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From: "Thomas Weißschuh" <thomas@t-8ch.de>
To: Zhangjin Wu <falcon@tinylab.org>
Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	 linux-riscv@lists.infradead.org, palmer@dabbelt.com,
	paul.walmsley@sifive.com, w@1wt.eu
Subject: Re: [PATCH 11/13] tools/nolibc: sys_select: riscv: use __NR_pselect6_time64 for rv32
Date: Thu, 25 May 2023 09:22:23 +0200	[thread overview]
Message-ID: <76a5f9a0-eec4-415a-9c5d-ac3bca4d4b0e@t-8ch.de> (raw)
In-Reply-To: <20230525071021.77223-1-falcon@tinylab.org>

On 2023-05-25 15:10:21+0800, Zhangjin Wu wrote:
> Hi, Thomas
> 
> > On 2023-05-25 01:59:55+0800, Zhangjin Wu wrote:
> > > rv32 uses the generic include/uapi/asm-generic/unistd.h and it has no
> > > __NR_pselect6 after kernel commit d4c08b9776b3 ("riscv: Use latest
> > > system call ABI"), use __NR_pselect6_time64 instead.
> > > 
> > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
> > > ---
> > >  tools/include/nolibc/sys.h | 7 ++++++-
> > >  1 file changed, 6 insertions(+), 1 deletion(-)
> > > 
> > > 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
> > 
> > Wouldn't this #define leak to the users of nolibc and lead to calls to
> > pselect6_time64 with the ABI of the __NR_pselect6 if userspace is doing
> > its own raw syscalls?
> >
> 
> Yeah, it would break the user-side raw __NR_pselect6 syscall for nolibc is a
> header-only libc, so, it is not safe to use such method like glibc.
> 
> Something like this will let the syscall call to pselect6_time64 instead of the
> user-required __NR_pselect6 and pass the wrong type of argument.
> 
>     #include "nolibc.h"  // If no __NR_pselect6 defined, __NR_pselect6 = __NR_pselect6_time64
> 
>     #ifdef __NR_pselect6
>         struct timespec t;  // come here for __NR_pselect6_time64, but t is not timespec64, broken
>         syscall(__NR_pselect6, nfds, rfds, wfds, efds, timeout ? &t : NULL, NULL);
>     #else
>         struct timespec64 t;
>         syscall(__NR_pselect6, nfds, rfds, wfds, efds, timeout ? &t : NULL, NULL);
>     #endif
> 
> I have used something like __NR_pselect6_time3264 locally, before
> sending the patchset, I found a cleaner method already used in sys.h:
> 
>     #ifndef __NR__newselect
>     #define __NR__newselect __NR_select
>     #endif
> 
> But I forgot the arguments mixing issue, __NR__newselect and __NR_select
> share the same type of arguments, but __NR_pselect6 and
> __NR_pselect6_time64 not, so, I will use back the old method but still
> need to find a better string, just like __NR__newselect, __NR__pselect6
> may be used in kernel space in the future, and __NR_pselect6_time3264 is
> too long, what about this?
> 
>     #ifdef __NR_pselect6
>             struct timespec t;
>     #define __NR_pselect6__ __NR_pselect6
>     #else
>             struct timespec64 t;
>     #define __NR_pselect6__ __NR_pselect6_time64
>     #endif
> 
> Or even ___NR_pselect6?

What about:

#ifdef __NR_pselect6
        struct timespec t;
        const long nr_pselect = __NR_pselect6;
#else
        struct timespec64 t;
        const long nr_pselect = __NR_pselect6_time64;
#endif

> 
> The same issue is in this patch:
> 
>     [PATCH 13/13] tools/nolibc: sys_gettimeofday: riscv: use __NR_clock_gettime64
> 
> will solve it with the same method.

Thanks!

