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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
tracing/urgent: warn in case of ftrace_start_up inbalance
tracing/urgent: fix unbalanced ftrace_start_up
function-graph: add stack frame test
function-graph: disable when both x86_32 and optimize for size are configured
ring-buffer: have benchmark test print to trace buffer
ring-buffer: do not grab locks in nmi
ring-buffer: add locks around rb_per_cpu_empty
ring-buffer: check for less than two in size allocation
ring-buffer: remove useless compile check for buffer_page size
ring-buffer: remove useless warn on check
ring-buffer: use BUF_PAGE_HDR_SIZE in calculating index
tracing: update sample event documentation
tracing/filters: fix race between filter setting and module unload
tracing/filters: free filter_string in destroy_preds()
ring-buffer: use commit counters for commit pointer accounting
ring-buffer: remove unused variable
ring-buffer: have benchmark test handle discarded events
ring-buffer: prevent adding write in discarded area
tracing/filters: strloc should be unsigned short
tracing/filters: operand can be negative
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Fix up kmemcheck-induced conflict in kernel/trace/ring_buffer.c manually
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (45 commits)
x86, mce: fix error path in mce_create_device()
x86: use zalloc_cpumask_var for mce_dev_initialized
x86: fix duplicated sysfs attribute
x86: de-assembler-ize asm/desc.h
i386: fix/simplify espfix stack switching, move it into assembly
i386: fix return to 16-bit stack from NMI handler
x86, ioapic: Don't call disconnect_bsp_APIC if no APIC present
x86: Remove duplicated #include's
x86: msr.h linux/types.h is only required for __KERNEL__
x86: nmi: Add Intel processor 0x6f4 to NMI perfctr1 workaround
x86, mce: mce_intel.c needs <asm/apic.h>
x86: apic/io_apic.c: dmar_msi_type should be static
x86, io_apic.c: Work around compiler warning
x86: mce: Don't touch THERMAL_APIC_VECTOR if no active APIC present
x86: mce: Handle banks == 0 case in K7 quirk
x86, boot: use .code16gcc instead of .code16
x86: correct the conversion of EFI memory types
x86: cap iomem_resource to addressable physical memory
x86, mce: rename _64.c files which are no longer 64-bit-specific
x86, mce: mce.h cleanup
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Manually fix up trivial conflict in arch/x86/mm/fault.c
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* 'for-linus' of git://git.monstr.eu/linux-2.6-microblaze:
microblaze: Add missing symbols for CONSTRUCTORS support
microblaze: remove init_mm
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (35 commits)
Input: add driver for Synaptics I2C touchpad
Input: synaptics - add support for reporting x/y resolution
Input: ALPS - handle touchpoints buttons correctly
Input: gpio-keys - change timer to workqueue
Input: ads7846 - pin change interrupt support
Input: add support for touchscreen on W90P910 ARM platform
Input: appletouch - improve finger detection
Input: wacom - clear Intuos4 wheel data when finger leaves proximity
Input: ucb1400 - move static function from header into core
Input: add driver for EETI touchpanels
Input: ads7846 - more detailed model name in sysfs
Input: ads7846 - support swapping x and y axes
Input: ati_remote2 - use non-atomic bitops
Input: introduce lm8323 keypad driver
Input: psmouse - ESD workaround fix for OLPC XO touchpad
Input: tsc2007 - make sure platform provides get_pendown_state()
Input: uinput - flush all pending ff effects before destroying device
Input: simplify name handling for certain input handles
Input: serio - do not use deprecated dev.power.power_state
Input: wacom - add support for Intuos4 tablets
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It's really not right to use 'access_ok()', since that is meant for the
normal "get_user()" and "copy_from/to_user()" accesses, which are done
through the TLB, rather than through the page tables.
Why? access_ok() does both too few, and too many checks. Too many,
because it is meant for regular kernel accesses that will not honor the
'user' bit in the page tables, and because it honors the USER_DS vs
KERNEL_DS distinction that we shouldn't care about in GUP. And too few,
because it doesn't do the 'canonical' check on the address on x86-64,
since the TLB will do that for us.
So instead of using a function that isn't meant for this, and does
something else and much more complicated, just do the real rules: we
don't want the range to overflow, and on x86-64, we want it to be a
canonical low address (on 32-bit, all addresses are canonical).
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit b99b87f70c7785ab1e253c6220f4b0b57ce3a7f7 add CONSTRUCTOR
support to Linux but Microblaze not defined KERNEL_CTORS symbols
which are used with that patch.
