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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
2014-04-25ARM: 8036/1: Enable IRQs before attempting to read user space in __und_usrCatalin Marinas
The Undef abort handler in the kernel reads the undefined instruction from user space. If the page table was modified from another CPU, the user access could fail and do_page_fault() will be executed with interrupts disabled. This can potentially deadlock on ARM11MPCore or on Cortex-A15 with erratum 798181 workaround enabled (both implying IPI for TLB maintenance with page table lock held). This patch enables the IRQs in __und_usr before attempting to read the instruction from user space. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: Arun KS <getarunks@gmail.com> Cc: Hartley Sweeten <hsweeten@visionengravers.com> Cc: Ryan Mallon <rmallon@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-14ARM: 8026/1: Fix emulation of multiply accumulate instructionsJay Foad
The emulation for single and double precision multiply accumulate instructions correctly normalised any denormal values in the operand registers, but failed to normalise the destination (accumulator) register. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=70501 Signed-off-by: Jay Foad <jay.foad@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-09ARM: 8018/1: Add {inc,dec}_preempt_count asm macrosCatalin Marinas
The patch adds asm macros for inc_preempt_count and dec_preempt_count_ti (which also gets the current thread_info) instead of open-coding them in arch/arm/vfp/*.S files. 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>
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>
2013-10-30ARM: 7873/1: vfp: clear vfp_current_hw_state for dying cpuYuanyuan Zhong
The CPU_DYING notifier is called by cpu stopper task which does not own the context held in the VFP hardware. Calling vfp_force_reload() has no effect. Replace it with clearing vfp_current_hw_state. Signed-off-by: Yuanyuan Zhong <zyy@motorola.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-07-08ARM: add support for kernel mode NEONArd Biesheuvel
In order to safely support the use of NEON instructions in kernel mode, some precautions need to be taken: - the userland context that may be present in the registers (even if the NEON/VFP is currently disabled) must be stored under the correct task (which may not be 'current' in the UP case), - to avoid having to keep track of additional vfpstates for the kernel side, disallow the use of NEON in interrupt context and run with preemption disabled, - after use, re-enable preemption and re-enable the lazy restore machinery by disabling the NEON/VFP unit. This patch adds the functions kernel_neon_begin() and kernel_neon_end() which take care of the above. It also adds the Kconfig symbol KERNEL_MODE_NEON to enable it. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org>
2013-07-08ARM: be strict about FP exceptions in kernel modeArd Biesheuvel
The support code in vfp_support_entry does not care whether the exception that caused it to be invoked occurred in kernel mode or in user mode. However, neither condition that could trigger this exception (lazy restore and VFP bounce to support code) is currently allowable in kernel mode. In either case, print a message describing the condition before letting the undefined instruction handler run its course and trigger an oops. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org>
2013-07-08ARM: move VFP init to an earlier boot stageArd Biesheuvel
In order to use the NEON unit in the kernel, we should initialize it a bit earlier in the boot process so NEON users that like to do a quick benchmark at load time (like the xor_blocks or RAID-6 code) find the NEON/VFP unit already enabled. Replaced late_initcall() with core_initcall(). Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org>
2013-05-22ARM: 7729/1: vfp: ensure VFP_arch is non-zero when VFP is not supportedWill Deacon
Commit d3f79584a8b5 ("ARM: cleanup undefined instruction entry code") improved the register scheduling when handling undefined instructions. A side effect of this is that r5 is now used as a temporary, whilst the VFP probing code relies on r5 containing a non-zero value when VFP is not supported. This patch fixes the VFP detection code so that we don't rely on the contents of r5. Without this patch, Linux dies loudly on CPUs without VFP support. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-03-01ARM: Fix broken commit 0cc41e4a21d43 corrupting kernel messagesRussell King
