If oprofilefs_ulong_from_user() is called with count equals
zero, *val remains unchanged. Depending on the implementation it
might be uninitialized.
Change oprofilefs_ulong_from_user()'s interface to return count
on success. Thus, we are able to return early if count equals
zero which avoids using *val uninitialized. Fixing all users of
oprofilefs_ulong_ from_user().
This follows write syscall implementation when count is zero:
"If count is zero ... [and if] no errors are detected, 0 will be
returned without causing any other effect." (man 2 write)
Reported-By: Mike Waychison <mikew@google.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The i.MX6 Quad SoC will work without the l2x0 L2 cache controller
support built into the kernel, so this patch removes the dependency
on CACHE_L2X0.
This makes the l2x0 support optional, so that it can be turned off
when desired for debugging purposes etc.
Since SOC_IMX6Q already depends on ARCH_IMX_V6_V7 and
ARCH_IMX_V6_V7 selects MIGHT_HAVE_CACHE_L2X0, there is no need to
select that option explicitly from SOC_IMX6Q.
Thanks to Shawn Guo for this suggestion. [1]
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074602.html
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
If running in the Normal World on a TrustZone-enabled SoC, Linux
does not have complete control over the L2 cache controller
configuration. The kernel cannot work reliably on such platforms
without the l2x0 cache support code built in.
This patch unconditionally enables l2x0 support for the Highbank
SoC.
Thanks to Rob Herring for this suggestion. [1]
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074495.html
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
If running in the Normal World on a TrustZone-enabled SoC, Linux
does not have complete control over the L2 cache controller
configuration. The kernel cannot work reliably on such platforms
without the l2x0 cache support code built in.
This patch unconditionally enables l2x0 support for the OMAP4 SoCs.
Thanks to Rob Herring for this suggestion. [1]
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074495.html
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Making SMP depend on (huge list of MACH_ and ARCH_ configs) is
bothersome to maintain and likely to lead to merge conflicts.
This patch moves the knowledge of which platforms are SMP-capable
to the individual machines. To enable this, a new HAVE_SMP config
option is introduced to allow machines to indicate that they can
run in a SMP configuration.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
(for nomadik, ux500)
Acked-by: Tony Lindgren <tony@atomide.com>
(for omap)
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
(for exynos)
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
(for imx)
Acked-by: Olof Johansson <olof@lixom.net>
(for tegra)
Making CACHE_L2X0 depend on (huge list of MACH_ and ARCH_ configs)
is bothersome to maintain and likely to lead to merge conflicts.
This patch moves the knowledge of which platforms have a L2x0 or
PL310 cache controller to the individual machines. To enable this,
a new MIGHT_HAVE_CACHE_L2X0 config option is introduced to allow
machines to indicate that they may have such a cache controller
independently of each other.
Boards/SoCs which cannot reliably operate without the L2 cache
controller support will need to select CACHE_L2X0 directly from
their own Kconfigs instead. This applies to some TrustZone-enabled
boards where Linux runs in the Normal World, for example.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
(for cns3xxx)
Acked-by: Tony Lindgren <tony@atomide.com>
(for omap)
Acked-by: Shawn Guo <shawn.guo@linaro.org>
(for imx)
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
(for exynos)
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
(for imx)
Acked-by: Olof Johansson <olof@lixom.net>
(for tegra)
in 0d6cfa3a75 I fixed the mach-types
records. We also need to make the name consistent in Kconfig else
the machine_is_eukrea_cpuimx35sd macro fails, and thus audio codec
is not properly initalized.
Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
commit 8d75a26 "ARM: mx35: use generic function for displaying silicon revision"
disabled IIM clock after reading silicon revision which will prevent
reboot in internal boot mode.
Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Jason Liu <jason.hui@linaro.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
in 0d6cfa3a75 I fixed the mach-types
records. We also need to make the name consistent in Kconfig else
the machine_is_eukrea_cpuimx25sd macro fails, and thus audio codec
is not properly initalized.
Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
WARNING: arch/arm/plat-mxc/built-in.o(.data+0x488): Section mismatch in reference from the variable mxc_driver to the function .init.text:mxc_cpufreq_init()
The variable mxc_driver references
the function __init mxc_cpufreq_init()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
According to imx pwm RM, the real period value should be
PERIOD value in PWMPR plus 2.
PWMO (Hz) = PCLK(Hz) / (period +2)
Signed-off-by: Jason Chen <jason.chen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: stable@kernel.org
As the kernels and initrd's get bigger boot-loaders and possibly
kexec-tools will need to place the initrd outside the RMO. When this
happens we end up with no lowmem and the boot doesn't get very far.
Only use initrd_end as the limit for alloc_bottom if it's inside the
RMO.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We support 16TB of user address space and half a million contexts
so update the comment to reflect this.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Commit d57af9b (taskstats: use real microsecond granularity for CPU times)
renamed msecs_to_cputime to usecs_to_cputime, but failed to update all
numbers on the way. This causes nonsensical cpu idle/iowait values to be
displayed in /proc/stat (the only user of usecs_to_cputime so far).
This also renames __cputime_msec_factor to __cputime_usec_factor, adapting
its value and using it directly in cputime_to_usecs instead of doing two
multiplications.
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
read_n_cells() cannot be marked as .devinit.text since it is referenced
from two functions that are not in that section: of_get_lmb_size() and
hot_add_drconf_scn_to_nid().
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
mark_reserved_regions_for_nid() is only called from do_init_bootmem(),
which is in .init.text, so it must be in the same section to avoid a
section mismatch warning.
Reported-by: Subrata Modak <subrata@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
PPC64 uses long long for u64 in the kernel, but powerpc's asm/types.h
prevents 64-bit userland from seeing this definition, instead defaulting
to u64 == long in userspace. Some user programs (e.g. kvmtool) may actually
want LL64, so this patch adds a check for __SANE_USERSPACE_TYPES__ so that,
if defined, int-ll64.h is included instead.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Implement a POWER7 optimised copy_to_user/copy_from_user using VMX.
For large aligned copies this new loop is over 10% faster, and for
large unaligned copies it is over 200% faster.
If we take a fault we fall back to the old version, this keeps
things relatively simple and easy to verify.
On POWER7 unaligned stores rarely slow down - they only flush when
a store crosses a 4KB page boundary. Furthermore this flush is
handled completely in hardware and should be 20-30 cycles.
Unaligned loads on the other hand flush much more often - whenever
crossing a 128 byte cache line, or a 32 byte sector if either sector
is an L1 miss.
Considering this information we really want to get the loads aligned
and not worry about the alignment of the stores. Microbenchmarks
confirm that this approach is much faster than the current unaligned
copy loop that uses shifts and rotates to ensure both loads and
stores are aligned.
We also want to try and do the stores in cacheline aligned, cacheline
sized chunks. If the store queue is unable to merge an entire
cacheline of stores then the L2 cache will have to do a
read/modify/write. Even worse, we will serialise this with the stores
in the next iteration of the copy loop since both iterations hit
the same cacheline.
Based on this, the new loop does the following things:
1 - 127 bytes
Get the source 8 byte aligned and use 8 byte loads and stores. Pretty
boring and similar to how the current loop works.
128 - 4095 bytes
Get the source 8 byte aligned and use 8 byte loads and stores,
1 cacheline at a time. We aren't doing the stores in cacheline
aligned chunks so we will potentially serialise once per cacheline.
Even so it is much better than the loop we have today.
4096 - bytes
If both source and destination have the same alignment get them both
16 byte aligned, then get the destination cacheline aligned. Do
cacheline sized loads and stores using VMX.
If source and destination do not have the same alignment, we get the
destination cacheline aligned, and use permute to do aligned loads.
