706221e6cd
commit b0c091ae04f6746f541b9be91809e1f4f43e9a65 upstream.
Clang errors out when building this macro:
lib/mpi/generic_mpih-mul1.c:37:24: error: invalid use of a cast in a
inline asm context requiring an l-value: remove the cast or build with
-fheinous-gnu-extensions
umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb);
~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/mpi/longlong.h:652:20: note: expanded from macro 'umul_ppmm'
: "=l" ((USItype)(w0)), \
~~~~~~~~~~^~~
lib/mpi/generic_mpih-mul1.c:37:3: error: invalid output constraint '=h'
in asm
umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb);
^
lib/mpi/longlong.h:653:7: note: expanded from macro 'umul_ppmm'
"=h" ((USItype)(w1)) \
^
2 errors generated.
The C version that is used for GCC 4.4 and up works well with clang;
however, it is not currently being used because Clang masks itself
as GCC 4.2.1 for compatibility reasons. As Nick points out, we require
GCC 4.6 and newer in the kernel so we can eliminate all of the
versioning checks and just use the C version of umul_ppmm for all
supported compilers.
Link: https://github.com/ClangBuiltLinux/linux/issues/605
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.