Patch "x86/init: Clear 'init_level4_pgt' earlier" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

x86/init: Clear 'init_level4_pgt' earlier

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-init-clear-init_level4_pgt-earlier.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andrey Ryabinin <[email protected]>
Date: Thu, 2 Jul 2015 12:09:33 +0300
Subject: x86/init: Clear 'init_level4_pgt' earlier

From: Andrey Ryabinin <[email protected]>

commit d0f77d4d04b222a817925d33ba3589b190bfa863 upstream.

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.

---
 arch/x86/kernel/head64.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -166,6 +166,8 @@ asmlinkage __visible void __init x86_64_
 	/* 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_
 	 */
 	load_ucode_bsp();
 
-	clear_page(init_level4_pgt);
 	/* set init_level4_pgt kernel high mapping*/
 	init_level4_pgt[511] = early_level4_pgt[511];
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/x86-kasan-fix-kasan-shadow-region-page-tables.patch queue-4.1/x86-kasan-fix-boot-crash-on-amd-processors.patch queue-4.1/x86-init-clear-init_level4_pgt-earlier.patch queue-4.1/x86-kasan-flush-tlbs-after-switching-cr3.patch