[RFC PATCH 0/8] tracing: probeevent: Improve fetcharg features

[RFC PATCH 0/8] tracing: probeevent: Improve fetcharg features

[Masami Hiramatsu]

Hi,

This series improves probeevent variable fetcharg framework,

- Rewrite fetcharg framework with fetch_insn, switch-case based
  instead of function pointer. (maybe good for retpoline)
- Add "symbol" type support, which shows symbol+offset instead of
  address value.
- Add "$argN" fetcharg, which fetches function parameters.
  (currently only for x86-64)
- Add array type support for basic types (except for string),
  which enables to get fixed length array from probeevents.

All ideas came from Steve's function event tracer. Thanks Steve!

I'll add string (pointer) array support and testcases for these
features in the next version.

Here are examples:

o 'symbol' type

 # echo 'p vfs_read $stack0:symbol' > kprobe_events 
 # echo 1 > events/kprobes/p_vfs_read_0/enable 
 # tail -n 3 trace
              sh-729   [007] ...2   105.753637: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=SyS_read+0x42/0x90
            tail-736   [000] ...2   105.754904: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=kernel_read+0x2c/0x40
            tail-736   [000] ...2   105.754929: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=kernel_read+0x2c/0x40


o $argN 

 # echo 'p vfs_read $arg0 $arg1 $arg2' > kprobe_events
 # echo 1 > events/kprobes/p_vfs_read_0/enable 
 # tail -n 3 trace
              sh-726   [007] ...2   134.288973: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d98ec00 arg2=0x7ffeb4330f79 arg3=0x1
            tail-731   [000] ...2   134.289987: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d9dd200 arg2=0xffff88001d8a0a00 arg3=0x80
            tail-731   [000] ...2   134.290016: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d9dd200 arg2=0xffff88001faf4a00 arg3=0x150


o Array type

 # echo 'p vfs_read +0($stack):x64 +0($stack):x8[8]' > kprobe_events 
 # echo 1 > events/kprobes/p_vfs_read_0/enable 
 # tail -n 3 trace
              sh-729   [007] ...2    91.701664: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b1252 arg2={0x52,0x12,0x1b,0x81,0xff,0xff,0xff,0xff}
            tail-734   [000] ...2    91.702366: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b0dec arg2={0xec,0xd,0x1b,0x81,0xff,0xff,0xff,0xff}
            tail-734   [000] ...2    91.702386: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b0dec arg2={0xec,0xd,0x1b,0x81,0xff,0xff,0xff,0xff}
 #
 # cat events/kprobes/p_vfs_read_0/format 
name: p_vfs_read_0
ID: 1069
format:
	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
	field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
	field:int common_pid;	offset:4;	size:4;	signed:1;

	field:unsigned long __probe_ip;	offset:8;	size:8;	signed:0;
	field:u64 arg1;	offset:16;	size:0;	signed:0;
	field:u8 arg2[8];	offset:24;	size:8;	signed:0;

print fmt: "(%lx) arg1=0x%Lx arg2={0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x}", REC->__probe_ip, REC->arg1, REC->arg2[0], REC->arg2[1], REC->arg2[2], REC->arg2[3], REC->arg2[4], REC->arg2[5], REC->arg2[6], REC->arg2[7]


Thanks,

---

Masami Hiramatsu (8):
      tracing: probeevent: Cleanup print argument functions
      tracing: probeevent: Cleanup argument field definition
      tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions
      tracing: probeevent: Introduce new argument fetching code
      tracing: probeevent: Add symbol type
      x86: ptrace: Add function argument access API
      tracing: probeevent: Add $argN for accessing function args
      tracing: probeevent: Add an array for basic types


 Documentation/trace/kprobetrace.txt |   20 +
 arch/Kconfig                        |    7 
 arch/x86/Kconfig                    |    1 
 arch/x86/include/asm/ptrace.h       |   38 ++
 kernel/trace/trace_kprobe.c         |  396 +++++++++--------------
 kernel/trace/trace_probe.c          |  614 ++++++++++++++++-------------------
 kernel/trace/trace_probe.h          |  313 +++++++++---------
 kernel/trace/trace_uprobe.c         |  188 ++++++-----
 8 files changed, 771 insertions(+), 806 deletions(-)

