Paul Burton b42aa3fd59 MIPS: tlbex: Fix build_restore_pagemask KScratch restore ... build_restore_pagemask() will restore the value of register $1/$at when its restore_scratch argument is non-zero, and aims to do so by filling a branch delay slot. Commit 0b24cae4d5 ("MIPS: Add missing EHB in mtc0 -> mfc0 sequence.") added an EHB instruction (Execution Hazard Barrier) prior to restoring $1 from a KScratch register, in order to resolve a hazard that can result in stale values of the KScratch register being observed. In particular, P-class CPUs from MIPS with out of order execution pipelines such as the P5600 & P6600 are affected. Unfortunately this EHB instruction was inserted in the branch delay slot causing the MFC0 instruction which performs the restoration to no longer execute along with the branch. The result is that the $1 register isn't actually restored, ie. the TLB refill exception handler clobbers it - which is exactly the problem the EHB is meant to avoid for the P-class CPUs. Similarly build_get_pgd_vmalloc() will restore the value of $1/$at when its mode argument equals refill_scratch, and suffers from the same problem. Fix this by in both cases moving the EHB earlier in the emitted code. There's no reason it needs to immediately precede the MFC0 - it simply needs to be between the MTC0 & MFC0. This bug only affects Cavium Octeon systems which use build_fast_tlb_refill_handler(). Signed-off-by: Paul Burton <paulburton@kernel.org> Fixes: 0b24cae4d5 ("MIPS: Add missing EHB in mtc0 -> mfc0 sequence.") Cc: Dmitry Korotin <dkorotin@wavecomp.com> Cc: stable@vger.kernel.org # v3.15+ Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org		2019-10-23 21:12:49 -07:00
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alchemy
ar7
ath25
ath79
bcm47xx
bcm63xx	MIPS: bmips: mark exception vectors as char arrays	2019-10-23 21:07:28 -07:00
bmips
boot	MIPS: dts: ar9331: fix interrupt-controller size	2019-09-30 15:22:35 -07:00
cavium-octeon	Main MIPS changes for v5.4:	2019-09-22 09:30:30 -07:00
cobalt
configs	USB: rio500: Remove Rio 500 kernel driver	2019-10-04 10:53:36 +02:00
crypto
dec
emma
fw	MIPS: fw: sni: Fix out of bounds init of o32 stack	2019-10-09 12:47:28 -07:00
generic
include	MIPS: bmips: mark exception vectors as char arrays	2019-10-23 21:07:28 -07:00
jazz
jz4740
kernel	MIPS: bmips: mark exception vectors as char arrays	2019-10-23 21:07:28 -07:00
kvm
lantiq
lasat
lib
loongson32
loongson64	MIPS: Disable Loongson MMI instructions for kernel build	2019-10-10 11:58:52 -07:00
math-emu
mm	MIPS: tlbex: Fix build_restore_pagemask KScratch restore	2019-10-23 21:12:49 -07:00
mti-malta
net
netlogic
oprofile
paravirt
pci	Main MIPS changes for v5.4:	2019-09-22 09:30:30 -07:00
pic32
pistachio
pmcs-msp71xx	MIPS: pmcs-msp71xx: Remove unused addr variable	2019-10-03 15:47:17 -07:00
pnx833x
power
ralink
rb532
sgi-ip22
sgi-ip27
sgi-ip32
sibyte
sni
tools
txx9
vdso	MIPS: Disable Loongson MMI instructions for kernel build	2019-10-10 11:58:52 -07:00
vr41xx
Kbuild
Kbuild.platforms
Kconfig	mips: use generic mmap top-down layout and brk randomization	2019-09-24 15:54:12 -07:00
Kconfig.debug
Makefile
Makefile.postlink