From 78cac48c0434c82e860fade3cd0420a7a4adbb08 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Wed, 1 Apr 2015 12:49:52 +0200 Subject: 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 Suggested-by: H. Peter Anvin Signed-off-by: Borislav Petkov Cc: Kees Cook Signed-off-by: Ingo Molnar --- Documentation/x86/boot.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation') 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. -- cgit v1.2.3