| 6fbc07bbe2b5a898532f970c5a397f8789ace0d5 |
|
18-Jun-2014 |
Tejun Heo <tj@kernel.org> |
percpu: invoke __verify_pcpu_ptr() from the generic part of accessors and operations
__verify_pcpu_ptr() is used to verify that a specified parameter is
actually an percpu pointer by percpu accessor and operation
implementations. Currently, where it's called isn't clearly defined
and we just ensure that it's invoked at least once for all accessors
and operations.
The lack of clarity on when it should be called isn't nice and given
that this is a completely generic issue, there's no reason to make
archs worry about it.
This patch updates __verify_pcpu_ptr() invocations such that it's
always invoked from the final generic wrapper once per access or
operation. As this is already the case for {raw|this}_cpu_*()
definitions through __pcpu_size_*(), only the {raw|per|this}_cpu_ptr()
accessors need to be updated.
This change makes it unnecessary for archs to worry about
__verify_pcpu_ptr(). x86's arch_raw_cpu_ptr() is updated accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
|
| bbc344e1e3aef3034a0edc79f7f64a912517926b |
|
18-Jun-2014 |
Tejun Heo <tj@kernel.org> |
percpu: introduce arch_raw_cpu_ptr()
Currently, archs can override raw_cpu_ptr() directly; however, we
wanna build a layer of indirection in the generic part of percpu so
that we can implement generic features there without affecting archs.
Introduce arch_raw_cpu_ptr() which is used to define raw_cpu_ptr() by
generic percpu code. The two are identical for now. x86 is currently
the only arch which overrides raw_cpu_ptr() and is converted to
define arch_raw_cpu_ptr() instead.
This doesn't introduce any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
|
| b3ca1c10d7b32fdfdfaf5484eda486323f52d9be |
|
08-Apr-2014 |
Christoph Lameter <cl@linux.com> |
percpu: add raw_cpu_ops
The kernel has never been audited to ensure that this_cpu operations are
consistently used throughout the kernel. The code generated in many
places can be improved through the use of this_cpu operations (which
uses a segment register for relocation of per cpu offsets instead of
performing address calculations).
The patch set also addresses various consistency issues in general with
the per cpu macros.
A. The semantics of __this_cpu_ptr() differs from this_cpu_ptr only
because checks are skipped. This is typically shown through a raw_
prefix. So this patch set changes the places where __this_cpu_ptr()
is used to raw_cpu_ptr().
B. There has been the long term wish by some that __this_cpu operations
would check for preemption. However, there are cases where preemption
checks need to be skipped. This patch set adds raw_cpu operations that
do not check for preemption and then adds preemption checks to the
__this_cpu operations.
C. The use of __get_cpu_var is always a reference to a percpu variable
that can also be handled via a this_cpu operation. This patch set
replaces all uses of __get_cpu_var with this_cpu operations.
D. We can then use this_cpu RMW operations in various places replacing
sequences of instructions by a single one.
E. The use of this_cpu operations throughout will allow other arches than
x86 to implement optimized references and RMV operations to work with
per cpu local data.
F. The use of this_cpu operations opens up the possibility to
further optimize code that relies on synchronization through
per cpu data.
The patch set works in a couple of stages:
I. Patch 1 adds the additional raw_cpu operations and raw_cpu_ptr().
Also converts the existing __this_cpu_xx_# primitive in the x86
code to raw_cpu_xx_#.
II. Patch 2-4 use the raw_cpu operations in places that would give
us false positives once they are enabled.
III. Patch 5 adds preemption checks to __this_cpu operations to allow
checking if preemption is properly disabled when these functions
are used.
IV. Patches 6-20 are patches that simply replace uses of __get_cpu_var
with this_cpu_ptr. They do not depend on any changes to the percpu
code. No preemption tests are skipped if they are applied.
V. Patches 21-46 are conversion patches that use this_cpu operations
in various kernel subsystems/drivers or arch code.
VI. Patches 47/48 (not included in this series) remove no longer used
functions (__this_cpu_ptr and __get_cpu_var). These should only be
applied after all the conversion patches have made it and after we
have done additional passes through the kernel to ensure that none of
the uses of these functions remain.
