The s390 idle accounting code uses a sequence counter which gets used
when the per cpu idle statistics get updated and read.
One assumption on read access is that only when the sequence counter is
even and did not change while reading all values the result is valid.
On cpu hotplug however the per cpu data structure gets initialized via
a cpu hotplug notifier on CPU_ONLINE.
CPU_ONLINE however is too late, since the onlined cpu is already running
and might access the per cpu data. Worst case is that the data structure
gets initialized while an idle thread is updating its idle statistics.
This will result in an uneven sequence counter after an update.
As a result user space tools like top, which access /proc/stat in order
to get idle stats, will busy loop waiting for the sequence counter to
become even again, which will never happen until the queried cpu will
update its idle statistics again. And even then the sequence counter
will only have an even value for a couple of cpu cycles.
Fix this by moving the initialization of the per cpu idle statistics
to cpu_init(). I prefer that solution in favor of changing the
notifier to CPU_UP_PREPARE, which would be a different solution to
the problem.
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
With git commit 85fe4025c6 ("fs: do not
assign default i_ino in new_inode") the get_next_ino() function was
moved from the new_inode() to the different file system implementations.
Unfortunately hypfs has been overlooked by the author. With this
patch the get_next_ino() is added also to hypfs.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Fix problem that was introduced with patch "s390/smp: make absolute
lowcore / cpu restart parameter". After that patch the "dumpreipl"
shutdown action does not work any more. To fix the problem we have
to assign "reipl_block_actual" instead of "&reipl_block_actual"
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Setting the cpu restart parameters is done in three different fashions:
- directly setting the four parameters individually
- copying the four parameters with memcpy (using 4 * sizeof(long))
- copying the four parameters using a private structure
In addition code in entry*.S relies on a certain order of the restart
members of struct _lowcore.
Make all of this more robust to future changes by adding a
mem_absolute_assign(dest, val) define, which assigns val to dest
using absolute addressing mode. Also the load multiple instructions
in entry*.S have been split into separate load instruction so the
order of the struct _lowcore members doesn't matter anymore.
In addition move the prototypes of memcpy_real/absolute from uaccess.h
to processor.h. These memcpy* variants are not related to uaccess at all.
string.h doesn't seem to match as well, so lets use processor.h.
Also replace the eight byte array in struct _lowcore which represents a
misaliged u64 with a u64. The compiler will always create code that
handles the misaligned u64 correctly.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The creator_id is no longer used. Just get rid of it.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Use sigp order code defines in assembly code as well.
With this change all places that use sigp constants should
have been converted to use self describing defines instead
of directly using constants.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
We got them from the kvm code, so let's use them.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The smp and the kvm code have different defines for the sigp order codes.
Let's just have a single place where these are defined.
Also move the sigp condition code and sigp cpu status bits to the new
sigp.h header file.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
condition code "status stored" for sigp sense running always implies
that only the "not running" status bit is set. Therefore no need to
check if it is set.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
After
commit 5e8010cb50
s390: replace TIF_SIE with PF_VCPU
there is no need to load the thread info before sie_loop where
it is also loaded.
Get rid of this duplicate instruction.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Pull timer updates from Thomas Gleixner:
"The clocksource driver is pure hardware enablement and the skew option
is default off, well tested and non dangerous."
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick: Move skew_tick option into the HIGH_RES_TIMER section
clocksource: em_sti: Add DT support
clocksource: em_sti: Emma Mobile STI driver
clockevents: Make clockevents_config() a global symbol
tick: Add tick skew boot option
Pull straggler x86 fixes from Peter Anvin:
"Three groups of patches:
- EFI boot stub documentation and the ability to print error messages;
- Removal for PTRACE_ARCH_PRCTL for x32 (obsolete interface which
should never have been ported, and the port is broken and
potentially dangerous.)
- ftrace stack corruption fixes. I'm not super-happy about the
technical implementation, but it is probably the least invasive in
the short term. In the future I would like a single method for
nesting the debug stack, however."
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, x32, ptrace: Remove PTRACE_ARCH_PRCTL for x32
x86, efi: Add EFI boot stub documentation
x86, efi; Add EFI boot stub console support
x86, efi: Only close open files in error path
ftrace/x86: Do not change stacks in DEBUG when calling lockdep
x86: Allow nesting of the debug stack IDT setting
x86: Reset the debug_stack update counter
ftrace: Use breakpoint method to update ftrace caller
ftrace: Synchronize variable setting with breakpoints
Pull vfs fix and a fix from the signal changes for frv from Al Viro.
