From 18bfee3216fa6f28d55ebf88d824a539d2bec3c7 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 30 Mar 2022 09:00:19 +0200 Subject: ftrace: Make ftrace_graph_is_dead() a static branch ftrace_graph_is_dead() is used on hot paths, it just reads a variable in memory and is not worth suffering function call constraints. For instance, at entry of prepare_ftrace_return(), inlining it avoids saving prepare_ftrace_return() parameters to stack and restoring them after calling ftrace_graph_is_dead(). While at it using a static branch is even more performant and is rather well adapted considering that the returned value will almost never change. Inline ftrace_graph_is_dead() and replace 'kill_ftrace_graph' bool by a static branch. The performance improvement is noticeable. Link: https://lkml.kernel.org/r/e0411a6a0ed3eafff0ad2bc9cd4b0e202b4617df.1648623570.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Signed-off-by: Steven Rostedt (Google) --- include/linux/ftrace.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 37b619185ec9..f15a4b76cbfc 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -9,6 +9,7 @@ #include #include +#include #include #include #include @@ -1015,7 +1016,20 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, extern int register_ftrace_graph(struct fgraph_ops *ops); extern void unregister_ftrace_graph(struct fgraph_ops *ops); -extern bool ftrace_graph_is_dead(void); +/** + * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called + * + * ftrace_graph_stop() is called when a severe error is detected in + * the function graph tracing. This function is called by the critical + * paths of function graph to keep those paths from doing any more harm. + */ +DECLARE_STATIC_KEY_FALSE(kill_ftrace_graph); + +static inline bool ftrace_graph_is_dead(void) +{ + return static_branch_unlikely(&kill_ftrace_graph); +} + extern void ftrace_graph_stop(void); /* The current handlers in use */ -- cgit From 5cfff569cab8bf544bab62c911c5d6efd5af5e05 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Fri, 1 Apr 2022 14:39:03 -0400 Subject: tracing: Move user_events.h temporarily out of include/uapi While user_events API is under development and has been marked for broken to not let the API become fixed, move the header file out of the uapi directory. This is to prevent it from being installed, then later changed, and then have an old distro user space update with a new kernel, where applications see the user_events being available, but the old header is in place, and then they get compiled incorrectly. Also, surround the include with CONFIG_COMPILE_TEST to the current location, but when the BROKEN tag is taken off, it will use the uapi directory, and fail to compile. This is a good way to remind us to move the header back. Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com Link: https://lkml.kernel.org/r/20220401143903.188384f3@gandalf.local.home Suggested-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google) --- include/linux/user_events.h | 63 ++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/user_events.h | 63 ---------------------------------------- kernel/trace/trace_events_user.c | 5 ++++ 3 files changed, 68 insertions(+), 63 deletions(-) create mode 100644 include/linux/user_events.h delete mode 100644 include/uapi/linux/user_events.h (limited to 'include/linux') diff --git a/include/linux/user_events.h b/include/linux/user_events.h new file mode 100644 index 000000000000..736e05603463 --- /dev/null +++ b/include/linux/user_events.h @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Copyright (c) 2021, Microsoft Corporation. + * + * Authors: + * Beau Belgrave + */ +#ifndef _UAPI_LINUX_USER_EVENTS_H +#define _UAPI_LINUX_USER_EVENTS_H + +#include +#include + +#ifdef __KERNEL__ +#include +#else +#include +#endif + +#define USER_EVENTS_SYSTEM "user_events" +#define USER_EVENTS_PREFIX "u:" + +/* Bits 0-6 are for known probe types, Bit 7 is for unknown probes */ +#define EVENT_BIT_FTRACE 0 +#define EVENT_BIT_PERF 1 +#define EVENT_BIT_OTHER 7 + +#define EVENT_STATUS_FTRACE (1 << EVENT_BIT_FTRACE) +#define EVENT_STATUS_PERF (1 << EVENT_BIT_PERF) +#define EVENT_STATUS_OTHER (1 << EVENT_BIT_OTHER) + +/* 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: Byte index of the event within the status page */ + __u32 status_index; + + /* Output: Index of the event to use when writing data */ + __u32 write_index; +}; + +#define DIAG_IOC_MAGIC '*' + +/* Requests to register a user_event */ +#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg*) + +/* Requests to delete a user_event */ +#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char*) + +#endif /* _UAPI_LINUX_USER_EVENTS_H */ diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h deleted file mode 100644 index 736e05603463..000000000000 --- a/include/uapi/linux/user_events.h +++ /dev/null @@ -1,63 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ -/* - * Copyright (c) 2021, Microsoft Corporation. - * - * Authors: - * Beau Belgrave - */ -#ifndef _UAPI_LINUX_USER_EVENTS_H -#define _UAPI_LINUX_USER_EVENTS_H - -#include -#include - -#ifdef __KERNEL__ -#include -#else -#include -#endif - -#define USER_EVENTS_SYSTEM "user_events" -#define USER_EVENTS_PREFIX "u:" - -/* Bits 0-6 are for known probe types, Bit 7 is for unknown probes */ -#define EVENT_BIT_FTRACE 0 -#define EVENT_BIT_PERF 1 -#define EVENT_BIT_OTHER 7 - -#define EVENT_STATUS_FTRACE (1 << EVENT_BIT_FTRACE) -#define EVENT_STATUS_PERF (1 << EVENT_BIT_PERF) -#define EVENT_STATUS_OTHER (1 << EVENT_BIT_OTHER) - -/* 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: Byte index of the event within the status page */ - __u32 status_index; - - /* Output: Index of the event to use when writing data */ - __u32 write_index; -}; - -#define DIAG_IOC_MAGIC '*' - -/* Requests to register a user_event */ -#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg*) - -/* Requests to delete a user_event */ -#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char*) - -#endif /* _UAPI_LINUX_USER_EVENTS_H */ diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 846c27bc7aef..706e1686b5eb 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -18,7 +18,12 @@ #include #include #include +/* Reminder to move to uapi when everything works */ +#ifdef CONFIG_COMPILE_TEST +#include +#else #include +#endif #include "trace.h" #include "trace_dynevent.h" -- cgit