linux.git/arch/arm/kernel/entry-armv.S, branch v3.12 Linux kernel source tree ARM: Fix !kuser helpers case 2013-08-07T13:00:11+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-08-06T08:48:42+00:00 1b16c4bcf80e319b2226a886b72b8466179c8e3a Fix yet another build failure caused by a weird set of configuration settings: LD init/built-in.o arch/arm/kernel/built-in.o: In function `__dabt_usr': /home/tom3q/kernel/arch/arm/kernel/entry-armv.S:377: undefined reference to `kuser_cmpxchg64_fixup' arch/arm/kernel/built-in.o: In function `__irq_usr': /home/tom3q/kernel/arch/arm/kernel/entry-armv.S:387: undefined reference to `kuser_cmpxchg64_fixup' caused by: CONFIG_KUSER_HELPERS=n CONFIG_CPU_32v6K=n CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG=n Reported-by: Tomasz Figa <tomasz.figa@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Fix yet another build failure caused by a weird set of configuration
settings:

  LD      init/built-in.o
arch/arm/kernel/built-in.o: In function `__dabt_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:377: undefined reference to `kuser_cmpxchg64_fixup'
arch/arm/kernel/built-in.o: In function `__irq_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:387: undefined reference to `kuser_cmpxchg64_fixup'

caused by:
CONFIG_KUSER_HELPERS=n
CONFIG_CPU_32v6K=n
CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG=n

Reported-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: allow kuser helpers to be removed from the vector page 2013-07-31T21:01:48+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-07-23T17:37:00+00:00 f6f91b0d9fd971c630cef908dde8fe8795aefbf8 Provide a kernel configuration option to allow the kernel user helpers to be removed from the vector page, thereby preventing their use with ROP (return orientated programming) attacks. This option is only visible for CPU architectures which natively support all the operations which kernel user helpers would normally provide, and must be enabled with caution. Cc: <stable@vger.kernel.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Provide a kernel configuration option to allow the kernel user helpers
to be removed from the vector page, thereby preventing their use with
ROP (return orientated programming) attacks.  This option is only
visible for CPU architectures which natively support all the operations
which kernel user helpers would normally provide, and must be enabled
with caution.

Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: update FIQ support for relocation of vectors 2013-07-31T20:34:56+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-07-09T00:03:17+00:00 e39e3f3ebfef03450cf7bfa7a974a8c61f7980c8 FIQ should no longer copy the FIQ code into the user visible vector page. Instead, it should use the hidden page. This change makes that happen. Cc: <stable@vger.kernel.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
FIQ should no longer copy the FIQ code into the user visible vector
page.  Instead, it should use the hidden page.  This change makes
that happen.

Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: use linker magic for vectors and vector stubs 2013-07-31T20:34:24+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-07-04T11:03:31+00:00 b9b32bf70f2fb710b07c94e13afbc729afe221da Use linker magic to create the vectors and vector stubs: we can tell the linker to place them at an appropriate VMA, but keep the LMA within the kernel. This gets rid of some unnecessary symbol manipulation, and have the linker calculate the relocations appropriately. Cc: <stable@vger.kernel.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Use linker magic to create the vectors and vector stubs: we can tell the
linker to place them at an appropriate VMA, but keep the LMA within the
kernel.  This gets rid of some unnecessary symbol manipulation, and
have the linker calculate the relocations appropriately.

Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: move vector stubs 2013-07-31T20:31:36+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-07-04T10:40:32+00:00 19accfd373847ac3d10623c5d20f948846299741 Move the machine vector stubs into the page above the vector page, which we can prevent from being visible to userspace. Also move the reset stub, and place the swi vector at a location that the 'ldr' can get to it. This hides pointers into the kernel which could give valuable information to attackers, and reduces the number of exploitable instructions at a fixed address. Cc: <stable@vger.kernel.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Move the machine vector stubs into the page above the vector page,
which we can prevent from being visible to userspace.  Also move
the reset stub, and place the swi vector at a location that the
'ldr' can get to it.

This hides pointers into the kernel which could give valuable
information to attackers, and reduces the number of exploitable
instructions at a fixed address.

Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: poison memory between kuser helpers 2013-07-31T20:31:09+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-07-04T10:32:04+00:00 5b43e7a383d69381ffe53423e46dd0fafae07da3 Poison the memory between each kuser helper. This ensures that any branch between the kuser helpers will be appropriately trapped. Cc: <stable@vger.kernel.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Poison the memory between each kuser helper.  This ensures that any
branch between the kuser helpers will be appropriately trapped.

Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7735/2: Preserve the user r/w register TPIDRURW on context switch and fork 2013-06-24T14:21:59+00:00 André Hentschel nerv@dawncrow.de 2013-06-18T22:23:26+00:00 a4780adeefd042482f624f5e0d577bf9cdcbb760 Since commit 6a1c53124aa1 the user writeable TLS register was zeroed to prevent it from being used as a covert channel between two tasks. There are more and more applications coming to Windows RT, Wine could support them, but mostly they expect to have the thread environment block (TEB) in TPIDRURW. This patch preserves that register per thread instead of clearing it. Unlike the TPIDRURO, which is already switched, the TPIDRURW can be updated from userspace so needs careful treatment in the case that we modify TPIDRURW and call fork(). To avoid this we must always read TPIDRURW in copy_thread. Signed-off-by: André Hentschel <nerv@dawncrow.de> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Jonathan Austin <jonathan.austin@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Since commit 6a1c53124aa1 the user writeable TLS register was zeroed to
prevent it from being used as a covert channel between two tasks.

There are more and more applications coming to Windows RT,
Wine could support them, but mostly they expect to have
the thread environment block (TEB) in TPIDRURW.

This patch preserves that register per thread instead of clearing it.
Unlike the TPIDRURO, which is already switched, the TPIDRURW
can be updated from userspace so needs careful treatment in the case that we
modify TPIDRURW and call fork(). To avoid this we must always read
TPIDRURW in copy_thread.

Signed-off-by: André Hentschel <nerv@dawncrow.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Merge branch 'cleanup' into for-linus 2013-05-02T20:31:29+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-05-02T20:31:29+00:00 33b9f582c5c1db515412cc7efff28f7d1779321f Conflicts: arch/arm/plat-omap/dmtimer.c 
Conflicts:
	arch/arm/plat-omap/dmtimer.c
Merge branches 'devel-stable', 'entry', 'fixes', 'mach-types', 'misc' and 'smp-hotplug' into for-linus 2013-05-02T20:30:36+00:00 Russell King rmk+kernel@arm.linux.org.uk 2013-05-02T20:30:36+00:00 946342d03ec4e8367bba7bb99e7155e97f69058a 






ARM: 7688/1: add support for context tracking subsystem
2013-04-03T16:00:01+00:00

Kevin Hilman
khilman@deeprootsystems.com

2013-03-28T21:54:40+00:00

b00884802043d9102ecc2abfdc37a7b35b30e52a

commit 91d1aa43 (context_tracking: New context tracking susbsystem)
generalized parts of the RCU userspace extended quiescent state into
the context tracking subsystem.  Context tracking is then used
to implement adaptive tickless (a.k.a extended nohz)

To support the new context tracking subsystem on ARM, the user/kernel
boundary transtions need to be instrumented.

For exceptions and IRQs in usermode, the existing usr_entry macro is
used to instrument the user->kernel transition.  For the return to
usermode path, the ret_to_user* path is instrumented.  Using the
usr_entry macro, this covers interrupts in userspace, data abort and
prefetch abort exceptions in userspace as well as undefined exceptions
in userspace (which is where FP emulation and VFP are handled.)

For syscalls, the slow return path is covered by instrumenting the
ret_to_user path.  In addition, the syscall entry point is
instrumented which covers the user->kernel transition for both fast
and slow syscalls, and an additional instrumentation point is added
for the fast syscall return path (ret_fast_syscall).

Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>





commit 91d1aa43 (context_tracking: New context tracking susbsystem)
generalized parts of the RCU userspace extended quiescent state into
the context tracking subsystem.  Context tracking is then used
to implement adaptive tickless (a.k.a extended nohz)

To support the new context tracking subsystem on ARM, the user/kernel
boundary transtions need to be instrumented.

For exceptions and IRQs in usermode, the existing usr_entry macro is
used to instrument the user->kernel transition.  For the return to
usermode path, the ret_to_user* path is instrumented.  Using the
usr_entry macro, this covers interrupts in userspace, data abort and
prefetch abort exceptions in userspace as well as undefined exceptions
in userspace (which is where FP emulation and VFP are handled.)

For syscalls, the slow return path is covered by instrumenting the
ret_to_user path.  In addition, the syscall entry point is
instrumented which covers the user->kernel transition for both fast
and slow syscalls, and an additional instrumentation point is added
for the fast syscall return path (ret_fast_syscall).

Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>