Greg Ungerer e419ddeabe 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@linux-m68k.org>
Link: https://lore.kernel.org/20231113133209.1367286-1-gerg@linux-m68k.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
2024-12-09 13:29:17 +01:00

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C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* include/lib/libgcc.h
*/
#ifndef __LIB_LIBGCC_H
#define __LIB_LIBGCC_H
#include <asm/byteorder.h>
typedef int word_type __attribute__ ((mode (__word__)));
#ifdef __BIG_ENDIAN
struct DWstruct {
int high, low;
};
#elif defined(__LITTLE_ENDIAN)
struct DWstruct {
int low, high;
};
#else
#error I feel sick.
#endif
typedef union {
struct DWstruct s;
long long ll;
} DWunion;
long long notrace __ashldi3(long long u, word_type b);
long long notrace __ashrdi3(long long u, word_type b);
word_type notrace __cmpdi2(long long a, long long b);
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 */