tracing: probeevent: Introduce new argument fetching code

Replace {k,u}probe event argument fetching framework with switch-case based.
Currently that is implemented with structures, macros and chain of
function-pointers, which is more complicated than necessary and may get a
performance penalty by retpoline.

This simplify that with an array of "fetch_insn" (opcode and oprands), and
make process_fetch_insn() just interprets it. No function pointers are used.

Link: http://lkml.kernel.org/r/152465868340.26224.2551120475197839464.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 43 insertions, 187 deletions

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index a1df7763b797..42c724a7ad11 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -79,25 +79,50 @@ static nokprobe_inline void *get_loc_data(u32 *dl, void *ent)
 	return (u8 *)ent + get_rloc_offs(*dl);
 }
 
-/* Data fetch function type */
-typedef	void (*fetch_func_t)(struct pt_regs *, void *, void *);
 /* Printing function type */
 typedef int (*print_type_func_t)(struct trace_seq *, void *, void *);
 
-/* Fetch types */
-enum {
-	FETCH_MTD_reg = 0,
-	FETCH_MTD_stack,
-	FETCH_MTD_retval,
-	FETCH_MTD_comm,
-	FETCH_MTD_memory,
-	FETCH_MTD_symbol,
-	FETCH_MTD_deref,
-	FETCH_MTD_bitfield,
-	FETCH_MTD_file_offset,
-	FETCH_MTD_END,
+enum fetch_op {
+	FETCH_OP_NOP = 0,
+	// Stage 1 (load) ops
+	FETCH_OP_REG,		/* Register : .param = offset */
+	FETCH_OP_STACK,		/* Stack : .param = index */
+	FETCH_OP_STACKP,	/* Stack pointer */
+	FETCH_OP_RETVAL,	/* Return value */
+	FETCH_OP_IMM,		/* Immediate : .immediate */
+	FETCH_OP_COMM,		/* Current comm */
+	FETCH_OP_FOFFS,		/* File offset: .immediate */
+	// Stage 2 (dereference) op
+	FETCH_OP_DEREF,		/* Dereference: .offset */
+	// Stage 3 (store) ops
+	FETCH_OP_ST_RAW,	/* Raw: .size */
+	FETCH_OP_ST_MEM,	/* Mem: .offset, .size */
+	FETCH_OP_ST_STRING,	/* String: .offset, .size */
+	// Stage 4 (modify) op
+	FETCH_OP_MOD_BF,	/* Bitfield: .basesize, .lshift, .rshift */
+	FETCH_OP_END,
 };
 
+struct fetch_insn {
+	enum fetch_op op;
+	union {
+		unsigned int param;
+		struct {
+			unsigned int size;
+			int offset;
+		};
+		struct {
+			unsigned char basesize;
+			unsigned char lshift;
+			unsigned char rshift;
+		};
+		unsigned long immediate;
+	};
+};
+
+/* fetch + deref*N + store + mod + end <= 16, this allows N=12, enough */
+#define FETCH_INSN_MAX	16
+
 /* Fetch type information table */
 struct fetch_type {
 	const char		*name;		/* Name of type */
@@ -106,13 +131,6 @@ struct fetch_type {
 	print_type_func_t	print;		/* Print functions */
 	const char		*fmt;		/* Fromat string */
 	const char		*fmttype;	/* Name in format file */
-	/* Fetch functions */
-	fetch_func_t		fetch[FETCH_MTD_END];
-};
-
-struct fetch_param {
-	fetch_func_t		fn;
-	void 			*data;
 };
 
 /* For defining macros, define string/string_size types */
@@ -142,66 +160,12 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
 
 DECLARE_BASIC_PRINT_TYPE_FUNC(string);
 
