From: Greg Kroah-Hartman Date: Fri, 2 Mar 2018 06:27:56 +0000 (+0100) Subject: 4.4-stable patches X-Git-Tag: v3.18.98~3 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=10b613aa56958daf99e3d789b16e77a41c0d4fa9;p=thirdparty%2Fkernel%2Fstable-queue.git 4.4-stable patches added patches: mips-implement-__multi3-for-gcc7-mips64r6-builds.patch --- diff --git a/queue-4.4/mips-implement-__multi3-for-gcc7-mips64r6-builds.patch b/queue-4.4/mips-implement-__multi3-for-gcc7-mips64r6-builds.patch new file mode 100644 index 00000000000..b398563c963 --- /dev/null +++ b/queue-4.4/mips-implement-__multi3-for-gcc7-mips64r6-builds.patch @@ -0,0 +1,145 @@ +From ebabcf17bcd7ce968b1631ebe08236275698f39b Mon Sep 17 00:00:00 2001 +From: James Hogan +Date: Thu, 7 Dec 2017 07:20:46 +0000 +Subject: MIPS: Implement __multi3 for GCC7 MIPS64r6 builds + +From: James Hogan + +commit ebabcf17bcd7ce968b1631ebe08236275698f39b upstream. + +GCC7 is a bit too eager to generate suboptimal __multi3 calls (128bit +multiply with 128bit result) for MIPS64r6 builds, even in code which +doesn't explicitly use 128bit types, such as the following: + +unsigned long func(unsigned long a, unsigned long b) +{ + return a > (~0UL) / b; +} + +Which GCC rearanges to: + +return (unsigned __int128)a * (unsigned __int128)b > 0xffffffffffffffff; + +Therefore implement __multi3, but only for MIPS64r6 with GCC7 as under +normal circumstances we wouldn't expect any calls to __multi3 to be +generated from kernel code. + +Reported-by: Thomas Petazzoni +Signed-off-by: James Hogan +Tested-by: Waldemar Brodkorb +Cc: Ralf Baechle +Cc: Maciej W. Rozycki +Cc: Matthew Fortune +Cc: Florian Fainelli +Cc: linux-mips@linux-mips.org +Patchwork: https://patchwork.linux-mips.org/patch/17890/ +Cc: Guenter Roeck +Signed-off-by: Greg Kroah-Hartman + +--- + arch/mips/lib/Makefile | 3 +- + arch/mips/lib/libgcc.h | 17 +++++++++++++++ + arch/mips/lib/multi3.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++ + 3 files changed, 73 insertions(+), 1 deletion(-) + +--- a/arch/mips/lib/Makefile ++++ b/arch/mips/lib/Makefile +@@ -15,4 +15,5 @@ obj-$(CONFIG_CPU_R3000) += r3k_dump_tlb + obj-$(CONFIG_CPU_TX39XX) += r3k_dump_tlb.o + + # libgcc-style stuff needed in the kernel +-obj-y += ashldi3.o ashrdi3.o bswapsi.o bswapdi.o cmpdi2.o lshrdi3.o ucmpdi2.o ++obj-y += ashldi3.o ashrdi3.o bswapsi.o bswapdi.o cmpdi2.o lshrdi3.o multi3.o \ ++ ucmpdi2.o +--- a/arch/mips/lib/libgcc.h ++++ b/arch/mips/lib/libgcc.h +@@ -9,10 +9,18 @@ typedef int word_type __attribute__ ((mo + struct DWstruct { + int high, low; + }; ++ ++struct TWstruct { ++ long long high, low; ++}; + #elif defined(__LITTLE_ENDIAN) + struct DWstruct { + int low, high; + }; ++ ++struct TWstruct { ++ long long low, high; ++}; + #else + #error I feel sick. + #endif +@@ -22,4 +30,13 @@ typedef union { + long long ll; + } DWunion; + ++#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) ++typedef int ti_type __attribute__((mode(TI))); ++ ++typedef union { ++ struct TWstruct s; ++ ti_type ti; ++} TWunion; ++#endif ++ + #endif /* __ASM_LIBGCC_H */ +--- /dev/null ++++ b/arch/mips/lib/multi3.c +@@ -0,0 +1,54 @@ ++// SPDX-License-Identifier: GPL-2.0 ++#include ++ ++#include "libgcc.h" ++ ++/* ++ * GCC 7 suboptimally generates __multi3 calls for mips64r6, so for that ++ * specific case only we'll implement it here. ++ * ++ * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981 ++ */ ++#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ == 7) ++ ++/* multiply 64-bit values, low 64-bits returned */ ++static inline long long notrace dmulu(long long a, long long b) ++{ ++ long long res; ++ ++ asm ("dmulu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b)); ++ return res; ++} ++ ++/* multiply 64-bit unsigned values, high 64-bits of 128-bit result returned */ ++static inline long long notrace dmuhu(long long a, long long b) ++{ ++ long long res; ++ ++ asm ("dmuhu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b)); ++ return res; ++} ++ ++/* multiply 128-bit values, low 128-bits returned */ ++ti_type notrace __multi3(ti_type a, ti_type b) ++{ ++ TWunion res, aa, bb; ++ ++ aa.ti = a; ++ bb.ti = b; ++ ++ /* ++ * a * b = (a.lo * b.lo) ++ * + 2^64 * (a.hi * b.lo + a.lo * b.hi) ++ * [+ 2^128 * (a.hi * b.hi)] ++ */ ++ res.s.low = dmulu(aa.s.low, bb.s.low); ++ res.s.high = dmuhu(aa.s.low, bb.s.low); ++ res.s.high += dmulu(aa.s.high, bb.s.low); ++ res.s.high += dmulu(aa.s.low, bb.s.high); ++ ++ return res.ti; ++} ++EXPORT_SYMBOL(__multi3); ++ ++#endif /* 64BIT && CPU_MIPSR6 && GCC7 */ diff --git a/queue-4.4/series b/queue-4.4/series index 7c55cc574aa..f84e769212f 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -31,3 +31,4 @@ xen-gntdev-fix-off-by-one-error-when-unmapping-with-holes.patch xen-gntdev-fix-partial-gntdev_mmap-cleanup.patch sctp-make-use-of-pre-calculated-len.patch net-gianfar_ptp-move-set_fipers-to-spinlock-protecting-area.patch +mips-implement-__multi3-for-gcc7-mips64r6-builds.patch