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received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: BffilrQA6oqujGywZOVW7npsdxdsVUAH/yjxVm5knb1tDnEytNRWwfiLe2/46s9RcBLFgAO09+JIG17kBfhmu7FqTUP6x9WDWGjWJ8HIj/C9jycB2x6J9qVjE2HkYr5e37oDAWbYgA5HR4eqjflXAx8/x4yRwHu6b8bU6+Kmcu9Mpbu+7A0bzdQaQV01BW3O35kh8d4d/+snz5Dd1Jg8RNPOoUNP66Is7IUuUlJpEG2vTm7FczQsrEo3Gb+3LxCrzbG0UEgqr3jaDe4+bpfRnizq84ccrGlC9wbqdtoztOqf3QWTzqHpWRrpIlncahwm spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-ID: <3B7DEC51D6E7CF419E6677AECC6376BA@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: d4a2254c-3efd-4dd6-9972-08d6759af9dc X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Jan 2019 18:56:19.5820 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1309 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-08_10:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks Peter! > On Jan 8, 2019, at 10:31 AM, Peter Zijlstra wrote: >=20 > On Thu, Dec 20, 2018 at 10:28:58AM -0800, Song Liu wrote: >=20 >> @@ -648,11 +649,18 @@ struct perf_event_mmap_page { >> * PERF_RECORD_MISC_COMM_EXEC - PERF_RECORD_COMM event >> * PERF_RECORD_MISC_FORK_EXEC - PERF_RECORD_FORK event (perf internal= ) >> * PERF_RECORD_MISC_SWITCH_OUT - PERF_RECORD_SWITCH* events >> + * PERF_RECORD_MISC_KSYMBOL_* - PERF_RECORD_KSYMBOL event >> */ >> #define PERF_RECORD_MISC_MMAP_DATA (1 << 13) >> #define PERF_RECORD_MISC_COMM_EXEC (1 << 13) >> #define PERF_RECORD_MISC_FORK_EXEC (1 << 13) >> #define PERF_RECORD_MISC_SWITCH_OUT (1 << 13) >> + >> +#define PERF_RECORD_MISC_KSYMBOL_UNREGISTER (1 << 3) >> +#define PERF_RECORD_MISC_KSYMBOL_TYPE_MASK (7 << 4) >> +#define PERF_RECORD_MISC_KSYMBOL_TYPE_UNKNOWN (0 << 4) >> +#define PERF_RECORD_MISC_KSYMBOL_TYPE_BPF (1 << 4) >=20 > So this gives us 8 possible types, of which 2 are claimed. >=20 > I suppose we already know of FTRACE_TRAMPOLINE and MODULE, which > accounts for half the space. >=20 >> + >> /* >> * These PERF_RECORD_MISC_* flags below are safely reused >> * for the following events: >> @@ -965,6 +973,19 @@ enum perf_event_type { >> */ >> PERF_RECORD_NAMESPACES =3D 16, >>=20 >> + /* >> + * Record ksymbol register/unregister events: >> + * >> + * struct { >> + * struct perf_event_header header; >> + * u64 addr; >> + * u64 len; >> + * char name[]; >> + * struct sample_id sample_id; >> + * }; >> + */ >> + PERF_RECORD_KSYMBOL =3D 17, >=20 > Do we really need u64 length? That is, are we willing to consider > symbols larger than 4G ? >=20 > Could we not reclaim the top 32 or 16 bits thereof for that type thing > instead of using a few misc bits? I don't think we need u64 length. 32 bit should be more than enough.=20 How about we revise it as: + /* + * Record ksymbol register/unregister events: + * + * struct { + * struct perf_event_header header; + * u64 addr; + * u32 len; + * u16 type; + * u16 reserved; + * char name[]; + * struct sample_id sample_id; + * }; + */ + PERF_RECORD_KSYMBOL =3D 17, [...] +#define PERF_RECORD_MISC_KSYMBOL_TYPE_UNKNOWN 0 +#define PERF_RECORD_MISC_KSYMBOL_TYPE_BPF 1 +#define PERF_RECORD_MISC_KSYMBOL_TYPE_MODULE 2 +#define PERF_RECORD_MISC_KSYMBOL_TYPE_FTRACE_TRAMPOLINE 3 Thanks again, Song