This patch (of 46):
The patches following this one will add preemption checks to __this_cpu
ops so we need to have an alternative way to use this_cpu operations
without preemption checks.
raw_cpu_ops will be the basis for all other ops since these will be the
operations that do not implement any checks.
Primitive operations are renamed by this patch from __this_cpu_xxx to
raw_cpu_xxxx.
Also change the uses of the x86 percpu primitives in preempt.h.
These depend directly on asm/percpu.h (header #include nesting issue).
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: David Daney <david.daney@cavium.com>
Cc: David Miller <davem@davemloft.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Hedi Berriche <hedi@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Robert Richter <rric@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
| bd09d9a35111b6ffc0c7585d3853d0ec7f9f1eb4 |
|
30-Oct-2013 |
Greg Thelen <gthelen@google.com> |
percpu: fix this_cpu_sub() subtrahend casting for unsigneds
this_cpu_sub() is implemented as negation and addition.
This patch casts the adjustment to the counter type before negation to
sign extend the adjustment. This helps in cases where the counter type
is wider than an unsigned adjustment. An alternative to this patch is
to declare such operations unsupported, but it seemed useful to avoid
surprises.
This patch specifically helps the following example:
unsigned int delta = 1
preempt_disable()
this_cpu_write(long_counter, 0)
this_cpu_sub(long_counter, delta)
preempt_enable()
Before this change long_counter on a 64 bit machine ends with value
0xffffffff, rather than 0xffffffffffffffff. This is because
this_cpu_sub(pcp, delta) boils down to this_cpu_add(pcp, -delta),
which is basically:
long_counter = 0 + 0xffffffff
Also apply the same cast to:
__this_cpu_sub()
__this_cpu_sub_return()
this_cpu_sub_return()
All percpu_test.ko passes, especially the following cases which
previously failed:
l -= ui_one;
__this_cpu_sub(long_counter, ui_one);
CHECK(l, long_counter, -1);
l -= ui_one;
this_cpu_sub(long_counter, ui_one);
CHECK(l, long_counter, -1);
CHECK(l, long_counter, 0xffffffffffffffff);
ul -= ui_one;
__this_cpu_sub(ulong_counter, ui_one);
CHECK(ul, ulong_counter, -1);
CHECK(ul, ulong_counter, 0xffffffffffffffff);
ul = this_cpu_sub_return(ulong_counter, ui_one);
CHECK(ul, ulong_counter, 2);
ul = __this_cpu_sub_return(ulong_counter, ui_one);
CHECK(ul, ulong_counter, 1);
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
| 90f2492cf9c84fd414ecfd2f40685fb5291a484e |
|
21-Oct-2013 |
Heiko Carstens <heiko.carstens@de.ibm.com> |
x86: remove this_cpu_xor() implementation
Remove the unused x86 implementation of this_cpu_xor().
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| d55c5a93db2d5fa95f233ab153f594365d95b777 |
|
28-Nov-2012 |
H. Peter Anvin <hpa@linux.intel.com> |
x86, 386 removal: Remove CONFIG_CMPXCHG
All 486+ CPUs support CMPXCHG, so remove the fallback 386 support
code.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1354132230-21854-3-git-send-email-hpa@linux.intel.com
|
| c35f77417ebfc7c21c02aa9c8c30aa4cecf331d6 |
|
10-Jun-2012 |
Ido Yariv <ido@wizery.com> |
x86: Define early read-mostly per-cpu macros
Some read-mostly per-cpu data may need to be declared or defined
early, so it can be initialized and accessed before per_cpu
areas are allocated.
Only the data that resides in the per_cpu areas should be
read-mostly, as there is little benefit in optimizing cache
lines on initialization.
Signed-off-by: Ido Yariv <ido@wizery.com>
[ Added the missing declarations in !SMP code. ]
Signed-off-by: Vlad Zolotarov <vlad@scalemp.com>
Acked-by: Shai Fultheim <shai@scalemp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/46188571.ddB8aVQYWo@vlad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
| 641b695c2f11397bd307ea689d4d3f128360ce49 |
|
14-May-2012 |
Alex Shi <alex.shi@intel.com> |
percpu: remove percpu_xxx() functions
Remove percpu_xxx serial functions, all of them were replaced by
this_cpu_xxx or __this_cpu_xxx serial functions
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| c6ae41e7d469f00d9c92a2b2887c7235d121c009 |
|
11-May-2012 |
Alex Shi <alex.shi@intel.com> |
x86: replace percpu_xxx funcs with this_cpu_xxx
Since percpu_xxx() serial functions are duplicated with this_cpu_xxx().