This patch fixed it.
Signed-off-by: Michal Simek <monstr@monstr.eu>
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Alexey removed the definition for init_mm from all architectures
but forgot microblaze, which was only recently added.
This fixes the microblaze build by dropping it there as well.
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michal Simek <monstr@monstr.eu>
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6:
sparc64: Fix UP bootup regression.
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git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (35 commits)
powerpc/5121: make clock debug output more readable
powerpc/5xxx: Add common mpc5xxx_get_bus_frequency() function
powerpc/5200: Update pcm030.dts to add i2c eeprom and delete cruft
powerpc/5200: convert mpc52xx_psc_spi to use cs_control callback
fbdev/xilinxfb: Fix improper casting and tighen up probe path
usb/ps3: Add missing annotations
powerpc: Add memory clobber to mtspr()
powerpc: Fix invalid construct in our CPU selection Kconfig
ps3rom: Use ps3_system_bus_[gs]et_drvdata() instead of direct access
powerpc: Add configurable -Werror for arch/powerpc
of_serial: Add UPF_FIXED_TYPE flag
drivers/hvc: Add missing __devexit_p()
net/ps3: gelic - Add missing annotations
powerpc: Introduce macro spin_event_timeout()
powerpc/warp: Fix ISA_DMA_THRESHOLD default
powerpc/bootwrapper: Custom build options for XPedite52xx targets
powerpc/85xx: Add defconfig for X-ES MPC85xx boards
powerpc/85xx: Add dts files for X-ES MPC85xx boards
powerpc/85xx: Add platform support for X-ES MPC85xx boards
83xx: add support for the kmeter1 board.
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git://git.kernel.org/pub/scm/linux/kernel/git/vapier/blackfin
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/vapier/blackfin:
Blackfin: convert page/tlb to asm-generic
Blackfin: convert types to asm-generic
Blackfin: convert irq/process to asm-generic
Blackfin: convert signal/mmap to asm-generic
Blackfin: convert locking primitives to asm-generic
Blackfin: convert termios to asm-generic
Blackfin: convert simple headers to asm-generic
Blackfin: convert socket/poll to asm-generic
Blackfin: convert user/elf to asm-generic
Blackfin: convert shm/sysv/ipc to asm-generic
Blackfin: convert asm/ioctls.h to asm-generic/ioctls.h
Blackfin: only build irqpanic.c when needed
Blackfin: pull in asm/io.h in ksyms for prototypes
Blackfin: use common test_bit() rather than __test_bit()
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This patch adds spi and mmc-spi-slot nodes, plus a gpio-controller for
PIXIS' sdcsr bank that is used for managing SPI chip-select and for
reading card's states.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: David Brownell <david-b@pacbell.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit b696fdc259f0d94348a9327bed352fac44d4883d ("sparc64: Defer
cpu_data() setup until end of per-cpu data initialization.") broke
bootup for UP builds because the cpu_data() initialization only
occurs in setup_per_cpu_areas() which is never compiled in nor
called in UP builds.
Fix this up by calling the setups directly from init_64.c when
non-SMP.
Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Tested-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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The irq_panic function is only used when CONFIG_DEBUG_ICACHE_CHECK is
enabled, so move the conditional build to the Makefile rather than
wrapping all of the contents of the file.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Make sure we pull in asm/io.h when exporting symbols for the I/O functions
so we don't end up with a build failure due to missing prototypes.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Convert to test_bit() as that is what pretty much everyone uses and allows
us to migrate asm/bitops.h to the asm-generic version.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.
An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.
This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.
There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.
This test detected the problem and pointed out where the issue was.
This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.
Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (56 commits)
sh: Fix declaration of __kernel_sigreturn and __kernel_rt_sigreturn
sh: Enable soc-camera in ap325rxa/migor/se7724 defconfigs.
sh: remove stray markers.
sh: defconfig updates.
sh: pci: Initial PCI-Express support for SH7786 Urquell board.
sh: Generic HAVE_PERF_COUNTER support.
SH: convert migor to soc-camera as platform-device
SH: convert ap325rxa to soc-camera as platform-device
soc-camera: unify i2c camera device platform data
sh: add platform data for r8a66597-hcd in setup-sh7723
sh: add platform data for r8a66597-hcd in setup-sh7366
sh: x3proto: add platform data for r8a66597-hcd
sh: highlander: add platform data for r8a66597-hcd
sh: sh7785lcr: add platform data for r8a66597-hcd
sh: turn off irqs when disabling CMT/TMU timers
sh: use kzalloc() for cpg clocks
sh: unbreak WARN_ON()
sh: Use generic atomic64_t implementation.
sh: Revised clock function in highlander
sh: Update r7780mp defconfig
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Add support for new relocs which may show up in MN10300 kernel modules due to
linker relaxation.
