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Date: Wed, 29 May 2024 14:17:29 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Nikolay Borisov <nik.borisov@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 
	Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, 
	"Rafael J. Wysocki" <rafael@kernel.org>, Peter Zijlstra <peterz@infradead.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, 
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>, Elena Reshetova <elena.reshetova@intel.com>, 
	Jun Nakajima <jun.nakajima@intel.com>, Rick Edgecombe <rick.p.edgecombe@intel.com>, 
	Tom Lendacky <thomas.lendacky@amd.com>, "Kalra, Ashish" <ashish.kalra@amd.com>, 
	Sean Christopherson <seanjc@google.com>, "Huang, Kai" <kai.huang@intel.com>, 
	Ard Biesheuvel <ardb@kernel.org>, Baoquan He <bhe@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, 
	"K. Y. Srinivasan" <kys@microsoft.com>, Haiyang Zhang <haiyangz@microsoft.com>, 
	kexec@lists.infradead.org, linux-hyperv@vger.kernel.org, linux-acpi@vger.kernel.org, 
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv11 05/19] x86/relocate_kernel: Use named labels for less
 confusion
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References: <20240528095522.509667-1-kirill.shutemov@linux.intel.com>
 <20240528095522.509667-6-kirill.shutemov@linux.intel.com>
 <1e1d1aea-7346-4022-9f5f-402d171adfda@suse.com>
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In-Reply-To: <1e1d1aea-7346-4022-9f5f-402d171adfda@suse.com>

On Wed, May 29, 2024 at 01:47:50PM +0300, Nikolay Borisov wrote:
> 
> 
> On 28.05.24 г. 12:55 ч., Kirill A. Shutemov wrote:
> > From: Borislav Petkov <bp@alien8.de>
> > 
> > That identity_mapped() functions was loving that "1" label to the point
> > of completely confusing its readers.
> > 
> > Use named labels in each place for clarity.
> > 
> > No functional changes.
> > 
> > Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > ---
> >   arch/x86/kernel/relocate_kernel_64.S | 13 +++++++------
> >   1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
> > index 56cab1bb25f5..085eef5c3904 100644
> > --- a/arch/x86/kernel/relocate_kernel_64.S
> > +++ b/arch/x86/kernel/relocate_kernel_64.S
> > @@ -148,9 +148,10 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
> >   	 */
> >   	movl	$X86_CR4_PAE, %eax
> >   	testq	$X86_CR4_LA57, %r13
> > -	jz	1f
> > +	jz	.Lno_la57
> >   	orl	$X86_CR4_LA57, %eax
> > -1:
> > +.Lno_la57:
> > +
> >   	movq	%rax, %cr4
> >   	jmp 1f
> 
> That jmp 1f becomes redundant now as it simply jumps 1 line below.
> 

Nothing changed wrt this jump. It dates back to initial kexec
implementation.

See 5234f5eb04ab ("[PATCH] kexec: x86_64 kexec implementation").

But I don't see functional need in it.

Anyway, it is outside of the scope of the patch.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov