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x86/kexec: Remove spurious unconditional JMP from from identity_mapped()

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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: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/55bc0649-c017-49ab-905d-212f140a403f@citrix.com/
This commit is contained in:
Nikolay Borisov
2024-05-29 18:28:50 +03:00
committed by Borislav Petkov (AMD)
parent f385f02463
commit 54183d103d
1 changed files with 0 additions and 3 deletions
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3
arch/x86/kernel/relocate_kernel_64.S
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@@ -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