Commit 0cc41e4a21d43 (arch: remove direct definitions of KERN_<LEVEL> uses) is broken - not enough thought was put into changing: .asciz "string" to .asciz "string1" "string2" The problem is that each string gets _separately_ NUL terminated, so the result is a string containing: "string1\0string2\0" rather than: "string1string2\0" With our new printk levels, this ends up as - eg, KERN_DEBUG "string": 0x01 0x00 0x07 0x00 "string" 0x00 which produces lots of \x01 in the kernel log. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-02-25ARM: VFP: fix emulation of second VFP instructionRussell King
Martin Storsjö reports that the sequence: ee312ac1 vsub.f32 s4, s3, s2 ee702ac0 vsub.f32 s5, s1, s0 e59f0028 ldr r0, [pc, #40] ee111a90 vmov r1, s3 on Raspberry Pi (implementor 41 architecture 1 part 20 variant b rev 5) where s3 is a denormal and s2 is zero results in incorrect behaviour - the instruction "vsub.f32 s5, s1, s0" is not executed: VFP: bounce: trigger ee111a90 fpexc d0000780 VFP: emulate: INST=0xee312ac1 SCR=0x00000000 ... As we can see, the instruction triggering the exception is the "vmov" instruction, and we emulate the "vsub.f32 s4, s3, s2" but fail to properly take account of the FPEXC_FP2V flag in FPEXC. This is because the test for the second instruction register being valid is bogus, and will always skip emulation of the second instruction. Cc: <stable@vger.kernel.org> Reported-by: Martin Storsjö <martin@martin.st> Tested-by: Martin Storsjö <martin@martin.st> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-01-16ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT aloneStephen Boyd
Patrik Kluba reports that the preempt count becomes invalid due to the preempt_enable() call being unbalanced with a preempt_disable() call in the vfp assembly routines. This happens because preempt_enable() and preempt_disable() update preempt counts under PREEMPT_COUNT=y but the vfp assembly routines do so under PREEMPT=y. In a configuration where PREEMPT=n and DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable() call in VFP_bounce() keeps subtracting from the preempt count until it goes negative. Fix this by always using PREEMPT_COUNT to decided when to update preempt counts in the ARM assembly code. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Reported-by: Patrik Kluba <pkluba@dension.com> Tested-by: Patrik Kluba <pkluba@dension.com> Cc: <stable@vger.kernel.org> # 2.6.30 Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-10-29ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and ↵Paul Walmsley
CONFIG_VFPv3 set After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("ARM: vfp: fix saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board started crashing during boot with omap2plus_defconfig: [ 3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB [ 3.915954] mmcblk0: p1 [ 4.086639] Internal error: Oops - undefined instruction: 0 [#1] SMP ARM [ 4.093719] Modules linked in: [ 4.096954] CPU: 0 Not tainted (3.6.0-02232-g759e00b #570) [ 4.103149] PC is at vfp_reload_hw+0x1c/0x44 [ 4.107666] LR is at __und_usr_fault_32+0x0/0x8 It turns out that the context save/restore fix unmasked a latent bug in commit 5aaf254409f8d58229107b59507a8235b715a960 ("ARM: 6203/1: Make VFPv3 usable on ARMv6"). When CONFIG_VFPv3 is set, but the kernel is booted on a pre-VFPv3 core, the code attempts to save and restore the d16-d31 VFP registers. These are only present on non-D16 VFPv3+, so this results in an undefined instruction exception. The code didn't crash before commit 846a136 because the save and restore code was only touching d0-d15, present on all VFP. Fix by implementing a request from Russell King to add a new HWCAP flag that affirmatively indicates the presence of the d16-d31 registers: http://marc.info/?l=linux-arm-kernel&m=135013547905283&w=2 and some feedback from Måns to clarify the name of the HWCAP flag. Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Tony Lindgren <tony@atomide.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <dave.martin@linaro.org> Cc: Måns Rullgård <mans.rullgard@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-08-11ARM: 7483/1: vfp: only advertise VFPv4 in hwcaps if CONFIG_VFPv3 is enabledWill Deacon