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>

[RFC PATCH 1/8] tracing: probeevent: Cleanup print argument functions

[Masami Hiramatsu]

Current print argument functions prints the argument
name too. It is not good for printing out multiple
values for one argument. This change it to just print
out the value.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_kprobe.c |   20 ++++++--------------
 kernel/trace/trace_probe.c  |   12 +++++-------
 kernel/trace/trace_probe.h  |   19 ++++++++++++++++---
 kernel/trace/trace_uprobe.c |    9 ++-------
 4 files changed, 29 insertions(+), 31 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 492700c5fb4d..7d9df336805e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1058,8 +1058,6 @@ print_kprobe_event(struct trace_iterator *iter, int flags,
 	struct kprobe_trace_entry_head *field;
 	struct trace_seq *s = &iter->seq;
 	struct trace_probe *tp;
-	u8 *data;
-	int i;
 
 	field = (struct kprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
@@ -1071,11 +1069,9 @@ print_kprobe_event(struct trace_iterator *iter, int flags,
 
 	trace_seq_putc(s, ')');
 
-	data = (u8 *)&field[1];
-	for (i = 0; i < tp->nr_args; i++)
-		if (!tp->args[i].type->print(s, tp->args[i].name,
-					     data + tp->args[i].offset, field))
-			goto out;
+	if (print_probe_args(s, tp->args, tp->nr_args,
+			     (u8 *)&field[1], field) < 0)
+		goto out;
 
 	trace_seq_putc(s, '\n');
  out:
@@ -1089,8 +1085,6 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
 	struct kretprobe_trace_entry_head *field;
 	struct trace_seq *s = &iter->seq;
 	struct trace_probe *tp;
-	u8 *data;
-	int i;
 
 	field = (struct kretprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
@@ -1107,11 +1101,9 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
 
 	trace_seq_putc(s, ')');
 
-	data = (u8 *)&field[1];
-	for (i = 0; i < tp->nr_args; i++)
-		if (!tp->args[i].type->print(s, tp->args[i].name,
-					     data + tp->args[i].offset, field))
-			goto out;
+	if (print_probe_args(s, tp->args, tp->nr_args,
+			     (u8 *)&field[1], field) < 0)
+		goto out;
 
 	trace_seq_putc(s, '\n');
 
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index d59357308677..4a6021fd14df 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -38,10 +38,9 @@ const char *reserved_field_names[] = {
 
 /* Printing  in basic type function template */
 #define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)			\
-int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, const char *name,	\
-				void *data, void *ent)			\
+int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
 {									\
-	trace_seq_printf(s, " %s=" fmt, name, *(type *)data);		\
+	trace_seq_printf(s, fmt, *(type *)data);			\
 	return !trace_seq_has_overflowed(s);				\
 }									\
 const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;				\
@@ -61,15 +60,14 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
 
 /* Print type function for string type */
-int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
-				 void *data, void *ent)
+int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
 {
 	int len = *(u32 *)data >> 16;
 
 	if (!len)
-		trace_seq_printf(s, " %s=(fault)", name);
+		trace_seq_puts(s, "(fault)");
 	else
-		trace_seq_printf(s, " %s=\"%s\"", name,
+		trace_seq_printf(s, "\"%s\"",
 				 (const char *)get_loc_data(data, ent));
 	return !trace_seq_has_overflowed(s);
 }
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index fb66e3eaa192..cbefd29a0131 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -94,7 +94,7 @@ static nokprobe_inline void *get_loc_data(u32 *dl, void *ent)
 /* 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 *, const char *, void *, void *);
+typedef int (*print_type_func_t)(struct trace_seq *, void *, void *);
 
 /* Fetch types */
 enum {
@@ -136,8 +136,7 @@ typedef u32 string_size;
 
