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SubjectRe: [PATCH] sh: Implement __get_user_u64() required for 64-bit get_user()
Hi Adrian,

On Fri, May 29, 2020 at 7:46 PM John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> Trying to build the kernel with CONFIG_INFINIBAND_USER_ACCESS enabled fails
>
> ERROR: "__get_user_unknown" [drivers/infiniband/core/ib_uverbs.ko] undefined!
>
> with on SH since the kernel misses a 64-bit implementation of get_user().
>
> Implement the missing 64-bit get_user() as __get_user_u64(), matching the
> already existing __put_user_u64() which implements the 64-bit put_user().
>
> Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Thanks for your patch!

> --- a/arch/sh/include/asm/uaccess_32.h
> +++ b/arch/sh/include/asm/uaccess_32.h
> @@ -26,6 +26,9 @@ do { \
> case 4: \
> __get_user_asm(x, ptr, retval, "l"); \
> break; \
> + case 8: \
> + __get_user_u64(x, ptr, retval); \
> + break; \
> default: \
> __get_user_unknown(); \
> break; \
> @@ -66,6 +69,52 @@ do { \
>
> extern void __get_user_unknown(void);
>
> +#if defined(CONFIG_CPU_LITTLE_ENDIAN)
> +#define __get_user_u64(x, addr, err) \
> +({ \
> +__asm__ __volatile__( \
> + "1:\n\t" \
> + "mov.l %2,%R1\n\t" \
> + "mov.l %T2,%S1\n\t" \
> + "2:\n" \
> + ".section .fixup,\"ax\"\n" \
> + "3:\n\t" \
> + "mov #0, %1\n\t" \

As this is the 64-bit variant, I think this single move should be
replaced by a double move:

"mov #0,%R1\n\t" \
"mov #0,%S1\n\t" \

Same for the big endian version below.

Disclaimer: uncompiled, untested, no SH assembler expert.

> + "mov.l 4f, %0\n\t" \
> + "jmp @%0\n\t" \
> + " mov %3, %0\n\t" \
> + ".balign 4\n" \
> + "4: .long 2b\n\t" \
> + ".previous\n" \
> + ".section __ex_table,\"a\"\n\t" \
> + ".long 1b, 3b\n\t" \
> + ".previous" \
> + :"=&r" (err), "=&r" (x) \
> + :"m" (__m(addr)), "i" (-EFAULT), "0" (err)); })

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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