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Linus Torvalds 3680785692 x86: get rid of 'rtype' argument to __put_user_goto() macro
The 'rtype' argument goes back to pre-git (and pre-BK) times, and comes
from the fact that we used to not necessarily have the same type sizes
for the arguments of the inline asm as we did for the actual accesses we
did.

So 'rtype' is the 'register type' - the override of the register size in
the inline asm when it doesn't match the actual size of the variable we
use as the output argument (for when you used "put_user()" on an "int"
value that was assigned to a byte-sized user space access etc).

That mismatch doesn't actually exist any more, and should probably never
have existed in the first place.  It's a horrid bug just waiting to
happen (using more - or less - of the variable that the compiler
expected us to use).

I think we had some odd casting going on to hide the effects of that
oddity after-the-fact, but those are long gone, and these days we should
always have the right size value in the first place, using things like

        __typeof__(*(ptr)) __pu_val = (x);

and gcc should thus have the right register size without any manual
'rtype' games.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
History 2020-04-01 10:52:01 -07:00
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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.