For quite some time there have been problems with memory barriers and
various races with NMI on multi processor systems using the kernel
debugger.  The algorithm for entering the kernel debug core and
resuming kernel execution was racy and had several known edge case
problems with attempting to debug something on a heavily loaded system
using breakpoints that are hit repeatedly and quickly.

The prior "locking" design entry worked as follows:

  * The atomic counter kgdb_active was used with atomic exchange in
    order to elect a master cpu out of all the cpus that may have
    taken a debug exception.
  * The master cpu increments all elements of passive_cpu_wait[].
  * The master cpu issues the round up cpus message.
  * Each "slave cpu" that enters the debug core increments its own
    element in cpu_in_kgdb[].
  * Each "slave cpu" spins on passive_cpu_wait[] until it becomes 0.
  * The master cpu debugs the system.

The new scheme removes the two arrays of atomic counters and replaces
them with 2 single counters.  One counter is used to count the number
of cpus waiting to become a master cpu (because one or more hit an
exception). The second counter is use to indicate how many cpus have
entered as slave cpus.

The new entry logic works as follows:

  * One or more cpus enters via kgdb_handle_exception() and increments
    the masters_in_kgdb. Each cpu attempts to get the spin lock called
    dbg_master_lock.
  * The master cpu sets kgdb_active to the current cpu.
  * The master cpu takes the spinlock dbg_slave_lock.
  * The master cpu asks to round up all the other cpus.
  * Each slave cpu that is not already in kgdb_handle_exception()
    will enter and increment slaves_in_kgdb.  Each slave will now spin
    try_locking on dbg_slave_lock.
  * The master cpu waits for the sum of masters_in_kgdb and slaves_in_kgdb
    to be equal to the sum of the online cpus.
  * The master cpu debugs the system.

In the new design the kgdb_active can only be changed while holding
dbg_master_lock.  Stress testing has not turned up any further
entry/exit races that existed in the prior locking design.  The prior
locking design suffered from atomic variables not being truly atomic
(in the capacity as used by kgdb) along with memory barrier races.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NDongdong Deng <dongdong.deng@windriver.com>

The kernel debug_core invokes hw breakpoint install and removal via
call backs.  The architecture specific kgdb stubs only need to
implement the call backs and not actually call the functions.
Signed-off-by: NDongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
CC: x86@kernel.org
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: H. Peter Anvin <hpa@zytor.com>

The slave cpus do not have the hw breakpoints disabled upon entry to
the debug_core and as a result could cause unrecoverable recursive
faults on badly placed breakpoints, or get out of sync with the arch
specific hw breakpoint operations.

This patch addresses the problem by invoking kgdb_disable_hw_debug()
earlier in kgdb_enter_cpu for each cpu that enters the debug core.

The hw breakpoint dis/enable flow should be:

master_debug_cpu   slave_debug_cpu
         \              /
          kgdb_cpu_enter
                |
        kgdb_disable_hw_debug --> uninstall pre-enabled hw_breakpoint
                |
 do add/rm dis/enable operates to hw_breakpoints on master_debug_cpu..
                |
        correct_hw_break --> correct/install the enabled hw_breakpoint
                |
           leave_kgdb
Signed-off-by: NDongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Fix the following sparse warnings:

kdb_main.c:328:5: warning: symbol 'kdbgetu64arg' was not declared. Should it be static?
kgdboc.c:246:12: warning: symbol 'kgdboc_early_init' was not declared. Should it be static?
kgdb.c:652:26: warning: incorrect type in argument 1 (different address spaces)
kgdb.c:652:26:    expected void const *ptr
kgdb.c:652:26:    got struct perf_event *[noderef] <asn:3>*pev

The one in kgdb.c required the (void * __force) because of the return
code from register_wide_hw_breakpoint looking like:

        return (void __percpu __force *)ERR_PTR(err);
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Nothing should try to use kdb_commands directly as sometimes it is
null.  Instead, use the for_each_kdbcmd() iterator.

