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>
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 5a46681..65c8985 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -166,6 +166,8 @@
/* 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 @@
*/
load_ucode_bsp();
- clear_page(init_level4_pgt);
/* set init_level4_pgt kernel high mapping*/
init_level4_pgt[511] = early_level4_pgt[511];
