Merge tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Addition of faultable tracepoints

   There's a tracepoint attached to both a system call entry and exit.
   This location is known to allow page faults. The tracepoints are
   called under an rcu_read_lock() which does not allow faults that can
   sleep. This limits the ability of tracepoint handlers to page fault
   in user space system call parameters. Now these tracepoints have been
   made "faultable", allowing the callbacks to fault in user space
   parameters and record them.

   Note, only the infrastructure has been implemented. The consumers
   (perf, ftrace, BPF) now need to have their code modified to allow
   faults.

 - Fix up of BPF code for the tracepoint faultable logic

 - Update tracepoints to use the new static branch API

 - Remove trace_*_rcuidle() variants and the SRCU protection they used

 - Remove unused TRACE_EVENT_FL_FILTERED logic

 - Replace strncpy() with strscpy() and memcpy()

 - Use replace per_cpu_ptr(smp_processor_id()) with this_cpu_ptr()

 - Fix perf events to not duplicate samples when tracing is enabled

 - Replace atomic64_add_return(1, counter) with
   atomic64_inc_return(counter)

 - Make stack trace buffer 4K instead of PAGE_SIZE

 - Remove TRACE_FLAG_IRQS_NOSUPPORT flag as it was never used

 - Get the true return address for function tracer when function graph
   tracer is also running.

   When function_graph trace is running along with function tracer, the
   parent function of the function tracer sometimes is
   "return_to_handler", which is the function graph trampoline to record
   the exit of the function. Use existing logic that calls into the
   fgraph infrastructure to find the real return address.

 - Remove (un)regfunc pointers out of tracepoint structure

 - Added last minute bug fix for setting pending modules in stack
   function filter.

     echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter

   Would cause a kernel NULL dereference.

 - Minor clean ups

* tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
  ftrace: Fix regression with module command in stack_trace_filter
  tracing: Fix function name for trampoline
  ftrace: Get the true parent ip for function tracer
  tracing: Remove redundant check on field->field in histograms
  bpf: ensure RCU Tasks Trace GP for sleepable raw tracepoint BPF links
  bpf: decouple BPF link/attach hook and BPF program sleepable semantics
  bpf: put bpf_link's program when link is safe to be deallocated
  tracing: Replace strncpy() with strscpy() when copying comm
  tracing: Add might_fault() check in __DECLARE_TRACE_SYSCALL
  tracing: Fix syscall tracepoint use-after-free
  tracing: Introduce tracepoint_is_faultable()
  tracing: Introduce tracepoint extended structure
  tracing: Remove TRACE_FLAG_IRQS_NOSUPPORT
  tracing: Replace multiple deprecated strncpy with memcpy
  tracing: Make percpu stack trace buffer invariant to PAGE_SIZE
  tracing: Use atomic64_inc_return() in trace_clock_counter()
  trace/trace_event_perf: remove duplicate samples on the first tracepoint event
  tracing/bpf: Add might_fault check to syscall probes
  tracing/perf: Add might_fault check to syscall probes
  tracing/ftrace: Add might_fault check to syscall probes
  ...

Author: torvalds

Documentation/trace/ftrace.rst

@@ -1031,9 +1031,6 @@ explains which is which.
   CPU#: The CPU which the process was running on.
 
   irqs-off: 'd' interrupts are disabled. '.' otherwise.
-	.. caution:: If the architecture does not support a way to
-		read the irq flags variable, an 'X' will always
-		be printed here.
 
   need-resched:
 	- 'N' both TIF_NEED_RESCHED and PREEMPT_NEED_RESCHED is set,

include/linux/bpf.h

@@ -1645,6 +1645,11 @@ struct bpf_link {
 	enum bpf_link_type type;
 	const struct bpf_link_ops *ops;
 	struct bpf_prog *prog;
+	/* whether BPF link itself has "sleepable" semantics, which can differ
+	 * from underlying BPF program having a "sleepable" semantics, as BPF
+	 * link's semantics is determined by target attach hook
+	 */
+	bool sleepable;
 	/* rcu is used before freeing, work can be used to schedule that
 	 * RCU-based freeing before that, so they never overlap
 	 */
@@ -1661,8 +1666,10 @@ struct bpf_link_ops {
 	 */
 	void (*dealloc)(struct bpf_link *link);
 	/* deallocate link resources callback, called after RCU grace period;
-	 * if underlying BPF program is sleepable we go through tasks trace
-	 * RCU GP and then "classic" RCU GP
+	 * if either the underlying BPF program is sleepable or BPF link's
+	 * target hook is sleepable, we'll go through tasks trace RCU GP and
+	 * then "classic" RCU GP; this need for chaining tasks trace and
+	 * classic RCU GPs is designated by setting bpf_link->sleepable flag
 	 */
 	void (*dealloc_deferred)(struct bpf_link *link);
 	int (*detach)(struct bpf_link *link);
@@ -2409,6 +2416,9 @@ int bpf_prog_new_fd(struct bpf_prog *prog);
 
 void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
 		   const struct bpf_link_ops *ops, struct bpf_prog *prog);
+void bpf_link_init_sleepable(struct bpf_link *link, enum bpf_link_type type,
+			     const struct bpf_link_ops *ops, struct bpf_prog *prog,
+			     bool sleepable);
 int bpf_link_prime(struct bpf_link *link, struct bpf_link_primer *primer);
 int bpf_link_settle(struct bpf_link_primer *primer);
 void bpf_link_cleanup(struct bpf_link_primer *primer);
@@ -2764,6 +2774,12 @@ static inline void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
 {
 }
 
