[PATCH] powerpc/kernel: Remove gcc 4 workaround from include/asm/io.h

[PATCH] powerpc/kernel: Remove gcc 4 workaround from include/asm/io.h

[Darren Stevens]

There are verions of DEF_MMIO_IN_X and DEF_MMIO_OUT_X in asm/io.h
that contain a workaround for a limitation in gcc <=4.0, but the
minimum supported version of gcc is now 4.6, so these can be safely
removed.

Signed-off-by: Darren Stevens <darren@stevens-zone.net>

---

diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index e0331e7..4433477 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -108,25 +108,6 @@
 #define IO_SET_SYNC_FLAG()
 #endif
 
-/* gcc 4.0 and older doesn't have 'Z' constraint */
-#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ == 0)
-#define DEF_MMIO_IN_X(name, size, insn)                \
-static inline u##size name(const volatile u##size __iomem *addr)   \
-{                                  \
-   u##size ret;                            \
-   __asm__ __volatile__("sync;"#insn" %0,0,%1;twi 0,%0,0;isync"    \
-       : "=r" (ret) : "r" (addr), "m" (*addr) : "memory"); \
-   return ret;                         \
-}
-
-#define DEF_MMIO_OUT_X(name, size, insn)               \
-static inline void name(volatile u##size __iomem *addr, u##size val)   \
-{                                  \
-   __asm__ __volatile__("sync;"#insn" %1,0,%2"         \
-       : "=m" (*addr) : "r" (val), "r" (addr) : "memory"); \
-   IO_SET_SYNC_FLAG();                     \
-}
-#else /* newer gcc */
 #define DEF_MMIO_IN_X(name, size, insn)                \
 static inline u##size name(const volatile u##size __iomem *addr)   \
 {                                  \
@@ -143,7 +124,6 @@ static inline void name(volatile u##size __iomem *addr, u##size val)    \
        : "=Z" (*addr) : "r" (val) : "memory");         \
    IO_SET_SYNC_FLAG();                     \
 }
-#endif
 
 #define DEF_MMIO_IN_D(name, size, insn)                \
 static inline u##size name(const volatile u##size __iomem *addr)   \

Re: [PATCH] powerpc/kernel: Remove gcc 4 workaround from include/asm/io.h

[Christophe LEROY]

Le 25/11/2018 à 22:14, Darren Stevens a écrit :
> There are verions of DEF_MMIO_IN_X and DEF_MMIO_OUT_X in asm/io.h
> that contain a workaround for a limitation in gcc <=4.0, but the
> minimum supported version of gcc is now 4.6, so these can be safely
> removed.

This code is already gone, see 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v4.20-rc4&id=a0e102914aa3f619a5bc68a0d33e17d1788cdf4c

Christophe

> 
> Signed-off-by: Darren Stevens <darren@stevens-zone.net>
> 
> ---
> 
> diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
> index e0331e7..4433477 100644
> --- a/arch/powerpc/include/asm/io.h
> +++ b/arch/powerpc/include/asm/io.h
> @@ -108,25 +108,6 @@
>   #define IO_SET_SYNC_FLAG()
>   #endif
>   
> -/* gcc 4.0 and older doesn't have 'Z' constraint */
> -#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ == 0)
> -#define DEF_MMIO_IN_X(name, size, insn)                \
> -static inline u##size name(const volatile u##size __iomem *addr)   \
> -{                                  \
> -   u##size ret;                            \
> -   __asm__ __volatile__("sync;"#insn" %0,0,%1;twi 0,%0,0;isync"    \
> -       : "=r" (ret) : "r" (addr), "m" (*addr) : "memory"); \
> -   return ret;                         \
> -}
> -
> -#define DEF_MMIO_OUT_X(name, size, insn)               \
> -static inline void name(volatile u##size __iomem *addr, u##size val)   \
> -{                                  \
> -   __asm__ __volatile__("sync;"#insn" %1,0,%2"         \
> -       : "=m" (*addr) : "r" (val), "r" (addr) : "memory"); \
> -   IO_SET_SYNC_FLAG();                     \
> -}
> -#else /* newer gcc */
>   #define DEF_MMIO_IN_X(name, size, insn)                \
>   static inline u##size name(const volatile u##size __iomem *addr)   \
>   {                                  \
> @@ -143,7 +124,6 @@ static inline void name(volatile u##size __iomem *addr, u##size val)    \
>          : "=Z" (*addr) : "r" (val) : "memory");         \
>      IO_SET_SYNC_FLAG();                     \
>   }
> -#endif
>   
>   #define DEF_MMIO_IN_D(name, size, insn)                \
>   static inline u##size name(const volatile u##size __iomem *addr)   \
>