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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>
21 lines
685 B
C
21 lines
685 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_M68K_LIBGCC_H
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#define __ASM_M68K_LIBGCC_H
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#ifndef CONFIG_CPU_HAS_NO_MULDIV64
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/*
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* For those 68K CPUs that support 64bit multiply define umul_ppm()
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* for the common muldi3 libgcc helper function (in lib/muldi3.c).
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* CPUs that don't have it (like the original 68000 and ColdFire)
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* will fallback to using the C-coded version of umul_ppmm().
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*/
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#define umul_ppmm(w1, w0, u, v) \
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__asm__ ("mulu%.l %3,%1:%0" \
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: "=d" ((unsigned long)(w0)), \
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"=d" ((unsigned long)(w1)) \
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: "%0" ((unsigned long)(u)), \
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"dmi" ((unsigned long)(v)))
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#endif /* !CONFIG_CPU_HAS_NO_MULDIV64 */
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#endif /* __ASM_M68K_LIBGCC_H */
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