASK) {
356 				vfp_fpscr_changable |= VFP_FPSCR_ESUM;
357 			}
358 			// If hardware supports propagation of NaNs, select it.
359 			if (f1 & ARM_MVFR1_D_NAN_MASK) {
360 				vfp_fpscr_default &= ~VFP_FPSCR_DN;
361 				vfp_fpscr_changable |= VFP_FPSCR_DN;
362 			}
363 			// If hardware supports denormalized numbers, use it.
364 			if (cpu_media_and_vfp_features[1] & ARM_MVFR1_FTZ_MASK) {
365 				vfp_fpscr_default &= ~VFP_FPSCR_FZ;
366 				vfp_fpscr_changable |= VFP_FPSCR_FZ;
367 			}
368 		}
369 	}
370 	evcnt_attach_dynamic(&ci->ci_vfp_evs[0], EVCNT_TYPE_MISC, NULL,
371 	    ci->ci_cpuname, "vfp coproc use");
372 	evcnt_attach_dynamic(&ci->ci_vfp_evs[1], EVCNT_TYPE_MISC, NULL,
373 	    ci->ci_cpuname, "vfp coproc re-use");
374 	evcnt_attach_dynamic(&ci->ci_vfp_evs[2], EVCNT_TYPE_TRAP, NULL,
375 	    ci->ci_cpuname, "vfp coproc fault");
376 	install_coproc_handler(VFP_COPROC, vfp_handler);
377 	install_coproc_handler(VFP_COPROC2, vfp_handler);
378 #ifdef CPU_CORTEX
379 	if (cpu_neon_present)
380 		install_coproc_handler(CORE_UNKNOWN_HANDLER, neon_handler);
381 #endif
382 }
383 
384 /* The real handler for VFP bounces.  */
385 static int
386 vfp_handler(u_int address, u_int insn, trapframe_t *frame, int fault_code)
387 {
388 	struct cpu_info * const ci = curcpu();
389 
390 	/* This shouldn't ever happen.  */
391 	if (fault_code != FAULT_USER)
392 		panic("VFP fault at %#x in non-user mode", frame->tf_pc);
393 
394 	if (ci->ci_vfp_id == 0) {
395 		/* No VFP detected, just fault.  */
396 		return 1;
397 	}
398 
399 	/*
400 	 * If we are just changing/fetching FPSCR, don't bother loading it
401 	 * just emulate the instruction.
402 	 */
403 	if (!vfp_fpscr_handler(address, insn, frame, fault_code))
404 		return 0;
405 
406 	/*
407 	 * If we already own the FPU and it's enabled (and no exception), raise
408 	 * SIGILL.  If there is an exception, drop through to raise a SIGFPE.
409 	 */
410 	if (curcpu()->ci_pcu_curlwp[PCU_FPU] == curlwp
411 	    && (armreg_fpexc_read() & (VFP_FPEXC_EX|VFP_FPEXC_EN)) == VFP_FPEXC_EN)
412 		return 1;
413 
414 	/*
415 	 * Make sure we own the FP.
416 	 */
417 	pcu_load(&arm_vfp_ops);
418 
419 	uint32_t fpexc = armreg_fpexc_read();
420 	if (fpexc & VFP_FPEXC_EX) {
421 		ksiginfo_t ksi;
422 		KASSERT(fpexc & VFP_FPEXC_EN);
423 
424 		curcpu()->ci_vfp_evs[2].ev_count++;
425 
426 		/*
427 		 * Need the clear the exception condition so any signal
428 		 * and future use can proceed.
429 		 */
430 		armreg_fpexc_write(fpexc & ~(VFP_FPEXC_EX|VFP_FPEXC_FSUM));
431 
432 		pcu_save(&arm_vfp_ops);
433 
434 		/*
435 		 * XXX Need to emulate bounce instructions here to get correct
436 		 * XXX exception codes, etc.
