Date: Sun, 5 Apr 1998 21:20:02 -0700 (PDT) From: Luoqi Chen <luoqi@chen.ml.org> To: freebsd-bugs Subject: Re: i386/6219: wine causes system crash Message-ID: <199804060420.VAA15406@hub.freebsd.org>
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The following reply was made to PR i386/6219; it has been noted by GNATS.
From: Luoqi Chen <luoqi@chen.ml.org>
To: freebsd-gnats-submit@freebsd.org
Cc: Subject: Re: i386/6219: wine causes system crash
Date: Mon, 06 Apr 1998 00:14:37 -0400
I figured out the cause of the problem myself. There was a mistake
made by the orignal submitter of the code. When disposing user ldt
before an exec, the default ldt should be loaded, instead, the very
user ldt that's being disposed of is loaded. The same mistake was made
in cpu_exit(), except in this case the consequence is not as dire.
Here's patch to fix the problem.
Index: machdep.c
===================================================================
RCS file: /fun/cvs/src/sys/i386/i386/machdep.c,v
retrieving revision 1.292
diff -u -r1.292 machdep.c
--- machdep.c 1998/03/07 20:16:47 1.292
+++ machdep.c 1998/04/06 02:59:59
@@ -776,8 +776,10 @@
/* was i386_user_cleanup() in NetBSD */
if (pcb->pcb_ldt) {
- if (pcb == curpcb)
- lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
+ if (pcb == curpcb) {
+ lldt(_default_ldt);
+ currentldt = _default_ldt;
+ }
kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ldt,
pcb->pcb_ldt_len * sizeof(union descriptor));
pcb->pcb_ldt_len = (int)pcb->pcb_ldt = 0;
@@ -792,6 +794,10 @@
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
regs->tf_cs = _ucodesel;
+
+ /* reset %fs and %gs as well */
+ __asm("mov %0,%%fs" : : "r" (_udatasel));
+ __asm("mov %0,%%gs" : : "r" (_udatasel));
/*
* Initialize the math emulator (if any) for the current
process.
Index: vm_machdep.c
===================================================================
RCS file: /fun/cvs/src/sys/i386/i386/vm_machdep.c,v
retrieving revision 1.101
diff -u -r1.101 vm_machdep.c
--- vm_machdep.c 1998/02/25 03:56:09 1.101
+++ vm_machdep.c 1998/04/06 02:56:47
@@ -692,8 +692,10 @@
#endif
#ifdef USER_LDT
if (pcb->pcb_ldt != 0) {
- if (pcb == curpcb)
- lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
+ if (pcb == curpcb) {
+ lldt(_default_ldt);
+ currentldt = _default_ldt;
+ }
kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ldt,
pcb->pcb_ldt_len * sizeof(union descriptor));
pcb->pcb_ldt_len = (int)pcb->pcb_ldt = 0;
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