"sub $reg, imm" is not a real MIPS instruction. The assembler can
replace that with "addi $reg, -imm". However, addi has been removed
from R6, so we replace the "sub" instruction with the "addiu" one.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
GCC versions supporting MIPS R6 use the ZC constraint to enforce a
9-bit offset for MIPS R6. We will use that for all MIPS R6 LL/SC
instructions.
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The GCC_OFF12_ASM macro is used for 12-bit immediate constrains
but we will also use it for 9-bit constrains on MIPS R6 so we
rename it to something more appropriate.
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 changed the 'cache' instruction opcode and reduced the
offset field to 8 bits. This means we now have to adjust the
base register every 256 bytes and as a result of which we can
no longer use the previous cache functions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The following instructions have been removed from MIPS R6
ulw, ulh, swl, lwr, lwl, swr.
However, all of them are used in the MIPS specific checksum implementation.
As a result of which, we will use the generic checksum on MIPS R6
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The HI/LO registers have been removed from MIPS R6. Instructions
such as MULT and DIV have been replaced with a new pair of
instructions for the HI/LO operations for example:
MULT -> MUL, MUH
DIV -> DIV, MOD
So we avoid preserving the pre-R6 HI/LO registers in MIPS R6
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
There are certain places where the code uses .set mips32 or .set mips64
or .set arch=r4000. In preparation of MIPS R6 support, and in order to
use as less #ifdefs as possible, we define new macros to set similar
annotations for MIPS R6.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 defines new opcodes for ll, sc, cache and pref instructions
so we need to take these into consideration in the micro-assembler.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Latest versions of QEMU added support for mips32r6-generic and
mips64r6-generic cpu types so add related definitions in preparation
of MIPS R6 support. This is also used for QEMU R2 generic cpus.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
activate_mm() and switch_mm() call get_new_mmu_context() which in turn
can enable the HTW before the entryhi is changed with the new ASID.
Since the latter will enable the HTW in local_flush_tlb_all(),
then there is a small timing window where the HTW is running with the
new ASID but with an old pgd since the TLBMISS_HANDLER_SETUP_PGD
hasn't assigned a new one yet. In order to prevent that, we introduce a
simple htw counter to avoid starting HTW accidentally due to nested
htw_{start,stop}() sequences. Moreover, since various IPI calls can
enforce TLB flushing operations on a different core, such an operation
may interrupt another htw_{stop,start} in progress leading inconsistent
updates of the htw_seq variable. In order to avoid that, we disable the
interrupts whenever we update that variable.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9118/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Whenever we modify a page table entry, we need to ensure that the HTW
will not fetch a stable entry. And for that to happen we need to ensure
that HTW is stopped before we modify the said entry otherwise the HTW
may already be in the process of reading that entry and fetching the
old information. As a result of which, we replace the htw_reset() calls
with htw_{stop,start} in more appropriate places. This also removes the
remaining users of htw_reset() and as a result we drop that macro
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9116/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull crypto update from Herbert Xu:
"Here is the crypto update for 3.20:
- Added 192/256-bit key support to aesni GCM.
- Added MIPS OCTEON MD5 support.
- Fixed hwrng starvation and race conditions.
- Added note that memzero_explicit is not a subsitute for memset.
- Added user-space interface for crypto_rng.
- Misc fixes"
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (71 commits)
crypto: tcrypt - do not allocate iv on stack for aead speed tests
crypto: testmgr - limit IV copy length in aead tests
crypto: tcrypt - fix buflen reminder calculation
crypto: testmgr - mark rfc4106(gcm(aes)) as fips_allowed
crypto: caam - fix resource clean-up on error path for caam_jr_init
crypto: caam - pair irq map and dispose in the same function
crypto: ccp - terminate ccp_support array with empty element
crypto: caam - remove unused local variable
crypto: caam - remove dead code
crypto: caam - don't emit ICV check failures to dmesg
hwrng: virtio - drop extra empty line
crypto: replace scatterwalk_sg_next with sg_next
crypto: atmel - Free memory in error path
crypto: doc - remove colons in comments
crypto: seqiv - Ensure that IV size is at least 8 bytes
crypto: cts - Weed out non-CBC algorithms
MAINTAINERS: add linux-crypto to hw random
crypto: cts - Remove bogus use of seqiv
crypto: qat - don't need qat_auth_state struct
crypto: algif_rng - fix sparse non static symbol warning
...
Pull KVM update from Paolo Bonzini:
"Fairly small update, but there are some interesting new features.
