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2015-08-26ARM: entry: provide uaccess assembly macro hooksRussell King
Provide hooks into the kernel entry and exit paths to permit control of userspace visibility to the kernel. The intended use is: - on entry to kernel from user, uaccess_disable will be called to disable userspace visibility - on exit from kernel to user, uaccess_enable will be called to enable userspace visibility - on entry from a kernel exception, uaccess_save_and_disable will be called to save the current userspace visibility setting, and disable access - on exit from a kernel exception, uaccess_restore will be called to restore the userspace visibility as it was before the exception occurred. These hooks allows us to keep userspace visibility disabled for the vast majority of the kernel, except for localised regions where we want to explicitly access userspace. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-08-26ARM: entry: get rid of multiple macro definitionsRussell King
The following structure is just asking for trouble: #ifdef CONFIG_symbol .macro foo ... .endm .macro bar ... .endm .macro baz ... .endm #else .macro foo ... .endm .macro bar ... .endm #ifdef CONFIG_symbol2 .macro baz ... .endm #else .macro baz ... .endm #endif #endif such as one defintion being updated, but the other definitions miss out. Where the contents of a macro needs to be conditional, the hint is in the first clause of this very sentence. "contents" "conditional". Not multiple separate definitions, especially not when much of the macro is the same between different configs. This patch fixes this bad style, which had caused the Thumb2 code to miss-out on the uaccess updates. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-01-12ARM: 8266/1: Remove early stack deallocation from restore_user_regsDaniel Thompson
Currently restore_user_regs deallocates the SVC stack early in its execution and relies on no exception being taken between the deallocation and the registers being restored. The introduction of a default FIQ handler that also uses the SVC stack breaks this assumption and can result in corrupted register state. This patch works around the problem by removing the early stack deallocation and using r2 as a temporary instead. I have not found a way to do this without introducing an extra mov instruction to the macro. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-10-02Merge branches 'fiq' (early part), 'fixes', 'l2c' (early part) and 'misc' ↵Russell King
into for-next
2014-09-26ARM: Avoid writing to control register on every exceptionRussell King
If we are not changing the control register value, avoid writing to it. Writes to the control register can be very expensive, taking around a hundred cycles or so. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-09-18ARM: 8150/3: fiq: Replace default FIQ handlerDaniel Thompson
This patch introduces a new default FIQ handler that is structured in a similar way to the existing ARM exception handler and result in the FIQ being handled by C code running on the SVC stack (despite this code run in the FIQ handler is subject to severe limitations with respect to locking making normal interaction with the kernel impossible). This default handler allows concepts that on x86 would be handled using NMIs to be realized on ARM. Credit: This patch is a near complete re-write of a patch originally provided by Anton Vorontsov. Today only a couple of small fragments survive, however without Anton's work to build from this patch would not exist. Thanks also to Russell King for spoonfeeding me a variety of fixes during the review cycle. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-08-27ARM: 8129/1: errata: work around Cortex-A15 erratum 830321 using dummy strexMark Rutland
On revisions of Cortex-A15 prior to r3p3, a CLREX instruction at PL1 may falsely trigger a watchpoint exception, leading to potential data aborts during exception return and/or livelock. This patch resolves the issue in the following ways: - Replacing our uses of CLREX with a dummy STREX sequence instead (as we did for v6 CPUs). - Removing the clrex code from v7_exit_coherency_flush and derivatives, since this only exists as a minor performance improvement when non-cached exclusives are in use (Linux doesn't use these). Benchmarking on a variety of ARM cores revealed no measurable performance difference with this change applied, so the change is performed unconditionally and no new Kconfig entry is added. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-07-18ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+Russell King
ARMv6 and greater introduced a new instruction ("bx") which can be used to return from function calls. Recent CPUs perform better when the "bx lr" instruction is used rather than the "mov pc, lr" instruction, and this sequence is strongly recommended to be used by the ARM architecture manual (section A.4.1.1). We provide a new macro "ret" with all its variants for the condition code which will resolve to the appropriate instruction. Rather than doing this piecemeal, and miss some instances, change all the "mov pc" instances to use the new macro, with the exception of the "movs" instruction and the kprobes code. This allows us to detect the "mov pc, lr" case and fix it up - and also gives us the possibility of deploying this for other registers depending on the CPU selection. Reported-by: Will Deacon <will.deacon@arm.com> Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1 Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood Tested-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385 Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-06-05Merge branches 'alignment', 'fixes', 'l2c' (early part) and 'misc' into for-nextRussell King
2014-06-02ARM: consolidate last remaining open-coded alignment trap enableRussell King
