Commit 5125d033 authored by Xi Ruoyao's avatar Xi Ruoyao Committed by Huacai Chen
Browse files

LoongArch: Select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 

This allows compiling a full 128-bit product of two 64-bit integers as a
mul/mulh pair, instead of a nasty long sequence of 20+ instructions.

However, after selecting ARCH_SUPPORTS_INT128, when optimizing for size
the compiler generates calls to __ashlti3, __ashrti3, and __lshrti3 for
shifting __int128 values, causing a link failure:

    loongarch64-unknown-linux-gnu-ld: kernel/sched/fair.o: in
    function `mul_u64_u32_shr':
    <PATH>/include/linux/math64.h:161:(.text+0x5e4): undefined
    reference to `__lshrti3'

So provide the implementation of these functions if ARCH_SUPPORTS_INT128.

Closes: https://lore.kernel.org/loongarch/CAAhV-H5EZ=7OF7CSiYyZ8_+wWuenpo=K2WT8-6mAT4CvzUC_4g@mail.gmail.com/


Signed-off-by: default avatarXi Ruoyao <xry111@xry111.site>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 2cce9059

arch/loongarch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ config LOONGARCH 
	select ARCH_SUPPORTS_ACPI

	select ARCH_SUPPORTS_ATOMIC_RMW

	select ARCH_SUPPORTS_HUGETLBFS

	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128

	select ARCH_SUPPORTS_LTO_CLANG

	select ARCH_SUPPORTS_LTO_CLANG_THIN

	select ARCH_SUPPORTS_NUMA_BALANCING

arch/loongarch/include/asm/asm-prototypes.h

+6 −0
Original line number Diff line number Diff line
@@ -6,3 +6,9 @@ 
#include <asm/page.h>

#include <asm/ftrace.h>

#include <asm-generic/asm-prototypes.h>



#ifdef CONFIG_ARCH_SUPPORTS_INT128

__int128_t __ashlti3(__int128_t a, int b);

__int128_t __ashrti3(__int128_t a, int b);

__int128_t __lshrti3(__int128_t a, int b);

#endif

arch/loongarch/lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ 
lib-y	+= delay.o memset.o memcpy.o memmove.o \

	   clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o



obj-$(CONFIG_ARCH_SUPPORTS_INT128) += tishift.o



obj-$(CONFIG_CPU_HAS_LSX) += xor_simd.o xor_simd_glue.o



obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

arch/loongarch/lib/tishift.S

0 → 100644
+56 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */



#include <asm/asmmacro.h>

#include <linux/export.h>

#include <linux/linkage.h>



SYM_FUNC_START(__ashlti3)

	srli.d	t2, a0, 1

	nor	t3, zero, a2

	sll.d	t1, a1, a2

	srl.d	t2, t2, t3

	andi	t0, a2, 64

	sll.d	a0, a0, a2

	or	t1, t2, t1

	maskeqz	a1, a0, t0

	masknez	a0, a0, t0

	masknez	t0, t1, t0

	or	a1, t0, a1

	jr	ra

SYM_FUNC_END(__ashlti3)

EXPORT_SYMBOL(__ashlti3)



SYM_FUNC_START(__ashrti3)

	nor	t3, zero, a2

	slli.d	t2, a1, 1

	srl.d	t1, a0, a2

	sll.d	t2, t2, t3

	andi	t0, a2, 64

	or	t1, t2, t1

	sra.d	a2, a1, a2

	srai.d	a1, a1, 63

	maskeqz	a0, a2, t0

	maskeqz	a1, a1, t0

	masknez	a2, a2, t0

	masknez	t0, t1, t0

	or	a1, a1, a2

	or	a0, t0, a0

	jr	ra

SYM_FUNC_END(__ashrti3)

EXPORT_SYMBOL(__ashrti3)



SYM_FUNC_START(__lshrti3)

	slli.d	t2, a1, 1

	nor	t3, zero, a2

	srl.d	t1, a0, a2

	sll.d	t2, t2, t3

	andi	t0, a2, 64

	srl.d	a1, a1, a2

	or	t1, t2, t1

	maskeqz	a0, a1, t0

	masknez	a1, a1, t0

	masknez	t0, t1, t0

	or	a0, t0, a0

	jr	ra

SYM_FUNC_END(__lshrti3)

EXPORT_SYMBOL(__lshrti3)