On Thu, Nov 15, 2018 at 7:14 AM Firoz Khan <firoz.khan@xxxxxxxxxx> wrote:
>
> The 2nd option will be the recommended one. For that, I
> added the __NR_syscalls macro in uapi/asm/unistd.h along
> with __NR_Linux_syscalls. The macro __NR_syscalls also
> added for making the name convention same across all
> architecture. While __NR_syscalls isn't strictly part of
> the uapi, having it as part of the generated header to
> simplifies the implementation. We also need to enclose
> this macro with #ifdef __KERNEL__ to avoid side effects.
I fear this doesn't work the way you hoped:
> --- a/arch/mips/include/uapi/asm/unistd.h
> +++ b/arch/mips/include/uapi/asm/unistd.h
> @@ -391,16 +391,19 @@
> #define __NR_rseq (__NR_Linux + 367)
> #define __NR_io_pgetevents (__NR_Linux + 368)
>
> +#ifdef __KERNEL__
> +#define __NR_syscalls 368
> +#endif
We now have three different definitions of __NR_syscalls,
one for each ABI. User space previously saw the correct
one (now it doesn't see any, but that's ok).
> /*
> * Offset of the last Linux o32 flavoured syscall
> */
> -#define __NR_Linux_syscalls 368
> +#define __NR_Linux_syscalls __NR_syscalls
so this part part again is ok.
> #endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
>
> #define __NR_O32_Linux 4000
> -#define __NR_O32_Linux_syscalls 368
> +#define __NR_O32_Linux_syscalls __NR_syscalls
but this part is not: Now __NR_O32_Linux_syscalls is defined
to __NR_syscalls, which may be one of the three values.
Any usage of __NR_O32_Linux_syscalls in a 64-bit kernel
is then clearly wrong.
> #endif /* _MIPS_SIM == _MIPS_SIM_NABI32 */
>
> #define __NR_N32_Linux 6000
> -#define __NR_N32_Linux_syscalls 332
> +#define __NR_N32_Linux_syscalls __NR_syscalls
Same for this one.
Arnd