Common:
Optional support for adding a small amount of polling on each HLT
instruction executed in the guest (or equivalent for other
architectures). This can improve latency up to 50% on some
scenarios (e.g. O_DSYNC writes or TCP_RR netperf tests). This
also has to be enabled manually for now, but the plan is to
auto-tune this in the future.
ARM/ARM64:
The highlights are support for GICv3 emulation and dirty page
tracking
s390:
Several optimizations and bugfixes. Also a first: a feature
exposed by KVM (UUID and long guest name in /proc/sysinfo) before
it is available in IBM's hypervisor! :)
MIPS:
Bugfixes.
x86:
Support for PML (page modification logging, a new feature in
Broadwell Xeons that speeds up dirty page tracking), nested
virtualization improvements (nested APICv---a nice optimization),
usual round of emulation fixes.
There is also a new option to reduce latency of the TSC deadline
timer in the guest; this needs to be tuned manually.
Some commits are common between this pull and Catalin's; I see you
have already included his tree.
Powerpc:
Nothing yet.
The KVM/PPC changes will come in through the PPC maintainers,
because I haven't received them yet and I might end up being
offline for some part of next week"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits)
KVM: ia64: drop kvm.h from installed user headers
KVM: x86: fix build with !CONFIG_SMP
KVM: x86: emulate: correct page fault error code for NoWrite instructions
KVM: Disable compat ioctl for s390
KVM: s390: add cpu model support
KVM: s390: use facilities and cpu_id per KVM
KVM: s390/CPACF: Choose crypto control block format
s390/kernel: Update /proc/sysinfo file with Extended Name and UUID
KVM: s390: reenable LPP facility
KVM: s390: floating irqs: fix user triggerable endless loop
kvm: add halt_poll_ns module parameter
kvm: remove KVM_MMIO_SIZE
KVM: MIPS: Don't leak FPU/DSP to guest
KVM: MIPS: Disable HTW while in guest
KVM: nVMX: Enable nested posted interrupt processing
KVM: nVMX: Enable nested virtual interrupt delivery
KVM: nVMX: Enable nested apic register virtualization
KVM: nVMX: Make nested control MSRs per-cpu
KVM: nVMX: Enable nested virtualize x2apic mode
KVM: nVMX: Prepare for using hardware MSR bitmap
...
If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target. This is because the
restart_block is held in the same memory allocation as the kernel stack.
Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.
Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.
It's also a decent simplification, since the restart code is more or less
identical on all architectures.
[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Userland code may be built using an ABI which permits linking to objects
that have more restrictive floating point requirements. For example,
userland code may be built to target the O32 FPXX ABI. Such code may be
linked with other FPXX code, or code built for either one of the more
restrictive FP32 or FP64. When linking with more restrictive code, the
overall requirement of the process becomes that of the more restrictive
code. The kernel has no way to know in advance which mode the process
will need to be executed in, and indeed it may need to change during
execution. The dynamic loader is the only code which will know the
overall required mode, and so it needs to have a means to instruct the
kernel to switch the FP mode of the process.
This patch introduces 2 new options to the prctl syscall which provide
such a capability. The FP mode of the process is represented as a
simple bitmask combining a number of mode bits mirroring those present
in the hardware. Userland can either retrieve the current FP mode of
the process:
mode = prctl(PR_GET_FP_MODE);
or modify the current FP mode of the process:
err = prctl(PR_SET_FP_MODE, new_mode);
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8899/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
LKP has triggered a compiler warning after my recent patch "mm: account
pmd page tables to the process":
mm/mmap.c: In function 'exit_mmap':
>> mm/mmap.c:2857:2: warning: right shift count >= width of type [enabled by default]
The code:
> 2857 WARN_ON(mm_nr_pmds(mm) >
2858 round_up(FIRST_USER_ADDRESS, PUD_SIZE) >> PUD_SHIFT);
In this, on tile, we have FIRST_USER_ADDRESS defined as 0. round_up() has
the same type -- int. PUD_SHIFT.
I think the best way to fix it is to define FIRST_USER_ADDRESS as unsigned
long. On every arch for consistency.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch introduces a new module parameter for the KVM module; when it
is present, KVM attempts a bit of polling on every HLT before scheduling
itself out via kvm_vcpu_block.
This parameter helps a lot for latency-bound workloads---in particular
I tested it with O_DSYNC writes with a battery-backed disk in the host.
In this case, writes are fast (because the data doesn't have to go all
the way to the platters) but they cannot be merged by either the host or
the guest. KVM's performance here is usually around 30% of bare metal,
or 50% if you use cache=directsync or cache=writethrough (these
parameters avoid that the guest sends pointless flush requests, and
at the same time they are not slow because of the battery-backed cache).