The __kernel_nlink_t for powerpc got scrogged because 64-bit powerpc
actually depended on the default "unsigned long", while 32-bit powerpc
had an explicit override to "unsigned short". Al didn't notice, and
made both of them be the unsigned short.
The frv signal fix is fallout from simplifying the do_notify_resume()
code, and leaving an extra parenthesis.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
powerpc: Fix size of st_nlink on 64bit
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
frv: Remove bogus closing parenthesis
commit e57f93cc53 (powerpc: get rid of nlink_t uses, switch to
explicitly-sized type) changed the size of st_nlink on ppc64 from
a long to a short, resulting in boot failures.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduced by commit 6fd84c0831
("TIF_RESTORE_SIGMASK can be set only when TIF_SIGPENDING is set")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
It includes:
- driver for AUO-K1900 and AUO-K1901 epaper controller
- large updates for OMAP (e.g. decouple HDMI audio and video)
- some updates for Exynos and SH Mobile
- various other small fixes and cleanups
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Merge tag 'fbdev-updates-for-3.5' of git://github.com/schandinat/linux-2.6
Pull fbdev updates from Florian Tobias Schandinat:
- driver for AUO-K1900 and AUO-K1901 epaper controller
- large updates for OMAP (e.g. decouple HDMI audio and video)
- some updates for Exynos and SH Mobile
- various other small fixes and cleanups
* tag 'fbdev-updates-for-3.5' of git://github.com/schandinat/linux-2.6: (130 commits)
video: bfin_adv7393fb: Fix cleanup code
video: exynos_dp: reduce delay time when configuring video setting
video: exynos_dp: move sw reset prioir to enabling sw defined function
video: exynos_dp: use devm_ functions
fb: handle NULL pointers in framebuffer release
OMAPDSS: HDMI: OMAP4: Update IRQ flags for the HPD IRQ request
OMAPDSS: Apply VENC timings even if panel is disabled
OMAPDSS: VENC/DISPC: Delay dividing Y resolution for managers connected to VENC
OMAPDSS: DISPC: Support rotation through TILER
OMAPDSS: VRFB: remove compiler warnings when CONFIG_BUG=n
OMAPFB: remove compiler warnings when CONFIG_BUG=n
OMAPDSS: remove compiler warnings when CONFIG_BUG=n
OMAPDSS: DISPC: fix usage of dispc_ovl_set_accu_uv
OMAPDSS: use DSI_FIFO_BUG workaround only for manual update displays
OMAPDSS: DSI: Support command mode interleaving during video mode blanking periods
OMAPDSS: DISPC: Update Accumulator configuration for chroma plane
drivers/video: fsl-diu-fb: don't initialize the THRESHOLDS registers
video: exynos mipi dsi: support reverse panel type
video: exynos mipi dsi: Properly interpret the interrupt source flags
video: exynos mipi dsi: Avoid races in probe()
...
- Updates to mxc_nand and gpmi drivers to support new boards and device tree
- Improve consistency of information about ECC strength in NAND devices
- Clean up partition handling of plat_nand
- Support NAND drivers without dedicated access to OOB area
- BCH hardware ECC support for OMAP
- Other fixes and cleanups, and a few new device IDs
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Merge tag 'for-linus-3.5-20120601' of git://git.infradead.org/linux-mtd
Pull mtd update from David Woodhouse:
- More robust parsing especially of xattr data in JFFS2
- Updates to mxc_nand and gpmi drivers to support new boards and device tree
- Improve consistency of information about ECC strength in NAND devices
- Clean up partition handling of plat_nand
- Support NAND drivers without dedicated access to OOB area
- BCH hardware ECC support for OMAP
- Other fixes and cleanups, and a few new device IDs
Fixed trivial conflict in drivers/mtd/nand/gpmi-nand/gpmi-nand.c due to
added include files next to each other.
