linux/arch/mips
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
..
alchemy treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 182 2019-05-30 11:29:20 -07:00
ar7 The main MIPS changes for a pretty light v5.3 cycle, including: 2019-07-17 09:42:03 -07:00
ath25 PCI: consolidate PCI config entry in drivers/pci 2018-11-23 11:45:34 +09:00
ath79 The main MIPS changes for a pretty light v5.3 cycle, including: 2019-07-17 09:42:03 -07:00
bcm47xx MIPS: BCM47XX: Add support for Netgear R6200 V1 2019-07-25 22:10:05 -07:00
bcm63xx MIPS: bmips: mark exception vectors as char arrays 2019-10-23 21:07:28 -07:00
bmips docs: arm: convert docs to ReST and rename to *.rst 2019-07-15 09:20:24 -03:00
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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 1 2019-05-21 11:28:39 +02:00
configs USB: rio500: Remove Rio 500 kernel driver 2019-10-04 10:53:36 +02:00
crypto MIPS: crypto: Add crc32 and crc32c hw accelerated module 2018-02-19 20:50:36 +00:00
dec treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
emma treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
fw MIPS: fw: sni: Fix out of bounds init of o32 stack 2019-10-09 12:47:28 -07:00
generic treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
include MIPS: bmips: mark exception vectors as char arrays 2019-10-23 21:07:28 -07:00
jazz dma-mapping: explicitly wire up ->mmap and ->get_sgtable 2019-09-04 11:13:18 +02:00
jz4740 Merge branch 'ingenic-tcu-v5.4' into mips-next 2019-08-08 15:33:16 -07:00
kernel MIPS: bmips: mark exception vectors as char arrays 2019-10-23 21:07:28 -07:00
kvm Bugfixes (arm and x86) and cleanups. 2019-08-09 15:46:29 -07:00
lantiq MIPS: lantiq: update the clock alias' for the mainline PCIe PHY driver 2019-08-24 15:13:22 +01:00
lasat treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 182 2019-05-30 11:29:20 -07:00
lib treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 504 2019-06-19 17:09:56 +02:00
loongson32 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
loongson64 MIPS: Disable Loongson MMI instructions for kernel build 2019-10-10 11:58:52 -07:00
math-emu treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 454 2019-06-19 17:09:09 +02:00
mm MIPS: tlbex: Fix build_restore_pagemask KScratch restore 2019-10-23 21:12:49 -07:00
mti-malta MIPS: malta: Drop prom_free_prom_memory 2019-08-23 14:47:13 +01:00
net treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
netlogic MIPS: xlp: Drop boot_mem_map 2019-08-23 14:47:21 +01:00
oprofile MIPS: OProfile: Mark expected switch fall-throughs 2019-07-30 09:40:17 -07:00
paravirt mips: unify prom_putchar() declarations 2018-07-17 09:40:17 -07:00
pci Main MIPS changes for v5.4: 2019-09-22 09:30:30 -07:00
pic32 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 445 2019-06-05 17:37:18 +02:00
pistachio A batch of MIPS fixes: 2019-06-08 13:09:31 -07:00
pmcs-msp71xx MIPS: pmcs-msp71xx: Remove unused addr variable 2019-10-03 15:47:17 -07:00
pnx833x A batch of MIPS fixes: 2019-06-08 13:09:31 -07:00
power treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 305 2019-06-05 17:37:04 +02:00
ralink MIPS: ralink: deactivate PCI support for SOC_MT7621 2019-09-06 08:45:03 -07:00
rb532 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 182 2019-05-30 11:29:20 -07:00
sgi-ip22 MIPS: ip22: Drop addr_is_ram 2019-08-23 14:47:18 +01:00
sgi-ip27 MIPS: SGI-IP27: restructure ioc3 register access 2019-08-30 13:54:35 -07:00
sgi-ip32 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-07-08 21:48:15 -07:00
sibyte treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
sni treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 210 2019-05-30 11:29:53 -07:00
tools treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
txx9 A batch of MIPS fixes: 2019-06-08 13:09:31 -07:00
vdso MIPS: Disable Loongson MMI instructions for kernel build 2019-10-10 11:58:52 -07:00
vr41xx treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kbuild.platforms treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig mips: use generic mmap top-down layout and brk randomization 2019-09-24 15:54:12 -07:00
Kconfig.debug Kconfig: consolidate the "Kernel hacking" menu 2018-08-02 08:06:48 +09:00
Makefile MIPS: Remove unused R8000 CPU support 2019-07-23 14:33:51 -07:00
Makefile.postlink License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00