This particular problem dates back to the initial kdb merge (2.6.35),
but at that point nothing was dynamically unregistering commands from
the kdb shell.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Now that include/linux/kdb.h properly exports all the functions
required to dynamically add a kdb shell command, the reference to the
private kdb header can be removed.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

In order to allow kernel modules to dynamically add a command to the
kdb shell the kdb_register, kdb_register_repeat, kdb_unregister, and
kdb_printf need to be exported as GPL symbols.

Any kernel module that adds a dynamic kdb shell function should only
need to include linux/kdb.h.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

When returning from the kernel debugger reset the rcu jiffies_stall
value to prevent the rcu stall detector from sending NMI events which
invoke a stack dump for each cpu in the system.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Move the various clock and watch dog syncs to a single function in
advance of adding another sync for the rcu stall detector.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

HW breakpoints events stopped working correctly with kgdb as a result
of commit: 018cbffe (Merge commit
'v2.6.33' into perf/core), later commit:
ba773f7c (x86,kgdb: Fix hw breakpoint
regression) allowed breakpoints to propagate to the debugger core but
did not completely address the original regression in functionality
found in 2.6.35.

When the DR_STEP flag is set in dr6 along with any of the DR_TRAP
bits, the kgdb exception handler will enter once from the
hw_breakpoint API call back and again from the die notifier for
do_debug(), which causes the debugger to stop twice and also for the
kgdb regression tests to fail running under kvm with:

echo V2I1 > /sys/module/kgdbts/parameters/kgdbts

To address the problem, the kgdb overflow handler needs to implement
the same logic as the ptrace overflow handler call back with respect
to updating the virtual copy of dr6.  This will allow the kgdb
do_debug() die notifier to properly handle the exception and the
attached debugger, or kgdb test suite, will only receive a single
notification.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: x86@kernel.org

* 'urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6:
  pcmcia: fix ni_daq_700 compilation
  pcmcia: IOCARD is also required for using IRQs

* git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  asm-generic/io.h: allow people to override individual funcs
  bitops: remove duplicated extern declarations
  bitops: make asm-generic/bitops/find.h more generic
  asm-generic: kdebug.h: Checkpatch cleanup
  asm-generic: fcntl: make exported headers use strict posix types
  asm-generic: cmpxchg does not handle non-long arguments
  asm-generic: make atomic_add_unless a function

* 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  vfs: make no_llseek the default
  vfs: don't use BKL in default_llseek
  llseek: automatically add .llseek fop
  libfs: use generic_file_llseek for simple_attr
  mac80211: disallow seeks in minstrel debug code
  lirc: make chardev nonseekable
  viotape: use noop_llseek
  raw: use explicit llseek file operations
  ibmasmfs: use generic_file_llseek
  spufs: use llseek in all file operations
  arm/omap: use generic_file_llseek in iommu_debug
  lkdtm: use generic_file_llseek in debugfs
  net/wireless: use generic_file_llseek in debugfs
  drm: use noop_llseek

* 'vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl: (30 commits)
  BKL: remove BKL from freevxfs
  BKL: remove BKL from qnx4
  autofs4: Only declare function when CONFIG_COMPAT is defined
  autofs: Only declare function when CONFIG_COMPAT is defined
  ncpfs: Lock socket in ncpfs while setting its callbacks
  fs/locks.c: prepare for BKL removal
  BKL: Remove BKL from ncpfs
  BKL: Remove BKL from OCFS2
  BKL: Remove BKL from squashfs
  BKL: Remove BKL from jffs2
  BKL: Remove BKL from ecryptfs
  BKL: Remove BKL from afs
  BKL: Remove BKL from USB gadgetfs
  BKL: Remove BKL from autofs4
  BKL: Remove BKL from isofs
  BKL: Remove BKL from fat
  BKL: Remove BKL from ext2 filesystem
  BKL: Remove BKL from do_new_mount()
  BKL: Remove BKL from cgroup
  BKL: Remove BKL from NTFS
  ...

