Commit e419ddea authored by Greg Ungerer's avatar Greg Ungerer Committed by Geert Uytterhoeven
Browse files

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: default avatarGreg Ungerer <gerg@linux-m68k.org>
Link: https://lore.kernel.org/20231113133209.1367286-1-gerg@linux-m68k.org


Reviewed-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 40384c84

arch/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -1526,6 +1526,14 @@ 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

arch/m68k/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -23,7 +23,9 @@ 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

arch/m68k/include/asm/libgcc.h

0 → 100644
+20 −0
Original line number Diff line number Diff line 
/* 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 */

arch/m68k/lib/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/m68k/lib/muldi3.c

deleted100644 → 0
+0 −97
Original line number Diff line number Diff line 
/* 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);