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authorJames Hogan <jhogan@kernel.org>2017-12-05 23:31:35 +0000
committerHerbert Xu <herbert@gondor.apana.org.au>2017-12-22 19:39:09 +1100
commitbbc25bee37d2b32cf3a1fab9195b6da3a185614a (patch)
treeb011592762672f66814270adfb607455c4416f03 /lib
parentd76c68109f37cb85b243a1cf0f40313afd2bae68 (diff)
download96b-common-bbc25bee37d2b32cf3a1fab9195b6da3a185614a.tar.gz
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 90a53e4432b1 ("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: 7fd08ca58ae6 ("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>
Diffstat (limited to 'lib')
-rw-r--r--lib/mpi/longlong.h18
1 files changed, 17 insertions, 1 deletions
diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h
index 57fd45ab7af1..08c60d10747f 100644
--- a/lib/mpi/longlong.h
+++ b/lib/mpi/longlong.h
@@ -671,7 +671,23 @@ do { \
************** MIPS/64 **************
***************************************/
#if (defined(__mips) && __mips >= 3) && W_TYPE_SIZE == 64
-#if (__GNUC__ >= 5) || (__GNUC__ >= 4 && __GNUC_MINOR__ >= 4)
+#if defined(__mips_isa_rev) && __mips_isa_rev >= 6
+/*
+ * 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.
+ */
+#define umul_ppmm(w1, w0, u, v) \
+do { \
+ __asm__ ("dmulu %0,%1,%2" \
+ : "=d" ((UDItype)(w0)) \
+ : "d" ((UDItype)(u)), \
+ "d" ((UDItype)(v))); \
+ __asm__ ("dmuhu %0,%1,%2" \
+ : "=d" ((UDItype)(w1)) \
+ : "d" ((UDItype)(u)), \
+ "d" ((UDItype)(v))); \
+} while (0)
+#elif (__GNUC__ >= 5) || (__GNUC__ >= 4 && __GNUC_MINOR__ >= 4)
#define umul_ppmm(w1, w0, u, v) \
do { \
typedef unsigned int __ll_UTItype __attribute__((mode(TI))); \