Pull locking and atomic updates from Ingo Molnar:
"Main changes in this cycle are:
- Extend atomic primitives with coherent logic op primitives
(atomic_{or,and,xor}()) and deprecate the old partial APIs
(atomic_{set,clear}_mask())
The old ops were incoherent with incompatible signatures across
architectures and with incomplete support. Now every architecture
supports the primitives consistently (by Peter Zijlstra)
- Generic support for 'relaxed atomics':
- _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return()
- atomic_read_acquire()
- atomic_set_release()
This came out of porting qwrlock code to arm64 (by Will Deacon)
- Clean up the fragile static_key APIs that were causing repeat bugs,
by introducing a new one:
DEFINE_STATIC_KEY_TRUE(name);
DEFINE_STATIC_KEY_FALSE(name);
which define a key of different types with an initial true/false
value.
Then allow:
static_branch_likely()
static_branch_unlikely()
to take a key of either type and emit the right instruction for the
case. To be able to know the 'type' of the static key we encode it
in the jump entry (by Peter Zijlstra)
- Static key self-tests (by Jason Baron)
- qrwlock optimizations (by Waiman Long)
- small futex enhancements (by Davidlohr Bueso)
- ... and misc other changes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
jump_label/x86: Work around asm build bug on older/backported GCCs
locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations
locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h
locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics
locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition
locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'
locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations
locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
locking/static_keys: Make verify_keys() static
jump label, locking/static_keys: Update docs
locking/static_keys: Provide a selftest
jump_label: Provide a self-test
s390/uaccess, locking/static_keys: employ static_branch_likely()
x86, tsc, locking/static_keys: Employ static_branch_likely()
locking/static_keys: Add selftest
locking/static_keys: Add a new static_key interface
locking/static_keys: Rework update logic
locking/static_keys: Add static_key_{en,dis}able() helpers
...
If we have a series of events from userpsace, with %fprs=FPRS_FEF,
like follows:
ETRAP
ETRAP
VIS_ENTRY(fprs=0x4)
VIS_EXIT
RTRAP (kernel FPU restore with fpu_saved=0x4)
RTRAP
We will not restore the user registers that were clobbered by the FPU
using kernel code in the inner-most trap.
Traps allocate FPU save slots in the thread struct, and FPU using
sequences save the "dirty" FPU registers only.
This works at the initial trap level because all of the registers
get recorded into the top-level FPU save area, and we'll return
to userspace with the FPU disabled so that any FPU use by the user
will take an FPU disabled trap wherein we'll load the registers
back up properly.
But this is not how trap returns from kernel to kernel operate.
The simplest fix for this bug is to always save all FPU register state
for anything other than the top-most FPU save area.
Getting rid of the optimized inner-slot FPU saving code ends up
making VISEntryHalf degenerate into plain VISEntry.
Longer term we need to do something smarter to reinstate the partial
save optimizations. Perhaps the fundament error is having trap entry
and exit allocate FPU save slots and restore register state. Instead,
the VISEntry et al. calls should be doing that work.
This bug is about two decades old.
Reported-by: James Y Knight <jyknight@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Implement atomic logic ops -- atomic_{or,xor,and}.
These will replace the atomic_{set,clear}_mask functions that are
available on some archs.
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Many of the atomic op implementations are the same except for one
instruction; fold the lot into a few CPP macros and reduce LoC.
This also prepares for easy addition of new ops.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20140508135852.825281379@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The functions
__down_read
__down_read_trylock
__down_write
__down_write_trylock
__up_read
__up_write
__downgrade_write
are implemented inline, so remove corresponding EXPORT_SYMBOLs
(They lead to compile errors on RT kernel).
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sparc32 already supported it, as a consequence of using the
generic atomic64 implementation. And the sparc64 implementation
is rather trivial.
This allows us to set ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE for all
of sparc, and avoid the annoying warning from lib/atomic64_test.c
Signed-off-by: David S. Miller <davem@davemloft.net>
Linus removed the end-of-address-space hackery from
fs/namei.c:do_getname() so we really have to validate these edge
conditions and cannot cheat any more (as x86 used to as well).
Move to a common C implementation like x86 did. And if both
src and dst are sufficiently aligned we'll do word at a time
copies and checks as well.
Signed-off-by: David S. Miller <davem@davemloft.net>
For the explicit calls to .udiv/.umul in assembler, I made a
mechanical (read as: safe) transformation. I didn't attempt
to make any simplifications.
In particular, __ndelay and __udelay can be simplified significantly.
Some of the %y reads are unnecessary and these routines have no need
any longer for allocating a register window, they can be leaf
functions.
Signed-off-by: David S. Miller <davem@davemloft.net>
atomic24 support was used to semaphores in the past - but is no longer used.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove the duplicate entries from kernel/sparc_ksyms_*.c
The rationale behind this is that the EXPORT_SYMBOL() should be close to
their definition and we cannot add designate a symbol to be exported in
assembler so at least put it in a file in the same directory.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Additions by Julian Calaby:
* Rebased over sparc-2.6.git HEAD
Signed-off-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
