diff options
| author | Greg Ungerer <gerg@linux-m68k.org> | 2023-11-13 23:32:09 +1000 |
|---|---|---|
| committer | Geert Uytterhoeven <geert@linux-m68k.org> | 2024-12-09 13:29:17 +0100 |
| commit | e419ddeabe7edd89650a19f411f928eea12b35b1 (patch) | |
| tree | 3479c722424ecdb4f7f5257570106c241c9f5ec2 /arch/m68k/include/asm/libgcc.h | |
| parent | 40384c840ea1944d7c5a392e8975ed088ecf0b37 (diff) | |
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>
Diffstat (limited to 'arch/m68k/include/asm/libgcc.h')
| -rw-r--r-- | arch/m68k/include/asm/libgcc.h | 20 |
1 files changed, 20 insertions, 0 deletions
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 */ |