* tag 'for-linus-3.5-20120601' of git://git.infradead.org/linux-mtd: (75 commits)
mtd: mxc_nand: move ecc strengh setup before nand_scan_tail
mtd: block2mtd: fix recursive call of mtd_writev
mtd: gpmi-nand: define ecc.strength
mtd: of_parts: fix breakage in Kconfig
mtd: nand: fix scan_read_raw_oob
mtd: docg3 fix in-middle of blocks reads
mtd: cfi_cmdset_0002: Slight cleanup of fixup messages
mtd: add fixup for S29NS512P NOR flash.
jffs2: allow to complete xattr integrity check on first GC scan
jffs2: allow to discriminate between recoverable and non-recoverable errors
mtd: nand: omap: add support for hardware BCH ecc
ARM: OMAP3: gpmc: add BCH ecc api and modes
mtd: nand: check the return code of 'read_oob/read_oob_raw'
mtd: nand: remove 'sndcmd' parameter of 'read_oob/read_oob_raw'
mtd: m25p80: Add support for Winbond W25Q80BW
jffs2: get rid of jffs2_sync_super
jffs2: remove unnecessary GC pass on sync
jffs2: remove unnecessary GC pass on umount
jffs2: remove lock_super
mtd: gpmi: add gpmi support for mx6q
...
Pull arm fixes for ux500 mismerge mishap from Arnd Bergmann:
"The device tree conversion for arm/ux500 in 3.5 turns out to be
incomplete because of a mismerge done by Linus Walleij that I failed
to notice early enough and that Lee Jones as the original author of
those patches did not manage to fix during the -next cycle. While we
originally to get a much larger set of ux500 device tree enablement
patches merged, this did not happen in time.
After some discussion at Linaro Connect conference this week, Lee has
been able to do damage control and provide a series to put the broken
platform back into usable shape for both DT and non-DT based booting.
This series has not been part of linux-next and is based on top of the
current state of the upstream kernel rather than an -rc, but this is
the best we could manage given the earlier breakage."
* 'ux500/hickup' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
ARM: ux500: Enable probing of pinctrl through Device Tree
ARM: ux500: Add support for ab8500 regulators into the Device Tree
ARM: ux500: Provide regulator support for SMSC911x via Device Tree
ARM: ux500: Allow PRCMU regulator to be probed during a DT enabled boot
ARM: ux500: Apply db8500-prcmu regulator information to db8500 Device Tree
ARM: ux500: Only initialise STE's UIBs on boards which support them
ARM: ux500: Disable platform setup of the ab8500 when DT is enabled
ARM: ux500: Use correct format for dynamic IRQ assignment
ARM: ux500: Re-enable SMSC911x platform code registration during non-DT boots
ARM: ux500: PRCMU related configuration and layout corrections for Device Tree
ARM: ux500: Remove DB8500 PRCMU platform registration when DT is enabled
ARM: ux500: Disable SMSC911x platform code registration when DT is enabled
ARM: ux500: New DT:ed u8500_init_devices for one-by-one device enablement
ARM: ux500: New DT:ed snowball_platform_devs for one-by-one device enablement
pinctrl-nomadik: Allow Device Tree driver probing
When I added x32 ptrace to 3.4 kernel, I also include PTRACE_ARCH_PRCTL
support for x32 GDB For ARCH_GET_FS/GS, it takes a pointer to int64. But
at user level, ARCH_GET_FS/GS takes a pointer to int32. So I have to add
x32 ptrace to glibc to handle it with a temporary int64 passed to kernel and
copy it back to GDB as int32. Roland suggested that PTRACE_ARCH_PRCTL
is obsolete and x32 GDB should use fs_base and gs_base fields of
user_regs_struct instead.
Accordingly, remove PTRACE_ARCH_PRCTL completely from the x32 code to
avoid possible memory overrun when pointer to int32 is passed to
kernel.
Link: http://lkml.kernel.org/r/CAMe9rOpDzHfS7NH7m1vmD9QRw8SSj4Sc%2BaNOgcWm_WJME2eRsQ@mail.gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org> v3.4
Pull third pile of signal handling patches from Al Viro:
"This time it's mostly helpers and conversions to them; there's a lot
of stuff remaining in the tree, but that'll either go in -rc2
(isolated bug fixes, ideally via arch maintainers' trees) or will sit
there until the next cycle."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
x86: get rid of calling do_notify_resume() when returning to kernel mode
blackfin: check __get_user() return value
whack-a-mole with TIF_FREEZE
FRV: Optimise the system call exit path in entry.S [ver #2]
FRV: Shrink TIF_WORK_MASK [ver #2]
FRV: Prevent syscall exit tracing and notify_resume at end of kernel exceptions
new helper: signal_delivered()
powerpc: get rid of restore_sigmask()
most of set_current_blocked() callers want SIGKILL/SIGSTOP removed from set
set_restore_sigmask() is never called without SIGPENDING (and never should be)
TIF_RESTORE_SIGMASK can be set only when TIF_SIGPENDING is set
don't call try_to_freeze() from do_signal()
pull clearing RESTORE_SIGMASK into block_sigmask()
sh64: failure to build sigframe != signal without handler
openrisc: tracehook_signal_handler() is supposed to be called on success
new helper: sigmask_to_save()
new helper: restore_saved_sigmask()
new helpers: {clear,test,test_and_clear}_restore_sigmask()
HAVE_RESTORE_SIGMASK is defined on all architectures now
Pull vfs changes from Al Viro.
