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Peter Anvin" , Kiryl Shutsemau , "Sean Christopherson" , Thomas Huth Subject: [RFC PATCH v2 1/7] x86/runtime-const: Introduce runtime_const_mask_32() Date: Mon, 16 Mar 2026 05:23:55 +0000 Message-ID: <20260316052401.18910-2-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260316052401.18910-1-kprateek.nayak@amd.com> References: <20260316052401.18910-1-kprateek.nayak@amd.com> 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 X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF00017099:EE_|SJ5PPF5D591B24D:EE_ X-MS-Office365-Filtering-Correlation-Id: 41d319a3-5435-47d6-928b-08de831c561d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|376014|36860700016|7416014|18002099003|22082099003|13003099007|56012099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(376014)(36860700016)(7416014)(18002099003)(22082099003)(13003099007)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: x1SYrVgjq5H7VXgy+jXyUZe47YIA2hTAosGXhHynvrFlt/ZOE84YmaJWQGuRzZcGlLPqyCHKNx0/WyktUAm4O5a0L1HFZIxQ7st7zxNkT1wlcEo0L48TmjkmZSVkDC4zy/V3urzTqKkES6OHyHflYooZW+6BseZ1FXoBnaXCTYJLGlnSoMxe1eJ4vstrJfSA5804ybyBwycmO54RcYWpnJ+6MJrBoFdaKNXu/jiwqJgLQdDW37o2qlmwJpWu+oU6IHR1GffDXCeXaoG5I09/QSjER7RsdIcLYRQUwMhQJLJGpx94+VU0MfOs6qQFMnEEIr0JLGRt2q15q8ux51lXkAHnDpJAO5zC/4XLU8rTRGjf2G3FpO+xLsMUokU+q6eFGt9j3aaP2vap+MTTETmLVugqX4ckGihbCr0yz76IzxWSRkBY3ScUBnARddt3HXkw X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Mar 2026 05:24:45.9817 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 41d319a3-5435-47d6-928b-08de831c561d X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF00017099.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPF5D591B24D Content-Type: text/plain; charset="utf-8" From: Peter Zijlstra Futex hash computation requires a mask operation with read-only after init data that will be converted to a runtime constant in the subsequent commit. Introduce runtime_const_mask_32 to further optimize the mask operation in the futex hash computation hot path. [ prateek: Broke off the x86 chunk, commit message. ] Link: https://patch.msgid.link/20260227161841.GH606826@noisy.programming.ki= cks-ass.net Not-yet-signed-off-by: Peter Zijlstra Signed-off-by: K Prateek Nayak --- arch/x86/include/asm/runtime-const.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/include/asm/runtime-const.h b/arch/x86/include/asm/ru= ntime-const.h index 4cd94fdcb45e..b13f7036c1c9 100644 --- a/arch/x86/include/asm/runtime-const.h +++ b/arch/x86/include/asm/runtime-const.h @@ -41,6 +41,15 @@ :"+r" (__ret)); \ __ret; }) =20 +#define runtime_const_mask_32(val, sym) ({ \ + typeof(0u+(val)) __ret =3D (val); \ + asm_inline("and $0x12345678, %k0\n1:\n" \ + ".pushsection runtime_mask_" #sym ",\"a\"\n\t"\ + ".long 1b - 4 - .\n" \ + ".popsection" \ + : "+r" (__ret)); \ + __ret; }) + #define runtime_const_init(type, sym) do { \ extern s32 __start_runtime_##type##_##sym[]; \ extern s32 __stop_runtime_##type##_##sym[]; \ @@ -65,6 +74,11 @@ static inline void __runtime_fixup_shift(void *where, un= signed long val) *(unsigned char *)where =3D val; } =20 +static inline void __runtime_fixup_mask(void *where, unsigned long val) +{ + *(unsigned int *)where =3D val; +} + static inline void runtime_const_fixup(void (*fn)(void *, unsigned long), unsigned long val, s32 *start, s32 *end) { --=20 2.43.0