[tip:x86/microcode] x86/asm, x86/microcode: Add __PAGE_OFFSET_BASE define on 32-bit

From: tip-bot for Borislav Petkov
Date: Wed Jul 27 2016 - 13:10:44 EST


Commit-ID: 4a1a8e1b8f9f37bdbba416eb0a5ff3f47d31cb28
Gitweb: http://git.kernel.org/tip/4a1a8e1b8f9f37bdbba416eb0a5ff3f47d31cb28
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Wed, 27 Jul 2016 14:09:39 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 27 Jul 2016 14:59:59 +0200

x86/asm, x86/microcode: Add __PAGE_OFFSET_BASE define on 32-bit

... in order to avoid #ifdeffery in code computing the ASLR randomization
offset. Remove that #ifdeffery in the microcode loader.

Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicolai Stange <nicstange@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160727120939.GA18911@xxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/page_32_types.h | 3 ++-
arch/x86/kernel/cpu/microcode/intel.c | 2 --
2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/page_32_types.h b/arch/x86/include/asm/page_32_types.h
index 3a52ee0..3bae496 100644
--- a/arch/x86/include/asm/page_32_types.h
+++ b/arch/x86/include/asm/page_32_types.h
@@ -13,7 +13,8 @@
* If you want more physical memory than this then see the CONFIG_HIGHMEM4G
* and CONFIG_HIGHMEM64G options in the kernel configuration.
*/
-#define __PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
+#define __PAGE_OFFSET_BASE _AC(CONFIG_PAGE_OFFSET, UL)
+#define __PAGE_OFFSET __PAGE_OFFSET_BASE

#define __START_KERNEL_map __PAGE_OFFSET

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 0f97ae9..cdc0dea 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -818,13 +818,11 @@ void load_ucode_intel_ap(void)
if (blobs_p->valid) {
start = blobs_p->start;

-#ifdef CONFIG_RANDOMIZE_MEMORY
/*
* Pay attention to CONFIG_RANDOMIZE_MEMORY=y as it shuffles
* physmem mapping too and there we have the initrd.
*/
start += PAGE_OFFSET - __PAGE_OFFSET_BASE;
-#endif
}

collect_cpu_info_early(&uci);