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Message-Id: <20231113133209.1367286-1-gerg@linux-m68k.org>
Date: Mon, 13 Nov 2023 23:32:09 +1000
From: Greg Ungerer <gerg@...ux-m68k.org>
To: linux-m68k@...ts.linux-m68k.org
Cc: geert@...ux-m68k.org, arnd@...db.de, linux-kernel@...r.kernel.org,
Greg Ungerer <gerg@...ux-m68k.org>
Subject: [PATCH v2] m68k: use kernel's generic muldi3 libgcc function
Use the kernels own generic lib/muldi3.c implementation of muldi3 for
68K machines. Some 68K CPUs support 64bit multiplies so move the arch
specific umul_ppmm() macro into a header file that is included by
lib/muldi3.c. That way it can take advantage of the single instruction
when available.
There does not appear to be any existing mechanism for the generic
lib/muldi3.c code to pick up an external arch definition of umul_ppmm().
Create an arch specific libgcc.h that can optionally be included by
the system include/linux/libgcc.h to allow for this.
Somewhat oddly there is also a similar definition of umul_ppmm() in
the non-architecture code in lib/crypto/mpi/longlong.h for a wide range
or machines. Its presence ends up complicating the include setup and
means not being able to use something like compiler.h instead. Actually
there is a few other defines of umul_ppmm() macros spread around in
various architectures, but not directly usable for the m68k case.
Signed-off-by: Greg Ungerer <gerg@...ux-m68k.org>
---
arch/Kconfig | 8 +++
arch/m68k/Kconfig | 2 +
arch/m68k/include/asm/libgcc.h | 20 +++++++
arch/m68k/lib/Makefile | 2 +-
arch/m68k/lib/muldi3.c | 97 ----------------------------------
include/linux/libgcc.h | 4 ++
6 files changed, 35 insertions(+), 98 deletions(-)
create mode 100644 arch/m68k/include/asm/libgcc.h
delete mode 100644 arch/m68k/lib/muldi3.c
v2: change to using arch libgcc.h instead of compiler.h
diff --git a/arch/Kconfig b/arch/Kconfig
index f4b210ab0612..3764328dd8b1 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1331,6 +1331,14 @@ config HAVE_ARCH_COMPILER_H
linux/compiler-*.h in order to override macro definitions that those
headers generally provide.
+config HAVE_ARCH_LIBGCC_H
+ bool
+ help
+ An architecture can select this if it provides an
+ asm/libgcc.h header that should be included after
+ linux/libgcc.h in order to override macro definitions that
+ header generally provides.
+
config HAVE_ARCH_PREL32_RELOCATIONS
bool
help
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 4b3e93cac723..1594f78e3666 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -22,7 +22,9 @@ config M68K
select GENERIC_LIB_ASHLDI3
select GENERIC_LIB_ASHRDI3
select GENERIC_LIB_LSHRDI3
+ select GENERIC_LIB_MULDI3
select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA
+ select HAVE_ARCH_LIBGCC_H
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS
diff --git a/arch/m68k/include/asm/libgcc.h b/arch/m68k/include/asm/libgcc.h
new file mode 100644
index 000000000000..1cce6d130d80
--- /dev/null
+++ b/arch/m68k/include/asm/libgcc.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_M68K_LIBGCC_H
+#define __ASM_M68K_LIBGCC_H
+
+#ifndef CONFIG_CPU_HAS_NO_MULDIV64
+/*
+ * For those 68K CPUs that support 64bit multiply define umul_ppm()
+ * for the common muldi3 libgcc helper function (in lib/muldi3.c).
+ * CPUs that don't have it (like the original 68000 and ColdFire)
+ * will fallback to using the C-coded version of umul_ppmm().
+ */
+#define umul_ppmm(w1, w0, u, v) \
+ __asm__ ("mulu%.l %3,%1:%0" \
+ : "=d" ((unsigned long)(w0)), \
+ "=d" ((unsigned long)(w1)) \
+ : "%0" ((unsigned long)(u)), \
+ "dmi" ((unsigned long)(v)))
