Commit 54183d10 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by Borislav Petkov (AMD)
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x86/kexec: Remove spurious unconditional JMP from from identity_mapped() 



This seemingly straightforward JMP was introduced in the initial version
of the the 64bit kexec code without any explanation.

It turns out (check accompanying Link) it's likely a copy/paste artefact
from 32-bit code, where such a JMP could be used as a serializing
instruction for the 486's prefetch queue. On x86_64 that's not needed
because there's already a preceding write to cr4 which itself is
a serializing operation.

  [ bp: Typos. Let's try this and see what cries out. If it does,
    reverting it is trivial. ]

Signed-off-by: default avatarNikolay Borisov <nik.borisov@suse.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/55bc0649-c017-49ab-905d-212f140a403f@citrix.com/
parent f385f024

arch/x86/kernel/relocate_kernel_64.S

+0 −3
Original line number Diff line number Diff line
@@ -153,9 +153,6 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
1:

	movq	%rax, %cr4



	jmp 1f

1:



	/* Flush the TLB (needed?) */

	movq	%r9, %cr3