The bad performance happens because on every halt the host CPU decides
to halt itself too. When the interrupt comes, the vCPU thread is then
migrated to a new physical CPU, and in general the latency is horrible
because the vCPU thread has to be scheduled back in.
With this patch performance reaches 60-65% of bare metal and, more
important, 99% of what you get if you use idle=poll in the guest. This
means that the tunable gets rid of this particular bottleneck, and more
work can be done to improve performance in the kernel or QEMU.
Of course there is some price to pay; every time an otherwise idle vCPUs
is interrupted by an interrupt, it will poll unnecessarily and thus
impose a little load on the host. The above results were obtained with
a mostly random value of the parameter (500000), and the load was around
1.5-2.5% CPU usage on one of the host's core for each idle guest vCPU.
The patch also adds a new stat, /sys/kernel/debug/kvm/halt_successful_poll,
that can be used to tune the parameter. It counts how many HLT
instructions received an interrupt during the polling period; each
successful poll avoids that Linux schedules the VCPU thread out and back
in, and may also avoid a likely trip to C1 and back for the physical CPU.
While the VM is idle, a Linux 4 VCPU VM halts around 10 times per second.
Of these halts, almost all are failed polls. During the benchmark,
instead, basically all halts end within the polling period, except a more
or less constant stream of 50 per second coming from vCPUs that are not
running the benchmark. The wasted time is thus very low. Things may
be slightly different for Windows VMs, which have a ~10 ms timer tick.
The effect is also visible on Marcelo's recently-introduced latency
test for the TSC deadline timer. Though of course a non-RT kernel has
awful latency bounds, the latency of the timer is around 8000-10000 clock
cycles compared to 20000-120000 without setting halt_poll_ns. For the TSC
deadline timer, thus, the effect is both a smaller average latency and
a smaller variance.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the GPIO descriptor API instead of the deprecated legacy GPIO API to
manage the busy GPIO.
The patch updates both the jz4740 nand driver and the only user of the driver
the qi-lb60 board driver.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Add a write_32bit_cp1_register() macro to compliment the
read_32bit_cp1_register() macro. This is to abstract whether .set
hardfloat needs to be used based on GAS_HAS_SET_HARDFLOAT.
The implementation of _read_32bit_cp1_register() .sets mips1 due to
failure of gas v2.19 to assemble cfc1 for Octeon (see commit
25c3000300 ("MIPS: Override assembler target architecture for
octeon.")). I haven't copied this over to _write_32bit_cp1_register() as
I'm uncertain whether it applies to ctc1 too, or whether anybody cares
about that version of binutils any longer.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9172/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[...]
struct component {
^
In file included from ./arch/mips/include/asm/sn/klconfig.h:58:0,
from ./arch/mips/include/asm/sn/module.h:12,
from ./arch/mips/include/asm/sn/node.h:8,
from ./arch/mips/include/asm/mach-ip35/mmzone.h:4,
from ./arch/mips/include/asm/mmzone.h:9,
from ./arch/mips/include/asm/mach-ip35/topology.h:7,
from ./arch/mips/include/asm/topology.h:11,
from include/linux/topology.h:35,
from include/linux/gfp.h:8,
from include/linux/device.h:29,
from drivers/base/component.c:14:
./arch/mips/include/asm/fw/arc/hinv.h:122:16: note: originally defined here
typedef struct component {
^
make[2]: *** [drivers/base/component.o] Error 1
make[2]: Target `__build' not remade because of errors.
make[1]: *** [drivers/base] Error 2
make[1]: Target `__build' not remade because of errors.
Fix by using an nameless struct definition in the COMPONENT definition.
Which is what the ARC spec uses anyway. While at it, do the same thing
for two other typedefs.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This isn't only short and easier to read and fully portable but also
shrinks a Malta kernel's by 160 bytes.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Sparse emits a bunch of warnings in mips-cm.h due to casting away of
__iomem by the addr_gcr_*() functions:
arch/mips/include/asm/mips-cm.h:134:1: warning: cast removes address space of expression
And subsequent passing of the return values to __raw_readl() and
__raw_writel() in the read_gcr_*() and write_gcr_*() functions:
arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 2 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1: expected void volatile [noderef] <asn:2>*mem
arch/mips/include/asm/mips-cm.h:134:1: got unsigned int [usertype] *
arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 1 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1: expected void const volatile [noderef] <asn:2>*mem
arch/mips/include/asm/mips-cm.h:134:1: got unsigned int [usertype] *
Fix by adding __iomem to the addr_gcr_*() return type and cast.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8874/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commit 4227a2d4ef (MIPS: Support for hybrid
FPRs) changes the kernel to execute read_c0_config5() even on processors
that don't have a Config5 register. According to the arch spec the
behaviour of trying to read or write this register is UNDEFINED where this
register doesn't exist, that is merely looking at this register is
already cruel because that might kill a kitten.