437 		 */
438 		KSI_INIT_TRAP(&ksi);
439 		ksi.ksi_signo = SIGFPE;
440 		if (fpexc & VFP_FPEXC_IXF)
441 			ksi.ksi_code = FPE_FLTRES;
442 		else if (fpexc & VFP_FPEXC_UFF)
443 			ksi.ksi_code = FPE_FLTUND;
444 		else if (fpexc & VFP_FPEXC_OFF)
445 			ksi.ksi_code = FPE_FLTOVF;
446 		else if (fpexc & VFP_FPEXC_DZF)
447 			ksi.ksi_code = FPE_FLTDIV;
448 		else if (fpexc & VFP_FPEXC_IOF)
449 			ksi.ksi_code = FPE_FLTINV;
450 		ksi.ksi_addr = (uint32_t *)address;
451 		ksi.ksi_trap = 0;
452 		trapsignal(curlwp, &ksi);
453 		return 0;
454 	}
455 
456 	/* Need to restart the faulted instruction.  */
457 //	frame->tf_pc -= INSN_SIZE;
458 	return 0;
459 }
460 
461 #ifdef CPU_CORTEX
462 /* The real handler for NEON bounces.  */
463 static int
464 neon_handler(u_int address, u_int insn, trapframe_t *frame, int fault_code)
465 {
466 	struct cpu_info * const ci = curcpu();
467 
468 	if (ci->ci_vfp_id == 0)
469 		/* No VFP detected, just fault.  */
470 		return 1;
471 
472 	if ((insn & 0xfe000000) != 0xf2000000
473 	    && (insn & 0xfe000000) != 0xf4000000)
474 		/* Not NEON instruction, just fault.  */
475 		return 1;
476 
477 	/* This shouldn't ever happen.  */
478 	if (fault_code != FAULT_USER)
479 		panic("NEON fault in non-user mode");
480 
481 	/* if we already own the FPU and it's enabled, raise SIGILL */
482 	if (curcpu()->ci_pcu_curlwp[PCU_FPU] == curlwp
483 	    && (armreg_fpexc_read() & VFP_FPEXC_EN) != 0)
484 		return 1;
485 
486 	pcu_load(&arm_vfp_ops);
487 
488 	/* Need to restart the faulted instruction.  */
489 //	frame->tf_pc -= INSN_SIZE;
490 	return 0;
491 }
492 #endif
493 
494 static void
495 vfp_state_load(lwp_t *l, u_int flags)
496 {
497 	struct pcb * const pcb = lwp_getpcb(l);
498 	struct vfpreg * const fregs = &pcb->pcb_vfp;
499 
500 	/*
501 	 * Instrument VFP usage -- if a process has not previously
502 	 * used the VFP, mark it as having used VFP for the first time,
503 	 * and count this event.
504 	 *
505 	 * If a process has used the VFP, count a "used VFP, and took
506 	 * a trap to use it again" event.
507 	 */
508 	if (__predict_false((flags & PCU_VALID) == 0)) {
509 		curcpu()->ci_vfp_evs[0].ev_count++;
510 		pcb->pcb_vfp.vfp_fpscr = vfp_fpscr_default;
511 	} else {
512 		curcpu()->ci_vfp_evs[1].ev_count++;
513 	}
514 
515 	/*
516 	 * If the VFP is already enabled we must be bouncing an instruction.
517 	 */
518 	if (flags & PCU_REENABLE) {
519 		uint32_t fpexc = armreg_fpexc_read();
520 		armreg_fpexc_write(fpexc | VFP_FPEXC_EN);
521 		return;
522 	}
523 
524 	/*
525 	 * Load and Enable the VFP (so that we can write the registers).
526 	 */
527 	bool enabled = fregs->vfp_fpexc & VFP_FPEXC_EN;
528 	fregs->vfp_fpexc |= VFP_FPEXC_EN;
529 	armreg_fpexc_write(fregs->vfp_fpexc);
530 	if (enabled) {
531 		/*
532 		 * If we think the VFP is enabled, it must have be
533 		 * disabled by vfp_state_release for another LWP so
534 		 * we can now just return.
