commit cd1334f03f7b799bc6893b511daf2080e8f73863
author Jack Steiner <steiner@sgi.com> Wed Jun 17 16:28:19 2009 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Thu Jun 18 13:03:59 2009 -0700
tree 468d9bc99e19aa7895321927eaf30c4dae55166f
parent d6580a9f15238b87e618310c862231ae3f352d2d

gru: bug fixes for GRU exception handling

Bug fixes for GRU exception handling.  Additional fields from the CBR must
be returned to the user to allow the user to correctly diagnose GRU
exceptions.

Handle endcase in TFH TLB miss handling.  Verify that TFH actually
indicates a pending exception.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/sgi-gru/grufault.c

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index ab11855..4089f86 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -334,6 +334,8 @@
 	 * Might be a hardware race OR a stupid user. Ignore FMM because FMM
 	 * is a transient state.
 	 */
+	if (tfh->status != TFHSTATUS_EXCEPTION)
+		goto failnoexception;
 	if (tfh->state == TFHSTATE_IDLE)
 		goto failidle;
 	if (tfh->state == TFHSTATE_MISS_FMM && cb)
@@ -401,8 +403,17 @@
 	gru_dbg(grudev, "FAILED fmm tfh: 0x%p, state %d\n", tfh, tfh->state);
 	return 0;
 
+failnoexception:
+	/* TFH status did not show exception pending */
+	gru_flush_cache(tfh);
+	if (cb)
+		gru_flush_cache(cb);
+	STAT(tlb_dropin_fail_no_exception);
+	gru_dbg(grudev, "FAILED non-exception tfh: 0x%p, status %d, state %d\n", tfh, tfh->status, tfh->state);
+	return 0;
+
 failidle:
-	/* TFH was idle  - no miss pending */
+	/* TFH state was idle  - no miss pending */
 	gru_flush_cache(tfh);
 	if (cb)
 		gru_flush_cache(cb);
@@ -472,7 +483,8 @@
 		 * This is running in interrupt context. Trylock the mmap_sem.
 		 * If it fails, retry the fault in user context.
 		 */
-		if (down_read_trylock(&gts->ts_mm->mmap_sem)) {
+		if (!gts->ts_force_cch_reload &&
+					down_read_trylock(&gts->ts_mm->mmap_sem)) {
 			gru_try_dropin(gts, tfh, NULL);
 			up_read(&gts->ts_mm->mmap_sem);
 		} else {
@@ -595,14 +607,19 @@
 		excdet.ecause = cbe->ecause;
 		excdet.exceptdet0 = cbe->idef1upd;
 		excdet.exceptdet1 = cbe->idef3upd;
+		excdet.cbrstate = cbe->cbrstate;
+		excdet.cbrexecstatus = cbe->cbrexecstatus;
 		ret = 0;
 	} else {
 		ret = -EAGAIN;
 	}
 	gru_unlock_gts(gts);
 
-	gru_dbg(grudev, "address 0x%lx, ecause 0x%x\n", excdet.cb,
-		excdet.ecause);
+	gru_dbg(grudev,
+		"cb 0x%lx, op %d, exopc %d, cbrstate %d, cbrexecstatus 0x%x, ecause 0x%x, "
+		"exdet0 0x%lx, exdet1 0x%x\n",
+		excdet.cb, excdet.opc, excdet.exopc, excdet.cbrstate, excdet.cbrexecstatus,
+		excdet.ecause, excdet.exceptdet0, excdet.exceptdet1);
 	if (!ret && copy_to_user((void __user *)arg, &excdet, sizeof(excdet)))
 		ret = -EFAULT;
 	return ret;