Hi,
> Am 12.04.2021 um 05:34 schrieb Huacai Chen <chenhuacai@xxxxxxxxxx>:
>
> There are many errors in div64.h caused by commit c21004cd5b4cb7d479514
> ("MIPS: Rewrite <asm/div64.h> to work with gcc 4.4.0."):
>
> 1, Only 32bit kernel need __div64_32(), but the above commit makes it
> depend on 64bit kernel by mistake. So div64.h is unused in fact.
>
> 2, asm-generic/div64.h should be included after __div64_32() definition.
>
> 3, __n should be initialized as *n before use (and "*__n >> 32" should
> be "__n >> 32") in __div64_32() definition.
>
> 4, linux/types.h should be included at the first place, otherwise BITS_
> PER_LONG is not defined.
>
> 5, As Nikolaus, Yunqiang Su and Yanjie Zhou said, the MIPS-specific
s/Nikolaus/Nikolaus Schaller/
> __div64_32() sometimes produces wrong results, which makes 32bit
> kernel boot fails.
>
> I have tried to fix theses errors but I have failed with the last one.
> Yunqiang's tests show that the MIPS-specific __div64_32() has no obvious
> advantage than the C version, so I just simply remove div64.h.
This version works on both, alpha400/jz4730 and ci20/jz4780 (both 32 bit).
I have cross-checked the tree for *div64* files and only found as mips
specific or lib files:
./arch/mips/include/generated/asm/div64.h -> #include <asm-generic/div64.h>
./include/asm-generic/div64.h
./lib/math/div64.c
So there were no remains from earlier compile runs.
And since it seems to have no advantage over the C version, I agree
that we can remove the special code instead of wasting time to fix it.
>
> Fixes: c21004cd5b4cb7d479514 ("MIPS: Rewrite <asm/div64.h> to work with gcc 4.4.0.")
> Cc: stable@xxxxxxxxxxxxxxx
Tested-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> # CI20/jz4780 and Alpha400/jz4730
BR and thanks,
Nikolaus Schaller
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---
> arch/mips/include/asm/div64.h | 68 -----------------------------------
> 1 file changed, 68 deletions(-)
> delete mode 100644 arch/mips/include/asm/div64.h
>
> diff --git a/arch/mips/include/asm/div64.h b/arch/mips/include/asm/div64.h
> deleted file mode 100644
> index dc5ea5736440..000000000000
> --- a/arch/mips/include/asm/div64.h
> +++ /dev/null
> @@ -1,68 +0,0 @@
> -/*
> - * Copyright (C) 2000, 2004 Maciej W. Rozycki
> - * Copyright (C) 2003, 07 Ralf Baechle (ralf@xxxxxxxxxxxxxx)
> - *
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License. See the file "COPYING" in the main directory of this archive
> - * for more details.
> - */
> -#ifndef __ASM_DIV64_H
> -#define __ASM_DIV64_H
> -
> -#include <asm-generic/div64.h>
> -
> -#if BITS_PER_LONG == 64
> -
> -#include <linux/types.h>
> -
> -/*
> - * No traps on overflows for any of these...
> - */
> -
> -#define __div64_32(n, base) \
> -({ \
> - unsigned long __cf, __tmp, __tmp2, __i; \
> - unsigned long __quot32, __mod32; \
> - unsigned long __high, __low; \
> - unsigned long long __n; \
> - \
> - __high = *__n >> 32; \
> - __low = __n; \
> - __asm__( \
> - " .set push \n" \
> - " .set noat \n" \
> - " .set noreorder \n" \
> - " move %2, $0 \n" \
> - " move %3, $0 \n" \
> - " b 1f \n" \
> - " li %4, 0x21 \n" \
> - "0: \n" \
> - " sll $1, %0, 0x1 \n" \
> - " srl %3, %0, 0x1f \n" \
> - " or %0, $1, %5 \n" \
> - " sll %1, %1, 0x1 \n" \
> - " sll %2, %2, 0x1 \n" \
> - "1: \n" \
> - " bnez %3, 2f \n" \
> - " sltu %5, %0, %z6 \n" \
> - " bnez %5, 3f \n" \
> - "2: \n" \
> - " addiu %4, %4, -1 \n" \
> - " subu %0, %0, %z6 \n" \
> - " addiu %2, %2, 1 \n" \
> - "3: \n" \
> - " bnez %4, 0b\n\t" \
> - " srl %5, %1, 0x1f\n\t" \
> - " .set pop" \
> - : "=&r" (__mod32), "=&r" (__tmp), \
> - "=&r" (__quot32), "=&r" (__cf), \
> - "=&r" (__i), "=&r" (__tmp2) \
> - : "Jr" (base), "0" (__high), "1" (__low)); \
> - \
> - (__n) = __quot32; \
> - __mod32; \
> -})
> -
> -#endif /* BITS_PER_LONG == 64 */
> -
> -#endif /* __ASM_DIV64_H */
> --
> 2.27.0
>
