From: Nathan Chancellor natechancellor@gmail.com
[ Upstream commit 18f1ca46858eac22437819937ae44aa9a8f9f2fa ]
When building 64r6_defconfig with CONFIG_MIPS32_O32 disabled and CONFIG_CRYPTO_RSA enabled:
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:664:22: note: expanded from macro 'umul_ppmm' : "=d" ((UDItype)(w0)) ~~~~~~~~~~^~~ lib/mpi/generic_mpih-mul1.c:37:13: 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:668:22: note: expanded from macro 'umul_ppmm' : "=d" ((UDItype)(w1)) ~~~~~~~~~~^~~ 2 errors generated.
This special case for umul_ppmm for MIPS64r6 was added in commit bbc25bee37d2b ("lib/mpi: Fix umul_ppmm() for MIPS64r6"), due to GCC being inefficient and emitting a __multi3 intrinsic.
There is no such issue with clang; with this patch applied, I can build this configuration without any problems and there are no link errors like mentioned in the commit above (which I can still reproduce with GCC 9.3.0 when that commit is reverted). Only use this definition when GCC is being used.
This really should have been caught by commit b0c091ae04f67 ("lib/mpi: Eliminate unused umul_ppmm definitions for MIPS") when I was messing around in this area but I was not testing 64-bit MIPS at the time.
Link: https://github.com/ClangBuiltLinux/linux/issues/885 Reported-by: Dmitry Golovin dima@golovin.in Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org --- lib/mpi/longlong.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h index 891e1c3549c4..afbd99987cf8 100644 --- a/lib/mpi/longlong.h +++ b/lib/mpi/longlong.h @@ -653,7 +653,7 @@ do { \ ************** MIPS/64 ************** ***************************************/ #if (defined(__mips) && __mips >= 3) && W_TYPE_SIZE == 64 -#if defined(__mips_isa_rev) && __mips_isa_rev >= 6 +#if defined(__mips_isa_rev) && __mips_isa_rev >= 6 && defined(CONFIG_CC_IS_GCC) /* * GCC ends up emitting a __multi3 intrinsic call for MIPS64r6 with the plain C * code below, so we special case MIPS64r6 until the compiler can do better.