Module Name: src
Committed By: riastradh
Date: Mon Jul 20 16:41:18 UTC 2020
Modified Files:
src/sys/arch/x86/x86: fpu.c
Log Message:
Save fpu state at IPL_VM to exclude fpu_kern_enter/leave.
This way fpu_kern_enter/leave cannot interrupt the transition, so the
transition from state-on-CPU to state-in-memory (with TS set) is
atomic whether in an interrupt or not.
(I am not 100% convinced that this is necessary, but it makes
reasoning about the transition simpler.)
To generate a diff of this commit:
cvs rdiff -u -r1.70 -r1.71 src/sys/arch/x86/x86/fpu.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/x86/x86/fpu.c
diff -u src/sys/arch/x86/x86/fpu.c:1.70 src/sys/arch/x86/x86/fpu.c:1.71
--- src/sys/arch/x86/x86/fpu.c:1.70 Mon Jul 20 16:38:47 2020
+++ src/sys/arch/x86/x86/fpu.c Mon Jul 20 16:41:18 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: fpu.c,v 1.70 2020/07/20 16:38:47 riastradh Exp $ */
+/* $NetBSD: fpu.c,v 1.71 2020/07/20 16:41:18 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 1.70 2020/07/20 16:38:47 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.71 2020/07/20 16:41:18 riastradh Exp $");
#include "opt_multiprocessor.h"
@@ -151,14 +151,15 @@ fpu_save_lwp(struct lwp *l)
{
struct pcb *pcb = lwp_getpcb(l);
union savefpu *area = &pcb->pcb_savefpu;
+ int s;
- kpreempt_disable();
+ s = splvm();
if (l->l_md.md_flags & MDL_FPU_IN_CPU) {
KASSERT((l->l_flag & LW_SYSTEM) == 0);
fpu_area_save(area, x86_xsave_features);
l->l_md.md_flags &= ~MDL_FPU_IN_CPU;
}
- kpreempt_enable();
+ splx(s);
}
/*
@@ -299,8 +300,12 @@ fpu_handle_deferred(void)
void
fpu_switch(struct lwp *oldlwp, struct lwp *newlwp)
{
+ struct cpu_info *ci __diagused = curcpu();
struct pcb *pcb;
+ KASSERTMSG(ci->ci_ilevel >= IPL_SCHED, "cpu%d ilevel=%d",
+ cpu_index(ci), ci->ci_ilevel);
+
if (oldlwp->l_md.md_flags & MDL_FPU_IN_CPU) {
KASSERT(!(oldlwp->l_flag & LW_SYSTEM));
pcb = lwp_getpcb(oldlwp);
@@ -334,11 +339,13 @@ fpu_lwp_fork(struct lwp *l1, struct lwp
void
fpu_lwp_abandon(struct lwp *l)
{
+ int s;
+
KASSERT(l == curlwp);
- kpreempt_disable();
+ s = splvm();
l->l_md.md_flags &= ~MDL_FPU_IN_CPU;
stts();
- kpreempt_enable();
+ splx(s);
}
/* -------------------------------------------------------------------------- */
