Date: Mon, 8 Jul 2002 21:19:20 +0300 (EEST) From: unicorn@forest.od.ua To: FreeBSD-gnats-submit@FreeBSD.org Subject: i386/40354: crash, whith floating ops in kernel mode Message-ID: <200207081819.g68IJKKD021203@Rainbow.Deep.Forest>
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>Number: 40354
>Category: i386
>Synopsis: crash, whith floating ops in kernel mode
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Mon Jul 08 11:30:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: unicorn
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD Rainbow.Deep.Forest 5.0-CURRENT FreeBSD 5.0-CURRENT #10: Sun Jun 23 22:13:00 EEST 2002 root@Rainbow.Deep.Forest:/www/src/sys/i386/compile/RAINBOW i386
>Description:
npx dna handler tries to modify curpcb even if it does not exist (yet).
it couses page fault in kernel mode.
>How-To-Repeat:
do some floating point operations before the first process created.
>Fix:
Index: npx.c
===================================================================
RCS file: /mnt/ncvs/src/sys/i386/isa/npx.c,v
retrieving revision 1.129
diff -u -r1.129 npx.c
--- npx.c 27 Mar 2002 05:39:20 -0000 1.129
+++ npx.c 8 Jul 2002 18:08:06 -0000
@@ -826,21 +826,27 @@
*/
PCPU_SET(fpcurthread, curthread);
- exstat = GET_FPU_EXSW_PTR(PCPU_GET(curpcb));
- *exstat = 0;
- /*
- * The following frstor may cause an IRQ13 when the state being
- * restored has a pending error. The error will appear to have been
- * triggered by the current (npx) user instruction even when that
- * instruction is a no-wait instruction that should not trigger an
- * error (e.g., fnclex). On at least one 486 system all of the
- * no-wait instructions are broken the same as frstor, so our
- * treatment does not amplify the breakage. On at least one
- * 386/Cyrix 387 system, fnclex works correctly while frstor and
- * fnsave are broken, so our treatment breaks fnclex if it is the
- * first FPU instruction after a context switch.
- */
- fpurstor(&PCPU_GET(curpcb)->pcb_save);
+ if(PCPU_GET(curpcb) == NULL)
+ printf("npxdna: Oops! No curpcb!\n");
+ else {
+ exstat = GET_FPU_EXSW_PTR(PCPU_GET(curpcb));
+ *exstat = 0;
+
+ /*
+ * The following frstor may cause an IRQ13 when the state being
+ * restored has a pending error. The error will appear to have been
+ * triggered by the current (npx) user instruction even when that
+ * instruction is a no-wait instruction that should not trigger an
+ * error (e.g., fnclex). On at least one 486 system all of the
+ * no-wait instructions are broken the same as frstor, so our
+ * treatment does not amplify the breakage. On at least one
+ * 386/Cyrix 387 system, fnclex works correctly while frstor and
+ * fnsave are broken, so our treatment breaks fnclex if it is the
+ * first FPU instruction after a context switch.
+ */
+ fpurstor(&PCPU_GET(curpcb)->pcb_save);
+ }
+
intr_restore(s);
return (1);
>Release-Note:
>Audit-Trail:
>Unformatted:
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