linux-kernel - [PATCH v4 4/4] x86/nospec: Remove barrier

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Date:   Tue,  4 May 2021 22:54:32 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Will Deacon <will@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <longman@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Andy Lutomirski <luto@...nel.org>,
        Christoph Hellwig <hch@....de>,
        David Laight <David.Laight@...lab.com>,
        Mark Rutland <mark.rutland@....com>,
        Borislav Petkov <bp@...en8.de>
Subject: [PATCH v4 4/4] x86/nospec: Remove barrier_nospec()

The barrier_nospec() macro is no longer used.  Its uses have been
replaced with address and array index masking.  Remove it.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/include/asm/barrier.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 4819d5e5a335..88f692d4f4ec 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -48,9 +48,6 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
 /* Override the default implementation from linux/nospec.h. */
 #define array_index_mask_nospec array_index_mask_nospec
 
-/* Prevent speculative execution past this barrier. */
-#define barrier_nospec() alternative("", "lfence", X86_FEATURE_LFENCE_RDTSC)
-
 #define dma_rmb()	barrier()
 #define dma_wmb()	barrier()
 
-- 
2.31.1