From e2c7698cd61f11d4077fdb28148b2d31b82ac848 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Wed, 10 Feb 2016 15:51:16 +0100 Subject: [PATCH] x86/mm: Fix INVPCID asm constraint MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Andrew Morton Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Michael Matz Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/tlbflush.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index fc9a2fda1404..d0cce90b0855 100644 --- 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 long pcid, unsigned long addr, * 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 -- 2.20.1