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x86/KASLR: Update KERNEL_IMAGE_SIZE description 

Currently CONFIG_RANDOMIZE_BASE=y is set by default, which makes some of the
old comments above the KERNEL_IMAGE_SIZE definition out of date. Update them
to the current state of affairs.

Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: corbet@lwn.net
Cc: linux-doc@vger.kernel.org
Cc: thgarnie@google.com
Link: http://lkml.kernel.org/r/20181006084327.27467-2-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Baoquan He 2018-10-06 16:43:25 +08:00 committed by Ingo Molnar
parent 992b649a3f
commit 06d4a462e9
1 changed files with 9 additions and 6 deletions
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15
arch/x86/include/asm/page_64_types.h
View File

@ -59,13 +59,16 @@
#endif
/*
* Kernel image size is limited to 1GiB due to the fixmap living in the
* next 1GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S). Use
* 512MiB by default, leaving 1.5GiB for modules once the page tables
* are fully set up. If kernel ASLR is configured, it can extend the
* kernel page table mapping, reducing the size of the modules area.
* Maximum kernel image size is limited to 1 GiB, due to the fixmap living
* in the next 1 GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S).
*
* On KASLR use 1 GiB by default, leaving 1 GiB for modules once the
* page tables are fully set up.
*
* If KASLR is disabled we can shrink it to 0.5 GiB and increase the size
* of the modules area to 1.5 GiB.
*/
#if defined(CONFIG_RANDOMIZE_BASE)
#ifdef CONFIG_RANDOMIZE_BASE
#define KERNEL_IMAGE_SIZE (1024 * 1024 * 1024)
#else
#define KERNEL_IMAGE_SIZE (512 * 1024 * 1024)