Removing percpu_xxx() definition and replacing them by this_cpu_xxx()
in code. There is no function change in this patch, just preparation for
later percpu_xxx serial function removing.
On x86 machine the this_cpu_xxx() serial functions are same as
__this_cpu_xxx() without no unnecessary premmpt enable/disable.
Thanks for Stephen Rothwell, he found and fixed a i386 build error in
the patch.
Also thanks for Andrew Morton, he kept updating the patchset in Linus'
tree.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 933393f58fef9963eac61db8093689544e29a600 |
|
22-Dec-2011 |
Christoph Lameter <cl@linux.com> |
percpu: Remove irqsafe_cpu_xxx variants
We simply say that regular this_cpu use must be safe regardless of
preemption and interrupt state. That has no material change for x86
and s390 implementations of this_cpu operations. However, arches that
do not provide their own implementation for this_cpu operations will
now get code generated that disables interrupts instead of preemption.
-tj: This is part of on-going percpu API cleanup. For detailed
discussion of the subject, please refer to the following thread.
http://thread.gmane.org/gmane.linux.kernel/1222078
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <alpine.DEB.2.00.1112221154380.11787@router.home>
|
| cebef5beed3de3037de85a521495897256b2c5da |
|
14-Dec-2011 |
Jan Beulich <JBeulich@suse.com> |
x86: Fix and improve percpu_cmpxchg{8,16}b_double()
They had several problems/shortcomings:
Only the first memory operand was mentioned in the 2x32bit asm()
operands, and 2x64-bit version had a memory clobber. The first
allowed the compiler to not recognize the need to re-load the
data in case it had it cached in some register, and the second
was overly destructive.
The memory operand in the 2x32-bit asm() was declared to only be
an output.
The types of the local copies of the old and new values were
incorrect (as in other per-CPU ops, the types of the per-CPU
variables accessed should be used here, to make sure the
respective types are compatible).
The __dummy variable was pointless (and needlessly initialized
in the 2x32-bit case), given that local copies of the inputs
already exist.
The 2x64-bit variant forced the address of the first object into
%rsi, even though this is needed only for the call to the
emulation function. The real cmpxchg16b can operate on an
memory.
At once also change the return value type to what it really is -
'bool'.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4EE86D6502000078000679FE@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 688d3be815b1563b1484ce67702249a4a7a6314e |
|
12-Jul-2011 |
Christoph Lameter <cl@linux.com> |
percpu: Fixup __this_cpu_xchg* operations
Somehow we got into a situation where the __this_cpu_xchg() operations were
not defined in the same way as this_cpu_xchg() and friends. I had some build
failures under 32 bit that were addressed by these fixes.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| b1e7734f024c9ce4393016a97c8d821e1f18d9b4 |
|
19-Apr-2011 |
H. Peter Anvin <hpa@linux.intel.com> |
x86, percpu: Use ASM_NOP4 instead of hardcoding P6_NOP4
For use in assembly constants, use the ASM_NOP* defines.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1303166160-10315-2-git-send-email-hpa@linux.intel.com
|
| 349c004e3d31fda23ad225b61861be38047fff16 |
|
12-Mar-2011 |
Christoph Lameter <cl@linux.com> |
x86: A fast way to check capabilities of the current cpu
Add this_cpu_has() which determines if the current cpu has a certain
ability using a segment prefix and a bit test operation.
For that we need to add bit operations to x86s percpu.h.
Many uses of cpu_has use a pointer passed to a function to determine
the current flags. That is no longer necessary after this patch.
However, this patch only converts the straightforward cases where
cpu_has is used with this_cpu_ptr. The rest is work for later.
-tj: Rolled up patch to add x86_ prefix and use percpu_read() instead
of percpu_read_stable().