In case of Qemu older than v2.2 Qemu has elected to implement this
UNDEFINED behaviour by taking a RI exception - which then fries the
kernel:
[...]
Freeing YAMON memory: 956k freed
Freeing unused kernel memory: 240K (80674000 - 806b0000)
Reserved instruction in kernel code[#1]:
CPU: 0 PID: 1 Comm: init Not tainted 3.18.0-rc6-00058-g4227a2d #26
task: 86047588 ti: 86048000 task.ti: 86048000
$ 0 : 00000000 77a638cc 00000000 00000000
[...]
For qemu v2.2.0 commit f31b035a9f10dc9b57f01c426110af845d453ce2
(target-mips: correctly handle access to unimplemented CP0 register)
changed the behaviour to returning zero on read and ignoring writes
which more matches how typical hardware implementations actually behave.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reintroduce run-time check for crypto features. The old one was deleted
because it was unreliable, now decide the crypto availability on early
boot when the model string is constructed.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add crypto helper functions which are needed for kernel level usage.
The code for these has been extracted from the EdgeRouter Pro GPL tarball.
While at it, also delete duplicate definitions of the functions.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull another networking update from David Miller:
"Small follow-up to the main merge pull from the other day:
1) Alexander Duyck's DMA memory barrier patch set.
2) cxgb4 driver fixes from Karen Xie.
3) Add missing export of fixed_phy_register() to modules, from Mark
Salter.
4) DSA bug fixes from Florian Fainelli"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (24 commits)
net/macb: add TX multiqueue support for gem
linux/interrupt.h: remove the definition of unused tasklet_hi_enable
jme: replace calls to redundant function
net: ethernet: davicom: Allow to select DM9000 for nios2
net: ethernet: smsc: Allow to select SMC91X for nios2
cxgb4: Add support for QSA modules
libcxgbi: fix freeing skb prematurely
cxgb4i: use set_wr_txq() to set tx queues
cxgb4i: handle non-pdu-aligned rx data
cxgb4i: additional types of negative advice
cxgb4/cxgb4i: set the max. pdu length in firmware
cxgb4i: fix credit check for tx_data_wr
cxgb4i: fix tx immediate data credit check
net: phy: export fixed_phy_register()
fib_trie: Fix trie balancing issue if new node pushes down existing node
vlan: Add ability to always enable TSO/UFO
r8169:update rtl8168g pcie ephy parameter
net: dsa: bcm_sf2: force link for all fixed PHY devices
fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads
r8169: Use dma_rmb() and dma_wmb() for DescOwn checks
...
There are a number of situations where the mandatory barriers rmb() and
wmb() are used to order memory/memory operations in the device drivers
and those barriers are much heavier than they actually need to be. For
example in the case of PowerPC wmb() calls the heavy-weight sync
instruction when for coherent memory operations all that is really needed
is an lsync or eieio instruction.
This commit adds a coherent only version of the mandatory memory barriers
rmb() and wmb(). In most cases this should result in the barrier being the
same as the SMP barriers for the SMP case, however in some cases we use a
barrier that is somewhere in between rmb() and smp_rmb(). For example on
ARM the rmb barriers break down as follows:
Barrier Call Explanation
--------- -------- ----------------------------------
rmb() dsb() Data synchronization barrier - system
dma_rmb() dmb(osh) data memory barrier - outer sharable
smp_rmb() dmb(ish) data memory barrier - inner sharable
These new barriers are not as safe as the standard rmb() and wmb().
Specifically they do not guarantee ordering between coherent and incoherent
memories. The primary use case for these would be to enforce ordering of
reads and writes when accessing coherent memory that is shared between the
CPU and a device.
It may also be noted that there is no dma_mb(). Most architectures don't
provide a good mechanism for performing a coherent only full barrier without
resorting to the same mechanism used in mb(). As such there isn't much to
be gained in trying to define such a function.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is meant to cleanup the handling of read_barrier_depends and
smp_read_barrier_depends. In multiple spots in the kernel headers
read_barrier_depends is defined as "do {} while (0)", however we then go
into the SMP vs non-SMP sections and have the SMP version reference
read_barrier_depends, and the non-SMP define it as yet another empty
do/while.
With this commit I went through and cleaned out the duplicate definitions
and reduced the number of definitions down to 2 per header. In addition I
moved the 50 line comments for the macro from the x86 and mips headers that
defined it as an empty do/while to those that were actually defining the
macro, alpha and blackfin.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