VFPv4 support depends on the VFPv3 context save/restore code, so only advertise support in the hwcaps if the kernel can actually handle it. Cc: <stable@vger.kernel.org> # 3.1+ Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-08-01Merge branch 'fixes' of git://git.linaro.org/people/rmk/linux-armLinus Torvalds
Pull ARM fixes from Russell King: "This fixes various issues found during July" * 'fixes' of git://git.linaro.org/people/rmk/linux-arm: ARM: 7479/1: mm: avoid NULL dereference when flushing gate_vma with VIVT caches ARM: Fix undefined instruction exception handling ARM: 7480/1: only call smp_send_stop() on SMP ARM: 7478/1: errata: extend workaround for erratum #720789 ARM: 7477/1: vfp: Always save VFP state in vfp_pm_suspend on UP ARM: 7476/1: vfp: only clear vfp state for current cpu in vfp_pm_suspend ARM: 7468/1: ftrace: Trace function entry before updating index ARM: 7467/1: mutex: use generic xchg-based implementation for ARMv6+ ARM: 7466/1: disable interrupt before spinning endlessly ARM: 7465/1: Handle >4GB memory sizes in device tree and mem=size@start option
2012-07-31ARM: Fix undefined instruction exception handlingRussell King
While trying to get a v3.5 kernel booted on the cubox, I noticed that VFP does not work correctly with VFP bounce handling. This is because of the confusion over 16-bit vs 32-bit instructions, and where PC is supposed to point to. The rule is that FP handlers are entered with regs->ARM_pc pointing at the _next_ instruction to be executed. However, if the exception is not handled, regs->ARM_pc points at the faulting instruction. This is easy for ARM mode, because we know that the next instruction and previous instructions are separated by four bytes. This is not true of Thumb2 though. Since all FP instructions are 32-bit in Thumb2, it makes things easy. We just need to select the appropriate adjustment. Do this by moving the adjustment out of do_undefinstr() into the assembly code, as only the assembly code knows whether it's dealing with a 32-bit or 16-bit instruction. Cc: <stable@vger.kernel.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-31ARM: 7477/1: vfp: Always save VFP state in vfp_pm_suspend on UPColin Cross
vfp_pm_suspend should save the VFP state in suspend after any lazy context switch. If it only saves when the VFP is enabled, the state can get lost when, on a UP system: Thread 1 uses the VFP Context switch occurs to thread 2, VFP is disabled but the VFP context is not saved Thread 2 initiates suspend vfp_pm_suspend is called with the VFP disabled, and the unsaved VFP context of Thread 1 in the registers Modify vfp_pm_suspend to save the VFP context whenever vfp_current_hw_state is not NULL. Includes a fix from Ido Yariv <ido@wizery.com>, who pointed out that on SMP systems, the state pointer can be pointing to a freed task struct if a task exited on another cpu, fixed by using #ifndef CONFIG_SMP in the new if clause. Cc: Barry Song <bs14@csr.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ido Yariv <ido@wizery.com> Cc: Daniel Drake <dsd@laptop.org> Cc: Will Deacon <will.deacon@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-31ARM: 7476/1: vfp: only clear vfp state for current cpu in vfp_pm_suspendColin Cross
vfp_pm_suspend runs on each cpu, only clear the hardware state pointer for the current cpu. Prevents a possible crash if one cpu clears the hw state pointer when another cpu has already checked if it is valid. Cc: stable@vger.kernel.org Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-31arch: remove direct definitions of KERN_<LEVEL> usesJoe Perches
Add #include <linux/kern_levels.h> so that the #define KERN_<LEVEL> macros don't have to be duplicated. Signed-off-by: Joe Perches <joe@perches.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-21Merge branch 'misc' into for-linusRussell King
Conflicts: arch/arm/kernel/ptrace.c
2012-05-17ARM: 7419/1: vfp: fix VFP flushing regression on sigreturn pathWill Deacon
