Re: [PATCH 2/3] powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address

On Sun, Sep 04, 2016 at 05:00:13PM +0530, Aneesh Kumar K.V wrote:
[snip]

quoted

@@ -1389,6 +1393,7 @@ unrecover_mce:
  * r3 has the faulting address
  * r9 - r13 are saved in paca->exslb.
  * r3 is saved in paca->slb_r3
+ * cr6.eq is set for a D-SLB miss, clear for a I-SLB miss
  * We assume we aren't going to take any exceptions during this procedure.
  */
 slb_miss_realmode:

@@ -1399,29 +1404,31 @@ slb_miss_realmode:
 
 	stw	r9,PACA_EXSLB+EX_CCR(r13)	/* save CR in exc. frame */
 	std	r10,PACA_EXSLB+EX_LR(r13)	/* save LR */
+	std	r3,PACA_EXSLB+EX_DAR(r13)

We already have that in EX_R3(r13) right ? Any specific reason we can't

No, what's in EX_R3(r13) is the original value of r3.  What's in r3
now is the faulting address.  We save that here so we can put it in
regs->dar later on.

Paul.