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sparc64: Fix corrupted thread fault code. 

[ Upstream commit 84bd6d8b9c ]

Every path that ends up at do_sparc64_fault() must install a valid
FAULT_CODE_* bitmask in the per-thread fault code byte.

Two paths leading to the label winfix_trampoline (which expects the
FAULT_CODE_* mask in register %g4) were not doing so:

1) For pre-hypervisor TLB protection violation traps, if we took
   the 'winfix_trampoline' path we wouldn't have %g4 initialized
   with the FAULT_CODE_* value yet.  Resulting in using the
   TLB_TAG_ACCESS register address value instead.

2) In the TSB miss path, when we notice that we are going to use a
   hugepage mapping, but we haven't allocated the hugepage TSB yet, we
   still have to take the window fixup case into consideration and
   in that particular path we leave %g4 not setup properly.

Errors on this sort were largely invisible previously, but after
commit 4ccb927289 ("sparc64: sun4v TLB
error power off events") we now have a fault_code mask bit
(FAULT_CODE_BAD_RA) that triggers due to this bug.

FAULT_CODE_BAD_RA triggers because this bit is set in TLB_TAG_ACCESS
(see #1 above) and thus we get seemingly random bus errors triggered
for user processes.

Fixes: 4ccb927289 ("sparc64: sun4v TLB error power off events")
Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David S. Miller 2014-10-18 23:03:09 -04:00 committed by Greg Kroah-Hartman
parent 1771ef5474
commit 6b837f132c
2 changed files with 6 additions and 6 deletions
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6
arch/sparc/kernel/dtlb_prot.S
View File

@ -24,11 +24,11 @@
mov TLB_TAG_ACCESS, %g4 ! For reload of vaddr
/* PROT ** ICACHE line 2: More real fault processing */
ldxa [%g4] ASI_DMMU, %g5 ! Put tagaccess in %g5
bgu,pn %xcc, winfix_trampoline ! Yes, perform winfixup
ldxa [%g4] ASI_DMMU, %g5 ! Put tagaccess in %g5
ba,pt %xcc, sparc64_realfault_common ! Nope, normal fault
mov FAULT_CODE_DTLB | FAULT_CODE_WRITE, %g4
nop
ba,pt %xcc, sparc64_realfault_common ! Nope, normal fault
nop
nop
nop
nop

6
arch/sparc/kernel/tsb.S
View File

@ -162,10 +162,10 @@ tsb_miss_page_table_walk_sun4v_fastpath:
nop
.previous
rdpr %tl, %g3
cmp %g3, 1
rdpr %tl, %g7
cmp %g7, 1
bne,pn %xcc, winfix_trampoline
nop
mov %g3, %g4
ba,pt %xcc, etrap
rd %pc, %g7
call hugetlb_setup