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Paul Burton cfd54de3b0
MIPS: Avoid move psuedo-instruction whilst using MIPS_ISA_LEVEL
MIPS_ISA_LEVEL is always defined as the 64 bit ISA that is a compatible
superset of the ISA that the kernel build is targeting, and is used to
allow us to emit instructions that we may detect support for at runtime.

When we use a .set MIPS_ISA_LEVEL directive & are building a 32-bit
kernel, we therefore are temporarily allowing the assembler to generate
MIPS64 instructions. Using the move pseudo-instruction whilst this is
the case is problematic because the assembler is likely to emit a daddu
instruction which will generate a reserved instruction exception when
executed on a MIPS32 machine.

Unfortunately the combination of commit a0a5ac3ce8 ("MIPS: Fix delay
slot bug in `atomic*_sub_if_positive' for R10000_LLSC_WAR") and commit
4936084c2e ("MIPS: Cleanup R10000_LLSC_WAR logic in atomic.h") causes
us to do exactly this in atomic_sub_if_positive(), and the result is
MIPS64 daddu instructions in 32-bit kernels.

Fix this by using .set mips0 to restore the default ISA after the ll
instruction, and use .set MIPS_ISA_LEVEL again prior to the sc. This
ensures everything but the ll & sc are assembled using the default ISA
for the kernel build & the move pseudo-instruction is emitted as a
MIPS32 addu instruction.

We appear to have another pre-existing instance of the same issue in our
atomic_fetch_*_relaxed() functions, and fix that up too by moving our
.set move0 such that it occurs prior to use of the move
pseudo-instruction.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: a0a5ac3ce8 ("MIPS: Fix delay slot bug in `atomic*_sub_if_positive' for R10000_LLSC_WAR")
Fixes: 4936084c2e ("MIPS: Cleanup R10000_LLSC_WAR logic in atomic.h")
Patchwork: https://patchwork.linux-mips.org/patch/20253/
Cc: James Hogan <jhogan@kernel.org>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
2018-08-17 16:40:11 -07:00
arch MIPS: Avoid move psuedo-instruction whilst using MIPS_ISA_LEVEL 2018-08-17 16:40:11 -07:00
block for-linus-20180623 2018-06-24 06:33:54 +08:00
certs docs: Fix some broken references 2018-06-15 18:10:01 -03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-06-24 06:31:54 +08:00
Documentation MIPS: ath79: Fix the USB PHY reset names 2018-07-26 11:21:28 -07:00
drivers MIPS: Loongson: Add Loongson-3A R3.1 basic support 2018-07-23 17:53:34 -07:00
firmware
fs binfmt_elf: Respect error return from `regset->active' 2018-07-19 13:46:34 -07:00
include MIPS: Add FP_MODE regset support 2018-07-19 13:58:44 -07:00
init dma-mapping: move all DMA mapping code to kernel/dma 2018-06-14 08:50:37 +02:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel dma-noncoherent: add a arch_sync_dma_for_cpu_all hook 2018-06-24 09:27:27 -07:00
lib Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-24 19:36:16 +08:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm for-linus-20180623 2018-06-24 06:33:54 +08:00
net NFS client bugfixes for Linux 4.18 2018-06-22 06:21:34 +09:00
samples VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
scripts tracing: Fix SKIP_STACK_VALIDATION=1 build due to bad merge with -mrecord-mcount 2018-06-21 15:12:56 -04:00
security docs: Fix some broken references 2018-06-15 18:10:01 -03:00
sound docs: Fix some broken references 2018-06-15 18:10:01 -03:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-24 20:29:15 +08:00
usr
virt KVM: arm64: Prevent KVM_COMPAT from being selected 2018-06-21 17:17:50 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING
CREDITS
Kbuild
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-24 19:59:52 +08:00
Makefile Linux 4.18-rc2 2018-06-24 20:54:29 +08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.