Date: Mon, 4 May 98 07:02:01 EDT From: luoqi@watermarkgroup.com (Luoqi Chen) To: jb@cimlogic.com.au, luoqi@watermarkgroup.com Cc: current@FreeBSD.ORG Subject: Re: 'fatal trap 12' on boot (smp and up) Message-ID: <9805041102.AA13313@watermarkgroup.com>
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> I think I made a mistake in my patch that cause the core dump. Try to
> enclose the two lines in the patch that reset fs and gs inside
> if (pcb == curpcb) {}. Without this, the code might trash fs & gs in
> another process' context.
Probably pcb->pcb_fs and pcb->pcb_gs need to be reset too. Please use the
following patch (I've also sent it in a follow-up to the original PR i386/6219).
-lq
Index: machdep.c
===================================================================
RCS file: /fun/cvs/src/sys/i386/i386/machdep.c,v
retrieving revision 1.294
diff -u -r1.294 machdep.c
--- machdep.c 1998/04/06 15:46:17 1.294
+++ machdep.c 1998/05/04 10:40:30
@@ -768,14 +768,15 @@
u_long stack;
{
struct trapframe *regs = p->p_md.md_regs;
-
-#ifdef USER_LDT
struct pcb *pcb = &p->p_addr->u_pcb;
+#ifdef USER_LDT
/* 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;
@@ -790,6 +791,14 @@
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
regs->tf_cs = _ucodesel;
+
+ /* reset %fs and %gs as well */
+ pcb->pcb_fs = _udatasel;
+ pcb->pcb_gs = _udatasel;
+ if (pcb == curpcb) {
+ __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 1.105
diff -u -r1.105 vm_machdep.c
--- vm_machdep.c 1998/03/23 19:52:42 1.105
+++ vm_machdep.c 1998/04/14 01:30:21
@@ -703,8 +703,10 @@
#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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