[src/trunk]: src/sys/arch/i386/i386 Revert "x86: Add kthread_fpu_enter/exit s...

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

details:   https://anonhg.NetBSD.org/src/rev/c2a45b883655
branches:  trunk
changeset: 373811:c2a45b883655
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Mar 03 14:32:27 2023 +0000

description:
Revert "x86: Add kthread_fpu_enter/exit support, take two -- forgot i386 bits."

kthread_fpu_enter/exit changes broke some hardware, unclear why, to
investigate before fixing and reapplying these changes.

diffstat:

 sys/arch/i386/i386/genassym.cf |   3 +--
 sys/arch/i386/i386/locore.S    |  21 +++------------------
 2 files changed, 4 insertions(+), 20 deletions(-)

diffs (66 lines):

diff -r 88dfdb366f40 -r c2a45b883655 sys/arch/i386/i386/genassym.cf
--- a/sys/arch/i386/i386/genassym.cf    Fri Mar 03 12:53:04 2023 +0000
+++ b/sys/arch/i386/i386/genassym.cf    Fri Mar 03 14:32:27 2023 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: genassym.cf,v 1.132 2023/02/25 18:35:54 riastradh Exp $
+#      $NetBSD: genassym.cf,v 1.133 2023/03/03 14:32:27 riastradh Exp $
 
 #
 # Copyright (c) 1998, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -175,7 +175,6 @@
 define L_MD_ASTPENDING         offsetof(struct lwp, l_md.md_astpending)
 
 define LW_SYSTEM               LW_SYSTEM
-define LW_SYSTEM_FPU           LW_SYSTEM_FPU
 define MDL_FPU_IN_CPU          MDL_FPU_IN_CPU
 
 define P_FLAG                  offsetof(struct proc, p_flag)
diff -r 88dfdb366f40 -r c2a45b883655 sys/arch/i386/i386/locore.S
--- a/sys/arch/i386/i386/locore.S       Fri Mar 03 12:53:04 2023 +0000
+++ b/sys/arch/i386/i386/locore.S       Fri Mar 03 14:32:27 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.S,v 1.193 2023/03/01 08:38:50 riastradh Exp $   */
+/*     $NetBSD: locore.S,v 1.194 2023/03/03 14:32:27 riastradh Exp $   */
 
 /*
  * Copyright-o-rama!
@@ -128,7 +128,7 @@
  */
 
 #include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.193 2023/03/01 08:38:50 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.194 2023/03/03 14:32:27 riastradh Exp $");
 
 #include "opt_copy_symtab.h"
 #include "opt_ddb.h"
@@ -1471,7 +1471,7 @@
 
        /* Don't bother with the rest if switching to a system process. */
        testl   $LW_SYSTEM,L_FLAG(%edi)
-       jnz     .Lswitch_system
+       jnz     switch_return
 
 #ifndef XENPV
        /* Restore thread-private %fs/%gs descriptors. */
@@ -1525,21 +1525,6 @@
        popl    %ebx
        ret
 
-.Lswitch_system:
-       /*
-        * If it has LWP_SYSTEM_FPU set, meaning it's running in
-        * kthread_fpu_enter/exit, we need to restore the FPU state
-        * and enable FPU instructions with fpu_handle_deferred.
-        *
-        * No need to test MDL_FPU_IN_CPU via HANDLE_DEFERRED_FPU --
-        * fpu_switch guarantees it is clear, so we can just call
-        * fpu_handle_deferred unconditionally.
-        */
-       testl   $LW_SYSTEM_FPU,L_FLAG(%edi)
-       jz      switch_return
-       call    _C_LABEL(fpu_handle_deferred)
-       jmp     switch_return
-
 .Lcopy_iobitmap:
        /* Copy I/O bitmap. */
        incl    _C_LABEL(pmap_iobmp_evcnt)+EV_COUNT