"A lot of misc stuff. The obvious groups:
* Miklos' atomic_open series; kills the damn abuse of
->d_revalidate() by NFS, which was the major stumbling block for
all work in that area.
* ripping security_file_mmap() and dealing with deadlocks in the
area; sanitizing the neighborhood of vm_mmap()/vm_munmap() in
general.
* ->encode_fh() switched to saner API; insane fake dentry in
mm/cleancache.c gone.
* assorted annotations in fs (endianness, __user)
* parts of Artem's ->s_dirty work (jff2 and reiserfs parts)
* ->update_time() work from Josef.
* other bits and pieces all over the place.
Normally it would've been in two or three pull requests, but
signal.git stuff had eaten a lot of time during this cycle ;-/"
Fix up trivial conflicts in Documentation/filesystems/vfs.txt (the
'truncate_range' inode method was removed by the VM changes, the VFS
update adds an 'update_time()' method), and in fs/btrfs/ulist.[ch] (due
to sparse fix added twice, with other changes nearby).
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (95 commits)
nfs: don't open in ->d_revalidate
vfs: retry last component if opening stale dentry
vfs: nameidata_to_filp(): don't throw away file on error
vfs: nameidata_to_filp(): inline __dentry_open()
vfs: do_dentry_open(): don't put filp
vfs: split __dentry_open()
vfs: do_last() common post lookup
vfs: do_last(): add audit_inode before open
vfs: do_last(): only return EISDIR for O_CREAT
vfs: do_last(): check LOOKUP_DIRECTORY
vfs: do_last(): make ENOENT exit RCU safe
vfs: make follow_link check RCU safe
vfs: do_last(): use inode variable
vfs: do_last(): inline walk_component()
vfs: do_last(): make exit RCU safe
vfs: split do_lookup()
Btrfs: move over to use ->update_time
fs: introduce inode operation ->update_time
reiserfs: get rid of resierfs_sync_super
reiserfs: mark the superblock as dirty a bit later
...
If we end up calling do_notify_resume() with !user_mode(refs), it
does nothing (do_signal() explicitly bails out and we can't get there
with TIF_NOTIFY_RESUME in such situations). Then we jump to
resume_userspace_sig, which rechecks the same thing and bails out
to resume_kernel, thus breaking the loop.
It's easier and cheaper to check *before* calling do_notify_resume()
and bail out to resume_kernel immediately. And kill the check in
do_signal()...
Note that on amd64 we can't get there with !user_mode() at all - asm
glue takes care of that.
Acked-and-reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Optimise the system call exit path in entry.S by packing some instructions.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Shrink TIF_WORK_MASK so that it will fit in the 12-bit signed immediate
operand field of an ANDI instruction.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Move the test for kernel mode processing from do_signal() into entry.S to also
prevent system call exit tracing and userspace resumption notification handling
happening when returning from kernel exceptions.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Does block_sigmask() + tracehook_signal_handler(); called when
sigframe has been successfully built. All architectures converted
to it; block_sigmask() itself is gone now (merged into this one).
I'm still not too happy with the signature, but that's a separate
story (IMO we need a structure that would contain signal number +
siginfo + k_sigaction, so that get_signal_to_deliver() would fill one,
signal_delivered(), handle_signal() and probably setup...frame() -
take one).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Only 3 out of 63 do not. Renamed the current variant to __set_current_blocked(),
added set_current_blocked() that will exclude unblockable signals, switched
open-coded instances to it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
replace boilerplate "should we use ->saved_sigmask or ->blocked?"
with calls of obvious inlined helper...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
first fruits of ..._restore_sigmask() helpers: now we can take
boilerplate "signal didn't have a handler, clear RESTORE_SIGMASK
and restore the blocked mask from ->saved_mask" into a common
helper. Open-coded instances switched...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since we can't expect every user to read the EFI boot stub code it
seems prudent to have a couple of paragraphs explaining what it is and
how it works.