* 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  block: autoconvert trivial BKL users to private mutex
  drivers: autoconvert trivial BKL users to private mutex
  ipmi: autoconvert trivial BKL users to private mutex
  mac: autoconvert trivial BKL users to private mutex
  mtd: autoconvert trivial BKL users to private mutex
  scsi: autoconvert trivial BKL users to private mutex

Fix up trivial conflicts (due to addition of private mutex right next to
deletion of a version string) in drivers/char/pcmcia/cm40[04]0_cs.c

* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  BKL: introduce CONFIG_BKL.
  dabusb: remove the BKL
  sunrpc: remove the big kernel lock
  init/main.c: remove BKL notations
  blktrace: remove the big kernel lock
  rtmutex-tester: make it build without BKL
  dvb-core: kill the big kernel lock
  dvb/bt8xx: kill the big kernel lock
  tlclk: remove big kernel lock
  fix rawctl compat ioctls breakage on amd64 and itanic
  uml: kill big kernel lock
  parisc: remove big kernel lock
  cris: autoconvert trivial BKL users
  alpha: kill big kernel lock
  isapnp: BKL removal
  s390/block: kill the big kernel lock
  hpet: kill BKL, add compat_ioctl

Reported-by: NAnca Emanuel <anca.emanuel@gmail.com>
Signed-off-by: NDominik Brodowski <linux@dominikbrodowski.net>

* 'x86-irq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, 32-bit: Align percpu area and irq stacks to THREAD_SIZE
  x86: Move alloc_desk_mask variables inside ifdef
  x86-32: Align IRQ stacks properly
  x86: Remove CONFIG_4KSTACKS
  x86: Always use irq stacks

Fixed up trivial conflicts in include/linux/{irq.h, percpu-defs.h}

Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Hpet: Avoid the comparator readback penalty

Fortunately this is only exploitable on very unusual hardware.

[Reported a while ago but nothing happened so just fixing it]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Dave Hinds pointed out to me that 37979e15 will break b43 and
ray_cs, as IOCARD is not -- as the name would suggest -- only needed
for cards using IO ports. Instead, as it re-deines several pins, it
is also required for using interrupts.
Signed-off-by: NDominik Brodowski <linux@dominikbrodowski.net>

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (71 commits)
  powerpc/44x: Update ppc44x_defconfig
  powerpc/watchdog: Make default timeout for Book-E watchdog a Kconfig option
  fsl_rio: Add comments for sRIO registers.
  powerpc/fsl-booke: Add e55xx (64-bit) smp defconfig
  powerpc/fsl-booke: Add p5020 DS board support
  powerpc/fsl-booke64: Use TLB CAMs to cover linear mapping on FSL 64-bit chips
  powerpc/fsl-booke: Add support for FSL Arch v1.0 MMU in setup_page_sizes
  powerpc/fsl-booke: Add support for FSL 64-bit e5500 core
  powerpc/85xx: add cache-sram support
  powerpc/85xx: add ngPIXIS FPGA device tree node to the P1022DS board
  powerpc: Fix compile error with paca code on ppc64e
  powerpc/fsl-booke: Add p3041 DS board support
  oprofile/fsl emb: Don't set MSR[PMM] until after clearing the interrupt.
  powerpc/fsl-booke: Add PCI device ids for P2040/P3041/P5010/P5020 QoirQ chips
  powerpc/mpc8xxx_gpio: Add support for 'qoriq-gpio' controllers
  powerpc/fsl_booke: Add support to boot from core other than 0
  powerpc/p1022: Add probing for individual DMA channels
  powerpc/fsl_soc: Search all global-utilities nodes for rstccr
  powerpc: Fix invalid page flags in create TLB CAM path for PTE_64BIT
  powerpc/mpc83xx: Support for MPC8308 P1M board
  ...

