From e5a26a4048eeb9558e5c84f340a989c78db4adf4 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 28 Mar 2023 16:52:08 -0700 Subject: tracing/user_events: Split header into uapi and kernel The UAPI parts need to be split out from the kernel parts of user_events now that other parts of the kernel will reference it. Do so by moving the existing include/linux/user_events.h into include/uapi/linux/user_events.h. Link: https://lkml.kernel.org/r/20230328235219.203-2-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/user_events.h | 48 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 include/uapi/linux/user_events.h (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h new file mode 100644 index 000000000000..03f92366068d --- /dev/null +++ b/include/uapi/linux/user_events.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Copyright (c) 2021-2022, Microsoft Corporation. + * + * Authors: + * Beau Belgrave + */ +#ifndef _UAPI_LINUX_USER_EVENTS_H +#define _UAPI_LINUX_USER_EVENTS_H + +#include +#include + +#define USER_EVENTS_SYSTEM "user_events" +#define USER_EVENTS_PREFIX "u:" + +/* Create dynamic location entry within a 32-bit value */ +#define DYN_LOC(offset, size) ((size) << 16 | (offset)) + +/* + * Describes an event registration and stores the results of the registration. + * This structure is passed to the DIAG_IOCSREG ioctl, callers at a minimum + * must set the size and name_args before invocation. + */ +struct user_reg { + + /* Input: Size of the user_reg structure being used */ + __u32 size; + + /* Input: Pointer to string with event name, description and flags */ + __u64 name_args; + + /* Output: Bitwise index of the event within the status page */ + __u32 status_bit; + + /* Output: Index of the event to use when writing data */ + __u32 write_index; +} __attribute__((__packed__)); + +#define DIAG_IOC_MAGIC '*' + +/* Request to register a user_event */ +#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg *) + +/* Request to delete a user_event */ +#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char *) + +#endif /* _UAPI_LINUX_USER_EVENTS_H */ -- cgit v1.2.3 From 7235759084a4f8524a46bd2638885ff3b34ce279 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 28 Mar 2023 16:52:10 -0700 Subject: tracing/user_events: Use remote writes for event enablement As part of the discussions for user_events aligned with user space tracers, it was determined that user programs should register a aligned value to set or clear a bit when an event becomes enabled. Currently a shared page is being used that requires mmap(). Remove the shared page implementation and move to a user registered address implementation. In this new model during the event registration from user programs 3 new values are specified. The first is the address to update when the event is either enabled or disabled. The second is the bit to set/clear to reflect the event being enabled. The third is the size of the value at the specified address. This allows for a local 32/64-bit value in user programs to support both kernel and user tracers. As an example, setting bit 31 for kernel tracers when the event becomes enabled allows for user tracers to use the other bits for ref counts or other flags. The kernel side updates the bit atomically, user programs need to also update these values atomically. User provided addresses must be aligned on a natural boundary, this allows for single page checking and prevents odd behaviors such as a enable value straddling 2 pages instead of a single page. Currently page faults are only logged, future patches will handle these. Link: https://lkml.kernel.org/r/20230328235219.203-4-beaub@linux.microsoft.com Suggested-by: Mathieu Desnoyers Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/user_events.h | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h index 03f92366068d..22521bc622db 100644 --- a/include/uapi/linux/user_events.h +++ b/include/uapi/linux/user_events.h @@ -27,12 +27,21 @@ struct user_reg { /* Input: Size of the user_reg structure being used */ __u32 size; + /* Input: Bit in enable address to use */ + __u8 enable_bit; + + /* Input: Enable size in bytes at address */ + __u8 enable_size; + + /* Input: Flags for future use, set to 0 */ + __u16 flags; + + /* Input: Address to update when enabled */ + __u64 enable_addr; + /* Input: Pointer to string with event name, description and flags */ __u64 name_args; - /* Output: Bitwise index of the event within the status page */ - __u32 status_bit; - /* Output: Index of the event to use when writing data */ __u32 write_index; } __attribute__((__packed__)); -- cgit v1.2.3 From dcb8177c13953872c9e5ce4a99b63a87a3c2f683 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 28 Mar 2023 16:52:12 -0700 Subject: tracing/user_events: Add ioctl for disabling addresses Enablements are now tracked by the lifetime of the task/mm. User processes need to be able to disable their addresses if tracing is requested to be turned off. Before unmapping the page would suffice. However, we now need a stronger contract. Add an ioctl to enable this. A new flag bit is added, freeing, to user_event_enabler to ensure that if the event is attempted to be removed while a fault is being handled that the remove is delayed until after the fault is reattempted. Link: https://lkml.kernel.org/r/20230328235219.203-6-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/user_events.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h index 22521bc622db..3e7275e3234a 100644 --- a/include/uapi/linux/user_events.h +++ b/include/uapi/linux/user_events.h @@ -46,6 +46,27 @@ struct user_reg { __u32 write_index; } __attribute__((__packed__)); +/* + * Describes an event unregister, callers must set the size, address and bit. + * This structure is passed to the DIAG_IOCSUNREG ioctl to disable bit updates. + */ +struct user_unreg { + /* Input: Size of the user_unreg structure being used */ + __u32 size; + + /* Input: Bit to unregister */ + __u8 disable_bit; + + /* Input: Reserved, set to 0 */ + __u8 __reserved; + + /* Input: Reserved, set to 0 */ + __u16 __reserved2; + + /* Input: Address to unregister */ + __u64 disable_addr; +} __attribute__((__packed__)); + #define DIAG_IOC_MAGIC '*' /* Request to register a user_event */ @@ -54,4 +75,7 @@ struct user_reg { /* Request to delete a user_event */ #define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char *) +/* Requests to unregister a user_event */ +#define DIAG_IOCSUNREG _IOW(DIAG_IOC_MAGIC, 2, struct user_unreg*) + #endif /* _UAPI_LINUX_USER_EVENTS_H */ -- cgit v1.2.3 From a4c40c1349e32f9510707ed09e0961626980d8cb Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 28 Mar 2023 16:52:19 -0700 Subject: tracing/user_events: Align structs with tabs for readability Add tabs to make struct members easier to read and unify the style of the code. Link: https://lkml.kernel.org/r/20230328235219.203-13-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/user_events.h | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h index 3e7275e3234a..2984aae4a2b4 100644 --- a/include/uapi/linux/user_events.h +++ b/include/uapi/linux/user_events.h @@ -25,25 +25,25 @@ struct user_reg { /* Input: Size of the user_reg structure being used */ - __u32 size; + __u32 size; /* Input: Bit in enable address to use */ - __u8 enable_bit; + __u8 enable_bit; /* Input: Enable size in bytes at address */ - __u8 enable_size; + __u8 enable_size; /* Input: Flags for future use, set to 0 */ - __u16 flags; + __u16 flags; /* Input: Address to update when enabled */ - __u64 enable_addr; + __u64 enable_addr; /* Input: Pointer to string with event name, description and flags */ - __u64 name_args; + __u64 name_args; /* Output: Index of the event to use when writing data */ - __u32 write_index; + __u32 write_index; } __attribute__((__packed__)); /* @@ -52,19 +52,19 @@ struct user_reg { */ struct user_unreg { /* Input: Size of the user_unreg structure being used */ - __u32 size; + __u32 size; /* Input: Bit to unregister */ - __u8 disable_bit; + __u8 disable_bit; /* Input: Reserved, set to 0 */ - __u8 __reserved; + __u8 __reserved; /* Input: Reserved, set to 0 */ - __u16 __reserved2; + __u16 __reserved2; /* Input: Address to unregister */ - __u64 disable_addr; + __u64 disable_addr; } __attribute__((__packed__)); #define DIAG_IOC_MAGIC '*' -- cgit v1.2.3