RE: [PATCH v2 4/4] tools/nolibc: sys.h: apply __syscall() helper

From: David Laight <David.Laight@ACULAB.COM>
To: 'Zhangjin Wu' <falcon@tinylab.org>, "w@1wt.eu" <w@1wt.eu>
Cc: "arnd@arndb.de" <arnd@arndb.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	"thomas@t-8ch.de" <thomas@t-8ch.de>
Subject: RE: [PATCH v2 4/4] tools/nolibc: sys.h: apply __syscall() helper
Date: Sat, 10 Jun 2023 16:34:16 +0000	[thread overview]
Message-ID: <0295105fe0744200bf2ef99e5bf7bc09@AcuMS.aculab.com> (raw)
In-Reply-To: <20230607053920.667272-1-falcon@tinylab.org>

From: Zhangjin Wu
> Sent: 07 June 2023 06:39
...
> As a summary, will use 'sysret()' and something like:
> 
>    static __attribute__((unused))
>    int chdir(const char *path)
>    {
>    	return sysret(chdir(path));
>    }
> 
> to renew the syscall helper patchset, Thanks you very much.

While I'm all for using 'cpp-magic' to abstract and (hopefully)
simplify things. Token-pasting the sys_ here doesn't seem to gain
anything.
Anyone grepping the code for 'sys_chdir' is also going to
wonder where it is used.

There might be scope for something like:
#define syscall_wrapper(func, type) \
	static __attribute__((unused)) \
	int func(type *arg) \
	{ \
		return sysret(sys_#func(arg)); \
	}
and then:
syscall_wrapper(chdir, const char *)
would expand to the code above.

I think you'd need separate defines for each number of arguments.

	David

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