Re: [PATCH v2 06/21] powerpc: Avoid comparison of unsigned long >= 0 in __access_ok

[christophe leroy]

Le 02/03/2018 à 20:50, Mathieu Malaterre a écrit :

Rewrite function-like macro into regular static inline function to avoid a
warning during macro expansion.
Fix warning (treated as error in W=1):

   CC  arch/powerpc/kernel/signal_32.o
In file included from ./include/linux/uaccess.h:14:0,
  from ./include/asm-generic/termios-base.h:8,
  from ./arch/powerpc/include/asm/termios.h:20,
  from ./include/uapi/linux/termios.h:6,
  from ./include/linux/tty.h:7,
  from arch/powerpc/kernel/signal_32.c:36:
./include/asm-generic/termios-base.h: In function 
‘user_termio_to_kernel_termios’:
./arch/powerpc/include/asm/uaccess.h:52:35: error: comparison of unsigned 
expression >= 0 is always true [-Werror=type-limits]
(((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)
^
./arch/powerpc/include/asm/uaccess.h:58:3: note: in expansion of macro 
‘__access_ok’
__access_ok((__force unsigned long)(addr), (size), get_fs()))
^~~
./arch/powerpc/include/asm/uaccess.h:262:6: note: in expansion of macro 
‘access_ok’
   if (access_ok(VERIFY_READ, __gu_addr, (size)))   \
   ^
./arch/powerpc/include/asm/uaccess.h:80:2: note: in expansion of macro 
‘__get_user_check’
   __get_user_check((x), (ptr), sizeof(*(ptr)))
   ^~~~
./include/asm-generic/termios-base.h:36:6: note: in expansion of macro 
‘get_user’
   if (get_user(termios->c_line, >c_line) < 0)
   ^~~~
[...]
cc1: all warnings being treated as errors

Suggested-by: Segher Boessenkool 
Signed-off-by: Mathieu Malaterre 


Reviewed-by: Christophe Leroy 


---
  arch/powerpc/include/asm/uaccess.h | 10 +++---
  1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h 
b/arch/powerpc/include/asm/uaccess.h
index 51bfeb8777f0..a62ee663b2c8 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -47,9 +47,13 @@
  
  #else
  
-#define __access_ok(addr, size, segment)	\

-   (((addr) <= (segment).seg) &&\
-(((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)
+static inline int __access_ok(unsigned long addr, unsigned long size,
+   mm_segment_t seg)
+{
+   if (addr > seg.seg)
+   return 0;
+   return (size == 0 || size - 1 <= seg.seg - addr);
+}
  
  #endif
  



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[PATCH v2 06/21] powerpc: Avoid comparison of unsigned long >= 0 in __access_ok

[Mathieu Malaterre]

Rewrite function-like macro into regular static inline function to avoid a
warning during macro expansion.
Fix warning (treated as error in W=1):

  CC  arch/powerpc/kernel/signal_32.o
In file included from ./include/linux/uaccess.h:14:0,
 from ./include/asm-generic/termios-base.h:8,
 from ./arch/powerpc/include/asm/termios.h:20,
 from ./include/uapi/linux/termios.h:6,
 from ./include/linux/tty.h:7,
 from arch/powerpc/kernel/signal_32.c:36:
./include/asm-generic/termios-base.h: In function 
‘user_termio_to_kernel_termios’:
./arch/powerpc/include/asm/uaccess.h:52:35: error: comparison of unsigned 
expression >= 0 is always true [-Werror=type-limits]
   (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)
   ^
./arch/powerpc/include/asm/uaccess.h:58:3: note: in expansion of macro 
‘__access_ok’
   __access_ok((__force unsigned long)(addr), (size), get_fs()))
   ^~~
./arch/powerpc/include/asm/uaccess.h:262:6: note: in expansion of macro 
‘access_ok’
  if (access_ok(VERIFY_READ, __gu_addr, (size)))   \
  ^
./arch/powerpc/include/asm/uaccess.h:80:2: note: in expansion of macro 
‘__get_user_check’
  __get_user_check((x), (ptr), sizeof(*(ptr)))
  ^~~~
./include/asm-generic/termios-base.h:36:6: note: in expansion of macro 
‘get_user’
  if (get_user(termios->c_line, >c_line) < 0)
  ^~~~
[...]
cc1: all warnings being treated as errors

Suggested-by: Segher Boessenkool 
Signed-off-by: Mathieu Malaterre 
---
 arch/powerpc/include/asm/uaccess.h | 10 +++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h 
b/arch/powerpc/include/asm/uaccess.h
index 51bfeb8777f0..a62ee663b2c8 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -47,9 +47,13 @@
 
 #else
 
-#define __access_ok(addr, size, segment)   \
-   (((addr) <= (segment).seg) &&   \
-(((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)
+static inline int __access_ok(unsigned long addr, unsigned long size,
+   mm_segment_t seg)
+{
+   if (addr > seg.seg)
+   return 0;
+   return (size == 0 || size - 1 <= seg.seg - addr);
+}
 
 #endif
 
-- 
2.11.0