Commit ff9a184c ("ARM: 7400/1: vfp: clear fpscr length and stride bits on entry to sig handler") flushes the VFP state prior to entering a signal handler so that a VFP operation inside the handler will trap and force a restore of ABI-compliant registers. Reflushing and disabling VFP on the sigreturn path is predicated on the saved thread state indicating that VFP was used by the handler -- however for SMP platforms this is only set on context-switch, making the check unreliable and causing VFP register corruption in userspace since the register values are not necessarily those restored from the sigframe. This patch unconditionally flushes the VFP state after a signal handler. Since we already perform the flush before the handler and the flushing itself happens lazily, the redundant flush when VFP is not used by the handler is essentially a nop. Reported-by: Jon Medhurst <tixy@linaro.org> Signed-off-by: Jon Medhurst <tixy@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-05-12ARM: 7417/1: vfp: ensure preemption is disabled when enabling VFP accessWill Deacon
The vfp_enable function enables access to the VFP co-processor register space (cp10 and cp11) on the current CPU and must be called with preemption disabled. Unfortunately, the vfp_init late initcall does not disable preemption and can lead to an oops during boot if thread migration occurs at the wrong time and we end up attempting to access the FPSID on a CPU with VFP access disabled. This patch fixes the initcall to call vfp_enable from a non-preemptible context on each CPU and adds a BUG_ON(preemptible) to ensure that any similar problems are easily spotted in the future. Cc: stable@vger.kernel.org Reported-by: Hyungwoo Yang <hwoo.yang@gmail.com> Signed-off-by: Hyungwoo Yang <hyungwooy@nvidia.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-05-11ARM: 7415/1: vfp: convert printk's to pr_*'sNicolas Pitre
This is mainly to get rid of the "vfp_pm_suspend: saving vfp state" message flooding the kernel message ring by default. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-04-23ARM: 7400/1: vfp: clear fpscr length and stride bits on entry to sig handlerWill Deacon
The ARM PCS mandates that the length and stride bits of the fpscr are cleared on entry to and return from a public interface. Although signal handlers run asynchronously with respect to the interrupted function, the handler itself expects to run as though it has been called like a normal function. This patch updates the state mirroring the VFP hardware before entry to a signal handler so that it adheres to the PCS. Furthermore, we disable VFP to ensure that we trap on any floating point operation performed by the signal handler and synchronise the hardware appropriately. A check is inserted after the signal handler to avoid redundant flushing if VFP was not used. Reported-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-04-23ARM: 7399/1: vfp: move user vfp state save/restore code out of signal.cWill Deacon
The user VFP state must be preserved (subject to ucontext modifications) across invocation of a signal handler and this is currently handled by vfp_{preserve,restore}_context in signal.c Since this code requires intimate low-level knowledge of the VFP state, this patch moves it into vfpmodule.c. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-03-28Disintegrate asm/system.h for ARMDavid Howells
Disintegrate asm/system.h for ARM. Signed-off-by: David Howells <dhowells@redhat.com> cc: Russell King <linux@arm.linux.org.uk> cc: linux-arm-kernel@lists.infradead.org
2012-03-28ARM: move CP15 definitions to separate header fileRussell King
Avoid namespace conflicts with drivers over the CP15 definitions by moving CP15 related prototypes and definitions to a private header file. Acked-by: Stephen Warren <swarren@nvidia.com> Tested-by: Stephen Warren <swarren@nvidia.com> [Tegra] Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com> Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com> [EP93xx] Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Kukjin Kim <kgene.kim@samsung.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com>
2011-10-31arm: remove several unnecessary module.h include instancesPaul Gortmaker
Building these files does not reveal a hidden need for any of these. Since module.h brings in the whole kitchen sink, it just needlessly adds 30k+ lines to the cpp burden. There are probably lots more, but ARM files of mach-* and plat-* don't get coverage via a simple yesconfig build. They will have to be cleaned up and tested via using their respective configs. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-28Merge branch 'devel-stable' of ↵Linus Torvalds
