Jack Ren and Eric Miao tracked down the following long standing
problem in the NOHZ code:
scheduler switch to idle task
enable interrupts
Window starts here
----> interrupt happens (does not set NEED_RESCHED)
irq_exit() stops the tick
----> interrupt happens (does set NEED_RESCHED)
return from schedule()
cpu_idle(): preempt_disable();
Window ends here
The interrupts can happen at any point inside the race window. The
first interrupt stops the tick, the second one causes the scheduler to
rerun and switch away from idle again and we end up with the tick
disabled.
The fact that it needs two interrupts where the first one does not set
NEED_RESCHED and the second one does made the bug obscure and extremly
hard to reproduce and analyse. Kudos to Jack and Eric.
Solution: Limit the NOHZ functionality to the idle loop to make sure
that we can not run into such a situation ever again.
cpu_idle()
{
preempt_disable();
while(1) {
tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we
are in the idle loop
while (!need_resched())
halt();
tick_nohz_restart_sched_tick(); <- disables NOHZ mode
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
In hindsight we should have done this forever, but ...
/me grabs a large brown paperbag.
Debugged-by: Jack Ren <jack.ren@marvell.com>,
Debugged-by: eric miao <eric.y.miao@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
[PATCH] return to old errno choice in mkdir() et.al.
[Patch] fs/binfmt_elf.c: fix wrong return values
[PATCH] get rid of leak in compat_execve()
[Patch] fs/binfmt_elf.c: fix a wrong free
[PATCH] avoid multiplication overflows and signedness issues for max_fds
[PATCH] dup_fd() part 4 - race fix
[PATCH] dup_fd() - part 3
[PATCH] dup_fd() part 2
[PATCH] dup_fd() fixes, part 1
[PATCH] take init_files to fs/file.c
This patch adds the missing MODULE_LICENSE("GPL").
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Martin Michlmayr reported that fuse complains:
ERROR: "copy_page" [fs/fuse/fuse.ko] undefined!
so export the needed function.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This replaces the duplicated arch-specific versions of "sys_pipe()" with
one unified implementation. This removes almost 250 lines of duplicated
code.
It's marked __weak, so that *if* an architecture wants to override the
default implementation it can do so by simply having its own replacement
version, since many architectures use alternate calling conventions for
the 'pipe()' system call for legacy reasons (ie traditional UNIX
implementations often return the two file descriptors in registers)
I still haven't changed the cris version even though Linus says the BKL
isn't needed. The arch maintainer can easily do it if there are really
no obstacles.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Yani Ioannou <yani.ioannou@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove proc_root export. Creation and removal works well if parent PDE is
supplied as NULL -- it worked always that way.
So, one useless export removed and consistency added, some drivers created
PDEs with &proc_root as parent but removed them as NULL and so on.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove proc_bus export and variable itself. Using pathnames works fine
and is slightly more understandable and greppable.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ARM kprobes arithmetic immediate instruction decoder
(space_cccc_001x()) was accidentally zero'ing out not only the Rn and
Rd arguments, but the lower nibble of the immediate argument as well
-- this patch fixes this.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Nicolas Pitre <nico@marvell.com>
It is more useful to flush the cache with the actual buffer address
rather than the address containing a pointer to the buffer.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Acked-by: Lennert Buytenhek <buytenh@marvell.com>
If we fail to boot due to an unsupported processor ID, print the
processor ID as part of the failure message.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch implements Thumb-2 application support in Linux. Original
implementation by Paul Brook with fixes for VFP and Neon by Catalin
Marinas.
Signed-off-by: Paul Brook <paul@codesourcery.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This patch adds a prefetch abort handler similar to the data abort one
and renames the latter for consistency. Initial implementation by Paul
Brook with some renaming by Catalin Marinas.
Signed-off-by: Paul Brook <paul@codesourcery.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Semaphores are no longer performance-critical, so a generic C
implementation is better for maintainability, debuggability and
extensibility. Thanks to Peter Zijlstra for fixing the lockdep
warning. Thanks to Harvey Harrison for pointing out that the
unlikely() was unnecessary.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Ccoreutils and other have started using fstatat64. Thus, we
need a shim for it if we want to support modern oldabi
userlands (such as Debian/arm/lenny) with EABI kernels.