 /* Printing  in basic type function template */
 #define DECLARE_BASIC_PRINT_TYPE_FUNC(type)				\
-int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, const char *name,	\
-				void *data, void *ent);			\
+int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, void *data, void *ent);\
 extern const char PRINT_TYPE_FMT_NAME(type)[]
 
 DECLARE_BASIC_PRINT_TYPE_FUNC(u8);
@@ -403,4 +402,18 @@ store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
 	}
 }
 
+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);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 40592e7b3568..3d7e039d5628 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -864,7 +864,6 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
 	struct trace_seq *s = &iter->seq;
 	struct trace_uprobe *tu;
 	u8 *data;
-	int i;
 
 	entry = (struct uprobe_trace_entry_head *)iter->ent;
 	tu = container_of(event, struct trace_uprobe, tp.call.event);
@@ -881,12 +880,8 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
 		data = DATAOF_TRACE_ENTRY(entry, false);
 	}
 
-	for (i = 0; i < tu->tp.nr_args; i++) {
-		struct probe_arg *parg = &tu->tp.args[i];
-
-		if (!parg->type->print(s, parg->name, data + parg->offset, entry))
-			goto out;
-	}
+	if (print_probe_args(s, tu->tp.args, tu->tp.nr_args, data, entry) < 0)
+		goto out;
 
 	trace_seq_putc(s, '\n');
 

[RFC PATCH 2/8] tracing: probeevent: Cleanup argument field definition

[Masami Hiramatsu]

Cleanup event argument definition code in one place for
maintenancability.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_kprobe.c |   32 ++++----------------------------
 kernel/trace/trace_probe.c  |   21 +++++++++++++++++++++
 kernel/trace/trace_probe.h  |    2 ++
 kernel/trace/trace_uprobe.c |   15 ++-------------
 4 files changed, 29 insertions(+), 41 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7d9df336805e..1fe29b7f4c32 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1114,49 +1114,25 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
 
 static int kprobe_event_define_fields(struct trace_event_call *event_call)
 {
-	int ret, i;
+	int ret;
 	struct kprobe_trace_entry_head field;
 	struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
 
 	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
-	/* Set argument names as fields */
-	for (i = 0; i < tk->tp.nr_args; i++) {
-		struct probe_arg *parg = &tk->tp.args[i];
 
-		ret = trace_define_field(event_call, parg->type->fmttype,
-					 parg->name,
-					 sizeof(field) + parg->offset,
-					 parg->type->size,
-					 parg->type->is_signed,
-					 FILTER_OTHER);
-		if (ret)
-			return ret;
-	}
-	return 0;
+	return traceprobe_define_arg_fields(event_call, sizeof(field), &tk->tp);
 }
 
 static int kretprobe_event_define_fields(struct trace_event_call *event_call)
 {
-	int ret, i;
+	int ret;
 	struct kretprobe_trace_entry_head field;
 	struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
 
 	DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
 	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
-	/* Set argument names as fields */
-	for (i = 0; i < tk->tp.nr_args; i++) {
-		struct probe_arg *parg = &tk->tp.args[i];
 
-		ret = trace_define_field(event_call, parg->type->fmttype,
-					 parg->name,
-					 sizeof(field) + parg->offset,
-					 parg->type->size,
-					 parg->type->is_signed,
-					 FILTER_OTHER);
-		if (ret)
-			return ret;
-	}
-	return 0;
+	return traceprobe_define_arg_fields(event_call, sizeof(field), &tk->tp);
 }
 