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 5f55924deaa62d6df687c131fb92aebe071ec787 |
|
28-Mar-2011 |
Eric Dumazet <eric.dumazet@gmail.com> |
percpu: Avoid extra NOP in percpu_cmpxchg16b_double
percpu_cmpxchg16b_double() uses alternative_io() and looks like :
e8 .. .. .. .. call this_cpu_cmpxchg16b_emu
X bytes NOPX
or, once patched (if cpu supports native instruction) on SMP build :
65 48 0f c7 0e cmpxchg16b %gs:(%rsi)
0f 94 c0 sete %al
on !SMP build :
48 0f c7 0e cmpxchg16b (%rsi)
0f 94 c0 sete %al
Therefore, NOPX should be :
P6_NOP3 on SMP
P6_NOP2 on !SMP
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| d7c3f8cee81f4548de0513403b74131aee655576 |
|
27-Mar-2011 |
Christoph Lameter <cl@linux.com> |
percpu: Omit segment prefix in the UP case for cmpxchg_double
Omit the segment prefix in the UP case. GS is not used then
and we will generate segfaults if cmpxchg16b is used otherwise.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
| b9ec40af0e18fb7d02106be148036c2ea490fdf9 |
|
28-Feb-2011 |
Christoph Lameter <cl@linux.com> |
percpu, x86: Add arch-specific this_cpu_cmpxchg_double() support
Support this_cpu_cmpxchg_double() using the cmpxchg16b and cmpxchg8b
instructions.
-tj: s/percpu_cmpxchg16b/percpu_cmpxchg16b_double/ for consistency and
other cosmetic changes.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 889a7a6a5d5e64063effd40056bdc7b8fb336bd1 |
|
25-Jan-2011 |
Eric Dumazet <eric.dumazet@gmail.com> |
percpu, x86: Fix percpu_xchg_op()
These recent percpu commits:
2485b6464cf8: x86,percpu: Move out of place 64 bit ops into X86_64 section
8270137a0d50: cpuops: Use cmpxchg for xchg to avoid lock semantics
Caused this 'perf top' crash:
Kernel panic - not syncing: Fatal exception in interrupt
Pid: 0, comm: swapper Tainted: G D
2.6.38-rc2-00181-gef71723 #413 Call Trace: <IRQ> [<ffffffff810465b5>]
? panic
? kmsg_dump
? kmsg_dump
? oops_end
? no_context
? __bad_area_nosemaphore
? perf_output_begin
? bad_area_nosemaphore
? do_page_fault
? __task_pid_nr_ns
? perf_event_tid
? __perf_event_header__init_id
? validate_chain
? perf_output_sample
? trace_hardirqs_off
? page_fault
? irq_work_run
? update_process_times
? tick_sched_timer
? tick_sched_timer
? __run_hrtimer
? hrtimer_interrupt
? account_system_vtime
? smp_apic_timer_interrupt
? apic_timer_interrupt
...
Looking at assembly code, I found:
list = this_cpu_xchg(irq_work_list, NULL);
gives this wrong code : (gcc-4.1.2 cross compiler)
ffffffff810bc45e:
mov %gs:0xead0,%rax
cmpxchg %rax,%gs:0xead0
jne ffffffff810bc45e <irq_work_run+0x3e>
test %rax,%rax
je ffffffff810bc4aa <irq_work_run+0x8a>
Tell gcc we dirty eax/rax register in percpu_xchg_op()
Compiler must use another register to store pxo_new__
We also dont need to reload percpu value after a jump,
since a 'failed' cmpxchg already updated eax/rax
Wrong generated code was :
xor %rax,%rax /* load 0 into %rax */
1: mov %gs:0xead0,%rax
cmpxchg %rax,%gs:0xead0
jne 1b
test %rax,%rax
After patch :
xor %rdx,%rdx /* load 0 into %rdx */
mov %gs:0xead0,%rax
1: cmpxchg %rdx,%gs:0xead0
jne 1b:
test %rax,%rax
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <1295973114.3588.312.camel@edumazet-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 2485b6464cf86a5bc361666838f2439c99c00567 |
|
11-Jan-2011 |
Christoph Lameter <cl@linux.com> |
x86,percpu: Move out of place 64 bit ops into X86_64 section
Some operations that operate on 64 bit operands are defined for 32 bit.