In both cases the VMX loop should be optimal - we always do aligned
loads and stores and are always doing stores in cacheline aligned,
cacheline sized chunks.
To be able to use VMX we must be careful about interrupts and
sleeping. We don't use the VMX loop when in an interrupt (which should
be rare anyway) and we wrap the VMX loop in disable/enable_pagefault
and fall back to the existing copy_tofrom_user loop if we do need to
sleep.
The VMX breakpoint of 4096 bytes was chosen using this microbenchmark:
http://ozlabs.org/~anton/junkcode/copy_to_user.c
Since we are using VMX and there is a cost to saving and restoring
the user VMX state there are two broad cases we need to benchmark:
- Best case - userspace never uses VMX
- Worst case - userspace always uses VMX
In reality a userspace process will sit somewhere between these two
extremes. Since we need to test both aligned and unaligned copies we
end up with 4 combinations. The point at which the VMX loop begins to
win is:
0% VMX
aligned 2048 bytes
unaligned 2048 bytes
100% VMX
aligned 16384 bytes
unaligned 8192 bytes
Considering this is a microbenchmark, the data is hot in cache and
the VMX loop has better store queue merging properties we set the
breakpoint to 4096 bytes, a little below the unaligned breakpoints.
Some future optimisations we can look at:
- Looking at the perf data, a significant part of the cost when a
task is always using VMX is the extra exception we take to restore
the VMX state. As such we should do something similar to the x86
optimisation that restores FPU state for heavy users. ie:
/*
* If the task has used fpu the last 5 timeslices, just do a full
* restore of the math state immediately to avoid the trap; the
* chances of needing FPU soon are obviously high now
*/
preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5;
and
/*
* fpu_counter contains the number of consecutive context switches
* that the FPU is used. If this is over a threshold, the lazy fpu
* saving becomes unlazy to save the trap. This is an unsigned char
* so that after 256 times the counter wraps and the behavior turns
* lazy again; this to deal with bursty apps that only use FPU for
* a short time
*/
- We could create a paca bit to mirror the VMX enabled MSR bit and check
that first, avoiding multiple calls to calling enable_kernel_altivec.
That should help with iovec based system calls like readv.
- We could have two VMX breakpoints, one for when we know the user VMX
state is loaded into the registers and one when it isn't. This could
be a second bit in the paca so we can calculate the break points quickly.
- One suggestion from Ben was to save and restore the VSX registers
we use inline instead of using enable_kernel_altivec.
[BenH: Fixed a problem with preempt and fixed build without CONFIG_ALTIVEC]
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The overlapping iotable mapping entries for the ux500 Cortex
A9 SCU, CPU control and TWD are no longer accepted by the
kernel. Remove the overlaps so the machine boots again.
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Rabin Vincent <rabin.vincent@stericsson.com>
Reported-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
sched_clock() is yet another blocker on the road to the single
image. This patch implements an idea by Russell King:
http://www.spinics.net/lists/linux-omap/msg49561.html
Instead of asking the platform to implement both sched_clock()
itself and the rollover callback, simply register a read()
function, and let the ARM code care about sched_clock() itself,
the conversion to ns and the rollover. sched_clock() uses
this read() function as an indirection to the platform code.
If the platform doesn't provide a read(), the code falls back
to the jiffy counter (just like the default sched_clock).
This allow some simplifications and possibly some footprint gain
when multiple platforms are compiled in. Among the drawbacks,
the removal of the *_fixed_sched_clock optimization which could
negatively impact some platforms (sa1100, tegra, versatile
and omap).
Tested on 11MPCore, OMAP4 and Tegra.
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Cc: STEricsson <STEricsson_nomadik_linux@list.st.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Tested-by: Jamie Iles <jamie@jamieiles.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
LAPIC related statistics are grouped inside the per-cpu
structure irq_stat, so there is no need for icr_read_retry_count
to be a standalone per-cpu variable.
