From: "David S. Miller" <da...@davemloft.net>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 84bd6d8b9c0f06b3f188efb479c77e20f05e9a8a ]
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 4ccb9272892c33ef1c19a783cfa87103b30c2784 ("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: 4ccb9272892c ("sparc64: sun4v TLB error power off events")
Reported-by: Meelis Roos <mr...@linux.ee>
Signed-off-by: David S. Miller <da...@davemloft.net>
---
arch/sparc/kernel/dtlb_prot.S | 6 +++---
arch/sparc/kernel/tsb.S | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/sparc/kernel/dtlb_prot.S b/arch/sparc/kernel/dtlb_prot.S
index b2c2c5be281c..d668ca149e64 100644
--- a/arch/sparc/kernel/dtlb_prot.S
+++ b/arch/sparc/kernel/dtlb_prot.S
@@ -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
diff --git a/arch/sparc/kernel/tsb.S b/arch/sparc/kernel/tsb.S
index a313e4a9399b..36a2eefb4754 100644
--- a/arch/sparc/kernel/tsb.S
+++ b/arch/sparc/kernel/tsb.S
@@ -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
--
2.1.2
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