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc; "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc; "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Enable gcov profiling of the entire kernel on x86_64. Required changes
include disabling profiling for:
* arch/kernel/acpi/realmode and arch/kernel/boot/compressed:
not linked to main kernel
* arch/vdso, arch/kernel/vsyscall_64 and arch/kernel/hpet:
profiling causes segfaults during boot (incompatible context)
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Enable the use of GCC's coverage testing tool gcov [1] with the Linux
kernel. gcov may be useful for:
* debugging (has this code been reached at all?)
* test improvement (how do I change my test to cover these lines?)
* minimizing kernel configurations (do I need this option if the
associated code is never run?)
The profiling patch incorporates the following changes:
* change kbuild to include profiling flags
* provide functions needed by profiling code
* present profiling data as files in debugfs
Note that on some architectures, enabling gcc's profiling option
"-fprofile-arcs" for the entire kernel may trigger compile/link/
run-time problems, some of which are caused by toolchain bugs and
others which require adjustment of architecture code.
For this reason profiling the entire kernel is initially restricted
to those architectures for which it is known to work without changes.
This restriction can be lifted once an architecture has been tested
and found compatible with gcc's profiling. Profiling of single files
or directories is still available on all platforms (see config help
text).
[1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix up the number of cells for the values of CPC925 Memory Controller,
and setup related platform device during system booting up, against
which CPC925 Memory Controller EDAC driver would be matched.
Signed-off-by: Harry Ciao <qingtao.cao@windriver.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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m32r: PTRACE_SINGLESTEP sets PT_DTRACE, it is never used except cleared
after do_execve().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hirokazu Takata <takata@linux-m32r.org>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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m68k sets PT_DTRACE in trap_c() but never uses it.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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avr32, mn10300, parisc, s390, sh, xtensa:
They never set PT_DTRACE, but clear it after do_execve().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Chris Zankel <chris@zankel.net>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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h8300 defines PT_DTRACE for asm but never uses it.
DEFINE(PT_PTRACED, PT_PTRACED) seems to be unused too.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Don't skip removing mce_attrs in route from error2.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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GCC 4.5.0 complains about the declaration of variables
__kernel_sigreturn and __kernel_rt_sigreturn because they have type
void. Correctly declare these symbols as functions to fix the
following error,
arch/sh/kernel/signal_32.c: In function 'setup_frame':
arch/sh/kernel/signal_32.c:368:14: error: taking address of expression of type 'void'
arch/sh/kernel/signal_32.c: In function 'setup_rt_frame':
arch/sh/kernel/signal_32.c:452:14: error: taking address of expression of type 'void'
make[1]: *** [arch/sh/kernel/signal_32.o] Error 1
make: *** [arch/sh/kernel] Error 2
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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The MEDIA_SUPPORT option disabled soc-camera support, so re-enable it for
the impacted defconfigs.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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We need a cleared cpu_mask to record if mce is initialized, especially
when MAXSMP is used.
used zalloc_... instead
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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The sysfs attribute cmci_disabled was accidentall turned into a
duplicate of ignore_ce, breaking all other attributes.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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arch/sh has a couple of stray markers without any users introduced
in commit 3d58695edbfac785161bf282dc11fd42a483d6c9. Remove them in
preparation of removing the markers in favour of the TRACE_EVENT
macro (and also because we don't keep dead code around).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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asm/desc.h is included in three assembly files, but the only macro
it defines, GET_DESC_BASE, is never used. This patch removes the
includes, removes the macro GET_DESC_BASE and the ASSEMBLY guard
from asm/desc.h.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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The espfix code triggers if we have a protected mode userspace
application with a 16-bit stack. On returning to userspace, with iret,
the CPU doesn't restore the high word of the stack pointer. This is an
"official" bug, and the work-around used in the kernel is to temporarily
switch to a 32-bit stack segment/pointer pair where the high word of the
pointer is equal to the high word of the userspace stackpointer.
