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Date:   Fri, 26 May 2023 11:19:05 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Zhangjin Wu" <falcon@tinylab.org>, "Willy Tarreau" <w@1wt.eu>
Cc:     linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        "Palmer Dabbelt" <palmer@dabbelt.com>,
        "Paul Walmsley" <paul.walmsley@sifive.com>, thomas@t-8ch.de
Subject: Re: [PATCH 11/13] tools/nolibc: sys_select: riscv: use __NR_pselect6_time64
 for rv32
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On Wed, May 24, 2023, at 19:59, Zhangjin Wu wrote:
> diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> index c0335a84f880..00c7197dcd50 100644
> --- a/tools/include/nolibc/sys.h
> +++ b/tools/include/nolibc/sys.h
> @@ -1041,8 +1041,13 @@ int sys_select(int nfds, fd_set *rfds, fd_set 
> *wfds, fd_set *efds, struct timeva
>  		struct timeval *t;
>  	} arg = { .n = nfds, .r = rfds, .w = wfds, .e = efds, .t = timeout };
>  	return my_syscall1(__NR_select, &arg);
> -#elif defined(__ARCH_WANT_SYS_PSELECT6) && defined(__NR_pselect6)
> +#elif defined(__ARCH_WANT_SYS_PSELECT6) && (defined(__NR_pselect6) || 
> defined(__NR_pselect6_time64))
> +#ifdef __NR_pselect6
>  	struct timespec t;
> +#else
> +	struct timespec64 t;
> +#define __NR_pselect6 __NR_pselect6_time64
> +#endif

Overriding the __NR_pselect6 constant seems wrong here, this can
easily lead to more bugs, as pselect6 and pselect6_time64 are
not compatible because of the different arguments, so anything
using the constant after including sys.h will be broken.

I would just use __kernel_timespec64 unconditionally and then
use __NR_pselect6_time64 on all 32-bit architectures here,
but use __NR_pselect6 on 32-bit architectures.

I think we can also kill off the oldselect and newselect 
cases, using pselect6/pselect6_time64 unconditionally here,
and no longer care about building against pre-5.1 kernel
headers, at least for the copy of nolibc that ships with the
kernel.

     Arnd