pm24.git/init/Kconfig, branch v5.2-rc2

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21T08:50:46Z

Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

mm: shuffle initial free memory to improve memory-side-cache utilization

2019-05-15T02:52:48Z

Patch series "mm: Randomize free memory", v10. This patch (of 3): Randomization of the page allocator improves the average utilization of a direct-mapped memory-side-cache. Memory side caching is a platform capability that Linux has been previously exposed to in HPC (high-performance computing) environments on specialty platforms. In that instance it was a smaller pool of high-bandwidth-memory relative to higher-capacity / lower-bandwidth DRAM. Now, this capability is going to be found on general purpose server platforms where DRAM is a cache in front of higher latency persistent memory [1]. Robert offered an explanation of the state of the art of Linux interactions with memory-side-caches [2], and I copy it here: It's been a problem in the HPC space: http://www.nersc.gov/research-and-development/knl-cache-mode-performance-coe/ A kernel module called zonesort is available to try to help: https://software.intel.com/en-us/articles/xeon-phi-software and this abandoned patch series proposed that for the kernel: https://lkml.kernel.org/r/20170823100205.17311-1-lukasz.daniluk@intel.com Dan's patch series doesn't attempt to ensure buffers won't conflict, but also reduces the chance that the buffers will. This will make performance more consistent, albeit slower than "optimal" (which is near impossible to attain in a general-purpose kernel). That's better than forcing users to deploy remedies like: "To eliminate this gradual degradation, we have added a Stream measurement to the Node Health Check that follows each job; nodes are rebooted whenever their measured memory bandwidth falls below 300 GB/s." A replacement for zonesort was merged upstream in commit cc9aec03e58f ("x86/numa_emulation: Introduce uniform split capability"). With this numa_emulation capability, memory can be split into cache sized ("near-memory" sized) numa nodes. A bind operation to such a node, and disabling workloads on other nodes, enables full cache performance. However, once the workload exceeds the cache size then cache conflicts are unavoidable. While HPC environments might be able to tolerate time-scheduling of cache sized workloads, for general purpose server platforms, the oversubscribed cache case will be the common case. The worst case scenario is that a server system owner benchmarks a workload at boot with an un-contended cache only to see that performance degrade over time, even below the average cache performance due to excessive conflicts. Randomization clips the peaks and fills in the valleys of cache utilization to yield steady average performance. Here are some performance impact details of the patches: 1/ An Intel internal synthetic memory bandwidth measurement tool, saw a 3X speedup in a contrived case that tries to force cache conflicts. The contrived cased used the numa_emulation capability to force an instance of the benchmark to be run in two of the near-memory sized numa nodes. If both instances were placed on the same emulated they would fit and cause zero conflicts. While on separate emulated nodes without randomization they underutilized the cache and conflicted unnecessarily due to the in-order allocation per node. 2/ A well known Java server application benchmark was run with a heap size that exceeded cache size by 3X. The cache conflict rate was 8% for the first run and degraded to 21% after page allocator aging. With randomization enabled the rate levelled out at 11%. 3/ A MongoDB workload did not observe measurable difference in cache-conflict rates, but the overall throughput dropped by 7% with randomization in one case. 4/ Mel Gorman ran his suite of performance workloads with randomization enabled on platforms without a memory-side-cache and saw a mix of some improvements and some losses [3]. While there is potentially significant improvement for applications that depend on low latency access across a wide working-set, the performance may be negligible to negative for other workloads. For this reason the shuffle capability defaults to off unless a direct-mapped memory-side-cache is detected. Even then, the page_alloc.shuffle=0 parameter can be specified to disable the randomization on those systems. Outside of memory-side-cache utilization concerns there is potentially security benefit from randomization. Some data exfiltration and return-oriented-programming attacks rely on the ability to infer the location of sensitive data objects. The kernel page allocator, especially early in system boot, has predictable first-in-first out behavior for physical pages. Pages are freed in physical address order when first onlined. Quoting Kees: "While we already have a base-address randomization (CONFIG_RANDOMIZE_MEMORY), attacks against the same hardware and memory layouts would certainly be using the predictability of allocation ordering (i.e. for attacks where the base address isn't important: only the relative positions between allocated memory). This is common in lots of heap-style attacks. They try to gain control over ordering by spraying allocations, etc. I'd really like to see this because it gives us something similar to CONFIG_SLAB_FREELIST_RANDOM but for the page allocator." While SLAB_FREELIST_RANDOM reduces the predictability of some local slab caches it leaves vast bulk of memory to be predictably in order allocated. However, it should be noted, the concrete security benefits are hard to quantify, and no known CVE is mitigated by this randomization. Introduce shuffle_free_memory(), and its helper shuffle_zone(), to perform a Fisher-Yates shuffle of the page allocator 'free_area' lists when they are initially populated with free memory at boot and at hotplug time. Do this based on either the presence of a page_alloc.shuffle=Y command line parameter, or autodetection of a memory-side-cache (to be added in a follow-on patch). The shuffling is done in terms of CONFIG_SHUFFLE_PAGE_ORDER sized free pages where the default CONFIG_SHUFFLE_PAGE_ORDER is MAX_ORDER-1 i.e. 10, 4MB this trades off randomization granularity for time spent shuffling. MAX_ORDER-1 was chosen to be minimally invasive to the page allocator while still showing memory-side cache behavior improvements, and the expectation that the security implications of finer granularity randomization is mitigated by CONFIG_SLAB_FREELIST_RANDOM. The performance impact of the shuffling appears to be in the noise compared to other memory initialization work. This initial randomization can be undone over time so a follow-on patch is introduced to inject entropy on page free decisions. It is reasonable to ask if the page free entropy is sufficient, but it is not enough due to the in-order initial freeing of pages. At the start of that process putting page1 in front or behind page0 still keeps them close together, page2 is still near page1 and has a high chance of being adjacent. As more pages are added ordering diversity improves, but there is still high page locality for the low address pages and this leads to no significant impact to the cache conflict rate. [1]: https://itpeernetwork.intel.com/intel-optane-dc-persistent-memory-operating-modes/ [2]: https://lkml.kernel.org/r/AT5PR8401MB1169D656C8B5E121752FC0F8AB120@AT5PR8401MB1169.NAMPRD84.PROD.OUTLOOK.COM [3]: https://lkml.org/lkml/2018/10/12/309 [dan.j.williams@intel.com: fix shuffle enable] Link: http://lkml.kernel.org/r/154943713038.3858443.4125180191382062871.stgit@dwillia2-desk3.amr.corp.intel.com [cai@lca.pw: fix SHUFFLE_PAGE_ALLOCATOR help texts] Link: http://lkml.kernel.org/r/20190425201300.75650-1-cai@lca.pw Link: http://lkml.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Signed-off-by: Qian Cai Reviewed-by: Kees Cook Acked-by: Michal Hocko Cc: Dave Hansen Cc: Keith Busch Cc: Robert Elliott Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2019-05-07T20:01:40Z