The current implementation uses THREAD_SIZE to determine the cut-off,
but there is no good reason not to use the more natural 64kb... However,
implementing this by simply substituting THREAD_SIZE with 65536 in
patch_espfix_desc crashed the test application. patch_espfix_desc tries
to do what is described above, but gets it subtly wrong if the userspace
stack pointer is just below a multiple of THREAD_SIZE: an overflow
occurs to bit 13... With a bit of luck, when the kernelspace
stackpointer is just below a 64kb-boundary, the overflow then ripples
trough to bit 16 and userspace will see its stack pointer changed by
65536.
This patch moves all espfix code into entry_32.S. Selecting a 16-bit
cut-off simplifies the code. The game with changing the limit dynamically
is removed too. It complicates matters and I see no value in it. Changing
only the top 16-bit word of ESP is one instruction and it also implies
that only two bytes of the ESPFIX GDT entry need to be changed and this
can be implemented in just a handful simple to understand instructions.
As a side effect, the operation to compute the original ESP from the
ESPFIX ESP and the GDT entry simplifies a bit too, and the remaining
three instructions have been expanded inline in entry_32.S.
impact: can now reliably run userspace with ESP=xxxxfffc on 16-bit
stack segment
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Acked-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Returning to a task with a 16-bit stack requires special care: the iret
instruction does not restore the high word of esp in that case. The
espfix code fixes this, but currently is not invoked on NMIs. This means
that a running task gets the upper word of esp clobbered due intervening
NMIs. To reproduce, compile and run the following program with the nmi
watchdog enabled (nmi_watchdog=2 on the command line). Using gdb you can
see that the high bits of esp contain garbage, while the low bits are
still correct.
This patch puts the espfix code back into the NMI code path.
The patch is slightly complicated due to the irqtrace infrastructure not
being NMI-safe. The NMI return path cannot call TRACE_IRQS_IRET.
Otherwise, the tail of the normal iret-code is correct for the nmi code
path too. To be able to share this code-path, the TRACE_IRQS_IRET was
move up a bit. The espfix code exists after the TRACE_IRQS_IRET, but
this code explicitly disables interrupts. This short interrupts-off
section is now not traced anymore. The return-to-kernel path now always
includes the preliminary test to decide if the espfix code should be
called. This is never the case, but doing it this way keeps the patch as
simple as possible and the few extra instructions should not affect
timing in any significant way.
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/ldt.h>
int modify_ldt(int func, void *ptr, unsigned long bytecount)
{
return syscall(SYS_modify_ldt, func, ptr, bytecount);
}
/* this is assumed to be usable */
#define SEGBASEADDR 0x10000
#define SEGLIMIT 0x20000
/* 16-bit segment */
struct user_desc desc = {
.entry_number = 0,
.base_addr = SEGBASEADDR,
.limit = SEGLIMIT,
.seg_32bit = 0,
.contents = 0, /* ??? */
.read_exec_only = 0,
.limit_in_pages = 0,
.seg_not_present = 0,
.useable = 1
};
int main(void)
{
setvbuf(stdout, NULL, _IONBF, 0);
/* map a 64 kb segment */
char *pointer = mmap((void *)SEGBASEADDR, SEGLIMIT+1,
PROT_EXEC|PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_ANONYMOUS, -1, 0);
if (pointer == NULL) {
printf("could not map space\n");
return 0;
}
/* write ldt, new mode */
int err = modify_ldt(0x11, &desc, sizeof(desc));
if (err) {
printf("error modifying ldt: %i\n", err);
return 0;
}
for (int i=0; i<1000; i++) {
asm volatile (
"pusha\n\t"
"mov %ss, %eax\n\t" /* preserve ss:esp */
"mov %esp, %ebp\n\t"
"push $7\n\t" /* index 0, ldt, user mode */
"push $65536-4096\n\t" /* esp */
"lss (%esp), %esp\n\t" /* switch to new stack */
"push %eax\n\t" /* save old ss:esp on new stack */
"push %ebp\n\t"
"add $17*65536, %esp\n\t" /* set high bits */
"mov %esp, %edx\n\t"
"mov $10000000, %ecx\n\t" /* wait... */
"1: loop 1b\n\t" /* ... a bit */
"cmp %esp, %edx\n\t"
"je 1f\n\t"
"ud2\n\t" /* esp changed inexplicably! */
"1:\n\t"
"sub $17*65536, %esp\n\t" /* restore high bits */
"lss (%esp), %esp\n\t" /* restore old ss:esp */
"popa\n\t");
printf("\rx%ix", i);
}
return 0;
}
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Acked-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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