http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm * 'devel-stable' of http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm: (178 commits) ARM: 7139/1: fix compilation with CONFIG_ARM_ATAG_DTB_COMPAT and large TEXT_OFFSET ARM: gic, local timers: use the request_percpu_irq() interface ARM: gic: consolidate PPI handling ARM: switch from NO_MACH_MEMORY_H to NEED_MACH_MEMORY_H ARM: mach-s5p64x0: remove mach/memory.h ARM: mach-s3c64xx: remove mach/memory.h ARM: plat-mxc: remove mach/memory.h ARM: mach-prima2: remove mach/memory.h ARM: mach-zynq: remove mach/memory.h ARM: mach-bcmring: remove mach/memory.h ARM: mach-davinci: remove mach/memory.h ARM: mach-pxa: remove mach/memory.h ARM: mach-ixp4xx: remove mach/memory.h ARM: mach-h720x: remove mach/memory.h ARM: mach-vt8500: remove mach/memory.h ARM: mach-s5pc100: remove mach/memory.h ARM: mach-tegra: remove mach/memory.h ARM: plat-tcc: remove mach/memory.h ARM: mach-mmp: remove mach/memory.h ARM: mach-cns3xxx: remove mach/memory.h ... Fix up mostly pretty trivial conflicts in: - arch/arm/Kconfig - arch/arm/include/asm/localtimer.h - arch/arm/kernel/Makefile - arch/arm/mach-shmobile/board-ap4evb.c - arch/arm/mach-u300/core.c - arch/arm/mm/dma-mapping.c - arch/arm/mm/proc-v7.S - arch/arm/plat-omap/Kconfig largely due to some CONFIG option renaming (ie CONFIG_PM_SLEEP -> CONFIG_ARM_CPU_SUSPEND for the arm-specific suspend code etc) and addition of NEED_MACH_MEMORY_H next to HAVE_IDE.
2011-10-01ARM: vfp: use -mfloat-abi=soft to build vfpArnd Bergmann
Distros are starting to ship with toolchains defaulting to hardfloat. Using such a compiler to build the kernel fails in the VFP directory with arch/arm/vfp/entry.S:1:0: sorry, unimplemented: -mfloat-abi=hard and VFP Adding -mfloat-abi=soft to the gcc command line fixes this. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2011-09-23ARM: vfp: Fix the comment to make it consistent with the code.Santosh Shilimkar
Function vfp_force_reload() clears vfp_current_hw_state, so update the comment accordingly. Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2011-09-23ARM: vfp: Use cpu pm notifiers to save vfp stateColin Cross
When the cpu is powered down in a low power mode, the vfp registers may be reset. This patch uses CPU_PM_ENTER and CPU_PM_EXIT notifiers to save and restore the cpu's vfp registers. Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Kevin Hilman <khilman@ti.com> Tested-and-Acked-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
2011-07-22Merge branch 'devel-stable' into for-nextRussell King
Conflicts: arch/arm/kernel/entry-armv.S
2011-07-09ARM: vfp: ensure that thread flushing works if preemptedRussell King
Prevent a preemption event causing the initialized VFP state being overwritten by ensuring that the VFP hardware access is disabled prior to starting initialization. We can then do this in safety while still allowing preemption to occur. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-09ARM: vfp: fix a hole in VFP thread migrationRussell King
Fix a hole in the VFP thread migration. Lets define two threads. Thread 1, we'll call 'interesting_thread' which is a thread which is running on CPU0, using VFP (so vfp_current_hw_state[0] = &interesting_thread->vfpstate) and gets migrated off to CPU1, where it continues execution of VFP instructions. Thread 2, we'll call 'new_cpu0_thread' which is the thread which takes over on CPU0. This has also been using VFP, and last used VFP on CPU0, but doesn't use it again. The following code will be executed twice: cpu = thread->cpu; /* * On SMP, if VFP is enabled, save the old state in * case the thread migrates to a different CPU. The * restoring is done lazily. */ if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) { vfp_save_state(vfp_current_hw_state[cpu], fpexc); vfp_current_hw_state[cpu]->hard.cpu = cpu; } /* * Thread migration, just force the reloading of the * state on the new CPU in case the VFP registers * contain stale data. */ if (thread->vfpstate.hard.cpu != cpu) vfp_current_hw_state[cpu] = NULL; The first execution will be on CPU0 to switch away from 'interesting_thread'. interesting_thread->cpu will be 0. So, vfp_current_hw_state[0] points at interesting_thread->vfpstate. The hardware state will be saved, along with the CPU number (0) that it was executing on. 