Pull driver core/kobject updates from Greg KH: "Here is the "big" set of driver core patches for 5.2-rc1 There are a number of ACPI patches in here as well, as Rafael said they should go through this tree due to the driver core changes they required. They have all been acked by the ACPI developers. There are also a number of small subsystem-specific changes in here, due to some changes to the kobject core code. Those too have all been acked by the various subsystem maintainers. As for content, it's pretty boring outside of the ACPI changes: - spdx cleanups - kobject documentation updates - default attribute groups for kobjects - other minor kobject/driver core fixes All have been in linux-next for a while with no reported issues" * tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (47 commits) kobject: clean up the kobject add documentation a bit more kobject: Fix kernel-doc comment first line kobject: Remove docstring reference to kset firmware_loader: Fix a typo ("syfs" -> "sysfs") kobject: fix dereference before null check on kobj Revert "driver core: platform: Fix the usage of platform device name(pdev->name)" init/config: Do not select BUILD_BIN2C for IKCONFIG Provide in-kernel headers to make extending kernel easier kobject: Improve doc clarity kobject_init_and_add() kobject: Improve docs for kobject_add/del driver core: platform: Fix the usage of platform device name(pdev->name) livepatch: Replace klp_ktype_patch's default_attrs with groups cpufreq: schedutil: Replace default_attrs field with groups padata: Replace padata_attr_type default_attrs field with groups irqdesc: Replace irq_kobj_type's default_attrs field with groups net-sysfs: Replace ktype default_attrs field with groups block: Replace all ktype default_attrs with groups samples/kobject: Replace foo_ktype's default_attrs field with groups kobject: Add support for default attribute groups to kobj_type driver core: Postpone DMA tear-down until after devres release for probe failure ...

init/config: Do not select BUILD_BIN2C for IKCONFIG

2019-04-29T14:48:04Z

Since commit 13610aa908dc ("kernel/configs: use .incbin directive to embed config_data.gz"), IKCONFIG no longer uses BUILD_BIN2C so prevent it from being selected in Kconfig. Reviewed-by: Masahiro Yamada Signed-off-by: Joel Fernandes (Google) Signed-off-by: Greg Kroah-Hartman

