On Fri, Jun 09, 2017 at 12:48:06PM -0700, Babu Moger wrote:
> While working on enabling queued rwlock on SPARC, found
> this following code in include/asm-generic/qrwlock.h
> which uses CONFIG_CPU_BIG_ENDIAN to clear a byte.
>
> static inline u8 *__qrwlock_write_byte(struct qrwlock *lock)
> {
> return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN);
> }
>
> Problem is many of the fixed big endian architectures don't define
> CPU_BIG_ENDIAN and clears the wrong byte.
>
> Define CPU_BIG_ENDIAN for all the fixed big endian architecture to fix it.
>
> Also found few more references of this config parameter in
> drivers/of/base.c
> drivers/of/fdt.c
> drivers/tty/serial/earlycon.c
> drivers/tty/serial/serial_core.c
> Be aware that this may cause regressions if someone has worked-around
> problems in the above code already. Remove the work-around.
>
> Here is our original discussion
> https://lkml.org/lkml/2017/5/24/620
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
> ---
> arch/frv/Kconfig | 3 +++
> arch/h8300/Kconfig | 3 +++
> arch/m68k/Kconfig | 3 +++
> arch/openrisc/Kconfig | 3 +++
> arch/parisc/Kconfig | 3 +++
> arch/sparc/Kconfig | 3 +++
> 6 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
> index eefd9a4..1cce824 100644
> --- a/arch/frv/Kconfig
> +++ b/arch/frv/Kconfig
> @@ -17,6 +17,9 @@ config FRV
> select HAVE_DEBUG_STACKOVERFLOW
> select ARCH_NO_COHERENT_DMA_MMAP
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
> config ZONE_DMA
> bool
> default y
> diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
> index 3ae8525..5380ac8 100644
> --- a/arch/h8300/Kconfig
> +++ b/arch/h8300/Kconfig
> @@ -23,6 +23,9 @@ config H8300
> select HAVE_ARCH_HASH
> select CPU_NO_EFFICIENT_FFS
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
> config RWSEM_GENERIC_SPINLOCK
> def_bool y
>
> diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> index d140206..029a58b 100644
> --- a/arch/m68k/Kconfig
> +++ b/arch/m68k/Kconfig
> @@ -23,6 +23,9 @@ config M68K
> select OLD_SIGSUSPEND3
> select OLD_SIGACTION
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
> config RWSEM_GENERIC_SPINLOCK
> bool
> default y
> diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
> index 1e95920..a0f2e4a 100644
> --- a/arch/openrisc/Kconfig
> +++ b/arch/openrisc/Kconfig
> @@ -29,6 +29,9 @@ config OPENRISC
> select CPU_NO_EFFICIENT_FFS if !OPENRISC_HAVE_INST_FF1
> select NO_BOOTMEM
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
Acked-by: Stafford Horne <shorne@xxxxxxxxx>
I actually have this patch in my SMP branch [0] I am working on. It would
be good to get this in, I have heard verious complaints about bugs with
endianness and mmio with OpenRISC but have not been able to look into it.
This might be related as well.
[0] https://github.com/stffrdhrn/linux/commit/2cc4b90eca865c54b87b8f59e523c131f30fc9ac
> config MMU
> def_bool y
>
> diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> index 531da9e..dda1f55 100644
> --- a/arch/parisc/Kconfig
> +++ b/arch/parisc/Kconfig
> @@ -47,6 +47,9 @@ config PARISC
> and later HP3000 series). The PA-RISC Linux project home page is
> at <http://www.parisc-linux.org/>.
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
> config MMU
> def_bool y
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 58243b0..eb213b5 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -92,6 +92,9 @@ config ARCH_DEFCONFIG
> config ARCH_PROC_KCORE_TEXT
> def_bool y
>
> +config CPU_BIG_ENDIAN
> + def_bool y
> +
> config ARCH_ATU
> bool
> default y if SPARC64
> --
> 1.7.1
>
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