Module Name: src
Committed By: maxv
Date: Sun Mar 24 15:58:32 UTC 2019
Modified Files:
src/sys/arch/amd64/amd64: machdep.c netbsd32_machdep.c
src/sys/compat/linux32/arch/amd64: linux32_machdep.c
Log Message:
Disable preemption when setting PCB_COMPAT32, to prevent a context switch
before cpu_fsgs_reload() finishes, otherwise we write garbage in the GDT.
On NetBSD-current it is harmless, however in NetBSD-8 it might cause
panics, because NetBSD-8 uses the old SegRegs model and under this model
we reload %fs and %gs during switches.
To generate a diff of this commit:
cvs rdiff -u -r1.328 -r1.329 src/sys/arch/amd64/amd64/machdep.c
cvs rdiff -u -r1.119 -r1.120 src/sys/arch/amd64/amd64/netbsd32_machdep.c
cvs rdiff -u -r1.43 -r1.44 \
src/sys/compat/linux32/arch/amd64/linux32_machdep.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/amd64/amd64/machdep.c
diff -u src/sys/arch/amd64/amd64/machdep.c:1.328 src/sys/arch/amd64/amd64/machdep.c:1.329
--- src/sys/arch/amd64/amd64/machdep.c:1.328 Sun Mar 24 13:15:42 2019
+++ src/sys/arch/amd64/amd64/machdep.c Sun Mar 24 15:58:32 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: machdep.c,v 1.328 2019/03/24 13:15:42 maxv Exp $ */
+/* $NetBSD: machdep.c,v 1.329 2019/03/24 15:58:32 maxv Exp $ */
/*
* Copyright (c) 1996, 1997, 1998, 2000, 2006, 2007, 2008, 2011
@@ -110,7 +110,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.328 2019/03/24 13:15:42 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.329 2019/03/24 15:58:32 maxv Exp $");
#include "opt_modular.h"
#include "opt_user_ldt.h"
@@ -2237,12 +2237,12 @@ cpu_segregs32_zero(struct lwp *l)
struct pcb *pcb;
uint64_t zero = 0;
+ KASSERT(kpreempt_disabled());
KASSERT(l->l_proc->p_flag & PK_32);
KASSERT(l == curlwp);
pcb = lwp_getpcb(l);
- kpreempt_disable();
tf->tf_fs = 0;
tf->tf_gs = 0;
setds(GSEL(GUDATA32_SEL, SEL_UPL));
@@ -2253,7 +2253,6 @@ cpu_segregs32_zero(struct lwp *l)
pcb->pcb_gs = 0;
update_descriptor(&curcpu()->ci_gdt[GUFS_SEL], &zero);
update_descriptor(&curcpu()->ci_gdt[GUGS_SEL], &zero);
- kpreempt_enable();
}
/*
Index: src/sys/arch/amd64/amd64/netbsd32_machdep.c
diff -u src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.119 src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.120
--- src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.119 Fri Mar 1 11:06:55 2019
+++ src/sys/arch/amd64/amd64/netbsd32_machdep.c Sun Mar 24 15:58:32 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: netbsd32_machdep.c,v 1.119 2019/03/01 11:06:55 pgoyette Exp $ */
+/* $NetBSD: netbsd32_machdep.c,v 1.120 2019/03/24 15:58:32 maxv Exp $ */
/*
* Copyright (c) 2001 Wasabi Systems, Inc.
@@ -36,7 +36,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.119 2019/03/01 11:06:55 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.120 2019/03/24 15:58:32 maxv Exp $");
#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
@@ -138,21 +138,22 @@ netbsd32_setregs(struct lwp *l, struct e
netbsd32_adjust_limits(p);
- l->l_md.md_flags = MDL_COMPAT32; /* Force iret not sysret */
- pcb->pcb_flags = PCB_COMPAT32;
-
fpu_save_area_clear(l, pack->ep_osversion >= 699002600
? __NetBSD_NPXCW__ : __NetBSD_COMPAT_NPXCW__);
-
x86_dbregs_clear(l);
+ kpreempt_disable();
+ pcb->pcb_flags = PCB_COMPAT32;
p->p_flag |= PK_32;
+ l->l_md.md_flags = MDL_COMPAT32; /* force iret not sysret */
+ cpu_segregs32_zero(l);
+ cpu_fsgs_reload(l, LSEL(LUDATA32_SEL, SEL_UPL),
+ LSEL(LUDATA32_SEL, SEL_UPL));
+ kpreempt_enable();
tf = l->l_md.md_regs;
tf->tf_ds = LSEL(LUDATA32_SEL, SEL_UPL);
tf->tf_es = LSEL(LUDATA32_SEL, SEL_UPL);
- cpu_segregs32_zero(l);
- cpu_fsgs_reload(l, tf->tf_ds, tf->tf_es);
tf->tf_rdi = 0;
tf->tf_rsi = 0;
tf->tf_rbp = 0;
Index: src/sys/compat/linux32/arch/amd64/linux32_machdep.c
diff -u src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.43 src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.44
--- src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.43 Sat Oct 21 07:24:26 2017
+++ src/sys/compat/linux32/arch/amd64/linux32_machdep.c Sun Mar 24 15:58:32 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: linux32_machdep.c,v 1.43 2017/10/21 07:24:26 maxv Exp $ */
+/* $NetBSD: linux32_machdep.c,v 1.44 2019/03/24 15:58:32 maxv Exp $ */
/*-
* Copyright (c) 2006 Emmanuel Dreyfus, all rights reserved.
@@ -31,7 +31,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux32_machdep.c,v 1.43 2017/10/21 07:24:26 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux32_machdep.c,v 1.44 2019/03/24 15:58:32 maxv Exp $");
#if defined(_KERNEL_OPT)
#include "opt_user_ldt.h"
@@ -287,10 +287,14 @@ linux32_setregs(struct lwp *l, struct ex
fpu_save_area_clear(l, __Linux_NPXCW__);
- l->l_md.md_flags = MDL_COMPAT32; /* Forces iret not sysret */
+ kpreempt_disable();
pcb->pcb_flags = PCB_COMPAT32;
-
p->p_flag |= PK_32;
+ l->l_md.md_flags = MDL_COMPAT32; /* force iret not sysret */
+ cpu_segregs32_zero(l);
+ cpu_fsgs_reload(l, GSEL(GUDATA32_SEL, SEL_UPL),
+ GSEL(GUDATA32_SEL, SEL_UPL));
+ kpreempt_enable();
tf = l->l_md.md_regs;
tf->tf_rax = 0;
@@ -315,8 +319,6 @@ linux32_setregs(struct lwp *l, struct ex
tf->tf_ss = GSEL(GUDATA32_SEL, SEL_UPL);
tf->tf_ds = GSEL(GUDATA32_SEL, SEL_UPL);
tf->tf_es = GSEL(GUDATA32_SEL, SEL_UPL);
- cpu_segregs32_zero(l);
- cpu_fsgs_reload(l, GSEL(GUDATA32_SEL, SEL_UPL), GSEL(GUDATA32_SEL, SEL_UPL));
}
static void