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  reply	other threads:[~2023-05-25  7:28 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-24 17:33 [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-24 17:41 ` [PATCH 01/13] Revert "tools/nolibc: riscv: Support __NR_llseek for rv32" Zhangjin Wu
2023-05-24 17:44 ` [PATCH 02/13] Revert "selftests/nolibc: Fix up compile error " Zhangjin Wu
2023-05-24 17:48 ` [PATCH 04/13] selftests/nolibc: syscall_args: use __NR_statx for rv32 Zhangjin Wu
2023-05-24 19:49   ` Thomas Weißschuh
2023-05-25  7:20     ` Zhangjin Wu
2023-05-26  9:21   ` Arnd Bergmann
2023-05-26 10:06     ` Willy Tarreau
2023-05-27  0:58     ` Zhangjin Wu
2023-05-24 17:50 ` [PATCH 05/13] selftests/nolibc: riscv: customize makefile " Zhangjin Wu
2023-05-26  6:57   ` Thomas Weißschuh
2023-05-26  9:20     ` Zhangjin Wu
2023-05-24 17:52 ` [PATCH 06/13] selftests/nolibc: allow specify a bios for qemu Zhangjin Wu
2023-05-26  7:00   ` Thomas Weißschuh
2023-05-26 10:25     ` Zhangjin Wu
2023-05-26 10:36       ` Conor Dooley
2023-05-26 13:38         ` Zhangjin Wu
2023-05-26 15:08           ` Conor Dooley
2023-05-28  7:52     ` Willy Tarreau
2023-05-24 17:54 ` [PATCH 07/13] selftests/nolibc: remove the duplicated gettimeofday_bad2 Zhangjin Wu
2023-05-24 17:55 ` [PATCH 08/13] tools/nolibc: sys_lseek: riscv: use __NR_llseek for rv32 Zhangjin Wu
2023-05-24 17:57 ` [PATCH 09/13] tools/nolibc: sys_poll: riscv: use __NR_ppoll_time64 " Zhangjin Wu
2023-05-26  7:15   ` Thomas Weißschuh
2023-05-26  9:34     ` Arnd Bergmann
2023-05-28  8:25       ` Zhangjin Wu
2023-05-28  8:48         ` Arnd Bergmann
2023-05-28 10:29         ` Willy Tarreau
2023-05-28 10:55           ` Arnd Bergmann
2023-05-28 11:03             ` Willy Tarreau
2023-05-24 17:58 ` [PATCH 10/13] tools/nolibc: ppoll/ppoll_time64: add a missing argument Zhangjin Wu
2023-05-24 17:59 ` [PATCH 11/13] tools/nolibc: sys_select: riscv: use __NR_pselect6_time64 for rv32 Zhangjin Wu
2023-05-24 20:22   ` Thomas Weißschuh
2023-05-25  7:10     ` Zhangjin Wu
2023-05-25  7:22       ` Thomas Weißschuh [this message]
2023-05-26  1:50         ` Zhangjin Wu
2023-05-26  9:19   ` Arnd Bergmann
2023-05-26 11:00     ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-26 11:13       ` Arnd Bergmann
2023-05-24 18:02 ` [PATCH 12/13] tools/nolibc: sys_wait4: riscv: use __NR_waitid for rv32 Zhangjin Wu
2023-05-24 18:03 ` [PATCH 13/13] tools/nolibc: sys_gettimeofday: riscv: use __NR_clock_gettime64 " Zhangjin Wu
2023-05-26  7:38   ` Thomas Weißschuh
2023-05-27  1:26     ` Zhangjin Wu
2023-05-27  3:39       ` Zhangjin Wu
2023-05-27  5:12       ` Willy Tarreau
2023-05-24 18:24 ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-24 18:28 ` [PATCH 03/13] selftests/nolibc: print name instead of number for EOVERFLOW Zhangjin Wu
2023-05-24 17:46   ` Zhangjin Wu
2023-05-24 20:23   ` Thomas Weißschuh
2023-05-28  7:59 ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Willy Tarreau
2023-05-28  8:42   ` Thomas Weißschuh
2023-05-28  9:41     ` Thomas Weißschuh
2023-05-28 10:17       ` Willy Tarreau
2023-05-28 10:39   ` Zhangjin Wu
2023-05-28 11:33     ` Willy Tarreau
2023-05-28 12:52       ` Zhangjin Wu
2023-05-28 13:45     ` Thomas Weißschuh 
2023-05-28 18:39       ` Zhangjin Wu
2023-05-29  8:45         ` Thomas Weißschuh
2023-05-29 11:31           ` Willy Tarreau
2023-05-30 10:06             ` Zhangjin Wu

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