Fix up conflict with the generic irq_work changes in arch/powerpc/kernel/time.c

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev: (26 commits)
  include/linux/libata.h: fix typo
  pata_bf54x: fix return type of bfin_set_devctl
  Drivers: ata: Makefile: replace the use of <module>-objs with <module>-y
  libahci: fix result_tf handling after an ATA PIO data-in command
  pata_sl82c105: implement sff_irq_check() method
  pata_sil680: implement sff_irq_check() method
  pata_pdc202xx_old: implement sff_irq_check() method
  pata_cmd640: implement sff_irq_check() method
  ata_piix: Add device ID for ICH4-L
  pata_sil680: make sil680_sff_exec_command() 'static'
  ata: Intel IDE-R support
  libata: reorder ata_queued_cmd to remove alignment padding on 64 bit builds
  libata: Signal that our SATL supports WRITE SAME(16) with UNMAP
  ata_piix: remove SIDPR locking
  libata: implement cross-port EH exclusion
  libata: add @ap to ata_wait_register() and introduce ata_msleep()
  ata_piix: implement LPM support
  libata: implement LPM support for port multipliers
  libata: reimplement link power management
  libata: implement sata_link_scr_lpm() and make ata_dev_set_feature() global
  ...

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: (48 commits)
  ocfs2: Avoid to evaluate xattr block flags again.
  ocfs2/cluster: Release debugfs file elapsed_time_in_ms
  ocfs2: Add a mount option "coherency=*" to handle cluster coherency for O_DIRECT writes.
  Initialize max_slots early
  When I tried to compile I got the following warning: fs/ocfs2/slot_map.c: In function ‘ocfs2_init_slot_info’: fs/ocfs2/slot_map.c:360: warning: ‘bytes’ may be used uninitialized in this function fs/ocfs2/slot_map.c:360: note: ‘bytes’ was declared here Compiler: gcc version 4.4.3 (GCC) on Mandriva I'm not sure why this warning occurs, I think compiler don't know that variable "bytes" is initialized when it is sent by reference to ocfs2_slot_map_physical_size and it throws that ugly warning. However, a simple initialization of "bytes" variable with 0 will fix it.
  ocfs2: validate bg_free_bits_count after update
  ocfs2/cluster: Bump up dlm protocol to version 1.1
  ocfs2/cluster: Show per region heartbeat elapsed time
  ocfs2/cluster: Add mlogs for heartbeat up/down events
  ocfs2/cluster: Create debugfs dir/files for each region
  ocfs2/cluster: Create debugfs files for live, quorum and failed region bitmaps
  ocfs2/cluster: Maintain bitmap of failed regions
  ocfs2/cluster: Maintain bitmap of quorum regions
  ocfs2/cluster: Track bitmap of live heartbeat regions
  ocfs2/cluster: Track number of global heartbeat regions
  ocfs2/cluster: Maintain live node bitmap per heartbeat region
  ocfs2/cluster: Reorganize o2hb debugfs init
  ocfs2/cluster: Check slots for unconfigured live nodes
  ocfs2/cluster: Print messages when adding/removing nodes
  ocfs2/cluster: Print messages when adding/removing heartbeat regions
  ...

Merge branch 'core-memblock-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-memblock-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (74 commits)
  x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S
  xen: Cope with unmapped pages when initializing kernel pagetable
  memblock, bootmem: Round pfn properly for memory and reserved regions
  memblock: Annotate memblock functions with __init_memblock
  memblock: Allow memblock_init to be called early
  memblock/arm: Fix memblock_region_is_memory() typo
  x86, memblock: Remove __memblock_x86_find_in_range_size()
  memblock: Fix wraparound in find_region()
  x86-32, memblock: Make add_highpages honor early reserved ranges
  x86, memblock: Fix crashkernel allocation
  arm, memblock: Fix the sparsemem build
  memblock: Fix section mismatch warnings
  powerpc, memblock: Fix memblock API change fallout
  memblock, microblaze: Fix memblock API change fallout
  x86: Remove old bootmem code
  x86, memblock: Use memblock_memory_size()/memblock_free_memory_size() to get correct dma_reserve
  x86: Remove not used early_res code
  x86, memblock: Replace e820_/_early string with memblock_
  x86: Use memblock to replace early_res
  x86, memblock: Use memblock_debug to control debug message print out
  ...

