Re: [PATCH] m68k/uaccess: Revive 64-bit get_user()

[Martijn Coenen]

On Mon, May 14, 2018 at 3:57 PM, Geert Uytterhoeven
 wrote:
> Revive support for 64-bit get_user(), which was disabled in commit
> d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
> typeof in (then brand new) gcc-4.1.
>
>   - Keep on using u64 for the temporary, as __typeof__() doesn't drop
> the const qualifier,
>   - Move it into a union (like mips32 does) to get rid of the cast, as
> using get_user() to fetch a __user pointer would cause a "cast to
> pointer from integer of different size" warning otherwise.

Can't vouch for the existing asm, but the changes to it look good to
me otherwise.

>
> Signed-off-by: Geert Uytterhoeven 

Acked-by: Martijn Coenen 

> ---
>  arch/m68k/include/asm/uaccess_mm.h | 16 +---
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/m68k/include/asm/uaccess_mm.h 
> b/arch/m68k/include/asm/uaccess_mm.h
> index 75c172e909acdf18..c4cb889660aa0c35 100644
> --- a/arch/m68k/include/asm/uaccess_mm.h
> +++ b/arch/m68k/include/asm/uaccess_mm.h
> @@ -141,10 +141,12 @@ asm volatile ("\n"  
>   \
> case 4: \
> __get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);   \
> break;  \
> -/* case 8: disabled because gcc-4.1 has a broken typeof\
> -   {   \
> -   const void *__gu_ptr = (ptr);   \
> -   u64 __gu_val;   \
> +   case 8: {   \
> +   const void *__gu_ptr = (ptr);   \
> +   union { \
> +   u64 l;  \
> +   __typeof__(*(ptr)) t;   \
> +   } __gu_val; \
> asm volatile ("\n"  \
> "1: "MOVES".l   (%2)+,%1\n" \
> "2: "MOVES".l   (%2),%R1\n" \
> @@ -162,13 +164,13 @@ asm volatile ("\n"  
>   \
> "   .long   1b,10b\n"   \
> "   .long   2b,10b\n"   \
> "   .previous"  \
> -   : "+d" (__gu_err), "=" (__gu_val),\
> +   : "+d" (__gu_err), "=" (__gu_val.l),  \
>   "+a" (__gu_ptr)   \
> : "i" (-EFAULT) \
> : "memory");\
> -   (x) = (__force typeof(*(ptr)))__gu_val; \
> +   (x) = __gu_val.t;   \
> break;  \
> -   }   */  \
> +   }   \
> default:\
> __gu_err = __get_user_bad();\
> break;  \
> --
> 2.7.4
>

Re: [PATCH] m68k/uaccess: Revive 64-bit get_user()

[Martijn Coenen]

On Mon, May 14, 2018 at 3:57 PM, Geert Uytterhoeven
 wrote:
> Revive support for 64-bit get_user(), which was disabled in commit
> d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
> typeof in (then brand new) gcc-4.1.
>
>   - Keep on using u64 for the temporary, as __typeof__() doesn't drop
> the const qualifier,
>   - Move it into a union (like mips32 does) to get rid of the cast, as
> using get_user() to fetch a __user pointer would cause a "cast to
> pointer from integer of different size" warning otherwise.

Can't vouch for the existing asm, but the changes to it look good to
me otherwise.

>
> Signed-off-by: Geert Uytterhoeven 

Acked-by: Martijn Coenen 

> ---
>  arch/m68k/include/asm/uaccess_mm.h | 16 +---
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/m68k/include/asm/uaccess_mm.h 
> b/arch/m68k/include/asm/uaccess_mm.h
> index 75c172e909acdf18..c4cb889660aa0c35 100644
> --- a/arch/m68k/include/asm/uaccess_mm.h
> +++ b/arch/m68k/include/asm/uaccess_mm.h
> @@ -141,10 +141,12 @@ asm volatile ("\n"  
>   \
> case 4: \
> __get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);   \
> break;  \
> -/* case 8: disabled because gcc-4.1 has a broken typeof\
> -   {   \
> -   const void *__gu_ptr = (ptr);   \
> -   u64 __gu_val;   \
> +   case 8: {   \
> +   const void *__gu_ptr = (ptr);   \
> +   union { \
> +   u64 l;  \
> +   __typeof__(*(ptr)) t;   \
> +   } __gu_val; \
> asm volatile ("\n"  \
> "1: "MOVES".l   (%2)+,%1\n" \
> "2: "MOVES".l   (%2),%R1\n" \
> @@ -162,13 +164,13 @@ asm volatile ("\n"  
>   \
> "   .long   1b,10b\n"   \
> "   .long   2b,10b\n"   \
> "   .previous"  \
> -   : "+d" (__gu_err), "=" (__gu_val),\
> +   : "+d" (__gu_err), "=" (__gu_val.l),  \
>   "+a" (__gu_ptr)   \
> : "i" (-EFAULT) \
> : "memory");\
> -   (x) = (__force typeof(*(ptr)))__gu_val; \
> +   (x) = __gu_val.t;   \
> break;  \
> -   }   */  \
> +   }   \
> default:\
> __gu_err = __get_user_bad();\
> break;  \
> --
> 2.7.4
>