See http://bugs.debian.org/462677
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Riku Voipio <riku.voipio@movial.fi>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
fix signal return code when enable CONFIG_OABI_COMPAT
Signed-off-by: Janboe Ye <janboe.ye@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move the definitions of ATAG_CORE and ATAG_CORE_SIZE in head.S to
head-common.S. There is no use of these in head.S itself, but they
are used in head-common.S. When building for the !CONFIG_MMU case
these were not defined when compiling head-nommu.S (which includes
head-common.S).
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Suppress A.OUT library support if CONFIG_ARCH_SUPPORTS_AOUT is not set.
Not all architectures support the A.OUT binfmt, so the ELF binfmt should not
be permitted to go looking for A.OUT libraries to load in such a case. Not
only that, but under such conditions A.OUT core dumps are not produced either.
To make this work, this patch also does the following:
(1) Makes the existence of the contents of linux/a.out.h contingent on
CONFIG_ARCH_SUPPORTS_AOUT.
(2) Renames dump_thread() to aout_dump_thread() as it's only called by A.OUT
core dumping code.
(3) Moves aout_dump_thread() into asm/a.out-core.h and makes it inline. This
is then included only where needed. This means that this bit of arch
code will be stored in the appropriate A.OUT binfmt module rather than
the core kernel.
(4) Drops A.OUT support for Blackfin (according to Mike Frysinger it's not
needed) and FRV.
This patch depends on the previous patch to move STACK_TOP[_MAX] out of
asm/a.out.h and into asm/processor.h as they're required whether or not A.OUT
format is available.
[jdike@addtoit.com: uml: re-remove accidentally restored code]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(with Martin Schwidefsky <schwidefsky@de.ibm.com>)
The pgd/pud/pmd/pte page table allocation functions get a mm_struct pointer as
first argument. The free functions do not get the mm_struct argument. This
is 1) asymmetrical and 2) to do mm related page table allocations the mm
argument is needed on the free function as well.
[kamalesh@linux.vnet.ibm.com: i386 fix]
[akpm@linux-foundation.org: coding-syle fixes]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the new timerfd API as it is implemented by the following patch:
int timerfd_create(int clockid, int flags);
int timerfd_settime(int ufd, int flags,
const struct itimerspec *utmr,
struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);
The timerfd_create() API creates an un-programmed timerfd fd. The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.
The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not
NULL).
The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter. Otherwise it's a relative time.
The timerfd_gettime() API returns the next expiration time of the timer, or
{0, 0} if the timerfd has not been set yet.
Like the previous timerfd API implementation, read(2) and poll(2) are
supported (with the same interface). Here's a simple test program I used to
exercise the new timerfd APIs:
http://www.xmailserver.org/timerfd-test2.c
[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: fix ia64 build]
[akpm@linux-foundation.org: fix m68k build]
[akpm@linux-foundation.org: fix mips build]
[akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds]
[heiko.carstens@de.ibm.com: fix s390]
[akpm@linux-foundation.org: fix powerpc build]
[akpm@linux-foundation.org: fix sparc64 more]
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* at91:
[ARM] 4802/1: Fix typo and remove vague comment
[ARM] 4660/3: at91: allow selecting UART for early kernel messages
[ARM] 4739/1: at91sam9263: make gpio bank C and D irqs work
* ixp:
[ARM] 4809/2: ixp4xx: Merge dsmg600-power.c into dsmg600-setup.c
[ARM] 4808/2: ixp4xx: Merge nas100d-power.c into nas100d-setup.c
[ARM] 4807/2: ixp4xx: Merge nslu2-power.c into nslu2-setup.c
[ARM] 4806/1: ixp4xx: Ethernet support for the nslu2 and nas100d boards
