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Mark Rutland
4a3f806eca
Currently the asm constraints for __put_mem_asm() require that the value is placed in a "real" GPR (i.e. one other than [XW]ZR or SP). This means that for cases such as: __put_user(0, addr) ... the compiler has to move '0' into "real" GPR, e.g. mov xN, #0 sttr xN, [<addr>] This is unfortunate, as using the zero register would require fewer instructions and save a "real" GPR for other usage, allowing the compiler to generate: sttr xzr, [<addr>] Modify the asm constaints for __put_mem_asm() to permit the use of the zero register for the value. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Robin Murphy <[email protected]> Cc: Will Deacon <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Will Deacon <[email protected]>
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.