[src/trunk]: src/sys/arch/x86/x86 Revert "Add kthread_fpu_enter/exit support ...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d531d61b2da3
branches:  trunk
changeset: 936732:d531d61b2da3
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Aug 02 18:23:33 2020 +0000

description:
Revert "Add kthread_fpu_enter/exit support to x86." for now.

Need to find all the paths out of interrupts back into _kernel_
context to add HANDLE_DEFERRED_FPU, I think, before this can be
enabled.

diffstat:

 sys/arch/x86/x86/fpu.c |  71 ++++++-------------------------------------------
 1 files changed, 9 insertions(+), 62 deletions(-)

diffs (159 lines):

diff -r e308b7ad7beb -r d531d61b2da3 sys/arch/x86/x86/fpu.c
--- a/sys/arch/x86/x86/fpu.c    Sun Aug 02 18:23:00 2020 +0000
+++ b/sys/arch/x86/x86/fpu.c    Sun Aug 02 18:23:33 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fpu.c,v 1.73 2020/08/01 02:13:34 riastradh Exp $       */
+/*     $NetBSD: fpu.c,v 1.74 2020/08/02 18:23:33 riastradh Exp $       */
 
 /*
  * Copyright (c) 2008, 2019 The NetBSD Foundation, Inc.  All
@@ -96,7 +96,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.73 2020/08/01 02:13:34 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.74 2020/08/02 18:23:33 riastradh Exp $");
 
 #include "opt_multiprocessor.h"
 
@@ -107,7 +107,6 @@
 #include <sys/file.h>
 #include <sys/proc.h>
 #include <sys/kernel.h>
-#include <sys/kthread.h>
 #include <sys/sysctl.h>
 #include <sys/xcall.h>
 
@@ -132,35 +131,13 @@
 
 uint32_t x86_fpu_mxcsr_mask __read_mostly = 0;
 
-/*
- * True if this a thread that is allowed to use the FPU -- either a
- * user thread, or a system thread with LW_SYSTEM_FPU enabled.
- */
-static inline bool
-lwp_can_haz_fpu(struct lwp *l)
-{
-
-       return (l->l_flag & (LW_SYSTEM|LW_SYSTEM_FPU)) != LW_SYSTEM;
-}
-
-/*
- * True if this is a system thread with its own private FPU state.
- */
-static inline bool
-lwp_system_fpu_p(struct lwp *l)
-{
-
-       return (l->l_flag & (LW_SYSTEM|LW_SYSTEM_FPU)) ==
-           (LW_SYSTEM|LW_SYSTEM_FPU);
-}
-
 static inline union savefpu *
 fpu_lwp_area(struct lwp *l)
 {
        struct pcb *pcb = lwp_getpcb(l);
        union savefpu *area = &pcb->pcb_savefpu;
 
-       KASSERT(lwp_can_haz_fpu(l));
+       KASSERT((l->l_flag & LW_SYSTEM) == 0);
        if (l == curlwp) {
                fpu_save();
        }
@@ -178,7 +155,7 @@
 
        s = splvm();
        if (l->l_md.md_flags & MDL_FPU_IN_CPU) {
-               KASSERT(lwp_can_haz_fpu(l));
+               KASSERT((l->l_flag & LW_SYSTEM) == 0);
                fpu_area_save(area, x86_xsave_features);
                l->l_md.md_flags &= ~MDL_FPU_IN_CPU;
        }
@@ -330,7 +307,7 @@
            cpu_index(ci), ci->ci_ilevel);
 
        if (oldlwp->l_md.md_flags & MDL_FPU_IN_CPU) {
-               KASSERT(lwp_can_haz_fpu(oldlwp));
+               KASSERT(!(oldlwp->l_flag & LW_SYSTEM));
                pcb = lwp_getpcb(oldlwp);
                fpu_area_save(&pcb->pcb_savefpu, x86_xsave_features);
                oldlwp->l_md.md_flags &= ~MDL_FPU_IN_CPU;
@@ -345,11 +322,11 @@
        union savefpu *fpu_save;
 
        /* Kernel threads have no FPU. */
-       if (__predict_false(!lwp_can_haz_fpu(l2))) {
+       if (__predict_false(l2->l_flag & LW_SYSTEM)) {
                return;
        }
        /* For init(8). */
-       if (__predict_false(!lwp_can_haz_fpu(l1))) {
+       if (__predict_false(l1->l_flag & LW_SYSTEM)) {
                memset(&pcb2->pcb_savefpu, 0, x86_fpu_save_size);
                return;
        }
@@ -373,8 +350,6 @@
 
 /* -------------------------------------------------------------------------- */
 
-static const union savefpu zero_fpu __aligned(64);
-
 /*
  * fpu_kern_enter()
  *
@@ -394,11 +369,6 @@
        struct cpu_info *ci;
        int s;
 
-       if (lwp_system_fpu_p(l) && !cpu_intr_p()) {
-               KASSERT(!cpu_softintr_p());
-               return;
-       }
-
        s = splvm();
 
        ci = curcpu();
@@ -431,16 +401,10 @@
 void
 fpu_kern_leave(void)
 {
-       struct cpu_info *ci;
+       static const union savefpu zero_fpu __aligned(64);
+       struct cpu_info *ci = curcpu();
        int s;
 
-       if (lwp_system_fpu_p(curlwp) && !cpu_intr_p()) {
-               KASSERT(!cpu_softintr_p());
-               return;
-       }
-
-       ci = curcpu();
-
        KASSERT(ci->ci_ilevel == IPL_VM);
        KASSERT(ci->ci_kfpu_spl != -1);
 
@@ -462,23 +426,6 @@
        splx(s);
 }
 
-void
-kthread_fpu_enter_md(void)
-{
-
-       /* Enable the FPU by clearing CR0_TS.  */
-       clts();
-}
-
-void
-kthread_fpu_exit_md(void)
-{
-
-       /* Zero the FPU state and disable the FPU by setting CR0_TS.  */
-       fpu_area_restore(&zero_fpu, x86_xsave_features);
-       stts();
-}
-
 /* -------------------------------------------------------------------------- */
 
 /*