This patch moves icr_read_retry_count to where it belongs.
Suggested-y: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Cc: Jörn Engel <joern@logfs.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
gcc noticed (when using -Wempty-body) that our use of
lock_cmos() and unlock_cmos() in
arch/x86/include/asm/mach_traps.h is potentially problematic :
arch/x86/include/asm/mach_traps.h:32:15: warning: suggest braces around empty body in an ¡else¢ statement [-Wempty-body]
arch/x86/include/asm/mach_traps.h:40:16: warning: suggest braces around empty body in an ¡else¢ statement [-Wempty-body]
Let's just use the standard 'do {} while (0)' solution. That
shuts up gcc and also prevents future problems if the macros
should end up being used in a similar situation elsewhere.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1112180103130.21784@swampdragon.chaosbits.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If one builds the kernel with -Wempty-body one gets this
warning:
mm/memory.c:3432:46: warning: suggest braces around empty body in an ¡if¢ statement [-Wempty-body]
due to the fact that 'flush_tlb_fix_spurious_fault' is a macro
that can sometimes be defined to nothing.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-mm@kvack.org
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1112180128070.21784@swampdragon.chaosbits.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
sparc32: Be less strict in matching %lo part of relocation.
sbus: convert drivers/sbus/char/* to use module_platform_driver()
bbc_i2c: Remove unneeded err variable
sparc: Use kmemdup rather than duplicating its implementation
mce-inject provides a mechanism to simulate errors so that test
scripts can check for correct operation of the kernel without
requiring any specialized hardware to create rare events.
The existing code can simulate events in normal process context
and also in NMI context - but not in IRQ context. This patch
fills that gap.
Link: https://lkml.org/lkml/2011/12/7/537
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
ARM: OMAP: rx51: fix USB
ARM: OMAP: mcbsp: Fix possible memory corruption
arm/imx: fix power button on imx51 babbage board
ARM: imx: fix cpufreq build errors
ARM: mx5: add __initconst for fec pdata
MXC PWM: should active during DOZE/WAIT/DBG mode
ARM: EXYNOS: Fix build error without CONFIG_LOCAL_TIMERS
ARM: EXYNOS: Fix for stall in case of cpu hotplug or sleep
ARM: S5PV210: Set 1000ns as PWM backlight period on SMDKV210
ARM: SAMSUNG: remove duplicated header include
Seems the commit 7e89098 was overly aggressive in adding iva and mailbox
hwmods so now they are registered twice.
------------[ cut here ]------------
WARNING: at arch/arm/mach-omap2/omap_hwmod.c:1959 omap_hwmod_register+0x104/0x12c()
omap_hwmod: iva: _register returned -22
Modules linked in:
[<c0012aa4>] (unwind_backtrace+0x0/0xec) from [<c002f970>] (warn_slowpath_common+0x4c/0x64)
[<c002f970>] (warn_slowpath_common+0x4c/0x64) from [<c002fa08>] (warn_slowpath_fmt+0x2c/0x3c)
[<c002fa08>] (warn_slowpath_fmt+0x2c/0x3c) from [<c02fdb4c>] (omap_hwmod_register+0x104/0x12c)
[<c02fdb4c>] (omap_hwmod_register+0x104/0x12c) from [<c02fbb44>] (omap3_init_early+0x1c/0x28)
[<c02fbb44>] (omap3_init_early+0x1c/0x28) from [<c02f9580>] (setup_arch+0x6b8/0x7a4)
[<c02f9580>] (setup_arch+0x6b8/0x7a4) from [<c02f754c>] (start_kernel+0x6c/0x264)
[<c02f754c>] (start_kernel+0x6c/0x264) from [<80008040>] (0x80008040)
---[ end trace 1b75b31a2719ed1c ]---
------------[ cut here ]------------
WARNING: at arch/arm/mach-omap2/omap_hwmod.c:1959 omap_hwmod_register+0x104/0x12c()
omap_hwmod: mailbox: _register returned -22
