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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jan 2024 11:07:14.3371 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 703c873b-f242-4a69-a68b-08dc20ba72fc 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0001709C.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB7312 Content-Type: text/plain; charset="utf-8" The Revision Guide for AMD Family 19h Model 10-1Fh processors, found at the link below, declares Erratum 1452 which states that non-branch entries may erroneously be recorded in the Last Branch Record (LBR) stack with the valid and spec bits set. Such entries can be recognized by inspecting bit 61 of the corresponding LastBranchStackToIp register. This bit is currently reserved but if found to be set, the associated branch entry should be discarded. Link: https://bugzilla.kernel.org/attachment.cgi?id=3D305518 Signed-off-by: Sandipan Das --- arch/x86/events/amd/lbr.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c index 110e34c59643..43bf2dbcdb82 100644 --- a/arch/x86/events/amd/lbr.c +++ b/arch/x86/events/amd/lbr.c @@ -173,9 +173,11 @@ void amd_pmu_lbr_read(void) =20 /* * Check if a branch has been logged; if valid =3D 0, spec =3D 0 - * then no branch was recorded + * then no branch was recorded; if reserved =3D 1 then an + * erroneous branch was recorded (see erratum 1452) */ - if (!entry.to.split.valid && !entry.to.split.spec) + if ((!entry.to.split.valid && !entry.to.split.spec) || + entry.to.split.reserved) continue; =20 perf_clear_branch_entry_bitfields(br + out); --=20 2.34.1