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

x86/mm: Fix INVPCID asm constraint

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-mm-fix-invpcid-asm-constraint.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From e2c7698cd61f11d4077fdb28148b2d31b82ac848 Mon Sep 17 00:00:00 2001

From: Borislav Petkov bp@suse.de Date: Wed, 10 Feb 2016 15:51:16 +0100 Subject: x86/mm: Fix INVPCID asm constraint MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Borislav Petkov bp@suse.de

commit e2c7698cd61f11d4077fdb28148b2d31b82ac848 upstream.

So we want to specify the dependency on both @pcid and @addr so that the compiler doesn't reorder accesses to them *before* the TLB flush. But for that to work, we need to express this properly in the inline asm and deref the whole desc array, not the pointer to it. See clwb() for an example.

This fixes the build error on 32-bit:

arch/x86/include/asm/tlbflush.h: In function ‘__invpcid’: arch/x86/include/asm/tlbflush.h:26:18: error: memory input 0 is not directly addressable

which gcc4.7 caught but 5.x didn't. Which is strange. :-\

Signed-off-by: Borislav Petkov bp@suse.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Andy Lutomirski luto@amacapital.net Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Luis R. Rodriguez mcgrof@suse.com Cc: Michael Matz matz@suse.de Cc: Oleg Nesterov oleg@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Toshi Kani toshi.kani@hp.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/include/asm/tlbflush.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -10,7 +10,7 @@ static inline void __invpcid(unsigned long pcid, unsigned long addr, unsigned long type) { - u64 desc[2] = { pcid, addr }; + struct { u64 d[2]; } desc = { { pcid, addr } };

/* * The memory clobber is because the whole point is to invalidate @@ -22,7 +22,7 @@ static inline void __invpcid(unsigned lo * invpcid (%rcx), %rax in long mode. */ asm volatile (".byte 0x66, 0x0f, 0x38, 0x82, 0x01" - : : "m" (desc), "a" (type), "c" (desc) : "memory"); + : : "m" (desc), "a" (type), "c" (&desc) : "memory"); }

#define INVPCID_TYPE_INDIV_ADDR 0

Patches currently in stable-queue which might be from bp@suse.de are

queue-4.4/x86-mm-sched-core-uninline-switch_mm.patch queue-4.4/x86-mm-add-a-noinvpcid-boot-option-to-turn-off-invpcid.patch queue-4.4/x86-mm-if-invpcid-is-available-use-it-to-flush-global-mappings.patch queue-4.4/x86-mm-add-invpcid-helpers.patch queue-4.4/sched-core-add-switch_mm_irqs_off-and-use-it-in-the-scheduler.patch queue-4.4/arm-hide-finish_arch_post_lock_switch-from-modules.patch queue-4.4/x86-mm-sched-core-turn-off-irqs-in-switch_mm.patch queue-4.4/x86-mm-fix-invpcid-asm-constraint.patch queue-4.4/x86-mm-build-arch-x86-mm-tlb.c-even-on-smp.patch queue-4.4/sched-core-idle_task_exit-shouldn-t-use-switch_mm_irqs_off.patch