-#define FETCH_FUNC_NAME(method, type)	fetch_##method##_##type
-
-/* Declare macro for basic types */
-#define DECLARE_FETCH_FUNC(method, type)				\
-extern void FETCH_FUNC_NAME(method, type)(struct pt_regs *regs, 	\
-					  void *data, void *dest)
-
-#define DECLARE_BASIC_FETCH_FUNCS(method) 	\
-DECLARE_FETCH_FUNC(method, u8);			\
-DECLARE_FETCH_FUNC(method, u16);		\
-DECLARE_FETCH_FUNC(method, u32);		\
-DECLARE_FETCH_FUNC(method, u64)
-
-DECLARE_BASIC_FETCH_FUNCS(reg);
-#define fetch_reg_string			NULL
-#define fetch_reg_string_size			NULL
-
-DECLARE_BASIC_FETCH_FUNCS(retval);
-#define fetch_retval_string			NULL
-#define fetch_retval_string_size		NULL
-
-DECLARE_BASIC_FETCH_FUNCS(symbol);
-DECLARE_FETCH_FUNC(symbol, string);
-DECLARE_FETCH_FUNC(symbol, string_size);
-
-DECLARE_BASIC_FETCH_FUNCS(deref);
-DECLARE_FETCH_FUNC(deref, string);
-DECLARE_FETCH_FUNC(deref, string_size);
-
-DECLARE_BASIC_FETCH_FUNCS(bitfield);
-#define fetch_bitfield_string			NULL
-#define fetch_bitfield_string_size		NULL
-
-/* comm only makes sense as a string */
-#define fetch_comm_u8		NULL
-#define fetch_comm_u16		NULL
-#define fetch_comm_u32		NULL
-#define fetch_comm_u64		NULL
-DECLARE_FETCH_FUNC(comm, string);
-DECLARE_FETCH_FUNC(comm, string_size);
-
-/*
- * Define macro for basic types - we don't need to define s* types, because
- * we have to care only about bitwidth at recording time.
- */
-#define DEFINE_BASIC_FETCH_FUNCS(method) \
-DEFINE_FETCH_##method(u8)		\
-DEFINE_FETCH_##method(u16)		\
-DEFINE_FETCH_##method(u32)		\
-DEFINE_FETCH_##method(u64)
-
 /* Default (unsigned long) fetch type */
 #define __DEFAULT_FETCH_TYPE(t) x##t
 #define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
 #define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
 #define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
 
-#define ASSIGN_FETCH_FUNC(method, type)	\
-	[FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)
-
 #define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)	\
 	{.name = _name,				\
 	 .size = _size,					\
@@ -209,17 +173,6 @@ DEFINE_FETCH_##method(u64)
 	 .print = PRINT_TYPE_FUNC_NAME(ptype),		\
 	 .fmt = PRINT_TYPE_FMT_NAME(ptype),		\
 	 .fmttype = _fmttype,				\
-	 .fetch = {					\
-ASSIGN_FETCH_FUNC(reg, ftype),				\
-ASSIGN_FETCH_FUNC(stack, ftype),			\
-ASSIGN_FETCH_FUNC(retval, ftype),			\
-ASSIGN_FETCH_FUNC(comm, ftype),				\
-ASSIGN_FETCH_FUNC(memory, ftype),			\
-ASSIGN_FETCH_FUNC(symbol, ftype),			\
-ASSIGN_FETCH_FUNC(deref, ftype),			\
-ASSIGN_FETCH_FUNC(bitfield, ftype),			\
-ASSIGN_FETCH_FUNC(file_offset, ftype),			\
-	  }						\
 	}
 
 #define ASSIGN_FETCH_TYPE(ptype, ftype, sign)			\
@@ -231,42 +184,13 @@ ASSIGN_FETCH_FUNC(file_offset, ftype),			\
 
 #define ASSIGN_FETCH_TYPE_END {}
 
-#define FETCH_TYPE_STRING	0
-#define FETCH_TYPE_STRSIZE	1
+#define FETCH_TYPE_STRING      0
+#define FETCH_TYPE_STRSIZE     1
 
