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Peter Anvin" , "Peter Zijlstra (Intel)" Subject: [PATCH -tip 1/3] x86/fsgsbase: Remove unnecessary "memory" clobbers from FS/GS base accessors Date: Tue, 10 Mar 2026 09:21:22 +0100 Message-ID: <20260310082142.93834-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The rdfsbase() and rdgsbase() helpers currently include a "memory" clobber in their inline assembly definitions. However, the RDFSBASE and RDGSBASE instructions only read the FS/GS base MSRs into a general-purpose register and do not access memory. As such, the "memory" clobber is unnecessary. No functional change intended. Signed-off-by: Uros Bizjak Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: "Peter Zijlstra (Intel)" --- arch/x86/include/asm/fsgsbase.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h index ab2547f97c2c..70ff4ef457b1 100644 --- a/arch/x86/include/asm/fsgsbase.h +++ b/arch/x86/include/asm/fsgsbase.h @@ -25,7 +25,7 @@ static __always_inline unsigned long rdfsbase(void) { unsigned long fsbase; - asm volatile("rdfsbase %0" : "=r" (fsbase) :: "memory"); + asm volatile("rdfsbase %0" : "=r" (fsbase)); return fsbase; } @@ -34,7 +34,7 @@ static __always_inline unsigned long rdgsbase(void) { unsigned long gsbase; - asm volatile("rdgsbase %0" : "=r" (gsbase) :: "memory"); + asm volatile("rdgsbase %0" : "=r" (gsbase)); return gsbase; } -- 2.53.0