Author: kib
Date: Sat Oct 4 19:33:58 2014
New Revision: 272540
URL: https://svnweb.freebsd.org/changeset/base/272540
Log:
MFC r271747:
- Use NULL instead of 0 for fpcurthread.
- Note the quirk with the interrupt enabled state of the dna handler.
- Use just panic() instead of printf() and panic(). Print tid instead
of pid, the fpu state is per-thread.
MFC r271924:
Update and clarify comments. Remove the useless counter for impossible, but
seen in wild situation (on buggy hypervisors).
Modified:
stable/10/sys/amd64/amd64/fpu.c
stable/10/sys/amd64/amd64/trap.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/amd64/amd64/fpu.c
==============================================================================
--- stable/10/sys/amd64/amd64/fpu.c Sat Oct 4 19:32:46 2014
(r272539)
+++ stable/10/sys/amd64/amd64/fpu.c Sat Oct 4 19:33:58 2014
(r272540)
@@ -362,7 +362,7 @@ fpuexit(struct thread *td)
stop_emulating();
fpusave(curpcb->pcb_save);
start_emulating();
- PCPU_SET(fpcurthread, 0);
+ PCPU_SET(fpcurthread, NULL);
}
critical_exit();
}
@@ -603,33 +603,37 @@ fputrap_sse(void)
}
/*
- * Implement device not available (DNA) exception
+ * Device Not Available (DNA, #NM) exception handler.
*
- * It would be better to switch FP context here (if curthread != fpcurthread)
- * and not necessarily for every context switch, but it is too hard to
- * access foreign pcb's.
+ * It would be better to switch FP context here (if curthread !=
+ * fpcurthread) and not necessarily for every context switch, but it
+ * is too hard to access foreign pcb's.
*/
-
-static int err_count = 0;
-
void
fpudna(void)
{
+ /*
+ * This handler is entered with interrupts enabled, so context
+ * switches may occur before critical_enter() is executed. If
+ * a context switch occurs, then when we regain control, our
+ * state will have been completely restored. The CPU may
+ * change underneath us, but the only part of our context that
+ * lives in the CPU is CR0.TS and that will be "restored" by
+ * setting it on the new CPU.
+ */
critical_enter();
+
if (PCPU_GET(fpcurthread) == curthread) {
- printf("fpudna: fpcurthread == curthread %d times\n",
- ++err_count);
+ printf("fpudna: fpcurthread == curthread\n");
stop_emulating();
critical_exit();
return;
}
if (PCPU_GET(fpcurthread) != NULL) {
- printf("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
- PCPU_GET(fpcurthread),
- PCPU_GET(fpcurthread)->td_proc->p_pid,
- curthread, curthread->td_proc->p_pid);
- panic("fpudna");
+ panic("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
+ PCPU_GET(fpcurthread), PCPU_GET(fpcurthread)->td_tid,
+ curthread, curthread->td_tid);
}
stop_emulating();
/*
Modified: stable/10/sys/amd64/amd64/trap.c
==============================================================================
--- stable/10/sys/amd64/amd64/trap.c Sat Oct 4 19:32:46 2014
(r272539)
+++ stable/10/sys/amd64/amd64/trap.c Sat Oct 4 19:33:58 2014
(r272540)
@@ -450,8 +450,8 @@ trap(struct trapframe *frame)
case T_XMMFLT: /* SIMD floating-point exception */
case T_FPOPFLT: /* FPU operand fetch fault */
/*
- * XXXKIB for now disable any FPU traps in kernel
- * handler registration seems to be overkill
+ * For now, supporting kernel handler
+ * registration for FPU traps is overkill.
*/
trap_fatal(frame, 0);
goto out;
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