[src/trunk]: src/sys/arch/i386/i386 x86: Add kthread_fpu_enter/exit support, ...

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

details:   https://anonhg.NetBSD.org/src/rev/6e8cc92235d3
branches:  trunk
changeset: 373751:6e8cc92235d3
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Feb 25 18:35:54 2023 +0000

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

diffstat:

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

diffs (66 lines):

diff -r 27be365a49ea -r 6e8cc92235d3 sys/arch/i386/i386/genassym.cf
--- a/sys/arch/i386/i386/genassym.cf    Sat Feb 25 18:28:57 2023 +0000
+++ b/sys/arch/i386/i386/genassym.cf    Sat Feb 25 18:35:54 2023 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: genassym.cf,v 1.131 2022/12/27 08:40:40 msaitoh Exp $
+#      $NetBSD: genassym.cf,v 1.132 2023/02/25 18:35:54 riastradh Exp $
 
 #
 # Copyright (c) 1998, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -175,6 +175,7 @@
 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 27be365a49ea -r 6e8cc92235d3 sys/arch/i386/i386/locore.S
--- a/sys/arch/i386/i386/locore.S       Sat Feb 25 18:28:57 2023 +0000
+++ b/sys/arch/i386/i386/locore.S       Sat Feb 25 18:35:54 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.S,v 1.191 2023/02/03 09:21:58 mlelstv Exp $     */
+/*     $NetBSD: locore.S,v 1.192 2023/02/25 18:35:54 riastradh Exp $   */
 
 /*
  * Copyright-o-rama!
@@ -128,7 +128,7 @@
  */
 
 #include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.191 2023/02/03 09:21:58 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.192 2023/02/25 18:35:54 riastradh Exp $");
 
 #include "opt_copy_symtab.h"
 #include "opt_ddb.h"
@@ -1447,7 +1447,7 @@
 
        /* Don't bother with the rest if switching to a system process. */
        testl   $LW_SYSTEM,L_FLAG(%edi)
-       jnz     switch_return
+       jnz     .Lswitch_system
 
 #ifndef XENPV
        /* Restore thread-private %fs/%gs descriptors. */
@@ -1501,6 +1501,21 @@
        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