[U-Boot] [PATCH v2 1/2] arm: Replace v7_maint_dcache_all(ARMV7_DCACHE_CLEAN_INVAL_ALL) with asm code

[Masahiro Yamada]

Hi Hans,

2016-04-09 20:53 GMT+09:00 Hans de Goede <hdegoede at redhat.com>:
> v7_maint_dcache_all() does not work reliable when build with gcc6,
> see: https://bugzilla.redhat.com/show_bug.cgi?id=1318788
>
> While debugging this I learned that v7_maint_dcache_all() is unreliable
> when build with gcc5 too when it is marked as noinline.
>
> This commit fixes the reliability issues by replacing the C-code with
> the ready to use asm implementation from the kernel.
>
> Given that this code when written as C-code clearly is quite fragile
> (also see the existing comments about the C-code being the way it is
>  to get optimal assembly) and that we have a proven asm alternative,
> I believe that this is the best solution.
>
> Note that we actually already had a copy of the kernel's
> v7_flush_dcache_all() before this commit in
> arch/arm/mach-uniphier/arm32/lowlevel_init.S.
>
> This commit moves that code arch/arm/cpu/armv7/cache_v7_asm.S, renames
> it to __v7_flush_dcache_all(), and adds a v7_flush_dcache_all() wrapper
> which saves / restores the clobbered registers for use from C-code.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
> Changes in v2:
> -Remove "Copyright (C) 2012-2015 Masahiro Yamada" from the header
> -Move the v7_flush_dcache_all asm code from
>  arch/arm/mach-uniphier/arm32/lowlevel_init.S to
>  arch/arm/cpu/armv7/cache_v7_asm.S instead of adding a second copy
> ---
>  arch/arm/cpu/armv7/Makefile                  |  2 +-
>  arch/arm/cpu/armv7/cache_v7.c                | 41 ++------------
>  arch/arm/cpu/armv7/cache_v7_asm.S            | 84 ++++++++++++++++++++++++++++
>  arch/arm/mach-uniphier/arm32/lowlevel_init.S | 67 +---------------------
>  4 files changed, 92 insertions(+), 102 deletions(-)
>  create mode 100644 arch/arm/cpu/armv7/cache_v7_asm.S


I tested this patch on my board and I did not see any problem.

So, for mach-uniphier portion,

Acked-by: Masahiro Yamada <yamada.masahiro at socionext.com>



Thanks!

-- 
Best Regards
Masahiro Yamada