+static inline void bpf_link_init_sleepable(struct bpf_link *link, enum bpf_link_type type,
+					   const struct bpf_link_ops *ops, struct bpf_prog *prog,
+					   bool sleepable)
+{
+}
+
 static inline int bpf_link_prime(struct bpf_link *link,
 				 struct bpf_link_primer *primer)
 {

include/linux/trace_events.h

@@ -184,7 +184,6 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status);
 
 enum trace_flag_type {
 	TRACE_FLAG_IRQS_OFF		= 0x01,
-	TRACE_FLAG_IRQS_NOSUPPORT	= 0x02,
 	TRACE_FLAG_NEED_RESCHED		= 0x04,
 	TRACE_FLAG_HARDIRQ		= 0x08,
 	TRACE_FLAG_SOFTIRQ		= 0x10,
@@ -193,7 +192,6 @@ enum trace_flag_type {
 	TRACE_FLAG_BH_OFF		= 0x80,
 };
 
-#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
 static inline unsigned int tracing_gen_ctx_flags(unsigned long irqflags)
 {
 	unsigned int irq_status = irqs_disabled_flags(irqflags) ?
@@ -207,17 +205,6 @@ static inline unsigned int tracing_gen_ctx(void)
 	local_save_flags(irqflags);
 	return tracing_gen_ctx_flags(irqflags);
 }
-#else
-
-static inline unsigned int tracing_gen_ctx_flags(unsigned long irqflags)
-{
-	return tracing_gen_ctx_irq_test(TRACE_FLAG_IRQS_NOSUPPORT);
-}
-static inline unsigned int tracing_gen_ctx(void)
-{
-	return tracing_gen_ctx_irq_test(TRACE_FLAG_IRQS_NOSUPPORT);
-}
-#endif
 
 static inline unsigned int tracing_gen_ctx_dec(void)
 {
@@ -326,7 +313,6 @@ void *trace_event_buffer_reserve(struct trace_event_buffer *fbuffer,
 void trace_event_buffer_commit(struct trace_event_buffer *fbuffer);
 
 enum {
-	TRACE_EVENT_FL_FILTERED_BIT,
 	TRACE_EVENT_FL_CAP_ANY_BIT,
 	TRACE_EVENT_FL_NO_SET_FILTER_BIT,
 	TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
@@ -341,7 +327,6 @@ enum {
 
 /*
  * Event flags:
- *  FILTERED	  - The event has a filter attached
  *  CAP_ANY	  - Any user can enable for perf
  *  NO_SET_FILTER - Set when filter has error and is to be ignored
  *  IGNORE_ENABLE - For trace internal events, do not enable with debugfs file
@@ -356,7 +341,6 @@ enum {
  *                   to a tracepoint yet, then it is cleared when it is.
  */
 enum {
-	TRACE_EVENT_FL_FILTERED		= (1 << TRACE_EVENT_FL_FILTERED_BIT),
 	TRACE_EVENT_FL_CAP_ANY		= (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
 	TRACE_EVENT_FL_NO_SET_FILTER	= (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
 	TRACE_EVENT_FL_IGNORE_ENABLE	= (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
@@ -381,7 +365,6 @@ struct trace_event_call {
 	};
 	struct trace_event	event;
 	char			*print_fmt;
-	struct event_filter	*filter;
 	/*
 	 * Static events can disappear with modules,
 	 * where as dynamic ones need their own ref count.

include/linux/tracepoint-defs.h

@@ -29,16 +29,22 @@ struct tracepoint_func {
 	int prio;
 };
 
+struct tracepoint_ext {
+	int (*regfunc)(void);
+	void (*unregfunc)(void);
+	/* Flags. */
+	unsigned int faultable:1;
+};
+
 struct tracepoint {
 	const char *name;		/* Tracepoint name */
-	struct static_key key;
+	struct static_key_false key;
 	struct static_call_key *static_call_key;
 	void *static_call_tramp;
 	void *iterator;
 	void *probestub;
-	int (*regfunc)(void);
-	void (*unregfunc)(void);
 	struct tracepoint_func __rcu *funcs;
+	struct tracepoint_ext *ext;
 };
 
 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
@@ -83,7 +89,7 @@ struct bpf_raw_event_map {
 
 #ifdef CONFIG_TRACEPOINTS
 # define tracepoint_enabled(tp) \
-	static_key_false(&(__tracepoint_##tp).key)
+	static_branch_unlikely(&(__tracepoint_##tp).key)
 #else
 # define tracepoint_enabled(tracepoint) false
 #endif