Thread (15 messages) 15 messages, 3 authors, 2018-10-09
STALE2830d
Revisions (3)
  1. v1 [diff vs current]
  2. v2 [diff vs current]
  3. v1 current

[PATCH 1/3] x86/KASLR: Update KERNEL_IMAGE_SIZE description

From: Baoquan He <hidden>
Date: 2018-10-06 08:43:49
Also in: lkml
Subsystem: the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

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old comments above the KERNEL_IMAGE_SIZE definition out of date.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 <redacted>
---
 arch/x86/include/asm/page_64_types.h | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 6afac386a434..cd0cf1c568b4 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -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)
-- 
2.13.6
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