535 		 */
536 		return;
537 	}
538 
539 	load_vfpregs(fregs);
540 	armreg_fpscr_write(fregs->vfp_fpscr);
541 
542 	if (fregs->vfp_fpexc & VFP_FPEXC_EX) {
543 		/* Need to restore the exception handling state.  */
544 		armreg_fpinst2_write(fregs->vfp_fpinst2);
545 		if (fregs->vfp_fpexc & VFP_FPEXC_FP2V)
546 			armreg_fpinst_write(fregs->vfp_fpinst);
547 	}
548 }
549 
550 void
551 vfp_state_save(lwp_t *l)
552 {
553 	struct pcb * const pcb = lwp_getpcb(l);
554 	struct vfpreg * const fregs = &pcb->pcb_vfp;
555 	uint32_t fpexc = armreg_fpexc_read();
556 
557 	/*
558 	 * Enable the VFP (so we can read the registers).
559 	 * Make sure the exception bit is cleared so that we can
560 	 * safely dump the registers.
561 	 */
562 	armreg_fpexc_write((fpexc | VFP_FPEXC_EN) & ~VFP_FPEXC_EX);
563 
564 	fregs->vfp_fpexc = fpexc;
565 	if (fpexc & VFP_FPEXC_EX) {
566 		/* Need to save the exception handling state */
567 		fregs->vfp_fpinst = armreg_fpinst_read();
568 		if (fpexc & VFP_FPEXC_FP2V)
569 			fregs->vfp_fpinst2 = armreg_fpinst2_read();
570 	}
571 	fregs->vfp_fpscr = armreg_fpscr_read();
572 	save_vfpregs(fregs);
573 
574 	/* Disable the VFP.  */
575 	armreg_fpexc_write(fpexc & ~VFP_FPEXC_EN);
576 }
577 
578 void
579 vfp_state_release(lwp_t *l)
580 {
581 	struct pcb * const pcb = lwp_getpcb(l);
582 
583 	/*
584 	 * Now mark the VFP as disabled (and our state
585 	 * has been already saved or is being discarded).
586 	 */
587 	pcb->pcb_vfp.vfp_fpexc &= ~VFP_FPEXC_EN;
588 
589 	/*
590 	 * Turn off the FPU so the next time a VFP instruction is issued
591 	 * an exception happens.  We don't know if this LWP's state was
592 	 * loaded but if we turned off the FPU for some other LWP, when
593 	 * pcu_load invokes vfp_state_load it will see that VFP_FPEXC_EN
594 	 * is still set so it just restore fpexc and return since its
595 	 * contents are still sitting in the VFP.
596 	 */
597 	armreg_fpexc_write(armreg_fpexc_read() & ~VFP_FPEXC_EN);
598 }
599 
600 void
601 vfp_savecontext(void)
602 {
603 	pcu_save(&arm_vfp_ops);
604 }
605 
606 void
607 vfp_discardcontext(bool used_p)
608 {
609 	pcu_discard(&arm_vfp_ops, used_p);
610 }
611 
612 bool
613 vfp_used_p(void)
614 {
615 	return pcu_valid_p(&arm_vfp_ops);
616 }
617 
618 void
619 vfp_getcontext(struct lwp *l, mcontext_t *mcp, int *flagsp)
620 {
621 	if (vfp_used_p()) {
622 		const struct pcb * const pcb = lwp_getpcb(l);
623 		pcu_save(&arm_vfp_ops);
624 		mcp->__fpu.__vfpregs.__vfp_fpscr = pcb->pcb_vfp.vfp_fpscr;
625 		memcpy(mcp->__fpu.__vfpregs.__vfp_fstmx, pcb->pcb_vfp.vfp_regs,
626 		    sizeof(mcp->__fpu.__vfpregs.__vfp_fstmx));
627 		*flagsp |= _UC_FPU|_UC_ARM_VFP;
628 	}
629 }
630 
631 void
632 vfp_setcontext(struct lwp *l, const mcontext_t *mcp)
633 {
634 	pcu_discard(&arm_vfp_ops, true);
635 	struct pcb * const pcb = lwp_getpcb(l);
636 	pcb->pcb_vfp.vfp_fpscr = mcp->__fpu.__vfpregs.__vfp_fpscr;
637 	memcpy(pcb->pcb_vfp.vfp_regs, mcp->__fpu.__vfpregs.__vfp_fstmx,
638 	    sizeof(mcp->__fpu.__vfpregs.__vfp_fstmx));
639 }
640 
641 #endif /* FPU_VFP */
642