3 Commits

Author	SHA1	Message	Date
Nathan Lynch	09edea4f8f	ARM: 8410/1: VDSO: fix coarse clock monotonicity regression ... Since 906c55579a ("timekeeping: Copy the shadow-timekeeper over the real timekeeper last") it has become possible on ARM to: - Obtain a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE timestamp via syscall. - Subsequently obtain a timestamp for the same clock ID via VDSO which predates the first timestamp (by one jiffy). This is because ARM's update_vsyscall is deriving the coarse time using the __current_kernel_time interface, when it should really be using the timekeeper object provided to it by the timekeeping core. It happened to work before only because __current_kernel_time would access the same timekeeper object which had been passed to update_vsyscall. This is no longer the case. Cc: stable@vger.kernel.org Fixes: 906c55579a ("timekeeping: Copy the shadow-timekeeper over the real timekeeper last") Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>	2015-08-11 13:42:44 +01:00
Linus Torvalds	bb0fd7ab09	Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm ... Pull ARM updates from Russell King: "Included in this update are both some long term fixes and some new features. Fixes: - An integer overflow in the calculation of ELF_ET_DYN_BASE. - Avoiding OOMs for high-order IOMMU allocations - SMP requires the data cache to be enabled for synchronisation primitives to work, so prevent the CPU_DCACHE_DISABLE option being visible on SMP builds. - A bug going back 10+ years in the noMMU ARM94* CPU support code, where it corrupts registers. Found by folk getting Linux running on their cameras. - Versatile Express needs an errata workaround enabled for CPU hot-unplug to work. Features: - Clean up module linker by handling out of range relocations separately from relocation cases we don't handle. - Fix a long term bug in the pci_mmap_page_range() code, which we hope won't impact userspace (we hope there's no users of the existing broken interface.) - Don't map DMA coherent allocations when we don't have a MMU. - Drop experimental status for SMP_ON_UP. - Warn when DT doesn't specify ePAPR mandatory cache properties. - Add documentation concerning how we find the start of physical memory for AUTO_ZRELADDR kernels, detailing why we have chosen the mask and the implications of changing it. - Updates from Ard Biesheuvel to address some issues with large kernels (such as allyesconfig) failing to link. - Allow hibernation to work on modern (ARMv7) CPUs - this appears to have never worked in the past on these CPUs. - Enable IRQ_SHOW_LEVEL, which changes the /proc/interrupts output format (hopefully without userspace breaking... let's hope that if it causes someone a problem, they tell us.) - Fix tegra-ahb DT offsets. - Rework ARM errata 643719 code (and ARMv7 flush_cache_louis()/ flush_dcache_all()) code to be more efficient, and enable this errata workaround by default for ARMv7+SMP CPUs. This complements the Versatile Express fix above. - Rework ARMv7 context code for errata 430973, so that only Cortex A8 CPUs are impacted by the branch target buffer flush when this errata is enabled. Also update the help text to indicate that all r1p* A8 CPUs are impacted. - Switch ARM to the generic show_mem() implementation, it conveys all the information which we were already reporting. - Prevent slow timer sources being used for udelay() - timers running at less than 1MHz are not useful for this, and can cause udelay() to return immediately, without any wait. Using such a slow timer is silly. - VDSO support for 32-bit ARM, mainly for gettimeofday() using the ARM architected timer. - Perf support for Scorpion performance monitoring units" vdso semantic conflict fixed up as per linux-next. * 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (52 commits) ARM: update errata 430973 documentation to cover Cortex A8 r1p* ARM: ensure delay timer has sufficient accuracy for delays ARM: switch to use the generic show_mem() implementation ARM: proc-v7: avoid errata 430973 workaround for non-Cortex A8 CPUs ARM: enable ARM errata 643719 workaround by default ARM: cache-v7: optimise test for Cortex A9 r0pX devices ARM: cache-v7: optimise branches in v7_flush_cache_louis ARM: cache-v7: consolidate initialisation of cache level index ARM: cache-v7: shift CLIDR to extract appropriate field before masking ARM: cache-v7: use movw/movt instructions ARM: allow 16-bit instructions in ALT_UP() ARM: proc-arm94*.S: fix setup function ARM: vexpress: fix CPU hotplug with CT9x4 tile. ARM: 8276/1: Make CPU_DCACHE_DISABLE depend on !SMP ARM: 8335/1: Documentation: DT bindings: Tegra AHB: document the legacy base address ARM: 8334/1: amba: tegra-ahb: detect and correct bogus base address ARM: 8333/1: amba: tegra-ahb: fix register offsets in the macros ARM: 8339/1: Enable CONFIG_GENERIC_IRQ_SHOW_LEVEL ARM: 8338/1: kexec: Relax SMP validation to improve DT compatibility ARM: 8337/1: mm: Do not invoke OOM for higher order IOMMU DMA allocations ...	2015-04-14 21:03:26 -07:00
Nathan Lynch	ecf99a4391	ARM: 8331/1: VDSO initialization, mapping, and synchronization ... Initialize the VDSO page list at boot, install the VDSO mapping at exec time, and update the data page during timer ticks. This code is not built if CONFIG_VDSO is not enabled. Account for the VDSO length when randomizing the offset from the stack. The [vdso] and [vvar] pages are placed immediately following the sigpage with separate _install_special_mapping calls. We want to "penalize" systems lacking the arch timer as little as possible. Previous versions of this code installed the VDSO unconditionally and unmodified, making it a measurably slower way for glibc to invoke the real syscalls on such systems. E.g. calling gettimeofday via glibc goes from ~560ns to ~630ns on i.MX6Q. If we can indicate to glibc that the time-related APIs in the VDSO are not accelerated, glibc can continue to invoke the syscalls directly instead of dispatching through the VDSO only to fall back to the slow path. Thus, if the architected timer is unusable for whatever reason, patch the VDSO at boot time so that symbol lookups for gettimeofday and clock_gettime return NULL. (This is similar to what powerpc does and borrows code from there.) This allows glibc to perform the syscall directly instead of passing control to the VDSO, which minimizes the penalty. In my measurements the time taken for a gettimeofday call via glibc goes from ~560ns to ~580ns (again on i.MX6Q), and this is solely due to adding a test and branch to glibc's gettimeofday syscall wrapper. An alternative to patching the VDSO at boot would be to not install the VDSO at all when the arch timer isn't usable. Another alternative is to include a separate "dummy" vdso.so without gettimeofday and clock_gettime, which would be selected at boot time. Either of these would get cumbersome if the VDSO were to gain support for an API such as getcpu which is unrelated to arch timer support. Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>	2015-03-27 22:20:45 +00:00