Move them into the correct section.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 8270137a0d50507a5b40f880db636527045b8466 |
|
14-Dec-2010 |
Christoph Lameter <cl@linux.com> |
cpuops: Use cmpxchg for xchg to avoid lock semantics
Use cmpxchg instead of xchg to realize this_cpu_xchg.
xchg will cause LOCK overhead since LOCK is always implied but cmpxchg
will not.
Baselines:
xchg() = 18 cycles (no segment prefix, LOCK semantics)
__this_cpu_xchg = 1 cycle
(simulated using this_cpu_read/write, two prefixes. Looks like the
cpu can use loop optimization to get rid of most of the overhead)
Cycles before:
this_cpu_xchg = 37 cycles (segment prefix and LOCK (implied by xchg))
After:
this_cpu_xchg = 11 cycle (using cmpxchg without lock semantics)
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 7296e08abac0a22a2534a4f6e493c764f2c77583 |
|
14-Dec-2010 |
Christoph Lameter <cl@linux.com> |
x86: this_cpu_cmpxchg and this_cpu_xchg operations
Provide support as far as the hardware capabilities of the x86 cpus
allow.
Define CONFIG_CMPXCHG_LOCAL in Kconfig.cpu to allow core code to test for
fast cpuops implementations.
V1->V2:
- Take out the definition for this_cpu_cmpxchg_8 and move it into
a separate patch.
tj: - Reordered ops to better follow this_cpu_* organization.
- Renamed macro temp variables similar to their existing
neighbours.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 403047754cf690b012369b8fb563b738b88086e6 |
|
17-Dec-2010 |
Tejun Heo <tj@kernel.org> |
percpu,x86: relocate this_cpu_add_return() and friends
- include/linux/percpu.h: this_cpu_add_return() and friends were
located next to __this_cpu_add_return(). However, the overall
organization is to first group by preemption safeness. Relocate
this_cpu_add_return() and friends to preemption-safe area.
- arch/x86/include/asm/percpu.h: Relocate percpu_add_return_op() after
other more basic operations. Relocate [__]this_cpu_add_return_8()
so that they're first grouped by preemption safeness.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
|
| 8f1d97c79eb65de1d05799d6b81d79cd94169114 |
|
06-Dec-2010 |
Christoph Lameter <cl@linux.com> |
x86: Support for this_cpu_add, sub, dec, inc_return
Supply an implementation for x86 in order to generate more efficient code.
V2->V3:
- Cleanup
- Remove strange type checking from percpu_add_return_op.
tj: - Dropped unused typedef from percpu_add_return_op().
- Renamed ret__ to paro_ret__ in percpu_add_return_op().
- Minor indentation adjustments.
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| db7829c6cc32f3c0c9a324118d743acb1abff081 |
|
09-Sep-2010 |
Brian Gerst <brgerst@gmail.com> |
x86, percpu: Optimize this_cpu_ptr
Allow arches to implement __this_cpu_ptr, and provide an x86 version.
Before:
movq $foo, %rax
movq %gs:this_cpu_off, %rdx
addq %rdx, %rax
After:
movq $foo, %rax
addq %gs:this_cpu_off, %rax
The benefit is doing it in one less instruction and not clobbering
a temporary register.
tj: * Beefed up the comment a bit and renamed in-macro temp variable
to match neighboring macros.
* Folded fix for const pointer case found in linux-next.
* Fixed sparse notation.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 23b764d056bfec0a212a67229074ac281e86e021 |
|
10-Jun-2010 |
Andi Kleen <andi@firstfloor.org> |
percpu, x86: Avoid warnings of unused variables in per cpu
Avoid hundreds of warnings with a gcc 4.6 -Wall build.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 402af0d7c692ddcfa2333e93d3f275ebd0487926 |
|
21-Apr-2010 |
Jan Beulich <JBeulich@novell.com> |
x86, asm: Introduce and use percpu_inc()
... generating slightly smaller code.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4BCF261F020000780003B33C@vpn.id2.novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
|
| 40f0a5d0a16e68a68ab3d230f1ddd96c81cf5340 |
|
19-Apr-2010 |
Justin P. Mattock <justinmattock@gmail.com> |
Fix comment typo in percpu.h
Fix a typo in arch/x86/include/asm/percpu.h
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
|
| 5917dae83cb02dfe74c9167b79e86e6d65183fa3 |
|
05-Jan-2010 |
Christoph Lameter <cl@linux-foundation.org> |
percpu, x86: Generic inc / dec percpu instructions
Optimize code generated for percpu access by checking for increment and
decrements.
tj: fix incorrect usage of __builtin_constant_p() and restructure
percpu_add_op() macro.