We can use the alignment_trap assembly macro here too. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-05-25ARM: 8064/1: fix v7-M signal returnRabin Vincent
According to the ARM ARM, the behaviour is UNPREDICTABLE if the PC read from the exception return stack is not half word aligned. See the pseudo code for ExceptionReturn() and PopStack(). The signal handler's address has the bit 0 set, and setup_return() directly writes this to regs->ARM_pc. Current hardware happens to discard this bit, but QEMU's emulation doesn't and this makes processes crash. Mask out bit 0 before the exception return in order to get predictable behaviour. Fixes: 19c4d593f0b4 ("ARM: ARMv7-M: Add support for exception handling") Cc: stable@kernel.org Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-09ARM: 8017/1: Move asm macro get_thread_info to asm/assembler.hCatalin Marinas
asm/assembler.h is a better place for this macro since it is used by asm files outside arch/arm/kernel/ Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: Arun KS <getarunks@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-09-27arm: Fix build error with context tracking callsFrederic Weisbecker
ad65782fba50 (context_tracking: Optimize main APIs off case with static key) converted context tracking main APIs to inline function and left ARM asm callers behind. This can be easily fixed by making ARM calling the post static keys context tracking function. We just need to replicate the static key checks there. We'll remove these later when ARM will support the context tracking static keys. Reported-by: Guenter Roeck <linux@roeck-us.net> Reported-by: Russell King <linux@arm.linux.org.uk> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Tested-by: Kevin Hilman <khilman@linaro.org> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Anil Kumar <anilk4.v@gmail.com> Cc: Tony Lindgren <tony@atomide.com> Cc: Benoit Cousson <b-cousson@ti.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Russell King <linux@arm.linux.org.uk> Cc: Kevin Hilman <khilman@linaro.org>
2013-05-22Merge branch 'for-next' of git://git.pengutronix.de/git/ukl/linux into ↵Russell King
devel-stable Pull ARM-v7M support from Uwe Kleine-König: "All but the last patch were in next since next-20130418 without issues. The last patch fixes a problem in combination with 8164f7a (ARM: 7680/1: Detect support for SDIV/UDIV from ISAR0 register) which triggers a WARN_ON without an implemented read_cpuid_ext. The branch merges fine into v3.10-rc1 and I'd be happy if you pulled it for 3.11-rc1. The only missing piece to be able to run a Cortex-M3 is the irqchip driver that will go in via Thomas Gleixner and platform specific stuff."
2013-05-02Merge branches 'devel-stable', 'entry', 'fixes', 'mach-types', 'misc' and ↵Russell King
'smp-hotplug' into for-linus
2013-04-17ARM: ARMv7-M: Add support for exception handlingUwe Kleine-König
This patch implements the exception handling for the ARMv7-M architecture (pretty different from the A or R profiles). It bases on work done earlier by Catalin for 2.6.33 but was nearly completely rewritten to use a pt_regs layout compatible to the A profile. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Jonathan Austin <jonathan.austin@arm.com> Tested-by: Jonathan Austin <jonathan.austin@arm.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-04-03ARM: 7688/1: add support for context tracking subsystemKevin Hilman
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>
2013-04-03ARM: entry: move disable_irq_notrace into svc_exitRussell King
All svc exit paths need IRQs off. Rather than placing this before every user of svc_exit, combine it into this macro. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-04-03ARM: entry: move IRQ tracing exit into svc_exitRussell King
The IRQ tracing exit path is much the same between all SVC mode exits, so move this into the svc_exit macro. Use a macro parameter to identify the IRQ case, which is the only different case there is. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-22Merge branch 'devel-stable' into for-nextRussell King
Conflicts: arch/arm/kernel/entry-armv.S
2011-07-13ARM: Thumb-2: Fix exception return sequence to restore stack correctlyJon Medhurst
The implementation of svc_exit didn't take into account any stack hole created by svc_entry; as happens with the undef handler when kprobes are configured. The fix is to read the saved value of SP rather than trying to calculate it. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02ARM: entry: avoid enabling interrupts in prefetch/data abort handlersRussell King
Avoid enabling interrupts if the parent context had interrupts enabled in the abort handler assembly code, and move this into the breakpoint/ page/alignment fault handlers instead. This gets rid of some special-casing for the breakpoint fault handlers from the low level abort handler path. Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-02ARM: v6k: select clear exclusive code seqences according to V6 variantsRussell King
If CONFIG_CPU_V6 is enabled, then the kernel must support ARMv6 CPUs which don't have the V6K extensions implemented. Always use the dummy store-exclusive method to ensure that the exclusive monitors are cleared. If CONFIG_CPU_V6 is not set, but CONFIG_CPU_32v6K is enabled, then we have the K extensions available on all CPUs we're building support for, so we can use the new clear-exclusive instruction. Acked-by: Tony Lindgren <tony@atomide.com> Tested-by: Sourav Poddar <sourav.poddar@ti.com> Tested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-12-06ARM: hw_breakpoint: disable preemption during debug exception handlingWill Deacon
