linux-kernel - Sparc miss chance to fix recoverable fault in copy_from

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Date:	Wed, 12 Aug 2009 09:53:01 +0800
From:	hyl <heyongli@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Sparc miss chance to fix recoverable fault in copy_from_user

if kernel code access the invalid address, ie, copy_from_user then tlb
miss handler
finally report error in sunv4_dtlb_errorthen halt. instead of halt,
should call do_sparc64_fault
to fix such fault by search extable.

a dirty fix like this can work( little testing,just boot and test the
copy_from_user).


--- a/arch/sparc/kernel/sun4v_tlb_miss.S
+++ b/arch/sparc/kernel/sun4v_tlb_miss.S
@@ -124,7 +124,7 @@ sun4v_dtlb_load:
 	mov	%g3, %o2		! PTE
 	mov	HV_MMU_DMMU, %o3	! flags
 	ta	HV_MMU_MAP_ADDR_TRAP
-	brnz,pn	%o0, sun4v_dtlb_error
+	brnz,pn	%o0, sun4v_dtlb_prot
 	 mov	%g2, %o1		! restore %o1
 	mov	%g1, %o0		! restore %o0
 	mov	%g5, %o2		! restore %o2



am i miss understanding the merged sparc/spar64?

this problem found on sparc64, via a simple module just access address 0
via copy_from_user. another simple test is kgdb, issue a cmd:
x 0
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