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| dd17c8f72993f9461e9c19250e3f155d6d99df22 |
|
29-Oct-2009 |
Rusty Russell <rusty@rustcorp.com.au> |
percpu: remove per_cpu__ prefix.
Now that the return from alloc_percpu is compatible with the address
of per-cpu vars, it makes sense to hand around the address of per-cpu
variables. To make this sane, we remove the per_cpu__ prefix we used
created to stop people accidentally using these vars directly.
Now we have sparse, we can use that (next patch).
tj: * Updated to convert stuff which were missed by or added after the
original patch.
* Kill per_cpu_var() macro.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
|
| 0f5e4816dbf38ce9488e611ca2296925c1e90d5e |
|
29-Oct-2009 |
Tejun Heo <tj@kernel.org> |
percpu: remove some sparse warnings
Make the following changes to remove some sparse warnings.
* Make DEFINE_PER_CPU_SECTION() declare __pcpu_unique_* before
defining it.
* Annotate pcpu_extend_area_map() that it is entered with pcpu_lock
held, releases it and then reacquires it.
* Make percpu related macros use unique nested variable names.
* While at it, add pcpu prefix to __size_call[_return]() macros as
to-be-implemented sparse annotations will add percpu specific stuff
to these macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
|
| 30ed1a79f5bf271d33e782afee3323582dcc621e |
|
03-Oct-2009 |
Christoph Lameter <cl@linux-foundation.org> |
this_cpu: Implement X86 optimized this_cpu operations
Basically the existing percpu ops can be used for this_cpu variants that allow
operations also on dynamically allocated percpu data. However, we do not pass a
reference to a percpu variable in. Instead a dynamically or statically
allocated percpu variable is provided.
Preempt, the non preempt and the irqsafe operations generate the same code.
It will always be possible to have the requires per cpu atomicness in a single
RMW instruction with segment override on x86.
64 bit this_cpu operations are not supported on 32 bit.
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| ed8d9adf357ec331603fa1049510399812cea7e5 |
|
03-Aug-2009 |
Linus Torvalds <torvalds@linux-foundation.org> |
x86, percpu: Add 'percpu_read_stable()' interface for cacheable accesses
This is very useful for some common things like 'get_current()' and
'get_thread_info()', which can be used multiple times in a function, and
where the result is cacheable.
tj: Added the magical undocumented "P" modifier to UP __percpu_arg()
to force gcc to dereference the pointer value passed in via the
"p" input constraint. Without this, percpu_read_stable() returns
the address of the percpu variable. Also added comment explaining
the difference between percpu_read() and percpu_read_stable().
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
|
| 8c4bfc6e8801616ab2e01c38140b2159b388d2ff |
|
04-Jul-2009 |
Tejun Heo <tj@kernel.org> |
x86,percpu: generalize lpage first chunk allocator
Generalize and move x86 setup_pcpu_lpage() into
pcpu_lpage_first_chunk(). setup_pcpu_lpage() now is a simple wrapper
around the generalized version. Other than taking size parameters and
using arch supplied callbacks to allocate/free/map memory,
pcpu_lpage_first_chunk() is identical to the original implementation.
This simplifies arch code and will help converting more archs to
dynamic percpu allocator.
While at it, factor out pcpu_calc_fc_sizes() which is common to
pcpu_embed_first_chunk() and pcpu_lpage_first_chunk().
[ Impact: code reorganization and generalization ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
|
| e59a1bb2fdfb745c685f5b40ffbed126331d3223 |
|
22-Jun-2009 |
Tejun Heo <tj@kernel.org> |
x86: fix pageattr handling for lpage percpu allocator and re-enable it
lpage allocator aliases a PMD page for each cpu and returns whatever
is unused to the page allocator. When the pageattr of the recycled
pages are changed, this makes the two aliases point to the overlapping
regions with different attributes which isn't allowed and known to
cause subtle data corruption in certain cases.