The "initrd=" option in particular is tricky because it only
understands absolute EFI-style paths (backslashes as directory
separators), and until now this hasn't been documented anywhere. This
has tripped up a couple of users.
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-4-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
We need a way of printing useful messages to the user, for example
when we fail to open an initrd file, instead of just hanging the
machine without giving the user any indication of what went wrong. So
sprinkle some error messages throughout the EFI boot stub code to make
it easier for users to diagnose/report problems.
Reported-by: Keshav P R <the.ridikulus.rat@gmail.com>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-3-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The loop at the 'close_handles' label in handle_ramdisks() should be
using 'i', which represents the number of initrd files that were
successfully opened, not 'nr_initrds' which is the number of initrd=
arguments passed on the command line.
Currently, if we execute the loop to close all file handles and we
failed to open any initrds we'll try to call the close function on a
garbage pointer, causing the machine to hang.
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-2-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
When both DYNAMIC_FTRACE and LOCKDEP are set, the TRACE_IRQS_ON/OFF
will call into the lockdep code. The lockdep code can call lots of
functions that may be traced by ftrace. When ftrace is updating its
code and hits a breakpoint, the breakpoint handler will call into
lockdep. If lockdep happens to call a function that also has a breakpoint
attached, it will jump back into the breakpoint handler resetting
the stack to the debug stack and corrupt the contents currently on
that stack.
The 'do_sym' call that calls do_int3() is protected by modifying the
IST table to point to a different location if another breakpoint is
hit. But the TRACE_IRQS_OFF/ON are outside that protection, and if
a breakpoint is hit from those, the stack will get corrupted, and
the kernel will crash:
[ 1013.243754] BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
[ 1013.272665] IP: [<ffff880145cc0000>] 0xffff880145cbffff
[ 1013.285186] PGD 1401b2067 PUD 14324c067 PMD 0
[ 1013.298832] Oops: 0010 [#1] PREEMPT SMP
[ 1013.310600] CPU 2
[ 1013.317904] Modules linked in: ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables crc32c_intel ghash_clmulni_intel microcode usb_debug serio_raw pcspkr iTCO_wdt i2c_i801 iTCO_vendor_support e1000e nfsd nfs_acl auth_rpcgss lockd sunrpc i915 video i2c_algo_bit drm_kms_helper drm i2c_core [last unloaded: scsi_wait_scan]
[ 1013.401848]
[ 1013.407399] Pid: 112, comm: kworker/2:1 Not tainted 3.4.0+ #30
[ 1013.437943] RIP: 8eb8:[<ffff88014630a000>] [<ffff88014630a000>] 0xffff880146309fff
[ 1013.459871] RSP: ffffffff8165e919:ffff88014780f408 EFLAGS: 00010046
[ 1013.477909] RAX: 0000000000000001 RBX: ffffffff81104020 RCX: 0000000000000000
[ 1013.499458] RDX: ffff880148008ea8 RSI: ffffffff8131ef40 RDI: ffffffff82203b20
[ 1013.521612] RBP: ffffffff81005751 R08: 0000000000000000 R09: 0000000000000000
[ 1013.543121] R10: ffffffff82cdc318 R11: 0000000000000000 R12: ffff880145cc0000
[ 1013.564614] R13: ffff880148008eb8 R14: 0000000000000002 R15: ffff88014780cb40
[ 1013.586108] FS: 0000000000000000(0000) GS:ffff880148000000(0000) knlGS:0000000000000000
[ 1013.609458] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 1013.627420] CR2: 0000000000000002 CR3: 0000000141f10000 CR4: 00000000001407e0
[ 1013.649051] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1013.670724] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 1013.692376] Process kworker/2:1 (pid: 112, threadinfo ffff88013fe0e000, task ffff88014020a6a0)
[ 1013.717028] Stack:
[ 1013.724131] ffff88014780f570 ffff880145cc0000 0000400000004000 0000000000000000
[ 1013.745918] cccccccccccccccc ffff88014780cca8 ffffffff811072bb ffffffff81651627
[ 1013.767870] ffffffff8118f8a7 ffffffff811072bb ffffffff81f2b6c5 ffffffff81f11bdb
[ 1013.790021] Call Trace:
[ 1013.800701] Code: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a <e7> d7 64 81 ff ff ff ff 01 00 00 00 00 00 00 00 65 d9 64 81 ff
[ 1013.861443] RIP [<ffff88014630a000>] 0xffff880146309fff
[ 1013.884466] RSP <ffff88014780f408>
[ 1013.901507] CR2: 0000000000000002
The solution was to reuse the NMI functions that change the IDT table to make the debug
stack keep its current stack (in kernel mode) when hitting a breakpoint:
call debug_stack_set_zero
TRACE_IRQS_ON
call debug_stack_reset
If the TRACE_IRQS_ON happens to hit a breakpoint then it will keep the current stack
and not crash the box.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the NMI handler runs, it checks if it preempted a debug handler
and if that handler is using the debug stack. If it is, it changes the
IDT table not to update the stack, otherwise it will reset the debug
stack and corrupt the debug handler it preempted.
