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x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY=y 

CONFIG_RANDOMIZE_MEMORY=y randomizes the physical memmap and thus the
address where the initrd is located. Therefore, we need to add the
offset KASLR put us to in order to find the initrd again on the AP path.

In the future, we will get rid of the initrd address caching and query
the address on both the BSP and AP paths but that would need more work.

Thanks to Nicolai Stange for the good bisection and debugging work.

Reported-and-tested-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160726095138.3470-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2016-07-26 11:51:38 +02:00 committed by Ingo Molnar
parent eb06158ee1
commit efaad554b4
1 changed files with 14 additions and 2 deletions
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16
arch/x86/kernel/cpu/microcode/intel.c
View File

@ -793,10 +793,10 @@ void __init load_ucode_intel_bsp(void)
void load_ucode_intel_ap(void)
{
struct ucode_blobs *blobs_p;
unsigned long *ptrs, start = 0;
struct mc_saved_data *mcs;
struct ucode_cpu_info uci;
enum ucode_state ret;
unsigned long *ptrs;
#ifdef CONFIG_X86_32
mcs = (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
@ -815,8 +815,20 @@ void load_ucode_intel_ap(void)
if (!mcs->num_saved)
return;
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);
ret = load_microcode(mcs, ptrs, blobs_p->start, &uci);
ret = load_microcode(mcs, ptrs, start, &uci);
if (ret != UCODE_OK)
return;