From: Heiko Carstens <hca@linux.ibm.com>
Date: Tue, 9 Jun 2026 10:33:43 +0000 (+0200)
Subject: s390/tishift: Convert __ashlti3(), __ashrti3(), __lshrti3() to C
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=51746fc082260b0d91fd39315e77cb0863a00136;p=thirdparty%2Flinux.git

s390/tishift: Convert __ashlti3(), __ashrti3(), __lshrti3() to C

There is no reason to have __ashlti3(), __ashrti3(), and __lshrti3()
implemented in assembler. Convert them all to C, which allows the
compiler to optimize the code if newer instructions allow that.

Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---

diff --git a/arch/s390/include/asm/asm-prototypes.h b/arch/s390/include/asm/asm-prototypes.h
index 7bd1801cf241c..d4da4436d02be 100644
--- a/arch/s390/include/asm/asm-prototypes.h
+++ b/arch/s390/include/asm/asm-prototypes.h
@@ -8,8 +8,4 @@
 #include <asm/nospec-branch.h>
 #include <asm-generic/asm-prototypes.h>
 
-__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 /* _ASM_S390_PROTOTYPES_H */
diff --git a/arch/s390/lib/tishift.S b/arch/s390/lib/tishift.S
deleted file mode 100644
index 96214f51f49b8..0000000000000
--- a/arch/s390/lib/tishift.S
+++ /dev/null
@@ -1,63 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-#include <linux/export.h>
-#include <linux/linkage.h>
-#include <asm/nospec-insn.h>
-
-	.section .noinstr.text, "ax"
-
-	GEN_BR_THUNK %r14
-
-SYM_FUNC_START(__ashlti3)
-	lmg	%r0,%r1,0(%r3)
-	cije	%r4,0,1f
-	lhi	%r3,64
-	sr	%r3,%r4
-	jnh	0f
-	srlg	%r3,%r1,0(%r3)
-	sllg	%r0,%r0,0(%r4)
-	sllg	%r1,%r1,0(%r4)
-	ogr	%r0,%r3
-	j	1f
-0:	sllg	%r0,%r1,-64(%r4)
-	lghi	%r1,0
-1:	stmg	%r0,%r1,0(%r2)
-	BR_EX	%r14
-SYM_FUNC_END(__ashlti3)
-EXPORT_SYMBOL(__ashlti3)
-
-SYM_FUNC_START(__ashrti3)
-	lmg	%r0,%r1,0(%r3)
-	cije	%r4,0,1f
-	lhi	%r3,64
-	sr	%r3,%r4
-	jnh	0f
-	sllg	%r3,%r0,0(%r3)
-	srlg	%r1,%r1,0(%r4)
-	srag	%r0,%r0,0(%r4)
-	ogr	%r1,%r3
-	j	1f
-0:	srag	%r1,%r0,-64(%r4)
-	srag	%r0,%r0,63
-1:	stmg	%r0,%r1,0(%r2)
-	BR_EX	%r14
-SYM_FUNC_END(__ashrti3)
-EXPORT_SYMBOL(__ashrti3)
-
-SYM_FUNC_START(__lshrti3)
-	lmg	%r0,%r1,0(%r3)
-	cije	%r4,0,1f
-	lhi	%r3,64
-	sr	%r3,%r4
-	jnh	0f
-	sllg	%r3,%r0,0(%r3)
-	srlg	%r1,%r1,0(%r4)
-	srlg	%r0,%r0,0(%r4)
-	ogr	%r1,%r3
-	j	1f
-0:	srlg	%r1,%r0,-64(%r4)
-	lghi	%r0,0
-1:	stmg	%r0,%r1,0(%r2)
-	BR_EX	%r14
-SYM_FUNC_END(__lshrti3)
-EXPORT_SYMBOL(__lshrti3)
diff --git a/arch/s390/lib/tishift.c b/arch/s390/lib/tishift.c
new file mode 100644
index 0000000000000..bb16cf639af3c
--- /dev/null
+++ b/arch/s390/lib/tishift.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <linux/types.h>
+#include "tishift.h"
+
+union ti {
+	__int128_t val;
+	struct {
+		u64 high;
+		u64 low;
+	};
+};
+
+noinstr __int128_t __ashlti3(__int128_t a, int shift)
+{
+	union ti ti = { .val = a };
+
+	if (!shift)
+		return ti.val;
+	if (shift < 64) {
+		ti.high = (ti.high << shift) | (ti.low >> (64 - shift));
+		ti.low = ti.low << shift;
+	} else {
+		ti.high = ti.low << (shift - 64);
+		ti.low = 0;
+	}
+	return ti.val;
+}
+EXPORT_SYMBOL(__ashlti3);
+
+noinstr __int128_t __ashrti3(__int128_t a, int shift)
+{
+	union ti ti = { .val = a };
+
+	if (!shift)
+		return ti.val;
+	if (shift < 64) {
+		ti.low = (ti.low >> shift) | (ti.high << (64 - shift));
+		ti.high = (int64_t)ti.high >> shift;
+	} else {
+		ti.low = (int64_t)ti.high >> (shift - 64);
+		ti.high = (int64_t)ti.high >> 63;
+	}
+	return ti.val;
+}
+EXPORT_SYMBOL(__ashrti3);
+
+noinstr __int128_t __lshrti3(__int128_t a, int shift)
+{
+	union ti ti = { .val = a };
+
+	if (!shift)
+		return ti.val;
+	if (shift < 64) {
+		ti.low = (ti.low >> shift) | (ti.high << (64 - shift));
+		ti.high = ti.high >> shift;
+	} else {
+		ti.low = ti.high >> (shift - 64);
+		ti.high = 0;
+	}
+	return ti.val;
+}
+EXPORT_SYMBOL(__lshrti3);
diff --git a/arch/s390/lib/tishift.h b/arch/s390/lib/tishift.h
new file mode 100644
index 0000000000000..43a9b8c8e545d
--- /dev/null
+++ b/arch/s390/lib/tishift.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _S390_LIB_TISHIFT_H
+#define _S390_LIB_TISHIFT_H
+
+__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 /* _S390_LIB_TISHIFT_H */