On ARM, debug exceptions occur in the form of data or prefetch aborts. One difference is that debug exceptions require access to per-cpu banked registers and data structures which are not saved in the low-level exception code. For kernels built with CONFIG_PREEMPT, there is an unlikely scenario that the debug handler ends up running on a different CPU from the one that originally signalled the event, resulting in random data being read from the wrong registers. This patch adds a debug_entry macro to the low-level exception handling code which checks whether the taken exception is a debug exception. If it is, the preempt count for the faulting process is incremented. After the debug handler has finished, the count is decremented. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2010-03-15ARM: 5991/1: Fix regression in restore_user_regs macroAnders Grafström
ARMv5T and earlier require that a ldm {}^ instruction is not followed by an instruction that accesses banked registers. This patch restores the nop that was lost in commit b86040a59feb255a8193173caa4d5199464433d5. Signed-off-by: Anders Grafström <grfstrm@users.sourceforge.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-10-14ARM: 5757/1: Thumb-2: Correct "mov.w pc, lr" instruction which is unpredictableCatalin Marinas
The 32-bit wide variant of "mov pc, reg" in Thumb-2 is unpredictable causing improper handling of the undefined instructions not caught by the kernel. This patch adds a movw_pc macro for such situations (currently only used in call_fpe). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-09-26make Linux bootable on ARM againNicolas Pitre
Commit 200b812d00 "Clear the exclusive monitor when returning from an exception" broke the vast majority of ARM systems in the wild which are still pre ARMv6. The kernel is crashing on the first occurrence of an exception due to the removal of the actual return instruction for them. Let's add it back. Signed-off-by: Nicolas Pitre <nico@marvell.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-18Clear the exclusive monitor when returning from an exceptionCatalin Marinas
The patch adds a CLREX or dummy STREX to the exception return path. This is needed because several atomic/locking operations use a pair of LDREX/STREXEQ and the EQ condition may not always be satisfied. This would leave the exclusive monitor status set and may cause problems with atomic/locking operations in the interrupted code. With this patch, the atomic_set() operation can be a simple STR instruction (on SMP systems, the global exclusive monitor is cleared by STR anyway). Clearing the exclusive monitor during context switch is no longer needed as this is handled by the exception return path anyway. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Jamie Lokier <jamie@shareable.org>
2009-07-24Thumb-2: Implementation of the unified start-up and exceptions codeCatalin Marinas
This patch implements the ARM/Thumb-2 unified kernel start-up and exception handling code. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2006-06-30Remove obsolete #include <linux/config.h>Jörn Engel
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-03-23[ARM] Move enable_irq and disable_irq to assembler.hRussell King
5d25ac038a317d454a4321cba955f756400835a5 broke VFP builds due to enable_irq not being defined as an assembly macro. Move it to assembler.h so everyone can use it. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-14[ARM] 3102/1: ARM EABI: stack pointer must be 64-bit aligned after a CPU ↵Nicolas Pitre
exception Patch from Nicolas Pitre The ARM EABI says that the stack pointer has to be 64-bit aligned for reasons already mentioned in patch #3101 when calling C functions. We therefore must verify and adjust sp accordingly when taking an exception from kernel mode since sp might not necessarily be 64-bit aligned if the exception occurs in the middle of a kernel function. If the exception occurs while in user mode then no sp fixup is needed as long as sizeof(struct pt_regs) as well as any additional syscall data stack space remain multiples of 8. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-09-09kbuild: arm - use generic asm-offsets.h supportSam Ravnborg
Delete obsoleted stuff from arch Makefile and rename constants.h to asm-offsets.h Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2005-05-31[PATCH] ARM SMP: convert alignment enableRussell King
The current vector entry system does not allow for SMP. In order to work around this, we need to eliminate our reliance on the fixed save areas, which breaks the way we enable alignment traps. This patch makes the alignment trap enable code independent of the way we handle the save areas. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: make entry*.S includes more logicalRussell King
Move common includes to entry-header, and file specific includes to the relevant file. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: Remove single-use user save/restore macrosRussell King
Assembly macros are pointless if they're only used once. Move them inline. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: remove PT_TRACESYSRussell King
PT_TRACESYS is unused, remove it. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: Remove SVC_MODE definitionRussell King
SVC_MODE reflects the MODE_SVC definition in asm/ptrace.h. Use the asm/ptrace.h definition instead, and remove SVC_MODE. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: Use __NR_SYSCALL_BASE and __ARM_NR_BASE in asm codeRussell King
Don't define our own local constants, but use those already defined in asm/unistd.h instead. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: pt_regs offsetsRussell King
Generate pt_regs S_xx offsets from the structure itself instead of #defining them. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-26[PATCH] ARM: Remove argument for disable_irq/enable_irqRussell King
Since we do not require a register for these operations, we can remove this unnecessary argument. Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!