2018-01-02 11:00:41

by Arnd Bergmann

Subject: [PATCH] xtensa: shut up gcc-8 warnings

Many uses of strncpy() on xtensa causes a warning like

arch/xtensa/include/asm/string.h:56:42: warning: array subscript is above array bounds [-Warray-bounds]
: "0" (__dest), "1" (__src), "r" (__src+__n)

This avoids the warning by turning the pointer arithmetic into an
integer operation that does not get checked the same way.

Signed-off-by: Arnd Bergmann <[email protected]>
---
arch/xtensa/include/asm/string.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/include/asm/string.h b/arch/xtensa/include/asm/string.h
index 586bad9fe187..89b51a0c752f 100644
--- a/arch/xtensa/include/asm/string.h
+++ b/arch/xtensa/include/asm/string.h
@@ -53,7 +53,7 @@ static inline char *strncpy(char *__dest, const char *__src, size_t __n)
"bne %1, %5, 1b\n"
"2:"
: "=r" (__dest), "=r" (__src), "=&r" (__dummy)
- : "0" (__dest), "1" (__src), "r" (__src+__n)
+ : "0" (__dest), "1" (__src), "r" ((uintptr_t)__src+__n)
: "memory");

return __xdest;
@@ -101,7 +101,7 @@ static inline int strncmp(const char *__cs, const char *__ct, size_t __n)
"2:\n\t"
"sub %2, %2, %3"
: "=r" (__cs), "=r" (__ct), "=&r" (__res), "=&r" (__dummy)
- : "0" (__cs), "1" (__ct), "r" (__cs+__n));
+ : "0" (__cs), "1" (__ct), "r" ((uintptr_t)__cs+__n));

return __res;
}
--
2.9.0

2018-01-02 11:29:20

by Max Filippov

Subject: Re: [PATCH] xtensa: shut up gcc-8 warnings

On Tue, Jan 2, 2018 at 3:00 AM, Arnd Bergmann <[email protected]> wrote:
> Many uses of strncpy() on xtensa causes a warning like
>
> arch/xtensa/include/asm/string.h:56:42: warning: array subscript is above array bounds [-Warray-bounds]
> : "0" (__dest), "1" (__src), "r" (__src+__n)
>
> This avoids the warning by turning the pointer arithmetic into an
> integer operation that does not get checked the same way.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> arch/xtensa/include/asm/string.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, applied to my xtensa tree.

-- Max