[ARM] 4805/1: ixp4xx: Use leds-gpio driver instead of IXP4XX-GPIO-LED driver
[ARM] 4715/2: Ethernet support for IXDP425 boards
[ARM] 4714/2: Headers for IXP4xx built-in Ethernet and WAN drivers
[ARM] 4713/3: Adds drivers for IXP4xx QMgr and NPE features
[ARM] 4712/2: Adds functions to read and write IXP4xx "feature" bits
[ARM] 4774/2: ixp4xx: Register dsmg600 rtc i2c_board_info
[ARM] 4773/2: ixp4xx: Register nas100d rtc i2c_board_info
[ARM] 4772/2: ixp4xx: Register nslu2 rtc i2c_board_info
[ARM] 4769/2: ixp4xx: Button updates for the dsmg600 board
[ARM] 4768/2: ixp4xx: Button and LED updates for the nas100d board
[ARM] 4767/2: ixp4xx: Add bitops.h include to io.h
[ARM] 4766/2: ixp4xx: Update ixp4xx_defconfig, enabling all supported boards
* master:
[ARM] 4810/1: - Fix 'section mismatch' building warnings
[ARM] xtime_seqlock: fix more ARM machines for xtime deadlocking
[ARM] 21285 serial: fix build error
* misc:
[ARM] 4736/1: Export atags to userspace and allow kexec to use customised atags
* pxa:
[ARM] 4798/1: pcm027: fix missing header file
[ARM] 4803/1: pxa: fix building issue of poodle.c caused by patch 4737/1
[ARM] 4801/1: pxa: fix building issues of missing pxa2xx-regs.h
[ARM] pxa: introduce sysdev for pxa3xx static memory controller
[ARM] pxa: add preliminary suspend/resume code for pxa3xx
[ARM] pxa: introduce sysdev for GPIO register saving/restoring
[ARM] pxa: introduce sysdev for IRQ register saving/restoring
[ARM] pxa: fix the warning of undeclared "struct pxaohci_platform_data"
[ARM] pxa: change set_kset_name() to direct name assignment for MFP sysclass
* realview:
[ARM] 4822/1: RealView: Change the REALVIEW_MPCORE configuration option
[ARM] 4821/1: RealView: Remove the platform dependencies from localtimer.c
[ARM] 4820/1: RealView: Select the timer IRQ at run-time
[ARM] 4819/1: RealView: Fix entry-macro.S to work with multiple platforms
[ARM] 4818/1: RealView: Add core-tile detection
[ARM] 4817/1: RealView: Move the AMBA resource definitions to realview_eb.c
[ARM] 4816/1: RealView: Move the platform-specific definitions into board-eb.h
[ARM] 4815/1: RealView: Add clockevents suport for the local timers
[ARM] 4814/1: RealView: Add broadcasting clockevents support for ARM11MPCore
[ARM] 4813/1: Add SMP helper functions for clockevents support
[ARM] 4812/1: RealView: clockevents support for the RealView platforms
[ARM] 4811/1: RealView: clocksource support for the RealView platforms
This patch adds dummy local timers for each CPU so that the board clock
device is used to broadcast events to the other CPUs. The patch also
adds the declaration for the dummy_timer_setup function (the equivalent
of local_timer_setup when CONFIG_LOCAL_TIMERS is not set).
Due to the way clockevents work, the dummy timer on the first CPU has to
be registered before the board timer.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch adds the smp_call_function_single and smp_timer_broadcast
functions and modifies ipi_timer to call the platform-specific function
local_timer_interrupt.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Currently, the atags used by kexec are fixed to the ones originally used
to boot the kernel. This is less than ideal as changing the commandline,
initrd and other options would be a useful feature.
This patch exports the atags used for the current kernel to userspace
through an "atags" file in procfs. The presence of the file is
controlled by its own Kconfig option and cleans up several ifdef blocks
into a separate file. The tags for the new kernel are assumed to be at
a fixed location before the kernel image itself. The location of the
tags used to boot the original kernel is unimportant and no longer
saved.
Based on a patch from Uli Luckas <u.luckas@road.de>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Uli Luckas <u.luckas@road.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Adds functions to read and write IXP4xx "feature" (aka "fuse")
bits, containing information about available/enabled CPU features.
