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Date: Fri, 26 Jan 2018 10:54:21 -0800
From: Linus Torvalds <>
To: Andy Lutomirski <>
Cc: Al Viro <>, Alan Cox <>, 
	David Laight <>, "the arch/x86 maintainers" <>, 
	LKML <>, 
	Greg Kroah-Hartman <>, Jann Horn <>, 
	Samuel Neves <>, Dan Williams <>, 
	Kernel Hardening <>, Borislav Petkov <>
Subject: Re: [PATCH] x86/retpoline/entry: Disable the entire SYSCALL64 fast
 path with retpolines on

On Fri, Jan 26, 2018 at 10:23 AM, Andy Lutomirski <> wrote:
> The issue is that doing it this way gives us, effectively:
> long sys_foo(int a, int b)
> {
>   body here;
> }
> long SyS_foo(const struct pt_regs *regs)
> {
>   return sys_foo(regs->di, regs->si);
> }
> whereas what we want is *static* long sys_foo(...).

How about just marking 'sys_foo()' as being always_inline (but still
not static)? Because the case that _matters_ is that SyS_foo(), thing
when this is enabled.

Sure, you'll get two copies of the code (one in SyS_foo(), the other
being the callable-from C 'sys_foo()' that is exported and almost
never used). But that seems a fairly small price to pay. We could
leave it for later to try to get rid of the unused copies entirely.


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