This can be handled in simliar manner to the x86_64 highmap alias.
pageattr code should detect if the target pages have PMD alias and
split the PMD alias and synchronize the attributes.
pcpur allocator is updated to keep the allocated PMD pages map sorted
in ascending address order and provide pcpu_lpage_remapped() function
which binary searches the array to determine whether the given address
is aliased and if so to which address. pageattr is updated to use
pcpu_lpage_remapped() to detect the PMD alias and split it up as
necessary from cpa_process_alias().
Jan Beulich spotted the original problem and incorrect usage of vaddr
instead of laddr for lookup.
With this, lpage percpu allocator should work correctly. Re-enable
it.
[ Impact: fix subtle lpage pageattr bug and re-enable lpage ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
|
| 3c598766a2bae1b208470e7cc934ac462561e3cb |
|
11-May-2009 |
Jan Beulich <JBeulich@novell.com> |
x86: fix percpu_{to,from}_op()
- the byte operand constraints were wrong for 32-bit
- the to-op's input operands weren't properly parenthesized
[ Impact: fix possible miscompilation or build failure ]
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
|
| e01009833e22dc87075d770554b34d797843ed23 |
|
10-Mar-2009 |
Tejun Heo <tj@kernel.org> |
percpu: make x86 addr <-> pcpu ptr conversion macros generic
Impact: generic addr <-> pcpu ptr conversion macros
There's nothing arch specific about x86 __addr_to_pcpu_ptr() and
__pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start
defined, they'll do the right thing regardless of actual layout.
Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c
and allow archs to override it as necessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 11124411aa95827404d6bfdfc14c908e1b54513c |
|
20-Feb-2009 |
Tejun Heo <tj@kernel.org> |
x86: convert to the new dynamic percpu allocator
Impact: use new dynamic allocator, unified access to static/dynamic
percpu memory
Convert to the new dynamic percpu allocator.
* implement populate_extra_pte() for both 32 and 64
* update setup_per_cpu_areas() to use pcpu_setup_static()
* define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr()
* define config HAVE_DYNAMIC_PER_CPU_AREA
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 2add8e235cbe0dcd672c33fc322754e15500238c |
|
08-Feb-2009 |
Brian Gerst <brgerst@gmail.com> |
x86: use linker to offset symbols by __per_cpu_load
Impact: cleanup and bug fix
Use the linker to create symbols for certain per-cpu variables
that are offset by __per_cpu_load. This allows the removal of
the runtime fixup of the GDT pointer, which fixes a bug with
resume reported by Jiri Slaby.
Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 299e26992a737804e13e74fdb97cdab470ed19ac |
|
21-Jan-2009 |
Brian Gerst <brgerst@gmail.com> |
x86: fix percpu_write with 64-bit constants
Impact: slightly better code generation for percpu_to_op()
The processor will sign-extend 32-bit immediate values in 64-bit
operations. Use the 'e' constraint ("32-bit signed integer constant,
or a symbolic reference known to fit that range") for 64-bit constants.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 947e76cdc34c782fc947313d4331380686eebbad |
|
18-Jan-2009 |
Brian Gerst <brgerst@gmail.com> |
x86: move stack_canary into irq_stack
Impact: x86_64 percpu area layout change, irq_stack now at the beginning
Now that the PDA is empty except for the stack canary, it can be removed.
The irqstack is moved to the start of the per-cpu section. If the stack
protector is enabled, the canary overlaps the bottom 48 bytes of the irqstack.
tj: * updated subject
* dropped asm relocation of irq_stack_ptr
* updated comments a bit
* rebased on top of stack canary changes
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 87b264065880fa696c121dad8498a60524e0f6de |
|
18-Jan-2009 |
Brian Gerst <brgerst@gmail.com> |
x86-64: Use absolute displacements for per-cpu accesses.
Accessing memory through %gs should not use rip-relative addressing.
