Rewrite the kernel FPU handling code. The new code saves the FPU state

in cpu_switch() instead of at the kernel edge and gets rid of the FPU
state tracking in struct cpu_info and struct pcb.  This fixes the random
crashes seen with SMP kernels on Apple M1.

ok patrick@

5 files changed, 32 insertions, 58 deletions

diff --git a/sys/arch/arm64/include/armreg.h b/sys/arch/arm64/include/armreg.h
index fe96344af2a..51d0373c9bf 100644
--- a/sys/arch/arm64/include/armreg.h
+++ b/sys/arch/arm64/include/armreg.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: armreg.h,v 1.17 2021/09/02 10:48:52 kettenis Exp $ */
+/* $OpenBSD: armreg.h,v 1.18 2022/01/01 18:52:37 kettenis Exp $ */
 /*-
  * Copyright (c) 2013, 2014 Andrew Turner
  * Copyright (c) 2015 The FreeBSD Foundation
@@ -159,7 +159,7 @@
 #define	ESR_ELx_EC_MASK		(0x3f << 26)
 #define	ESR_ELx_EXCEPTION(esr)	(((esr) & ESR_ELx_EC_MASK) >> ESR_ELx_EC_SHIFT)
 #define	 EXCP_UNKNOWN		0x00	/* Unkwn exception */
-#define	 EXCP_FP_SIMD		0x07	/* VFP/SIMD trap */
+#define	 EXCP_FP_SIMD		0x07	/* FP/SIMD trap */
 #define	 EXCP_ILL_STATE		0x0e	/* Illegal execution state */
 #define	 EXCP_SVC		0x15	/* SVC trap */
 #define	 EXCP_MSR		0x18	/* MSR/MRS trap */
diff --git a/sys/arch/arm64/include/cpu.h b/sys/arch/arm64/include/cpu.h
index 109dd9c1141..c09ff800e25 100644
--- a/sys/arch/arm64/include/cpu.h
+++ b/sys/arch/arm64/include/cpu.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cpu.h,v 1.23 2021/11/22 19:22:59 kettenis Exp $ */
+/* $OpenBSD: cpu.h,v 1.24 2022/01/01 18:52:37 kettenis Exp $ */
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -99,7 +99,6 @@ struct cpu_info {
 
 	struct proc		*ci_curproc;
 	struct pmap		*ci_curpm;
-	struct proc		*ci_fpuproc;
 	u_int32_t		ci_randseed;
 
 	struct pcb		*ci_curpcb;
diff --git a/sys/arch/arm64/include/fpu.h b/sys/arch/arm64/include/fpu.h
new file mode 100644
index 00000000000..74faa8dc0ba
--- /dev/null
+++ b/sys/arch/arm64/include/fpu.h
@@ -0,0 +1,28 @@
+/*	$OpenBSD: fpu.h,v 1.1 2022/01/01 18:52:37 kettenis Exp $	*/
+/*
+ * Copyright (c) 2022 Mark Kettenis <kettenis@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _MACHINE_FPU_H
+#define _MACHINE_FPU_H
+
+void fpu_save(struct proc *);
+void fpu_load(struct proc *);
+void fpu_drop(void);
+
+void fpu_kernel_enter(void);
+void fpu_kernel_exit(void);
+
+#endif /* !_MACHINE_FPU_H */
diff --git a/sys/arch/arm64/include/pcb.h b/sys/arch/arm64/include/pcb.h
index d56a1c1f7ab..968236180cc 100644
--- a/sys/arch/arm64/include/pcb.h
+++ b/sys/arch/arm64/include/pcb.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: pcb.h,v 1.4 2018/07/04 17:52:29 drahn Exp $ */
+/* $OpenBSD: pcb.h,v 1.5 2022/01/01 18:52:37 kettenis Exp $ */
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -38,7 +38,6 @@ struct pcb {
 
 	caddr_t		pcb_onfault;	// On fault handler
 	struct fpreg	pcb_fpstate;	// Floating Point state */
-	struct cpu_info	*pcb_fpcpu;
 
 	void		*pcb_tcb;
 };
diff --git a/sys/arch/arm64/include/vfp.h b/sys/arch/arm64/include/vfp.h
deleted file mode 100644
index cc060163130..00000000000
--- a/sys/arch/arm64/include/vfp.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/* $OpenBSD: vfp.h,v 1.4 2018/07/02 07:23:37 kettenis Exp $ */
-/*-
- * Copyright (c) 2015 The FreeBSD Foundation
- * All rights reserved.
- *
- * This software was developed by Andrew Turner under
- * sponsorship from the FreeBSD Foundation.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * $FreeBSD: head/sys/arm64/include/vfp.h 281494 2015-04-13 14:43:10Z andrew $
- */
-
-#ifndef _MACHINE_VFP_H_
-#define	_MACHINE_VFP_H_
-
-#ifdef _KERNEL
-
-#define	VFP_KFPEN	(1 << 20)
-#define	VFP_UFPEN	(3 << 20)
-
-#ifndef LOCORE
-void	vfp_discard(struct proc *);
-void	vfp_save(void);
-void	vfp_enable(void);
-int	vfp_fault(vaddr_t, uint32_t, trapframe_t *, int);
-void	vfp_kernel_enter(void);
-void	vfp_kernel_exit(void);
-#endif
-
-#endif
-
-#endif /* !_MACHINE_VFP_H_ */