 #ifdef CONFIG_KPROBE_EVENTS
-struct symbol_cache;
-unsigned long update_symbol_cache(struct symbol_cache *sc);
-void free_symbol_cache(struct symbol_cache *sc);
-struct symbol_cache *alloc_symbol_cache(const char *sym, long offset);
 bool trace_kprobe_on_func_entry(struct trace_event_call *call);
 bool trace_kprobe_error_injectable(struct trace_event_call *call);
 #else
-/* uprobes do not support symbol fetch methods */
-#define fetch_symbol_u8			NULL
-#define fetch_symbol_u16		NULL
-#define fetch_symbol_u32		NULL
-#define fetch_symbol_u64		NULL
-#define fetch_symbol_string		NULL
-#define fetch_symbol_string_size	NULL
-
-struct symbol_cache {
-};
-static inline unsigned long __used update_symbol_cache(struct symbol_cache *sc)
-{
-	return 0;
-}
-
-static inline void __used free_symbol_cache(struct symbol_cache *sc)
-{
-}
-
-static inline struct symbol_cache * __used
-alloc_symbol_cache(const char *sym, long offset)
-{
-	return NULL;
-}
-
 static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
 {
 	return false;
@@ -279,8 +203,8 @@ static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
 #endif /* CONFIG_KPROBE_EVENTS */
 
 struct probe_arg {
-	struct fetch_param	fetch;
-	struct fetch_param	fetch_size;
+	struct fetch_insn	*code;
+	bool			dynamic;/* Dynamic array (string) is used */
 	unsigned int		offset;	/* Offset from argument entry */
 	const char		*name;	/* Name of this argument */
 	const char		*comm;	/* Command of this argument */
@@ -312,12 +236,6 @@ static inline bool trace_probe_is_registered(struct trace_probe *tp)
 	return !!(tp->flags & TP_FLAG_REGISTERED);
 }
 
-static nokprobe_inline void call_fetch(struct fetch_param *fprm,
-				 struct pt_regs *regs, void *dest)
-{
-	return fprm->fn(regs, fprm->data, dest);
-}
-
 /* Check the name is good for event/group/fields */
 static inline bool is_good_name(const char *name)
 {
@@ -354,68 +272,6 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
 
 extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
 
-/* Sum up total data length for dynamic arraies (strings) */
-static nokprobe_inline int
-__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
-{
-	int i, ret = 0;
-	u32 len;
-
-	for (i = 0; i < tp->nr_args; i++)
-		if (unlikely(tp->args[i].fetch_size.fn)) {
-			call_fetch(&tp->args[i].fetch_size, regs, &len);
-			ret += len;
-		}
-
-	return ret;
-}
-
-/* Store the value of each argument */
-static nokprobe_inline void
-store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
-		 u8 *data, int maxlen)
-{
-	int i;
-	u32 end = tp->size;
-	u32 *dl;	/* Data (relative) location */
-
-	for (i = 0; i < tp->nr_args; i++) {
-		if (unlikely(tp->args[i].fetch_size.fn)) {
-			/*
-			 * First, we set the relative location and
-			 * maximum data length to *dl
-			 */
-			dl = (u32 *)(data + tp->args[i].offset);
-			*dl = make_data_rloc(maxlen, end - tp->args[i].offset);
-			/* Then try to fetch string or dynamic array data */
-			call_fetch(&tp->args[i].fetch, regs, dl);
-			/* Reduce maximum length */
-			end += get_rloc_len(*dl);
-			maxlen -= get_rloc_len(*dl);
-			/* Trick here, convert data_rloc to data_loc */
-			*dl = convert_rloc_to_loc(*dl,
-				 ent_size + tp->args[i].offset);
-		} else
-			/* Just fetching data normally */
-			call_fetch(&tp->args[i].fetch, regs,
-				   data + tp->args[i].offset);
-	}
-}
-
-static inline int
-print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
-		 u8 *data, void *field)
-{
-	int i;
-
-	for (i = 0; i < nr_args; i++) {
-		trace_seq_printf(s, " %s=", args[i].name);
-		if (!args[i].type->print(s, data + args[i].offset, field))
-			return -ENOMEM;
-	}
-	return 0;
-}
-
 extern int set_print_fmt(struct trace_probe *tp, bool is_return);
 
 #ifdef CONFIG_PERF_EVENTS