'thread' will be 'new_cpu0_thread' with new_cpu0_thread->cpu = 0. Also, because it was executing on CPU0, new_cpu0_thread->vfpstate.hard.cpu = 0, and so the thread migration check is not triggered. This means that vfp_current_hw_state[0] remains pointing at interesting_thread. The second execution will be on CPU1 to switch _to_ 'interesting_thread'. So, 'thread' will be 'interesting_thread' and interesting_thread->cpu now will be 1. The previous thread executing on CPU1 is not relevant to this so we shall ignore that. We get to the thread migration check. Here, we discover that interesting_thread->vfpstate.hard.cpu = 0, yet interesting_thread->cpu is now 1, indicating thread migration. We set vfp_current_hw_state[1] to NULL. So, at this point vfp_current_hw_state[] contains the following: [0] = &interesting_thread->vfpstate [1] = NULL Our interesting thread now executes a VFP instruction, takes a fault which loads the state into the VFP hardware. Now, through the assembly we now have: [0] = &interesting_thread->vfpstate [1] = &interesting_thread->vfpstate CPU1 stops due to ptrace (and so saves its VFP state) using the thread switch code above), and CPU0 calls vfp_sync_hwstate(). if (vfp_current_hw_state[cpu] == &thread->vfpstate) { vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); BANG, we corrupt interesting_thread's VFP state by overwriting the more up-to-date state saved by CPU1 with the old VFP state from CPU0. Fix this by ensuring that we have sane semantics for the various state describing variables: 1. vfp_current_hw_state[] points to the current owner of the context information stored in each CPUs hardware, or NULL if that state information is invalid. 2. thread->vfpstate.hard.cpu always contains the most recent CPU number which the state was loaded into or NR_CPUS if no CPU owns the state. So, for a particular CPU to be a valid owner of the VFP state for a particular thread t, two things must be true: vfp_current_hw_state[cpu] == &t->vfpstate && t->vfpstate.hard.cpu == cpu. and that is valid from the moment a CPU loads the saved VFP context into the hardware. This gives clear and consistent semantics to interpreting these variables. This patch also fixes thread copying, ensuring that t->vfpstate.hard.cpu is invalidated, otherwise CPU0 may believe it was the last owner. The hole can happen thus: - thread1 runs on CPU2 using VFP, migrates to CPU3, exits and thread_info freed. - New thread allocated from a previously running thread on CPU2, reusing memory for thread1 and copying vfp.hard.cpu. At this point, the following are true: new_thread1->vfpstate.hard.cpu == 2 &new_thread1->vfpstate == vfp_current_hw_state[2] Lastly, this also addresses thread flushing in a similar way to thread copying. Hole is: - thread runs on CPU0, using VFP, migrates to CPU1 but does not use VFP. - thread calls execve(), so thread flush happens, leaving vfp_current_hw_state[0] intact. This vfpstate is memset to 0 causing thread->vfpstate.hard.cpu = 0. - thread migrates back to CPU0 before using VFP. At this point, the following are true: thread->vfpstate.hard.cpu == 0 &thread->vfpstate == vfp_current_hw_state[0] Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-09ARM: vfp: rename check_exception to vfp_hw_state_validRussell King
Rename this branch to more accurately reflect why its taken, rather than what the following code does. It is the only caller of this code. This helps to clarify following changes, yet this change results in no actual code change. Document the VFP hardware state at the target of this branch. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-09ARM: vfp: rename last_VFP_context to vfp_current_hw_stateRussell King
Rename the slightly confusing 'last_VFP_context' variable to be more descriptive of what it actually is. This variable stores a pointer to the current owner's vfpstate structure for the context held in the VFP hardware. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: vfp: add VFPv4 capability detection and populate elf_hwcapWill Deacon
The presence of VFPv4 cannot be detected simply by looking at the FPSID subarchitecture field, as a value >= 2 signifies the architecture as VFPv3 or later. This patch reads from MVFR1 to check whether or not the fused multiply accumulate instructions are supported. Since these are introduced with VFPv4, this tells us what we need to know. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-04-24ARM: Use struct syscore_ops instead of sysdevs for PM in common codeRafael J. Wysocki
