• Dan Williams's avatar
    x86/asm/memcpy_mcsafe: Return bytes remaining · 60622d68
    Dan Williams authored
    Machine check safe memory copies are currently deployed in the pmem
    driver whenever reading from persistent memory media, so that -EIO is
    returned rather than triggering a kernel panic. While this protects most
    pmem accesses, it is not complete in the filesystem-dax case. When
    filesystem-dax is enabled reads may bypass the block layer and the
    driver via dax_iomap_actor() and its usage of copy_to_iter().
    
    In preparation for creating a copy_to_iter() variant that can handle
    machine checks, teach memcpy_mcsafe() to return the number of bytes
    remaining rather than -EFAULT when an exception occurs.
    Co-developed-by: default avatarTony Luck <tony.luck@intel.com>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: hch@lst.de
    Cc: linux-fsdevel@vger.kernel.org
    Cc: linux-nvdimm@lists.01.org
    Link: http://lkml.kernel.org/r/152539238119.31796.14318473522414462886.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    60622d68
memcpy_64.S 5.17 KB