linux-kernel - Re: [patch 3/3] x86/paravirt: Replace paravirt patch asm magic

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Message-ID: <alpine.DEB.2.21.1904250921010.1762@nanos.tec.linutronix.de>
Date:   Thu, 25 Apr 2019 09:22:48 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Ingo Molnar <mingo@...nel.org>
cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Juergen Gross <jgross@...e.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [patch 3/3] x86/paravirt: Replace paravirt patch asm magic

On Thu, 25 Apr 2019, Ingo Molnar wrote:
> > +# else
> > +	.irq_restore_fl		= { 0x50, 0x9d },	// push %eax; popf
> > +	.mmu_write_cr3		= { 0x0f, 0x22, 0xd8 },	// mov %eax, %cr3
> > +	.cpu_iret		= { 0xcf },		// iret
> > +# endif
> 
> I think these open-coded hexa versions are somewhat fragile as well, how 
> about putting these into a .S file and controlling the sections in an LTO 
> safe manner there?
> 
> That will also allow us to write proper asm, and global labels can be 
> used to extract the patchlets and their length?

We are not changing these any other day and I really don't see a reason to
have these things global just because.

Thanks,

	tglx