8278cc1626
The get_current() code uses the mfctl() macro to get the pointer to the current task struct from %cr30. The problem with the mfctl() macro is, that it is marked volatile which is basically correct, because mfctl() is used to get e.g. the current internal timer or interrupt flags as well. But specifically the task struct pointer (%cr30) doesn't change over time when the kernel executes code for a task. So, by dropping the volatile when retrieving %cr30 the compiler is now able to get this value only once and optimize the generated code a lot. A bloat-o-meter comparism shows that this patch saves ~5kB kernel code on a 32-bit kernel and ~6kB kernel code on a 64-bit kernel. Signed-off-by: Helge Deller <deller@gmx.de>
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.