Modules linked in:
[<c0012aa4>] (unwind_backtrace+0x0/0xec) from [<c002f970>] (warn_slowpath_common+0x4c/0x64)
[<c002f970>] (warn_slowpath_common+0x4c/0x64) from [<c002fa08>] (warn_slowpath_fmt+0x2c/0x3c)
[<c002fa08>] (warn_slowpath_fmt+0x2c/0x3c) from [<c02fdb4c>] (omap_hwmod_register+0x104/0x12c)
[<c02fdb4c>] (omap_hwmod_register+0x104/0x12c) from [<c02fbb44>] (omap3_init_early+0x1c/0x28)
[<c02fbb44>] (omap3_init_early+0x1c/0x28) from [<c02f9580>] (setup_arch+0x6b8/0x7a4)
[<c02f9580>] (setup_arch+0x6b8/0x7a4) from [<c02f754c>] (start_kernel+0x6c/0x264)
[<c02f754c>] (start_kernel+0x6c/0x264) from [<80008040>] (0x80008040)
---[ end trace 1b75b31a2719ed1d ]---
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
As of commit dd472da38, rwsem.h was moved into asm-generic.
This patch removes the arch file and points the build at
its new location.
Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The code for "powersurge" SMP would kick in and cause a crash
at boot due to the lack of a NULL test.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In the old days, we treated all interrupts from the legacy Apple home made
interrupt controllers as level, with a trick reading the "level" register
along with the "event" register to work arounds bugs where it would
occasionally fail to latch some events.
Doing so appeared to work fine for both level and edge interrupts.
Later on, we discovered in Darwin source the magic masks that define which
interrupts are actually level and which are edge, and implemented a
different algorithm, more similar to what Apple does, that treats those
differently.
I recently discovered however that this caused problems (including loss
of interrupts) with an old Wallstreet PowerBook when trying to use the
internal modem (connected to a cascaded controller).
It looks like some interrupts are treated as edge while they are really
level and I'm starting to seriously doubt the correctness of the Darwin
code (which has other obvious bugs when you read it, so ...)
This patch reverts to our original behaviour of treating everything as
a level interrupt. It appears to solve the problems with the modem on
the Wallstreet and everything else seems to be working properly as well.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
fls(N), ffs(N) and fls64(N) can be optimised on x86_64. Currently they use a
CMOV instruction after the BSR/BSF to set the destination register to -1 if the
value to be scanned was 0 (in which case BSR/BSF set the Z flag).
Instead, according to the AMD64 specification, we can make use of the fact that
BSR/BSF doesn't modify its output register if its input is 0. By preloading
the output with -1 and incrementing the result, we achieve the desired result
without the need for a conditional check.
The Intel x86_64 specification, however, says that the result of BSR/BSF in
such a case is undefined. That said, when queried, one of the Intel CPU
architects said that the behaviour on all Intel CPUs is that:
(1) with BSRQ/BSFQ, the 64-bit destination register is written with its
original value if the source is 0, thus, in essence, giving the effect we
want. And,
(2) with BSRL/BSFL, the lower half of the 64-bit destination register is
written with its original value if the source is 0, and the upper half is
cleared, thus giving us the effect we want (we return a 4-byte int).
Further, it was indicated that they (Intel) are unlikely to get away with
changing the behaviour.
It might be possible to optimise the 32-bit versions of these functions, but
there's a lot more variation, and so the effective non-destructive property of
BSRL/BSRF cannot be relied on.
