Commit d0f77d4d authored Jul 02, 2015 by Andrey Ryabinin Committed by Ingo Molnar Jul 06, 2015

x86/init: Clear 'init_level4_pgt' earlier



Currently x86_64_start_kernel() has two KASAN related
function calls. The first call maps shadow to early_level4_pgt,
the second maps shadow to init_level4_pgt.

If we move clear_page(init_level4_pgt) earlier, we could hide
KASAN low level detail from generic x86_64 initialization code.
The next patch will do it.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: <stable@vger.kernel.org> # 4.0+
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
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/1435828178-10975-2-git-send-email-a.ryabinin@samsung.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 5aac644a

arch/x86/kernel/head64.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -166,6 +166,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
		/* clear bss before set_intr_gate with early_idt_handler */
		clear_bss();

		clear_page(init_level4_pgt);

		for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
		set_intr_gate(i, early_idt_handler_array[i]);
		load_idt((const struct desc_ptr *)&idt_descr);
		@@ -177,7 +179,6 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
		*/
		load_ucode_bsp();

		clear_page(init_level4_pgt);
		/* set init_level4_pgt kernel high mapping*/
		init_level4_pgt[511] = early_level4_pgt[511];