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427fda2c8a
The old 'copy_user_generic_unrolled' function was oddly implemented for largely historical reasons: it had been largely based on the uncached copy case, which has some other concerns. For example, the __copy_user_nocache() function uses 'movnti' for the destination stores, and those want the destination to be aligned. In contrast, the regular copy function doesn't really care, and trying to align things only complicates matters. Also, like the clear_user function, the copy function had some odd handling of the repeat counts, complicating the exception handling for no really good reason. So as with clear_user, just write it to keep all the byte counts in the %rcx register, exactly like the 'rep movs' functionality that this replaces. Unlike a real 'rep movs', we do allow for this to trash a few temporary registers to not have to unnecessarily save/restore registers on the stack. And like the clearing case, rename this to what it now clearly is: 'rep_movs_alternative', and make it one coherent function, so that it shows up as such in profiles (instead of the odd split between "copy_user_generic_unrolled" and "copy_user_short_string", the latter of which was not about strings at all, and which was shared with the uncached case). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.