Convert some ARM architecture's common code to using struct syscore_ops objects for power management instead of sysdev classes and sysdevs. This simplifies the code and reduces the kernel's memory footprint. It also is necessary for removing sysdevs from the kernel entirely in the future. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-04-10ARM: 6868/1: Preserve the VFP state during forkCatalin Marinas
VFP registers d16-d31 are callee saved registers and must be preserved during function calls, including fork(). The VFP configuration should also be preserved. The patch copies the full VFP state to the child process. Reported-by: Paul Wright <paul.wright@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-04-10ARM: 6867/1: Introduce THREAD_NOTIFY_COPY for copy_thread() hooksCatalin Marinas
This patch adds THREAD_NOTIFY_COPY for calling registered handlers during the copy_thread() function call. It also changes the VFP handler to use a switch statement rather than if..else and ignore this event. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-03-21Merge branch 'trivial' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 * 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6: (25 commits) video: change to new flag variable scsi: change to new flag variable rtc: change to new flag variable rapidio: change to new flag variable pps: change to new flag variable net: change to new flag variable misc: change to new flag variable message: change to new flag variable memstick: change to new flag variable isdn: change to new flag variable ieee802154: change to new flag variable ide: change to new flag variable hwmon: change to new flag variable dma: change to new flag variable char: change to new flag variable fs: change to new flag variable xtensa: change to new flag variable um: change to new flag variables s390: change to new flag variable mips: change to new flag variable ... Fix up trivial conflict in drivers/hwmon/Makefile
2011-03-17arm: change to new flag variablesmatt mooney
Replace EXTRA_CFLAGS with ccflags-y and EXTRA_AFLAGS with asflags-y. Signed-off-by: matt mooney <mfm@muteddisk.com> Acked-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.cz>
2011-02-23ARM: vfp: improve commentry for hotplug eventsRussell King
Improve the documentation for the VFP hotplug notifier handler, so that people better understand what's going on there and what has been done for them. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-23ARM: fix some sparse errors in generic ARM codeRussell King
arch/arm/kernel/return_address.c:37:6: warning: symbol 'return_address' was not declared. Should it be static? arch/arm/kernel/setup.c:76:14: warning: symbol 'processor_id' was not declared. Should it be static? arch/arm/kernel/traps.c:259:1: warning: symbol 'die_lock' was not declared. Should it be static? arch/arm/vfp/vfpmodule.c:156:6: warning: symbol 'vfp_raise_sigfpe' was not declared. Should it be static? Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-01-06Merge branch 'misc' into develRussell King
Conflicts: arch/arm/Kconfig arch/arm/common/Makefile arch/arm/kernel/Makefile arch/arm/kernel/smp.c
2010-12-20ARM: VFP: re-initialize VFP coprocessor access enables on CPU hotplugRussell King
We can not guarantee that VFP will be enabled when CPU hotplug brings a CPU back online from a reset state. Add a hotplug CPU notifier to ensure that the VFP coprocessor access is enabled whenever a CPU comes back online. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-11-30ARM: 6498/1: vfp: Correct data alignment for CONFIG_THUMB2_KERNELDave Martin
Directives such as .long and .word do not magically cause the assembler location counter to become aligned in gas. As a result, using these directives in code sections can result in misaligned data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL). This is a Bad Thing, since the ABI permits the compiler to assume that fundamental types of word size or above are word- aligned when accessing them from C. If the data is not really word-aligned, this can cause impaired performance and stray alignment faults in some circumstances. In general, the following rules should be applied when using data word declaration directives inside code sections: * .quad and .double: .align 3 * .long, .word, .single, .float: .align (or .align 2) * .short: No explicit alignment required, since Thumb-2 instructions are always 2 or 4 bytes in size. immediately after an instruction. Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Dave Martin <dave.martin@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>