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authorBorislav Petkov <bp@suse.de>2015-04-01 12:49:52 +0200
committerIngo Molnar <mingo@kernel.org>2015-04-03 15:26:15 +0200
commit78cac48c0434c82e860fade3cd0420a7a4adbb08 (patch)
tree76e1afefb1a0f9baad05487738de9f1b4a126aa7 /Documentation/x86
parent47091e3c5b072daca29a15d2a3caf40359b0d140 (diff)
downloadlinux-78cac48c0434c82e860fade3cd0420a7a4adbb08.tar.bz2
x86/mm/KASLR: Propagate KASLR status to kernel proper
Commit: e2b32e678513 ("x86, kaslr: randomize module base load address") made module base address randomization unconditional and didn't regard disabled KKASLR due to CONFIG_HIBERNATION and command line option "nokaslr". For more info see (now reverted) commit: f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation") In order to propagate KASLR status to kernel proper, we need a single bit in boot_params.hdr.loadflags and we've chosen bit 1 thus leaving the top-down allocated bits for bits supposed to be used by the bootloader. Originally-From: Jiri Kosina <jkosina@suse.cz> Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/x86')
-rw-r--r--Documentation/x86/boot.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index a75e3adaa39d..88b85899d309 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -406,6 +406,12 @@ Protocol: 2.00+
- If 0, the protected-mode code is loaded at 0x10000.
- If 1, the protected-mode code is loaded at 0x100000.
+ Bit 1 (kernel internal): ALSR_FLAG
+ - Used internally by the compressed kernel to communicate
+ KASLR status to kernel proper.
+ If 1, KASLR enabled.
+ If 0, KASLR disabled.
+
Bit 5 (write): QUIET_FLAG
- If 0, print early messages.
- If 1, suppress early messages.