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Message-ID: <2d25e3bb829cbca51387eb84985db919f50ccd37.camel@xry111.site>
Subject: Re: Chromium sandbox on LoongArch and statx -- seccomp deep
 argument inspection again?
From: Xi Ruoyao <xry111@xry111.site>
To: WANG Xuerui <kernel@xen0n.name>, linux-api@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>, Christian Brauner <brauner@kernel.org>, 
 Kees Cook <keescook@chromium.org>, Huacai Chen <chenhuacai@kernel.org>,
 Xuefeng Li <lixuefeng@loongson.cn>, Jianmin Lv <lvjianmin@loongson.cn>,
 Xiaotian Wu <wuxiaotian@loongson.cn>, WANG Rui <wangrui@loongson.cn>, Miao
 Wang <shankerwangmiao@gmail.com>, Icenowy Zheng <uwu@icenowy.me>, 
 "loongarch@lists.linux.dev" <loongarch@lists.linux.dev>, linux-arch
 <linux-arch@vger.kernel.org>, Linux Kernel Mailing List
 <linux-kernel@vger.kernel.org>
Date: Wed, 21 Feb 2024 18:31:46 +0800
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On Wed, 2024-02-21 at 14:31 +0800, Xi Ruoyao wrote:
> On Wed, 2024-02-21 at 14:09 +0800, WANG Xuerui wrote:
>=20
> > - just restore fstat and be done with it;
> > - add a flag to statx so we can do the equivalent of just fstat(fd,=20
> > &out) with statx, and ensuring an error happens if path is not empty in=
=20
> > that case;
>=20
> It's worse than "just restore fstat" considering the performance.=C2=A0 R=
ead
> this thread:
> https://sourceware.org/pipermail/libc-alpha/2023-September/151320.html

Hmm, but it looks like statx already suffers the same performance issue.
And in this libc-alpha discussion Linus said:

   If the user asked for 'fstat()', just give the user 'fstat()'.
  =20
So to me we should just add fstat (and use it in Glibc for LoongArch, only
falling back to statx if fstat returns -ENOSYS), or am I missing something?

--=20
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University