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Peter Anvin" , Thomas Huth , Sean Christopherson Subject: [PATCH v5 1/8] x86/runtime-const: Introduce runtime_const_mask_32() Date: Tue, 30 Jun 2026 04:55:24 +0000 Message-ID: <20260630045531.3939-2-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260630045531.3939-1-kprateek.nayak@amd.com> References: <20260630045531.3939-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain 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: SN1PEPF00026367:EE_|SN7PR12MB7835:EE_ X-MS-Office365-Filtering-Correlation-Id: 27276124-c3c1-4b54-e45b-08ded663ece9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|7416014|1800799024|82310400026|36860700016|13003099007|22082099003|11063799006|18002099003|56012099006; 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)(23010399003)(376014)(7416014)(1800799024)(82310400026)(36860700016)(13003099007)(22082099003)(11063799006)(18002099003)(56012099006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: +B6wd/xiuwO/sFz6vzlIphvssXLa1R16sxEpMCVgIQE0lNcI4ulF6NUKkuNKQ6epfFC2zr2TTbTPD8T69PcEgWOE8w2Cf7emwQ7n/r/zFhTpSDLJQKm5994gFDX72hPgzFNjSyN/nrw51utOp7bgquJ+P8H6qUPnau5dUaxDZIdSS5tGlEpeVD9fpP35dRRDNp8YWccA0xU/MoSZYyMO2Iz03J6FaD9JmczOUDXEcOI16rdFy0SE6esdUR70263QqybSkmDb516lq+VZHGhHquyp+ARwg5egCJxPEpPmlAAx40h0AYKrruGaHb14UVLa7vFCD0wRxSLBqphb+sqmwcBW8lvCKF+OLdk4CZycTrEDx/vBK1nYpjT+p4ofxI5hhHTkVob+IfN6910KICKUaDOg+jpAbM+MX0mv55KnCkZVqhwTErRRzgnqh800gApK X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jun 2026 04:56:19.7402 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 27276124-c3c1-4b54-e45b-08ded663ece9 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: SN1PEPF00026367.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7835 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.kicks-ass.net Not-yet-signed-off-by: Peter Zijlstra Signed-off-by: K Prateek Nayak --- changelog v4..v5: o No changes. --- 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/runtime-const.h index 4cd94fdcb45e2..b13f7036c1c9b 100644 --- a/arch/x86/include/asm/runtime-const.h +++ b/arch/x86/include/asm/runtime-const.h @@ -41,6 +41,15 @@ :"+r" (__ret)); \ __ret; }) +#define runtime_const_mask_32(val, sym) ({ \ + typeof(0u+(val)) __ret = (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, unsigned long val) *(unsigned char *)where = val; } +static inline void __runtime_fixup_mask(void *where, unsigned long val) +{ + *(unsigned int *)where = val; +} + static inline void runtime_const_fixup(void (*fn)(void *, unsigned long), unsigned long val, s32 *start, s32 *end) { -- 2.34.1