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Peter Anvin" Subject: [PATCH 1/2] x86/bitops: Use TZCNT mnemonic in Date: Tue, 25 Mar 2025 18:52:01 +0100 Message-ID: <20250325175215.330659-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Current minimum required version of binutils is 2.25, which supports TZCNT instruction mnemonic. Replace "REP; BSF" in variable__{ffs,ffz}() function with this proper mnemonic. 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" --- arch/x86/include/asm/bitops.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 100413aff640..bbaf75ea6703 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -248,7 +248,7 @@ arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr) static __always_inline unsigned long variable__ffs(unsigned long word) { - asm("rep; bsf %1,%0" + asm("tzcnt %1,%0" : "=r" (word) : ASM_INPUT_RM (word)); return word; @@ -267,7 +267,7 @@ static __always_inline unsigned long variable__ffs(unsigned long word) static __always_inline unsigned long variable_ffz(unsigned long word) { - asm("rep; bsf %1,%0" + asm("tzcnt %1,%0" : "=r" (word) : "r" (~word)); return word; -- 2.42.0