Fix up trivial conflicts in arch/x86/kernel/setup.c and kernel/Makefile

Signed-off-by: NAndrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

The new devctl func added for us to the driver has the wrong return
type.  Which is to say there shouldn't be any.  This fixes compile
time warnings as there shouldn't be any runtime difference.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Changed <module>-objs to <module>-y in Makefile.
Signed-off-by: NTracey Dent <tdent48227@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

ATA devices don't send D2H Reg FIS after an successful ATA PIO data-in
command.  The host is supposed to take the TF and E_Status of the
preceding PIO Setup FIS.  Update ahci_qc_fill_rtf() such that it takes
TF + E_Status from PIO Setup FIS after a successful ATA PIO data-in
command.

Without this patch, result_tf for such a command is filled with the
content of the previous D2H Reg FIS which belongs to a previous
command, which can make the command incorrectly seen as failed.

* Patch updated to grab the whole TF + E_Status from PIO Setup FIS
  instead of just E_Status as suggested by Robert Hancock.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NMark Lord <kernel@teksavvy.com>
Cc: Robert Hancock <hancockrwd@gmail.com>
Cc: stable@kernel.org
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

ICH4-L is a variant of ICH4 lacking USB2 functionality and with some
different device IDs.

It is documented in Intel specification update 290745-025, currently
at <http://www.intel.com/assets/pdf/specupdate/290745.pdf>, and is
included in the device ID table for piix.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

... since, of course, it's not used outside this driver.
Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Intel IDE-R devices are part of the Intel AMT management setup. They don't
have any special configuration registers or settings so the ata_generic
driver will support them fully.

Rather than add a huge table of IDs for each chipset and keep sending in
new ones this patch autodetects them.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Reorder structure ata_queued_cmd to remove 8 bytes of alignment padding
on 64 bit builds & therefore reduce the size of structure ata_port by
256 bytes.

Overall this will have little impact, other than reducing the amount of
memory that is cleared when allocating ata_ports.
Signed-off-by: NRichard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Until now identifying that a device supports WRITE SAME(16) with the
UNMAP bit set has been black magic.  Implement support for the SBC-3
Thin Provisioning VPD page and set the TPWS bit.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Now that libata provides proper cross-port EH exclusion.  The SIDPR
locking added by commit 213373cf (ata_piix: fix locking around SIDPR
access) is no longer necessary.  Remove it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

In libata, the non-EH code paths should always take and release
ap->lock explicitly when accessing hardware or shared data structures.
However, once EH is active, it's assumed that the port is owned by EH
and EH methods don't explicitly take ap->lock unless race from irq
handler or other code paths are expected.  However, libata EH didn't
guarantee exclusion among EHs for ports of the same host.  IOW,
multiple EHs may execute in parallel on multiple ports of the same
controller.

In many cases, especially in SATA, the ports are completely
independent of each other and this doesn't cause problems; however,
there are cases where different ports share the same resource, which
lead to obscure timing related bugs such as the one fixed by commit
213373cf (ata_piix: fix locking around SIDPR access).

This patch implements exclusion among EHs of the same host.  When EH
begins, it acquires per-host EH ownership by calling ata_eh_acquire().
When EH finishes, the ownership is released by calling
ata_eh_release().  EH ownership is also released whenever the EH
thread goes to sleep from ata_msleep() or explicitly and reacquired
after waking up.

This ensures that while EH is actively accessing the hardware, it has
exclusive access to it while allowing EHs to interleave and progress
in parallel as they hit waiting stages, which dominate the time spent
in EH.  This achieves cross-port EH exclusion without pervasive and
fragile changes while still allowing parallel EH for the most part.

This was first reported by yuanding02@gmail.com more than three years
ago in the following bugzilla.  :-)

  https://bugzilla.kernel.org/show_bug.cgi?id=8223Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Reported-by: yuanding02@gmail.com
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>