Adding a P prefix for the argument tells gcc to not add (%rip) to
the memory references.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 6dbde3530850d4d8bfc1b6bd4006d92786a2787f |
|
15-Jan-2009 |
Ingo Molnar <mingo@elte.hu> |
percpu: add optimized generic percpu accessors
It is an optimization and a cleanup, and adds the following new
generic percpu methods:
percpu_read()
percpu_write()
percpu_add()
percpu_sub()
percpu_and()
percpu_or()
percpu_xor()
and implements support for them on x86. (other architectures will fall
back to a default implementation)
The advantage is that for example to read a local percpu variable,
instead of this sequence:
return __get_cpu_var(var);
ffffffff8102ca2b: 48 8b 14 fd 80 09 74 mov -0x7e8bf680(,%rdi,8),%rdx
ffffffff8102ca32: 81
ffffffff8102ca33: 48 c7 c0 d8 59 00 00 mov $0x59d8,%rax
ffffffff8102ca3a: 48 8b 04 10 mov (%rax,%rdx,1),%rax
We can get a single instruction by using the optimized variants:
return percpu_read(var);
ffffffff8102ca3f: 65 48 8b 05 91 8f fd mov %gs:0x7efd8f91(%rip),%rax
I also cleaned up the x86-specific APIs and made the x86 code use
these new generic percpu primitives.
tj: * fixed generic percpu_sub() definition as Roel Kluin pointed out
* added percpu_and() for completeness's sake
* made generic percpu ops atomic against preemption
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
| 49357d19e4fb31e28796eaff83499e7584c26878 |
|
13-Jan-2009 |
Tejun Heo <tj@kernel.org> |
x86: convert pda ops to wrappers around x86 percpu accessors
pda is now a percpu variable and there's no reason it can't use plain
x86 percpu accessors. Add x86_test_and_clear_bit_percpu() and replace
pda op implementations with wrappers around x86 percpu accessors.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 9939ddaff52787b2a7c1adf1b2afc95421aa0884 |
|
13-Jan-2009 |
Tejun Heo <tj@kernel.org> |
x86: merge 64 and 32 SMP percpu handling
Now that pda is allocated as part of percpu, percpu doesn't need to be
accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP
one. Other than the segment register, operand size and the base of
percpu symbols, they behave identical now.
This patch replaces now unnecessary pda->data_offset with a dummy
field which is necessary to keep stack_canary at its place. This
patch also moves per_cpu_offset initialization out of init_gdt() into
setup_per_cpu_areas(). Note that this change also necessitates
explicit per_cpu_offset initializations in voyager_smp.c.
With this change, x86_OP_percpu()'s are as efficient on x86_64 as on
x86_32 and also x86_64 can use assembly PER_CPU macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 1a51e3a0aed18767cf2762e95456ecfeb0bca5e6 |
|
13-Jan-2009 |
Tejun Heo <tj@kernel.org> |
x86: fold pda into percpu area on SMP
[ Based on original patch from Christoph Lameter and Mike Travis. ]
Currently pdas and percpu areas are allocated separately. %gs points
to local pda and percpu area can be reached using pda->data_offset.
This patch folds pda into percpu area.
Due to strange gcc requirement, pda needs to be at the beginning of
the percpu area so that pda->stack_canary is at %gs:40. To achieve
this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is
added and used to reserve pda sized chunk at the start of the percpu
area.
After this change, for boot cpu, %gs first points to pda in the
data.init area and later during setup_per_cpu_areas() gets updated to
point to the actual pda. This means that setup_per_cpu_areas() need
to reload %gs for CPU0 while clearing pda area for other cpus as cpu0
already has modified it when control reaches setup_per_cpu_areas().
This patch also removes now unnecessary get_local_pda() and its call
sites.
A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into
per cpu area" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| f10fcd47120e80f66665567dbe17f5071c7aef52 |
|
13-Jan-2009 |
Tejun Heo <tj@kernel.org> |
x86: make early_per_cpu() a lvalue and use it
Make early_per_cpu() a lvalue as per_cpu() is and use it where
applicable.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 1965aae3c98397aad957412413c07e97b1bd4e64 |
|
23-Oct-2008 |
H. Peter Anvin <hpa@zytor.com> |
x86: Fix ASM_X86__ header guards
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:
a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
|
| bb8985586b7a906e116db835c64773b7a7d51663 |
|
18-Aug-2008 |
Al Viro <viro@zeniv.linux.org.uk> |
x86, um: ... and asm-x86 move
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
|