[PATCH] m68k/uaccess: Revive 64-bit get_user()

[Geert Uytterhoeven]

Revive support for 64-bit get_user(), which was disabled in commit
d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
typeof in (then brand new) gcc-4.1.

  - Keep on using u64 for the temporary, as __typeof__() doesn't drop
the const qualifier,
  - Move it into a union (like mips32 does) to get rid of the cast, as
using get_user() to fetch a __user pointer would cause a "cast to
pointer from integer of different size" warning otherwise.

Signed-off-by: Geert Uytterhoeven 
---
 arch/m68k/include/asm/uaccess_mm.h | 16 +---
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/m68k/include/asm/uaccess_mm.h 
b/arch/m68k/include/asm/uaccess_mm.h
index 75c172e909acdf18..c4cb889660aa0c35 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess_mm.h
@@ -141,10 +141,12 @@ asm volatile ("\n"
\
case 4: \
__get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);   \
break;  \
-/* case 8: disabled because gcc-4.1 has a broken typeof\
-   {   \
-   const void *__gu_ptr = (ptr);   \
-   u64 __gu_val;   \
+   case 8: {   \
+   const void *__gu_ptr = (ptr);   \
+   union { \
+   u64 l;  \
+   __typeof__(*(ptr)) t;   \
+   } __gu_val; \
asm volatile ("\n"  \
"1: "MOVES".l   (%2)+,%1\n" \
"2: "MOVES".l   (%2),%R1\n" \
@@ -162,13 +164,13 @@ asm volatile ("\n"
\
"   .long   1b,10b\n"   \
"   .long   2b,10b\n"   \
"   .previous"  \
-   : "+d" (__gu_err), "=" (__gu_val),\
+   : "+d" (__gu_err), "=" (__gu_val.l),  \
  "+a" (__gu_ptr)   \
: "i" (-EFAULT) \
: "memory");\
-   (x) = (__force typeof(*(ptr)))__gu_val; \
+   (x) = __gu_val.t;   \
break;  \
-   }   */  \
+   }   \
default:\
__gu_err = __get_user_bad();\
break;  \
-- 
2.7.4

[PATCH] m68k/uaccess: Revive 64-bit get_user()

[Geert Uytterhoeven]

Revive support for 64-bit get_user(), which was disabled in commit
d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
typeof in (then brand new) gcc-4.1.

  - Keep on using u64 for the temporary, as __typeof__() doesn't drop
the const qualifier,
  - Move it into a union (like mips32 does) to get rid of the cast, as
using get_user() to fetch a __user pointer would cause a "cast to
pointer from integer of different size" warning otherwise.

Signed-off-by: Geert Uytterhoeven 
---
 arch/m68k/include/asm/uaccess_mm.h | 16 +---
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/m68k/include/asm/uaccess_mm.h 
b/arch/m68k/include/asm/uaccess_mm.h
index 75c172e909acdf18..c4cb889660aa0c35 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess_mm.h
@@ -141,10 +141,12 @@ asm volatile ("\n"
\
case 4: \
__get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);   \
break;  \
-/* case 8: disabled because gcc-4.1 has a broken typeof\
-   {   \
-   const void *__gu_ptr = (ptr);   \
-   u64 __gu_val;   \
+   case 8: {   \
+   const void *__gu_ptr = (ptr);   \
+   union { \
+   u64 l;  \
+   __typeof__(*(ptr)) t;   \
+   } __gu_val; \
asm volatile ("\n"  \
"1: "MOVES".l   (%2)+,%1\n" \
"2: "MOVES".l   (%2),%R1\n" \
@@ -162,13 +164,13 @@ asm volatile ("\n"
\
"   .long   1b,10b\n"   \
"   .long   2b,10b\n"   \
"   .previous"  \
-   : "+d" (__gu_err), "=" (__gu_val),\
+   : "+d" (__gu_err), "=" (__gu_val.l),  \
  "+a" (__gu_ptr)   \
: "i" (-EFAULT) \
: "memory");\
-   (x) = (__force typeof(*(ptr)))__gu_val; \
+   (x) = __gu_val.t;   \
break;  \
-   }   */  \
+   }   \
default:\
__gu_err = __get_user_bad();\
break;  \
-- 
2.7.4