Merge tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "New tracing features:

   - New PERMANENT flag to ftrace_ops when attaching a callback to a
     function.

     As /proc/sys/kernel/ftrace_enabled when set to zero will disable
     all attached callbacks in ftrace, this has a detrimental impact on
     live kernel tracing, as it disables all that it patched. If a
     ftrace_ops is registered to ftrace with the PERMANENT flag set, it
     will prevent ftrace_enabled from being disabled, and if
     ftrace_enabled is already disabled, it will prevent a ftrace_ops
     with PREMANENT flag set from being registered.

   - New register_ftrace_direct().

     As eBPF would like to register its own trampolines to be called by
     the ftrace nop locations directly, without going through the ftrace
     trampoline, this function has been added. This allows for eBPF
     trampolines to live along side of ftrace, perf, kprobe and live
     patching. It also utilizes the ftrace enabled_functions file that
     keeps track of functions that have been modified in the kernel, to
     allow for security auditing.

   - Allow for kernel internal use of ftrace instances.

     Subsystems in the kernel can now create and destroy their own
     tracing instances which allows them to have their own tracing
     buffer, and be able to record events without worrying about other
     users from writing over their data.

   - New seq_buf_hex_dump() that lets users use the hex_dump() in their
     seq_buf usage.

   - Notifications now added to tracing_max_latency to allow user space
     to know when a new max latency is hit by one of the latency
     tracers.

   - Wider spread use of generic compare operations for use of bsearch
     and friends.

   - More synthetic event fields may be defined (32 up from 16)

   - Use of xarray for architectures with sparse system calls, for the
     system call trace events.

  This along with small clean ups and fixes"

* tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (51 commits)
  tracing: Enable syscall optimization for MIPS
  tracing: Use xarray for syscall trace events
  tracing: Sample module to demonstrate kernel access to Ftrace instances.
  tracing: Adding new functions for kernel access to Ftrace instances
  tracing: Fix Kconfig indentation
  ring-buffer: Fix typos in function ring_buffer_producer
  ftrace: Use BIT() macro
  ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not configured
  ftrace: Rename ftrace_graph_stub to ftrace_stub_graph
  ftrace: Add a helper function to modify_ftrace_direct() to allow arch optimization
  ftrace: Add helper find_direct_entry() to consolidate code
  ftrace: Add another check for match in register_ftrace_direct()
  ftrace: Fix accounting bug with direct->count in register_ftrace_direct()
  ftrace/selftests: Fix spelling mistake "wakeing" -> "waking"
  tracing: Increase SYNTH_FIELDS_MAX for synthetic_events
  ftrace/samples: Add a sample module that implements modify_ftrace_direct()
  ftrace: Add modify_ftrace_direct()
  tracing: Add missing "inline" in stub function of latency_fsnotify()
  tracing: Remove stray tab in TRACE_EVAL_MAP_FILE's help text
  tracing: Use seq_buf_hex_dump() to dump buffers
  ...

1 files changed, 92 insertions, 20 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9141f2263286..7247d35c3d16 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -51,6 +51,7 @@ static inline void early_trace_init(void) { }
 
 struct module;
 struct ftrace_hash;
+struct ftrace_direct_func;
 
 #if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_MODULES) && \
 	defined(CONFIG_DYNAMIC_FTRACE)
@@ -142,24 +143,30 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  * PID     - Is affected by set_ftrace_pid (allows filtering on those pids)
  * RCU     - Set when the ops can only be called when RCU is watching.
  * TRACE_ARRAY - The ops->private points to a trace_array descriptor.
+ * PERMANENT - Set when the ops is permanent and should not be affected by
+ *             ftrace_enabled.
+ * DIRECT - Used by the direct ftrace_ops helper for direct functions
+ *            (internal ftrace only, should not be used by others)
  */
 enum {
-	FTRACE_OPS_FL_ENABLED			= 1 << 0,
-	FTRACE_OPS_FL_DYNAMIC			= 1 << 1,
-	FTRACE_OPS_FL_SAVE_REGS			= 1 << 2,
-	FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED	= 1 << 3,
-	FTRACE_OPS_FL_RECURSION_SAFE		= 1 << 4,
-	FTRACE_OPS_FL_STUB			= 1 << 5,
-	FTRACE_OPS_FL_INITIALIZED		= 1 << 6,
-	FTRACE_OPS_FL_DELETED			= 1 << 7,
-	FTRACE_OPS_FL_ADDING			= 1 << 8,
-	FTRACE_OPS_FL_REMOVING			= 1 << 9,
-	FTRACE_OPS_FL_MODIFYING			= 1 << 10,
-	FTRACE_OPS_FL_ALLOC_TRAMP		= 1 << 11,
-	FTRACE_OPS_FL_IPMODIFY			= 1 << 12,
-	FTRACE_OPS_FL_PID			= 1 << 13,
-	FTRACE_OPS_FL_RCU			= 1 << 14,
-	FTRACE_OPS_FL_TRACE_ARRAY		= 1 << 15,
+	FTRACE_OPS_FL_ENABLED			= BIT(0),
+	FTRACE_OPS_FL_DYNAMIC			= BIT(1),
+	FTRACE_OPS_FL_SAVE_REGS			= BIT(2),
+	FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED	= BIT(3),
+	FTRACE_OPS_FL_RECURSION_SAFE		= BIT(4),
+	FTRACE_OPS_FL_STUB			= BIT(5),
+	FTRACE_OPS_FL_INITIALIZED		= BIT(6),
+	FTRACE_OPS_FL_DELETED			= BIT(7),
+	FTRACE_OPS_FL_ADDING			= BIT(8),
+	FTRACE_OPS_FL_REMOVING			= BIT(9),
+	FTRACE_OPS_FL_MODIFYING			= BIT(10),
+	FTRACE_OPS_FL_ALLOC_TRAMP		= BIT(11),
+	FTRACE_OPS_FL_IPMODIFY			= BIT(12),
+	FTRACE_OPS_FL_PID			= BIT(13),
+	FTRACE_OPS_FL_RCU			= BIT(14),
+	FTRACE_OPS_FL_TRACE_ARRAY		= BIT(15),
+	FTRACE_OPS_FL_PERMANENT                 = BIT(16),
+	FTRACE_OPS_FL_DIRECT			= BIT(17),
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -239,6 +246,70 @@ static inline void ftrace_free_init_mem(void) { }
 static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { }
 #endif /* CONFIG_FUNCTION_TRACER */
 
