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([193.77.86.199]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ac3efb51cebsm1202845666b.107.2025.03.27.02.56.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Mar 2025 02:56:44 -0700 (PDT) From: Uros Bizjak To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Uros Bizjak , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH] x86/bitops: Implement variable_ffz() as variable__ffs(~word) Date: Thu, 27 Mar 2025 10:56:28 +0100 Message-ID: <20250327095641.131483-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Find first zero (FFZ) can be implemented by negating the input and using find first set (FFS). No functional changes 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 | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index bbaf75ea6703..eebbc8889e70 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -267,10 +267,7 @@ static __always_inline unsigned long variable__ffs(uns= igned long word) =20 static __always_inline unsigned long variable_ffz(unsigned long word) { - asm("tzcnt %1,%0" - : "=3Dr" (word) - : "r" (~word)); - return word; + return variable__ffs(~word); } =20 /** --=20 2.49.0