kernel.git/arch/x86/lib/usercopy_64.c, branch linux-4.20.y

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-10-23T14:24:22Z

Pull x86 asm updates from Ingo Molnar: "The main changes in this cycle were the fsgsbase related preparatory patches from Chang S. Bae - but there's also an optimized memcpy_flushcache() and a cleanup for the __cmpxchg_double() assembly glue" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fsgsbase/64: Clean up various details x86/segments: Introduce the 'CPUNODE' naming to better document the segment limit CPU/node NR trick x86/vdso: Initialize the CPU/node NR segment descriptor earlier x86/vdso: Introduce helper functions for CPU and node number x86/segments/64: Rename the GDT PER_CPU entry to CPU_NUMBER x86/fsgsbase/64: Factor out FS/GS segment loading from __switch_to() x86/fsgsbase/64: Convert the ELF core dump code to the new FSGSBASE helpers x86/fsgsbase/64: Make ptrace use the new FS/GS base helpers x86/fsgsbase/64: Introduce FS/GS base helper functions x86/fsgsbase/64: Fix ptrace() to read the FS/GS base accurately x86/asm: Use CC_SET()/CC_OUT() in __cmpxchg_double() x86/asm: Optimize memcpy_flushcache()

x86/asm: Optimize memcpy_flushcache()

2018-09-10T13:17:12Z

I use memcpy_flushcache() in my persistent memory driver for metadata updates, there are many 8-byte and 16-byte updates and it turns out that the overhead of memcpy_flushcache causes 2% performance degradation compared to "movnti" instruction explicitly coded using inline assembler. The tests were done on a Skylake processor with persistent memory emulated using the "memmap" kernel parameter. dd was used to copy data to the dm-writecache target. This patch recognizes memcpy_flushcache calls with constant short length and turns them into inline assembler - so that I don't have to use inline assembler in the driver. Signed-off-by: Mikulas Patocka Cc: Dan Williams Cc: Linus Torvalds Cc: Mike Snitzer Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: device-mapper development Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1808081720460.24747@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Ingo Molnar

x86/extable: Introduce _ASM_EXTABLE_UA for uaccess fixups

2018-09-03T13:12:09Z

Currently, most fixups for attempting to access userspace memory are handled using _ASM_EXTABLE, which is also used for various other types of fixups (e.g. safe MSR access, IRET failures, and a bunch of other things). In order to make it possible to add special safety checks to uaccess fixups (in particular, checking whether the fault address is actually in userspace), introduce a new exception table handler ex_handler_uaccess() and wire it up to all the user access fixups (excluding ones that already use _ASM_EXTABLE_EX). Signed-off-by: Jann Horn Signed-off-by: Thomas Gleixner Tested-by: Kees Cook Cc: Andy Lutomirski Cc: kernel-hardening@lists.openwall.com Cc: dvyukov@google.com Cc: Masami Hiramatsu Cc: "Naveen N. Rao" Cc: Anil S Keshavamurthy Cc: "David S. Miller" Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: Borislav Petkov Link: https://lkml.kernel.org/r/20180828201421.157735-5-jannh@google.com

Merge branch 'x86-dax-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-06-05T02:23:13Z

Pull x86 dax updates from Ingo Molnar: "This contains x86 memcpy_mcsafe() fault handling improvements the nvdimm tree would like to make more use of" * 'x86-dax-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe() x86/asm/memcpy_mcsafe: Add write-protection-fault handling x86/asm/memcpy_mcsafe: Return bytes remaining x86/asm/memcpy_mcsafe: Add labels for __memcpy_mcsafe() write fault handling x86/asm/memcpy_mcsafe: Remove loop unrolling

x86/asm/memcpy_mcsafe: Add write-protection-fault handling

2018-05-15T06:32:42Z

In preparation for using memcpy_mcsafe() to handle user copies it needs to be to handle write-protection faults while writing user pages. Add MMU-fault handlers alongside the machine-check exception handlers. Note that the machine check fault exception handling makes assumptions about source buffer alignment and poison alignment. In the write fault case, given the destination buffer is arbitrarily aligned, it needs a separate / additional fault handling approach. The mcsafe_handle_tail() helper is reused. The @limit argument is set to @len since there is no safety concern about retriggering an MMU fault, and this simplifies the assembly. Co-developed-by: Tony Luck Reported-by: Mika Penttilä Signed-off-by: Dan Williams Cc: Al Viro Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tony Luck Cc: hch@lst.de Cc: linux-fsdevel@vger.kernel.org Cc: linux-nvdimm@lists.01.org Link: http://lkml.kernel.org/r/152539238635.31796.14056325365122961778.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar

x86/asm/64: Micro-optimize __clear_user() - Use immediate constants

2018-05-14T09:38:51Z

Save two registers. Adding constants should be just as fast as adding registers. Signed-off-by: Alexey Dobriyan Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180507213937.GB32406@avx2 Signed-off-by: Ingo Molnar

x86, dax, libnvdimm: remove wb_cache_pmem() indirection

2017-06-15T21:35:24Z

With all handling of the CONFIG_ARCH_HAS_PMEM_API case being moved to libnvdimm and the pmem driver directly we do not need to provide global wrappers and fallbacks in the CONFIG_ARCH_HAS_PMEM_API=n case. The pmem driver will simply not link to arch_wb_cache_pmem() in that case. Same as before, pmem flushing is only defined for x86_64, via clean_cache_range(), but it is straightforward to add other archs in the future. arch_wb_cache_pmem() is an exported function since the pmem module needs to find it, but it is privately declared in drivers/nvdimm/pmem.h because there are no consumers outside of the pmem driver. Cc: Cc: Jan Kara Cc: Jeff Moyer Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Oliver O'Halloran Cc: Matthew Wilcox Cc: Ross Zwisler Suggested-by: Christoph Hellwig Signed-off-by: Dan Williams

x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations

2017-06-09T16:09:56Z

The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: Cc: Jan Kara Cc: Jeff Moyer Cc: Ingo Molnar Cc: Christoph Hellwig Cc: Toshi Kani Cc: "H. Peter Anvin" Cc: Al Viro Cc: Thomas Gleixner Cc: Matthew Wilcox Reviewed-by: Ross Zwisler Signed-off-by: Dan Williams

x86: don't wank with magical size in __copy_in_user()

2017-03-29T16:04:35Z

... especially since copy_in_user() doesn't Signed-off-by: Al Viro

amd64: get rid of zeroing

2017-03-28T22:24:04Z

Signed-off-by: Al Viro