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Date: Mon, 23 Mar 2015 13:45:10 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] x86: stop using PER_CPU_VAR(kernel_stack)
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On Mon, 23 Mar 2015 18:38:09 +0100
Denys Vlasenko <dvlasenk@redhat.com> wrote:

> > Can we do a:
> > 
> >  #define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
> 
> We already do something similar:
> 
> static inline unsigned long current_top_of_stack(void)
> {
> #ifdef CONFIG_X86_64
>         return this_cpu_read_stable(cpu_tss.x86_tss.sp0);
> #else
>         /* sp0 on x86_32 is special in and around vm86 mode. */
>         return this_cpu_read_stable(cpu_current_top_of_stack);
> #endif
> }

So can we then have:

#ifdef __ASSEMBLY__
# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
#else
# define cpu_current_top_of_stack (cpu_tss.x86_tss.sp0)
#endif

And get rid of that if statement in the static inline?

-- Steve