Now that ftrace uses breakpoints to change functions from nops to
callers, many more places may hit a breakpoint. Unfortunately this
includes some of the calls that lockdep performs. Which causes issues
with the debug stack. It too needs to change the debug stack before
tracing (if called from the debug handler).
Allow the debug_stack_set_zero() and debug_stack_reset() to be nested
so that the debug handlers can take advantage of them too.
[ Used this_cpu_*() over __get_cpu_var() as suggested by H. Peter Anvin ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When an NMI goes off and it sees that it preempted the debug stack,
to keep the debug stack safe, it changes the IDT to point to one that
does not modify the stack on breakpoint (to allow breakpoints in NMIs).
But the variable that gets set to know to undo it on exit never gets
cleared on exit. Thus every NMI will reset it on exit the first time
it is done even if it does not need to be reset.
[ Added H. Peter Anvin's suggestion to use this_cpu_read/write ]
Cc: <stable@vger.kernel.org> # v3.3
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On boot up and module load, it is fine to modify the code directly,
without the use of breakpoints. This is because boot up modification
is done before SMP is initialized, thus the modification is serial,
and module load is done before the module executes.
But after that we must use a SMP safe method to modify running code.
Otherwise, if we are running the function tracer and update its
function (by starting off the stack tracer, or perf tracing)
the change of the function called by the ftrace trampoline is done
directly. If this is being executed on another CPU, that CPU may
take a GPF and crash the kernel.
The breakpoint method is used to change the nops at all the functions, but
the change of the ftrace callback handler itself was still using a
direct modification. If tracing was enabled and the function callback
was changed then another CPU could fault if it was currently calling
the original callback. This modification must use the breakpoint method
too.
Note, the direct method is still used for boot up and module load.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the function tracer starts modifying the code via breakpoints
it sets a variable (modifying_ftrace_code) to inform the breakpoint
handler to call the ftrace int3 code.
But there's no synchronization between setting this code and the
handler, thus it is possible for the handler to be called on another
CPU before it sees the variable. This will cause a kernel crash as
the int3 handler will not know what to do with it.
I originally added smp_mb()'s to force the visibility of the variable
but H. Peter Anvin suggested that I just make it atomic.
[ Added comments as suggested by Peter Zijlstra ]
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull second pile of signal handling patches from Al Viro:
"This one is just task_work_add() series + remaining prereqs for it.
There probably will be another pull request from that tree this
cycle - at least for helpers, to get them out of the way for per-arch
fixes remaining in the tree."
Fix trivial conflict in kernel/irq/manage.c: the merge of Andrew's pile
had brought in commit 97fd75b7b8 ("kernel/irq/manage.c: use the
pr_foo() infrastructure to prefix printks") which changed one of the
pr_err() calls that this merge moves around.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
keys: kill task_struct->replacement_session_keyring
keys: kill the dummy key_replace_session_keyring()
keys: change keyctl_session_to_parent() to use task_work_add()
genirq: reimplement exit_irq_thread() hook via task_work_add()
task_work_add: generic process-context callbacks
avr32: missed _TIF_NOTIFY_RESUME on one of do_notify_resume callers
parisc: need to check NOTIFY_RESUME when exiting from syscall
move key_repace_session_keyring() into tracehook_notify_resume()
TIF_NOTIFY_RESUME is defined on all targets now
