Re: [PATCH v2 1/2] x86: introduce kaslr_offset()

From: Jiri Kosina
Date: Tue Apr 28 2015 - 11:57:22 EST


On Tue, 28 Apr 2015, Jiri Kosina wrote:

> Offset that has been chosen for kaslr during kernel decompression can be
> easily computed as a difference between _text and __START_KERNEL. We are
> already making use of this in dump_kernel_offset() notifier and in
> arch_crash_save_vmcoreinfo().
>
> Introduce kaslr_offset() that makes this computation instead of
> hard-coding it, so that other kernel code (such as live patching) can make
> use of it. Also convert existing users to make use of it.
>
> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> ---
>
> It'd be great to potentially have Ack from x86 guys for this patch so that
> I could take it through livepatching.git with the depending 2/2 patch.
> Thanks.
>
> v1 -> v2: convert arch_crash_save_vmcoreinfo(), as spotted by Josh
> Poimboeuf.

FWIW this patch is equivalent transofrmation without any effects on the
resulting code:

$ diff -u vmlinux.old.asm vmlinux.new.asm
--- vmlinux.old.asm 2015-04-28 17:55:19.520983368 +0200
+++ vmlinux.new.asm 2015-04-28 17:55:24.141206072 +0200
@@ -1,5 +1,5 @@

-vmlinux.old: file format elf64-x86-64
+vmlinux.new: file format elf64-x86-64


Disassembly of section .text:
$

--
Jiri Kosina
SUSE Labs
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