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From: Xi Ruoyao <xry111@xry111.site>
To: Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>
Cc: loongarch@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	Tiezhu Yang <yangtiezhu@loongson.cn>,
	Xi Ruoyao <xry111@xry111.site>
Subject: [PATCH] LoongArch: Provide __lshrti3, __ashrti3, and __ashrti3
Date: Fri, 26 Apr 2024 20:14:42 +0800
Message-ID: <20240426121442.882029-1-xry111@xry111.site>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

After selecting ARCH_SUPPORTS_INT128, when optimizing for size the
compiler generates calls to __lshrti3, __ashrti3, and __ashrti3 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'

Provide the implementation of these functions if ARCH_SUPPORTS_INT128.

Reported-by: Huacai Chen <chenhuacai@kernel.org>
Closes: https://lore.kernel.org/loongarch/CAAhV-H5EZ=7OF7CSiYyZ8_+wWuenpo=K2WT8-6mAT4CvzUC_4g@mail.gmail.com/
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---
 arch/loongarch/include/asm/asm-prototypes.h |  6 +++
 arch/loongarch/lib/Makefile                 |  2 +
 arch/loongarch/lib/tishift.S                | 56 +++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 arch/loongarch/lib/tishift.S

diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h
index cf8e1a4e7c19..51f224bcfc65 100644
--- a/arch/loongarch/include/asm/asm-prototypes.h
+++ b/arch/loongarch/include/asm/asm-prototypes.h
@@ -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
diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile
index a77bf160bfc4..f61af161f16e 100644
--- a/arch/loongarch/lib/Makefile
+++ b/arch/loongarch/lib/Makefile
@@ -9,3 +9,5 @@ lib-y	+= delay.o memset.o memcpy.o memmove.o \
 obj-$(CONFIG_CPU_HAS_LSX) += xor_simd.o xor_simd_glue.o
 
 obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
+
+obj-$(CONFIG_ARCH_SUPPORTS_INT128) += tishift.o
diff --git a/arch/loongarch/lib/tishift.S b/arch/loongarch/lib/tishift.S
new file mode 100644
index 000000000000..eb43f29f4d0b
--- /dev/null
+++ b/arch/loongarch/lib/tishift.S
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <asm/asmmacro.h>
+#include <linux/linkage.h>
+#include <linux/export.h>
+
+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)
+
+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(__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)
-- 
2.44.0