From 5dbd04eddb2c0841d1b3930e0a9944a2343c9cac Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 12 Sep 2023 18:07:02 +0000 Subject: tracing/user_events: Allow events to persist for perfmon_capable users There are several scenarios that have come up where having a user_event persist even if the process that registered it exits. The main one is having a daemon create events on bootup that shouldn't get deleted if the daemon has to exit or reload. Another is within OpenTelemetry exporters, they wish to potentially check if a user_event exists on the system to determine if exporting the data out should occur. The user_event in this case must exist even in the absence of the owning process running (such as the above daemon case). Expose the previously internal flag USER_EVENT_REG_PERSIST to user processes. Upon register or delete of events with this flag, ensure the user is perfmon_capable to prevent random user processes with access to tracefs from creating events that persist after exit. Link: https://lkml.kernel.org/r/20230912180704.1284-2-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/user_events.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include/uapi') diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h index 2984aae4a2b4..f74f3aedd49c 100644 --- a/include/uapi/linux/user_events.h +++ b/include/uapi/linux/user_events.h @@ -17,6 +17,15 @@ /* Create dynamic location entry within a 32-bit value */ #define DYN_LOC(offset, size) ((size) << 16 | (offset)) +/* List of supported registration flags */ +enum user_reg_flag { + /* Event will not delete upon last reference closing */ + USER_EVENT_REG_PERSIST = 1U << 0, + + /* This value or above is currently non-ABI */ + USER_EVENT_REG_MAX = 1U << 1, +}; + /* * Describes an event registration and stores the results of the registration. * This structure is passed to the DIAG_IOCSREG ioctl, callers at a minimum @@ -33,7 +42,7 @@ struct user_reg { /* Input: Enable size in bytes at address */ __u8 enable_size; - /* Input: Flags for future use, set to 0 */ + /* Input: Flags to use, if any */ __u16 flags; /* Input: Address to update when enabled */ -- cgit