linux-kernel - Re: [PATCH] x86/syscalls: shrink entry/syscall

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Message-ID: <20231228002614.GI1674809@ZenIV>
Date: Thu, 28 Dec 2023 00:26:14 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Tanzir Hasan <tanzirh@...gle.com>, Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Nick Desaulniers <nnn@...gle.com>
Subject: Re: [PATCH] x86/syscalls: shrink entry/syscall_32.i via IWYU

On Wed, Dec 27, 2023 at 03:50:33PM -0800, H. Peter Anvin wrote:
> > /*
> >  * Only the low 32 bits of orig_ax are meaningful, so we return int.
> >  * This importantly ignores the high bits on 64-bit, so comparisons
> 
> __visible is for LTO, no?

If we need it in cases when array defined in entry/syscall_32.c and
used in entry/common.c, I would respectfully suggest that whatever
we need it for is misguided garbage.  I don't think that LTO does
need it, though.  How is arch/x86/entry/{syscall_32,common}.c
different from e.g. fs/{namespace,d_path}.c, where we have
fs/namespace.c:100:__cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock);
and
fs/d_path.c:166:        read_seqbegin_or_lock(&mount_lock, &m_seq);
respectively?