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Peter Anvin" , Dapeng Mi , Andrii Nakryiko , Song Liu , Ravi Bangoria , Ananth Narayan , Sandipan Das Subject: [PATCH v2 0/2] perf/x86: Limit branch snapshots to valid entries Date: Thu, 15 Oct 2026 17:16:10 +0530 Message-ID: X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH01EPF000BE94F:EE_|MW6PR12MB8960:EE_ X-MS-Office365-Filtering-Correlation-Id: 40cb7bf7-4382-41d0-c409-08df2ab21f12 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|7416014|23010399003|82310400026|36860700016|11063799006|56012099006|261009223027099003|18002099003|13003099007|10067099003; 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)(376014)(1800799024)(7416014)(23010399003)(82310400026)(36860700016)(11063799006)(56012099006)(261009223027099003)(18002099003)(13003099007)(10067099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: JKl1zT5sU4JGNS314927Zj5C12S2oMvBN3E8Q10iVCWBmurSwiXjOj1v6w7Jn0OtwX/Il6Lg7pS4soEzYQixzvxjrnH1ARoK5TdDDO8ocWGQ39C9EEGfWUjL9/eRYQHnk3l4P4STgiOFvM5Y0inEZLaGzuleAHXXRNIsGWsnFnDGwQqKuZLYEMIE9BVmerj1LHnVHo2SeR7xSfMVU/6KKhx6WFyDr2eL3ovV6nGhKeRkyijFABRC26sBM0IkbBZ56Q/jBXJrD8tOrX6KNvZnttRdqm4wL2bYt205bskbBnltoPEHsqGGMJ2B48MdNPMRwkpt2cD/l35BIvEG5w+baPJYxeiViAfTJxOHpxqgnezGgP9EWfOARlkLJBMk1dpJn9LCBvVL9/GrBh74ITXI2tjaz1RUY9+KKWOFUVmYDNRLszVTecXKLA/b/inlsPtH X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Oct 2026 11:47:42.3216 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 40cb7bf7-4382-41d0-c409-08df2ab21f12 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: CH01EPF000BE94F.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR12MB8960 Sashiko reported that the vendor-specific branch snapshot callbacks used by bpf_get_branch_snapshot() copy up to x86_pmu.lbr_nr entries from cpuc->lbr_entries[], regardless of how many valid entries the last LBR read produced. This makes BPF programs read stale or invalid branch records. Patch 1 addresses AMD and patch 2 addresses Intel. Previous version(s) can be found at v1: https://lore.kernel.org/all/20261007181002.4005262-1-sandipan.das@amd.com/ Changes in v2: * Include a fix for Intel LBR. * Add Tested-by from Dapeng to the Intel fix. https://lore.kernel.org/all/eb6c7bda-0dcf-4fac-ad69-9f5b24abc21b@linux.intel.com/ Sandipan Das (2): perf/x86/amd/lbr: Limit branch snapshots to valid entries perf/x86/intel/lbr: Limit branch snapshots to valid entries arch/x86/events/amd/core.c | 2 +- arch/x86/events/amd/lbr.c | 4 +++- arch/x86/events/intel/core.c | 2 +- arch/x86/events/intel/lbr.c | 4 +++- 4 files changed, 8 insertions(+), 4 deletions(-) -- 2.53.0