The uncompress.h included by boot/compressed/misc.c resides in
a different space than rest of the kernel and thus can't use
asm/hardware.h (including asm/arch/cpu.h - which, in turn, may use
EXPORTed symbol "processor_id").
Posted to linux-arm-kernel on 2 Dec 2007 and revised.
Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch consolidate all definitions of .init.text, .init.data
and .exit.text, .exit.data section definitions in
the generic vmlinux.lds.h.
This is a preparational patch - alone it does not buy
us much good.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Move the xtime write mode seqlock into timer_tick(), so it only
surrounds the call to do_timer().
This avoids a deadlock in update_process_times() ...
hrtimer_get_softirq_time() which tries to get a read mode seqlock
on xtime, thereby preventing booting.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The kprobes code is already able to cope with reentrant probes, so its
handler must be called outside of the region protected by undef_lock.
If ever this lock is released when handlers are called then this commit
could be reverted.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
If kprobes installs a breakpoint on a "stmdb sp!, {...}" instruction,
and then single-step it by simulation from the exception context, it will
corrupt the saved regs on the stack from the previous context.
To avoid this, let's add an optional parameter to the svc_entry macro
allowing for a hole to be created on the stack before saving the
interrupted context, and use it in the undef_svc handler when kprobes
is enabled.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
This is a full implementation of Kprobes including Jprobes and
Kretprobes support.
This ARM implementation does not follow the usual kprobes double-
exception model. The traditional model is where the initial kprobes
breakpoint calls kprobe_handler(), which returns from exception to
execute the instruction in its original context, then immediately
re-enters after a second breakpoint (or single-stepping exception)
into post_kprobe_handler(), each time the probe is hit.. The ARM
implementation only executes one kprobes exception per hit, so no
post_kprobe_handler() phase. All side-effects from the kprobe'd
instruction are resolved before returning from the initial exception.
As a result, all instructions are _always_ effectively boosted
regardless of the type of instruction, and even regardless of whether
or not there is a post-handler for the probe.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Quentin Barnes <qbarnes@gmail.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
This is the code implementing instruction single-stepping for kprobes
on ARM.
To get around the limitation of no Next-PC and no hardware single-
stepping, all kprobe'd instructions are split into three camps:
simulation, emulation, and rejected. "Simulated" instructions are
those instructions which behavior is reproduced by straight C code.
"Emulated" instructions are ones that are copied, slightly altered
and executed directly in the instruction slot to reproduce their
behavior. "Rejected" instructions are ones that could be simulated,
but work hasn't been put into simulating them. These instructions
should be very rare, if not unencountered, in the kernel. If ever
needed, code could be added to simulate them.
One might wonder why this and the ptrace singlestep facility are not
sharing some code. Both approaches are fundamentally different because
the ptrace code regains control after the stepped instruction by installing
a breakpoint after the instruction itself, and possibly at the location
where the instruction might be branching to, instead of simulating or
emulating the target instruction.
The ptrace approach isn't suitable for kprobes because the breakpoints
would have to be moved back, and the icache flushed, everytime the
probe is hit to let normal code execution resume, which would have a
significant performance impact. It is also racy on SMP since another
CPU could, with the right timing, sail through the probe point without
being caught. Because ptrace single-stepping always result in a
different process to be scheduled, the concern for performance is much
less significant.
On the other hand, the kprobes approach isn't (currently) suitable for
ptrace because it has no provision for proper user space memory
protection and translation, and even if that was implemented, the gain
wouldn't be worth the added complexity in the ptrace path compared to
the current approach.
So, until kprobes does support user space, both kprobes and ptrace are
best kept independent and separate.
Signed-off-by: Quentin Barnes <qbarnes@gmail.com>
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
This patch enables the use of the Advanced SIMD (NEON) extension on
ARMv7. The NEON technology is a 64/128-bit hybrid SIMD architecture
for accelerating the performance of multimedia and signal processing
applications. The extension shares the registers with the VFP unit and
enabling/disabling and saving/restoring follow the same rules. In
addition, there are instructions that do not have the appropriate CP
number encoded, the checks being made in the call_fpe function.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