[ hpa: specifically, some 486 chips are known to NOT have this property. ]
I have benchmarked these functions on my Core2 Duo test machine using the
following program:
#include <stdlib.h>
#include <stdio.h>
#ifndef __x86_64__
#error
#endif
#define PAGE_SHIFT 12
typedef unsigned long long __u64, u64;
typedef unsigned int __u32, u32;
#define noinline __attribute__((noinline))
static __always_inline int fls64(__u64 x)
{
long bitpos = -1;
asm("bsrq %1,%0"
: "+r" (bitpos)
: "rm" (x));
return bitpos + 1;
}
static inline unsigned long __fls(unsigned long word)
{
asm("bsr %1,%0"
: "=r" (word)
: "rm" (word));
return word;
}
static __always_inline int old_fls64(__u64 x)
{
if (x == 0)
return 0;
return __fls(x) + 1;
}
static noinline // __attribute__((const))
int old_get_order(unsigned long size)
{
int order;
size = (size - 1) >> (PAGE_SHIFT - 1);
order = -1;
do {
size >>= 1;
order++;
} while (size);
return order;
}
static inline __attribute__((const))
int get_order_old_fls64(unsigned long size)
{
int order;
size--;
size >>= PAGE_SHIFT;
order = old_fls64(size);
return order;
}
static inline __attribute__((const))
int get_order(unsigned long size)
{
int order;
size--;
size >>= PAGE_SHIFT;
order = fls64(size);
return order;
}
unsigned long prevent_optimise_out;
static noinline unsigned long test_old_get_order(void)
{
unsigned long n, total = 0;
long rep, loop;
for (rep = 1000000; rep > 0; rep--) {
for (loop = 0; loop <= 16384; loop += 4) {
n = 1UL << loop;
total += old_get_order(n);
}
}
return total;
}
static noinline unsigned long test_get_order_old_fls64(void)
{
unsigned long n, total = 0;
long rep, loop;
for (rep = 1000000; rep > 0; rep--) {
for (loop = 0; loop <= 16384; loop += 4) {
n = 1UL << loop;
total += get_order_old_fls64(n);
}
}
return total;
}
static noinline unsigned long test_get_order(void)
{
unsigned long n, total = 0;
long rep, loop;
for (rep = 1000000; rep > 0; rep--) {
for (loop = 0; loop <= 16384; loop += 4) {
n = 1UL << loop;
total += get_order(n);
}
}
return total;
}
int main(int argc, char **argv)
{
unsigned long total;
switch (argc) {
case 1: total = test_old_get_order(); break;
case 2: total = test_get_order_old_fls64(); break;
default: total = test_get_order(); break;
}
prevent_optimise_out = total;
return 0;
}
This allows me to test the use of the old fls64() implementation and the new
fls64() implementation and also to contrast these to the out-of-line loop-based
implementation of get_order(). The results were:
warthog>time ./get_order
real 1m37.191s
user 1m36.313s
sys 0m0.861s
warthog>time ./get_order x
real 0m16.892s
user 0m16.586s
sys 0m0.287s
warthog>time ./get_order x x
real 0m7.731s
user 0m7.727s
sys 0m0.002s
Using the current upstream fls64() as a basis for an inlined get_order() [the
second result above] is much faster than using the current out-of-line
loop-based get_order() [the first result above].
Using my optimised inline fls64()-based get_order() [the third result above]
is even faster still.
[ hpa: changed the selection of 32 vs 64 bits to use CONFIG_X86_64
instead of comparing BITS_PER_LONG, updated comments, rebased manually
on top of 83d99df7c4 x86, bitops: Move fls64.h inside __KERNEL__ ]
Signed-off-by: David Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20111213145654.14362.39868.stgit@warthog.procyon.org.uk
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
We would include <asm-generic/bitops/fls64.h> even without __KERNEL__,
but that doesn't make sense, as:
1. That file provides fls64(), but the corresponding function fls() is
not exported to user space.
2. The implementation of fls64.h uses kernel-only symbols.
3. fls64.h is not exported to user space.
