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>
84bd6d8b9c