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James Hogan bbc25bee37 lib/mpi: Fix umul_ppmm() for MIPS64r6 
Current MIPS64r6 toolchains aren't able to generate efficient
DMULU/DMUHU based code for the C implementation of umul_ppmm(), which
performs an unsigned 64 x 64 bit multiply and returns the upper and
lower 64-bit halves of the 128-bit result. Instead it widens the 64-bit
inputs to 128-bits and emits a __multi3 intrinsic call to perform a 128
x 128 multiply. This is both inefficient, and it results in a link error
since we don't include __multi3 in MIPS linux.

For example commit 90a53e4432 ("cfg80211: implement regdb signature
checking") merged in v4.15-rc1 recently broke the 64r6_defconfig and
64r6el_defconfig builds by indirectly selecting MPILIB. The same build
errors can be reproduced on older kernels by enabling e.g. CRYPTO_RSA:

lib/mpi/generic_mpih-mul1.o: In function `mpihelp_mul_1':
lib/mpi/generic_mpih-mul1.c:50: undefined reference to `__multi3'
lib/mpi/generic_mpih-mul2.o: In function `mpihelp_addmul_1':
lib/mpi/generic_mpih-mul2.c:49: undefined reference to `__multi3'
lib/mpi/generic_mpih-mul3.o: In function `mpihelp_submul_1':
lib/mpi/generic_mpih-mul3.c:49: undefined reference to `__multi3'
lib/mpi/mpih-div.o In function `mpihelp_divrem':
lib/mpi/mpih-div.c:205: undefined reference to `__multi3'
lib/mpi/mpih-div.c:142: undefined reference to `__multi3'

Therefore add an efficient MIPS64r6 implementation of umul_ppmm() using
inline assembly and the DMULU/DMUHU instructions, to prevent __multi3
calls being emitted.

Fixes: 7fd08ca58a ("MIPS: Add build support for the MIPS R6 ISA")
Signed-off-by: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-mips@linux-mips.org
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22 19:39:09 +11:00
..
generic_mpih-add1.c
generic_mpih-lshift.c
generic_mpih-mul1.c
generic_mpih-mul2.c
generic_mpih-mul3.c
generic_mpih-rshift.c
generic_mpih-sub1.c
longlong.h lib/mpi: Fix umul_ppmm() for MIPS64r6 2017-12-22 19:39:09 +11:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpi-bit.c MPILIB: Provide count_leading/trailing_zeros() based on arch functions 2012-10-08 13:50:11 +10:30
mpi-cmp.c MPILIB: Fix comparison of negative MPIs 2015-01-14 16:10:12 +00:00
mpi-inline.h lib/mpi: use "static inline" instead of "extern inline" 2016-02-28 03:26:34 +08:00
mpi-internal.h lib/mpi: use "static inline" instead of "extern inline" 2016-02-28 03:26:34 +08:00
mpi-pow.c lib/mpi: call cond_resched() from mpi_powm() loop 2017-11-10 19:20:26 +08:00
mpicoder.c lib/mpi: kunmap after finishing accessing buffer 2017-08-22 14:45:01 +08:00
mpih-cmp.c
mpih-div.c Remove unused code from MPI library 2012-05-26 11:51:03 +10:00
mpih-mul.c Remove unused code from MPI library 2012-05-26 11:51:03 +10:00
mpiutil.c MPILIB: add mpi_read_buf() and mpi_get_size() helpers 2015-06-16 14:35:06 +08:00