Alexander Duyck
1077fa36f2
arch: Add lightweight memory barriers dma_rmb() and dma_wmb() ...
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>
2014-12-11 21:15:06 -05:00
arch: Mass conversion of smp_mb__*()
2014-04-18 14:20:48 +02:00
locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read()
2014-10-03 06:06:23 +02:00
locking,arch: Rewrite generic atomic support
2014-08-14 12:48:14 +02:00
audit: Modify a set of system calls in audit class definitions
2014-01-17 17:01:46 -05:00
audit: Modify a set of system calls in audit class definitions
2014-01-17 17:01:46 -05:00
arch: Add lightweight memory barriers dma_rmb() and dma_wmb()
2014-12-11 21:15:06 -05:00
arch: Prepare for smp_mb__{before,after}_atomic()
2014-04-18 11:40:30 +02:00
UAPI: (Scripted) Disintegrate include/asm-generic
2012-10-04 18:20:15 +01:00
bug: Make BUG() always stop the machine
2014-04-07 16:36:10 -07:00
asm-generic headers: Allow yet more arch overrides in checksum.h
2013-02-11 20:00:33 +05:30
asm-generic: COMMON_CLK defines __clk_{get,put}
2014-09-25 18:00:45 -07:00
LLVMLinux: Remove warning about returning an uninitialized variable
2014-04-09 13:44:35 -07:00
asm-generic: move cmpxchg*_local defs to cmpxchg.h
2013-03-13 06:11:05 +01:00
cputime: Generic on-demand virtual cputime accounting
2013-01-27 19:23:27 +01:00
sched, time: Fix build error with 64 bit cputime_t on 32 bit systems
2014-10-03 05:46:55 +02:00
sched, time: Fix build error with 64 bit cputime_t on 32 bit systems
2014-10-03 05:46:55 +02:00
DMA-API: Change dma_declare_coherent_memory() CPU address to phys_addr_t
2014-05-20 16:55:23 -06:00
asm-generic: Add dma-contiguous.h
2014-09-22 13:35:51 +02:00
asm-generic/dma-mapping-broken.h: Provide dma_alloc_attrs()/dma_free_attrs()
2012-12-25 20:14:54 +01:00
Merge branch 'for-v3.18' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping
2014-10-10 16:56:08 -04:00
mm: create generic early_ioremap() support
2014-04-07 16:36:15 -07:00
arm64: fixmap: fix missing sub-page offset for earlyprintk
2014-05-03 22:20:31 +01:00
asm-generic: add generic futex for !CONFIG_SMP
2014-12-08 12:55:48 +08:00
gpio: Increase ARCH_NR_GPIOs to 512
2014-09-23 17:51:39 +02:00
mm: Fix generic hugetlb pte check return type.
2013-10-02 20:02:35 -04:00
UAPI: (Scripted) Disintegrate include/asm-generic
2012-10-04 18:20:15 +01:00
readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q
2014-07-04 13:27:30 +02:00
readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q
2014-07-04 13:27:30 +02:00
Merge branch 'io' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into asm-generic
2014-11-11 19:55:45 +01:00
include/asm-generic/ioctl.h: fix _IOC_TYPECHECK sparse error
2014-06-06 16:08:13 -07:00
Kconfig: rename HAS_IOPORT to HAS_IOPORT_MAP
2014-04-07 16:36:11 -07:00
irq_work: Introduce arch_irq_work_has_interrupt()
2014-09-13 18:38:07 +02:00
UAPI: Set up uapi/asm/Kbuild.asm
2012-10-02 18:01:56 +01:00
KVM: add kvm_para_available to asm-generic/kvm_para.h
2013-06-05 13:21:29 +03:00
locking/mcs: Allow architecture specific asm files to be used for contended case
2014-02-09 21:18:52 +01:00
__page_to_pfn: Fix typo in comment
2013-10-14 15:28:29 +02:00
mm: Make arch_unmap()/bprm_mm_init() available to all architectures
2014-11-19 11:54:13 +01:00
asm-generic/mmu.h: Add support for FDPIC
2012-12-09 23:14:14 +01:00
asm-generic: Remove asm-generic arch_bprm_mm_init()
2014-11-22 21:52:08 +01:00
Make most arch asm/module.h files use asm-generic/module.h
2012-09-28 14:31:03 +09:30
asm-generic: Add msi.h
2014-11-23 13:01:47 +01:00
arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
2013-06-26 12:10:55 +02:00
arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
2013-06-26 12:10:55 +02:00
arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
2013-06-26 12:10:55 +02:00
UAPI: (Scripted) Disintegrate include/asm-generic
2012-10-04 18:20:15 +01:00
include: remove __dev* attributes.
2013-01-03 15:57:16 -08:00
pci-dma-compat: add pci_zalloc_consistent helper
2014-08-08 15:57:28 -07:00
percpu: preffity percpu header files
2014-06-17 19:12:40 -04:00
mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared
2014-10-14 02:18:28 +02:00
sched: Kill task_preempt_count()
2014-10-28 10:47:56 +01:00
locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocks
2014-06-06 07:58:28 +02:00
locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocks
2014-06-06 07:58:28 +02:00
asm-generic: remove _STK_LIM_MAX
2014-05-15 00:32:09 +01:00
asm-generic: rwsem: de-PPCify rwsem.h
2014-03-14 18:02:08 +00:00
asm-generic: add generic seccomp.h for secure computing mode 1
2014-11-28 10:24:58 +00:00
nosave: consolidate __nosave_{begin,end} in <asm/sections.h>
2014-10-09 22:26:04 -04:00
constify copy_siginfo_to_user{,32}()
2013-11-09 00:16:29 -05:00
unify default ptrace_signal_deliver
2012-11-29 00:01:23 -05:00
crypto: create generic version of ablk_helper
2013-09-24 06:02:24 +10:00
UAPI: (Scripted) Disintegrate include/asm-generic
2012-10-04 18:20:15 +01:00
syscall.h: fix doc text for syscall_get_arch()
2014-09-23 16:20:00 -04:00
burying unused conditionals
2013-02-14 09:21:15 -05:00
UAPI: (Scripted) Disintegrate include/asm-generic
2012-10-04 18:20:15 +01:00
mmu_gather: move minimal range calculations into generic code
2014-11-17 10:12:42 +00:00
tracing,x86: Add a TSC trace_clock
2012-11-13 15:48:27 -05:00
asm-generic: uaccess: Spelling s/a ny/any/
2014-01-02 10:45:23 +01:00
asm-generic: allow generic unaligned access if the arch supports it
2014-05-08 10:22:23 +02:00
We get rid of the general module prefix confusion with a binary config option,
2013-05-05 10:58:06 -07:00
ARM: 8168/1: extend __init_end to a page align address
2014-10-02 21:28:16 +01:00
include/asm-generic/vtime.h: avoid zero-length file
2013-09-30 14:31:02 -07:00
word-at-a-time: simplify big-endian zero_bytemask macro
2014-05-01 08:57:44 -07:00
asm-generic: xor: mark static functions as __maybe_unused
2012-10-03 21:21:06 +02:00
1077fa36f2