Provide in-kernel headers to make extending kernel easier

2019-04-29T14:48:03Z

Introduce in-kernel headers which are made available as an archive through proc (/proc/kheaders.tar.xz file). This archive makes it possible to run eBPF and other tracing programs that need to extend the kernel for tracing purposes without any dependency on the file system having headers. A github PR is sent for the corresponding BCC patch at: https://github.com/iovisor/bcc/pull/2312 On Android and embedded systems, it is common to switch kernels but not have kernel headers available on the file system. Further once a different kernel is booted, any headers stored on the file system will no longer be useful. This is an issue even well known to distros. By storing the headers as a compressed archive within the kernel, we can avoid these issues that have been a hindrance for a long time. The best way to use this feature is by building it in. Several users have a need for this, when they switch debug kernels, they do not want to update the filesystem or worry about it where to store the headers on it. However, the feature is also buildable as a module in case the user desires it not being part of the kernel image. This makes it possible to load and unload the headers from memory on demand. A tracing program can load the module, do its operations, and then unload the module to save kernel memory. The total memory needed is 3.3MB. By having the archive available at a fixed location independent of filesystem dependencies and conventions, all debugging tools can directly refer to the fixed location for the archive, without concerning with where the headers on a typical filesystem which significantly simplifies tooling that needs kernel headers. The code to read the headers is based on /proc/config.gz code and uses the same technique to embed the headers. Other approaches were discussed such as having an in-memory mountable filesystem, but that has drawbacks such as requiring an in-kernel xz decompressor which we don't have today, and requiring usage of 42 MB of kernel memory to host the decompressed headers at anytime. Also this approach is simpler than such approaches. Reviewed-by: Masahiro Yamada Signed-off-by: Joel Fernandes (Google) Signed-off-by: Greg Kroah-Hartman

Make anon_inodes unconditional

2019-04-19T12:03:11Z

Make the anon_inodes facility unconditional so that it can be used by core VFS code and pidfd code. Signed-off-by: David Howells Signed-off-by: Al Viro [christian@brauner.io: adapt commit message to mention pidfds] Signed-off-by: Christian Brauner

Merge tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2019-03-11T00:48:21Z

Pull Kbuild updates from Masahiro Yamada: - do not generate unneeded top-level built-in.a - let git ignore O= directory entirely - optimize scripts/kallsyms slightly - exclude DWARF info from *.s regardless of config options - fix GCC toolchain search path for Clang to prepare ld.lld support - do not generate modules.order when CONFIG_MODULES is disabled - simplify single target rules and remove VPATH for external module build - allow to add optional flags to dpkg-buildpackage when building deb-pkg - move some compiler option tests from Makefile to Kconfig - various Makefile cleanups * tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits) kbuild: remove scripts/basic/% build target kbuild: use -Werror=implicit-... instead of -Werror-implicit-... kbuild: clean up scripts/gcc-version.sh kbuild: remove cc-version macro kbuild: update comment block of scripts/clang-version.sh kbuild: remove commented-out INITRD_COMPRESS kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig kbuild: [bin]deb-pkg: add DPKG_FLAGS variable kbuild: move ".config not found!" message from Kconfig to Makefile kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing kbuild: simplify single target rules kbuild: remove empty rules for makefiles kbuild: make -r/-R effective in top Makefile for old Make versions kbuild: move tools_silent to a more relevant place kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig kbuild: refactor cc-cross-prefix implementation kbuild: hardcode genksyms path and remove GENKSYMS variable scripts/gdb: refactor rules for symlink creation kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target scripts/gdb: do not descend into scripts/gdb from scripts ...

Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-03-10T20:58:33Z

Pull timer fix from Thomas Gleixner: "A single fix to prevent a unmet dependencies warning in Kconfig" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: time: Make VIRT_CPU_ACCOUNTING_GEN depend on GENERIC_CLOCKEVENTS

time: Make VIRT_CPU_ACCOUNTING_GEN depend on GENERIC_CLOCKEVENTS

2019-03-06T19:43:08Z

Moving the CONTEXT_TRACKING Kconfig option into kernel/time/Kconfig added an implicit dependency on the surrounding GENERIC_CLOCKEVENTS option, but this is not always enabled when it is possible to select VIRT_CPU_ACCOUNTING_GEN: WARNING: unmet direct dependencies detected for CONTEXT_TRACKING Depends on [n]: GENERIC_CLOCKEVENTS [=n] Selected by [y]: - VIRT_CPU_ACCOUNTING_GEN [=y] && && HAVE_CONTEXT_TRACKING [=y] && HAVE_VIRT_CPU_ACCOUNTING_GEN [=y] Platforms without GENERIC_CLOCKEVENTS are rare enough so that corner case can be just ignored. Make it a dependency for VIRT_CPU_ACCOUNTING_GEN to simplify the configuration. Fixes: a4cffdad7314 ("time: Move CONTEXT_TRACKING to kernel/time/Kconfig") Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Cc: "Paul E . McKenney" Cc: Frederic Weisbecker Link: https://lkml.kernel.org/r/20190304200202.1163250-1-arnd@arndb.de

kbuild: clean up scripts/gcc-version.sh

2019-03-04T13:35:04Z

Now that the Kconfig is the only user of this script, we can drop unneeded code. Remove the -p option, and stop prepending the output with zero, so that Kconfig can directly use the output from this script. Signed-off-by: Masahiro Yamada