This appears to have been a bug introduced in checkin:
d57594c203 bitops: use __fls for fls64 on 64-bit archs
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Alexander van Heukelum <heukelum@mailshack.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/4EEA77E1.6050009@zytor.com
The bisection implemented in unwind_find_origin() stopped to early. If
there is only a single entry left to check the original code just took
the end point as origin which might be wrong.
This was introduced in commit de66a97901 ("ARM: 7187/1: fix unwinding
for XIP kernels").
Reported-and-tested-by: Nick Bowler <nbowler@elliptictech.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'stable/for-linus-fixes-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/swiotlb: Use page alignment for early buffer allocation.
xen: only limit memory map to maximum reservation for domain 0.
d312ae878b "xen: use maximum reservation to limit amount of usable RAM"
clamped the total amount of RAM to the current maximum reservation. This is
correct for dom0 but is not correct for guest domains. In order to boot a guest
"pre-ballooned" (e.g. with memory=1G but maxmem=2G) in order to allow for
future memory expansion the guest must derive max_pfn from the e820 provided by
the toolstack and not the current maximum reservation (which can reflect only
the current maximum, not the guest lifetime max). The existing algorithm
already behaves this correctly if we do not artificially limit the maximum
number of pages for the guest case.
For a guest booted with maxmem=512, memory=128 this results in:
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] Xen: 0000000000000000 - 00000000000a0000 (usable)
[ 0.000000] Xen: 00000000000a0000 - 0000000000100000 (reserved)
-[ 0.000000] Xen: 0000000000100000 - 0000000008100000 (usable)
-[ 0.000000] Xen: 0000000008100000 - 0000000020800000 (unusable)
+[ 0.000000] Xen: 0000000000100000 - 0000000020800000 (usable)
...
[ 0.000000] NX (Execute Disable) protection: active
[ 0.000000] DMI not present or invalid.
[ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved)
[ 0.000000] e820 remove range: 00000000000a0000 - 0000000000100000 (usable)
-[ 0.000000] last_pfn = 0x8100 max_arch_pfn = 0x1000000
+[ 0.000000] last_pfn = 0x20800 max_arch_pfn = 0x1000000
[ 0.000000] initial memory mapped : 0 - 027ff000
[ 0.000000] Base memory trampoline at [c009f000] 9f000 size 4096
-[ 0.000000] init_memory_mapping: 0000000000000000-0000000008100000
-[ 0.000000] 0000000000 - 0008100000 page 4k
-[ 0.000000] kernel direct mapping tables up to 8100000 @ 27bb000-27ff000
+[ 0.000000] init_memory_mapping: 0000000000000000-0000000020800000
+[ 0.000000] 0000000000 - 0020800000 page 4k
+[ 0.000000] kernel direct mapping tables up to 20800000 @ 26f8000-27ff000
[ 0.000000] xen: setting RW the range 27e8000 - 27ff000
[ 0.000000] 0MB HIGHMEM available.
-[ 0.000000] 129MB LOWMEM available.
-[ 0.000000] mapped low ram: 0 - 08100000
-[ 0.000000] low ram: 0 - 08100000
+[ 0.000000] 520MB LOWMEM available.
+[ 0.000000] mapped low ram: 0 - 20800000
+[ 0.000000] low ram: 0 - 20800000
With this change "xl mem-set <domain> 512M" will successfully increase the
guest RAM (by reducing the balloon).
There is no change for dom0.
Reported-and-Tested-by: George Shuklin <george.shuklin@gmail.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: stable@kernel.org
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
My box with following cpuinfo needs the cx8 enabling still:
vendor_id : CentaurHauls
cpu family : 6
model : 13
model name : VIA Eden Processor 1200MHz
stepping : 0
cpu MHz : 1199.940
cache size : 128 KB
This fixes valgrind to work on my box (it requires and checks
cx8 from cpuinfo).
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Link: http://lkml.kernel.org/r/1323961888-10223-1-git-send-email-timo.teras@iki.fi
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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>