+struct ftrace_func_entry {
+	struct hlist_node hlist;
+	unsigned long ip;
+	unsigned long direct; /* for direct lookup only */
+};
+
+struct dyn_ftrace;
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+extern int ftrace_direct_func_count;
+int register_ftrace_direct(unsigned long ip, unsigned long addr);
+int unregister_ftrace_direct(unsigned long ip, unsigned long addr);
+int modify_ftrace_direct(unsigned long ip, unsigned long old_addr, unsigned long new_addr);
+struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr);
+int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
+				struct dyn_ftrace *rec,
+				unsigned long old_addr,
+				unsigned long new_addr);
+#else
+# define ftrace_direct_func_count 0
+static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
+{
+	return -ENOTSUPP;
+}
+static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
+{
+	return -ENOTSUPP;
+}
+static inline int modify_ftrace_direct(unsigned long ip,
+				       unsigned long old_addr, unsigned long new_addr)
+{
+	return -ENOTSUPP;
+}
+static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
+{
+	return NULL;
+}
+static inline int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
+					      struct dyn_ftrace *rec,
+					      unsigned long old_addr,
+					      unsigned long new_addr)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
+
+#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+/*
+ * This must be implemented by the architecture.
+ * It is the way the ftrace direct_ops helper, when called
+ * via ftrace (because there's other callbacks besides the
+ * direct call), can inform the architecture's trampoline that this
+ * routine has a direct caller, and what the caller is.
+ *
+ * For example, in x86, it returns the direct caller
+ * callback function via the regs->orig_ax parameter.
+ * Then in the ftrace trampoline, if this is set, it makes
+ * the return from the trampoline jump to the direct caller
+ * instead of going back to the function it just traced.
+ */
+static inline void arch_ftrace_set_direct_caller(struct pt_regs *regs,
+						 unsigned long addr) { }
+#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
+
 #ifdef CONFIG_STACK_TRACER
 
 extern int stack_tracer_enabled;
@@ -291,8 +362,6 @@ static inline void stack_tracer_enable(void) { }
 int ftrace_arch_code_modify_prepare(void);
 int ftrace_arch_code_modify_post_process(void);
 
-struct dyn_ftrace;
-
 enum ftrace_bug_type {
 	FTRACE_BUG_UNKNOWN,
 	FTRACE_BUG_INIT,
@@ -330,6 +399,7 @@ bool is_ftrace_trampoline(unsigned long addr);
  *  REGS_EN - the function is set up to save regs.
  *  IPMODIFY - the record allows for the IP address to be changed.
  *  DISABLED - the record is not ready to be touched yet
+ *  DIRECT   - there is a direct function to call
  *
  * When a new ftrace_ops is registered and wants a function to save
  * pt_regs, the rec->flag REGS is set. When the function has been
@@ -345,10 +415,12 @@ enum {
 	FTRACE_FL_TRAMP_EN	= (1UL << 27),
 	FTRACE_FL_IPMODIFY	= (1UL << 26),
 	FTRACE_FL_DISABLED	= (1UL << 25),
+	FTRACE_FL_DIRECT	= (1UL << 24),
+	FTRACE_FL_DIRECT_EN	= (1UL << 23),
 };
 
-#define FTRACE_REF_MAX_SHIFT	25
-#define FTRACE_FL_BITS		7
+#define FTRACE_REF_MAX_SHIFT	23
+#define FTRACE_FL_BITS		9
 #define FTRACE_FL_MASKED_BITS	((1UL << FTRACE_FL_BITS) - 1)
 #define FTRACE_FL_MASK		(FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT)
 #define FTRACE_REF_MAX		((1UL << FTRACE_REF_MAX_SHIFT) - 1)