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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?544R491pXTDksRYrmIzCsgx0+UfZfoclw4cCwuFoF8pmSxGPkmniIxg+h8y8?= =?us-ascii?Q?giI5uSZSGXwNRUJPZMP/SZku19RlbqoW3P9SR+JJ7L+61Bac2y4Im+sF+yoX?= =?us-ascii?Q?+gAU+yYJ1FcxRLDNgbioE6i+RIVRnx7o1L/3GQKgRTyHKeFrpBhFUpoddqtg?= =?us-ascii?Q?VCZgBI62ltLj4d2W60B7hBVgXSgGHUVv6bFT9TRoGby2OImOeToYTXF8MajM?= =?us-ascii?Q?NuFWDHHmY+fdFdbbW6Tt4GnqksGqewuXbsjhoZ8NpzkLiXqBNG5P1FREKXud?= =?us-ascii?Q?HUWQhgoB/Bf+hqoZVL4jdGBrAzk2U4ov0lfkLLYsY7mRtNI2yVGl6m7G6uST?= =?us-ascii?Q?HzAfi/+jtSdBJlYazgFfoxBxhjUeJ3vExbcxQ3XMPefwhU6pVaq/LNANqbDE?= =?us-ascii?Q?ur9wpFOs2VuCKmyF107QWsHqHLfLelp9ZRfJi9zI38rMb++mRxxxF9UpY/tK?= =?us-ascii?Q?oJoF8Zao4xdlnX8qF1fN4Ezf3hgxej2E6xPZC9HPuLs60VGyCrPhBSSI+AaM?= =?us-ascii?Q?kAOBKiwdlpok4TAWDiStFyD8CzTTQrgACKb/xkipcy+aVZoAo+dKIFWpJS6n?= =?us-ascii?Q?lPiyrFs4+D0t+BmRgc78om04r/ViDZmbIfjYVr6h31jKtZpjmkr0+RRNGQEa?= =?us-ascii?Q?YxjnB+9c+iEhjrub2xA1Ati0/D/qrdtlovHC4UfUvNtcmkTRYv8rOZEOnHHZ?= =?us-ascii?Q?nzMrRKuN+fJKZQKn3CXy8/5h4PtQvXZABV/3m7Quc5rGO+ZH5h2ImU1qDNCL?= =?us-ascii?Q?/vh6H3qNqAgZdB6P4W/9Jcimujwzb77Ne4S5pInsCuwYBdUQBvRe0AeHMxoA?= =?us-ascii?Q?g78tOgUtJaAi0yFMgdcbKjT54+IRlzONMUKiL/UehJUooBVFkBezE0tMld33?= =?us-ascii?Q?Vac6j/HBQqsATWtzGX2Kz0DWy6d14ui403Ocj3TVGLhadCQXhtBz2K7DdzMF?= =?us-ascii?Q?vlwMsJmeaAk7dAe81kjI8M4VwGpZdrKnXXNwz53w2ruRLcfJ+n6BhKCU4vad?= =?us-ascii?Q?4fiLLgeXVTIdWdeOHr9dv4KSy4w/9QaMJRe0lRBKdDW7H03PeE9tvPX4zUuJ?= =?us-ascii?Q?3e586fVkpPzU4RnHuw/wHs0KmK1Dcl9Ar0VVpJFiQDPCP205vh7r+sWgx1Rb?= =?us-ascii?Q?ZiTOOf8jPT72g6ogkMJDhZ5n9ieNPlWSaYiIJ320QW5iwsJa6szgQIAk5kzp?= =?us-ascii?Q?OjT6sKlUQTrcmvQGCJ+2PA4UH72iyMntODTeo7NHwupixp6QZP4RPLdFT9zz?= =?us-ascii?Q?w9S6rtqL734wTOsUjCQTgEKyqnIwCoJKOuU4S0wXsgFC+1I76x0kxzXzaeQn?= =?us-ascii?Q?QA5liQtzCrptZr3qoteBaEtC?= X-OriginatorOrg: synaptics.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8130316d-07b3-45ba-aa9d-08d8fa80e95e X-MS-Exchange-CrossTenant-AuthSource: BY5PR03MB5345.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Apr 2021 11:24:45.2342 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335d1fbc-2124-4173-9863-17e7051a2a0e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 8v48ak4WF4Kn9oOMM0xyERmyVZekGM6wpX0TQaVHnZdJj5TTnb1NI0zqoXSb/BZOgC/mn7K7Ds6dhtm+D5uEYw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR03MB4423 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 3 Apr 2021 20:30:53 +0200 (CEST) "Maciej W. Rozycki" wrote: > CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe. > > > On Thu, 1 Apr 2021, Masami Hiramatsu wrote: > > > > > > Current riscv's kprobe handlers are run with both preemption and > > > > > interrupt enabled, this violates kprobe requirements. Fix this issue > > > > > by keeping interrupts disabled for BREAKPOINT exception. > > > > > > > > Not only while the breakpoint exception but also until the end of > > > > the single step (maybe you are using __BUG_INSN_32 ??) need to be > > > > disable interrupts. Can this do that? > > > > > > > > > > interrupt is disabled during "single step" by kprobes_save_local_irqflag() > > > and kprobes_restore_local_irqflag(). The code flow looks like: > > > > > > do_trap_break() // for bp > > > kprobe_breakpoint_handler() > > > setup_singlestep() > > > kprobes_restore_local_irqflag() > > > > > > do_trap_break() // for ss > > > kprobe_single_step_handler() > > > kprobes_restore_local_irqflag() > > > > OK, thanks for the confirmation! > > Is this approach guaranteed to keep interrupt handling latency low enough > for the system not to be negatively affected, e.g. for the purpose of NTP > timekeeping? IMHO, interrupt latency can't be ensured if kprobes is triggered. thanks