+#endif /* !CONFIG_CPU_HAS_NO_MULDIV64 */
+
+#endif /* __ASM_M68K_LIBGCC_H */
diff --git a/arch/m68k/lib/Makefile b/arch/m68k/lib/Makefile
index 9158688e6cc6..15278a95259e 100644
--- a/arch/m68k/lib/Makefile
+++ b/arch/m68k/lib/Makefile
@@ -4,7 +4,7 @@
# Makefile for m68k-specific library files..
#
-lib-y := muldi3.o memcpy.o memset.o memmove.o
+lib-y := memcpy.o memset.o memmove.o
lib-$(CONFIG_MMU) += uaccess.o
lib-$(CONFIG_CPU_HAS_NO_MULDIV64) += mulsi3.o divsi3.o udivsi3.o
diff --git a/arch/m68k/lib/muldi3.c b/arch/m68k/lib/muldi3.c
deleted file mode 100644
index 5012a9b218c7..000000000000
--- a/arch/m68k/lib/muldi3.c
+++ /dev/null
@@ -1,97 +0,0 @@
-/* muldi3.c extracted from gcc-2.7.2.3/libgcc2.c and
- gcc-2.7.2.3/longlong.h which is: */
-/* Copyright (C) 1989, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
-
-This file is part of GNU CC.
-
-GNU CC is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
-
-GNU CC is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details. */
-
-#include <linux/compiler.h>
-#include <linux/export.h>
-#include <linux/libgcc.h>
-
-#ifdef CONFIG_CPU_HAS_NO_MULDIV64
-
-#define SI_TYPE_SIZE 32
-#define __BITS4 (SI_TYPE_SIZE / 4)
-#define __ll_B (1L << (SI_TYPE_SIZE / 2))
-#define __ll_lowpart(t) ((USItype) (t) % __ll_B)
-#define __ll_highpart(t) ((USItype) (t) / __ll_B)
-
-#define umul_ppmm(w1, w0, u, v) \
- do { \
- USItype __x0, __x1, __x2, __x3; \
- USItype __ul, __vl, __uh, __vh; \
- \
- __ul = __ll_lowpart (u); \
- __uh = __ll_highpart (u); \
- __vl = __ll_lowpart (v); \
- __vh = __ll_highpart (v); \
- \
- __x0 = (USItype) __ul * __vl; \
- __x1 = (USItype) __ul * __vh; \
- __x2 = (USItype) __uh * __vl; \
- __x3 = (USItype) __uh * __vh; \
- \
- __x1 += __ll_highpart (__x0);/* this can't give carry */ \
- __x1 += __x2; /* but this indeed can */ \
- if (__x1 < __x2) /* did we get it? */ \
- __x3 += __ll_B; /* yes, add it in the proper pos. */ \
- \
- (w1) = __x3 + __ll_highpart (__x1); \
- (w0) = __ll_lowpart (__x1) * __ll_B + __ll_lowpart (__x0); \
- } while (0)
-
-#else
-
-#define umul_ppmm(w1, w0, u, v) \
- __asm__ ("mulu%.l %3,%1:%0" \
- : "=d" ((USItype)(w0)), \
- "=d" ((USItype)(w1)) \
- : "%0" ((USItype)(u)), \
- "dmi" ((USItype)(v)))
-
-#endif
-
-#define __umulsidi3(u, v) \
- ({DIunion __w; \
- umul_ppmm (__w.s.high, __w.s.low, u, v); \
- __w.ll; })
-
-typedef int SItype __mode(SI);
-typedef unsigned int USItype __mode(SI);
-typedef int DItype __mode(DI);
-typedef int word_type __mode(__word__);
-
-struct DIstruct {SItype high, low;};
-
-typedef union
-{
- struct DIstruct s;
- DItype ll;
-} DIunion;
-
-DItype
-__muldi3 (DItype u, DItype v)
-{
- DIunion w;
- DIunion uu, vv;
-
- uu.ll = u;
- vv.ll = v;
-
- w.ll = __umulsidi3 (uu.s.low, vv.s.low);
- w.s.high += ((USItype) uu.s.low * (USItype) vv.s.high
- + (USItype) uu.s.high * (USItype) vv.s.low);
-
- return w.ll;
-}
-EXPORT_SYMBOL(__muldi3);
diff --git a/include/linux/libgcc.h b/include/linux/libgcc.h
index fc388da6a027..0d68f9d6a6a7 100644
--- a/include/linux/libgcc.h
+++ b/include/linux/libgcc.h
@@ -34,4 +34,8 @@ long long notrace __lshrdi3(long long u, word_type b);
long long notrace __muldi3(long long u, long long v);
word_type notrace __ucmpdi2(unsigned long long a, unsigned long long b);
+#ifdef CONFIG_HAVE_ARCH_LIBGCC_H
+#include <asm/libgcc.h>
+#endif
+
#endif /* __ASM_LIBGCC_H */
--
2.25.1
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