 #ifdef CONFIG_PERF_EVENTS
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4a6021fd14df..157cfdfa8430 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -682,3 +682,24 @@ int set_print_fmt(struct trace_probe *tp, bool is_return)
 
 	return 0;
 }
+
+int traceprobe_define_arg_fields(struct trace_event_call *event_call,
+				 size_t offset, struct trace_probe *tp)
+{
+	int ret, i;
+
+	/* Set argument names as fields */
+	for (i = 0; i < tp->nr_args; i++) {
+		struct probe_arg *parg = &tp->args[i];
+
+		ret = trace_define_field(event_call, parg->type->fmttype,
+					 parg->name,
+					 offset + parg->offset,
+					 parg->type->size,
+					 parg->type->is_signed,
+					 FILTER_OTHER);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index cbefd29a0131..a1490e279658 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -417,3 +417,5 @@ print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
 }
 
 extern int set_print_fmt(struct trace_probe *tp, bool is_return);
+extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
+					size_t offset, struct trace_probe *tp);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 3d7e039d5628..968bd403d68c 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -982,7 +982,7 @@ probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
 
 static int uprobe_event_define_fields(struct trace_event_call *event_call)
 {
-	int ret, i, size;
+	int ret, size;
 	struct uprobe_trace_entry_head field;
 	struct trace_uprobe *tu = event_call->data;
 
@@ -994,19 +994,8 @@ static int uprobe_event_define_fields(struct trace_event_call *event_call)
 		DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
 		size = SIZEOF_TRACE_ENTRY(false);
 	}
-	/* Set argument names as fields */
-	for (i = 0; i < tu->tp.nr_args; i++) {
-		struct probe_arg *parg = &tu->tp.args[i];
-
-		ret = trace_define_field(event_call, parg->type->fmttype,
-					 parg->name, size + parg->offset,
-					 parg->type->size, parg->type->is_signed,
-					 FILTER_OTHER);
 
-		if (ret)
-			return ret;
-	}
-	return 0;
+	return traceprobe_define_arg_fields(event_call, size, &tu->tp);
 }
 
 #ifdef CONFIG_PERF_EVENTS

[RFC PATCH 3/8] tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions

[Masami Hiramatsu]

Remove unneeded NOKPROBE_SYMBOL from print functions since
the print functions are only used when printing out the
trace data, and not from kprobe handler.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_probe.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 157cfdfa8430..be98a58416a9 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -43,8 +43,7 @@ int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
 	trace_seq_printf(s, fmt, *(type *)data);			\
 	return !trace_seq_has_overflowed(s);				\
 }									\
-const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;				\
-NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(tname));
+const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;
 
 DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
@@ -71,7 +70,6 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
 				 (const char *)get_loc_data(data, ent));
 	return !trace_seq_has_overflowed(s);
 }
-NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
 
 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
 

[RFC PATCH 4/8] tracing: probeevent: Introduce new argument fetching code

[Masami Hiramatsu]

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.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_kprobe.c |  313 ++++++++++++------------------
 kernel/trace/trace_probe.c  |  446 +++++++++++++++----------------------------
 kernel/trace/trace_probe.h  |  252 +++++++++++-------------
 kernel/trace/trace_uprobe.c |  149 ++++++++------
 4 files changed, 472 insertions(+), 688 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1fe29b7f4c32..1d0554c6bb34 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -97,184 +97,6 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 				struct pt_regs *regs);
 
-/* Memory fetching by symbol */
-struct symbol_cache {
-	char		*symbol;
-	long		offset;
-	unsigned long	addr;
-};
-
-unsigned long update_symbol_cache(struct symbol_cache *sc)
-{
-	sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
-
-	if (sc->addr)
-		sc->addr += sc->offset;
-
-	return sc->addr;
-}
-
-void free_symbol_cache(struct symbol_cache *sc)
-{
-	kfree(sc->symbol);
-	kfree(sc);
-}
-
-struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
-{
-	struct symbol_cache *sc;
-
-	if (!sym || strlen(sym) == 0)
-		return NULL;
-
-	sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
-	if (!sc)
-		return NULL;
-
-	sc->symbol = kstrdup(sym, GFP_KERNEL);
-	if (!sc->symbol) {
-		kfree(sc);
-		return NULL;
-	}
-	sc->offset = offset;
-	update_symbol_cache(sc);
-
-	return sc;
-}
-
-/*
- * Kprobes-specific fetch functions
- */
-#define DEFINE_FETCH_stack(type)					\
-static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,		\
-					  void *offset, void *dest)	\
-{									\
-	*(type *)dest = (type)regs_get_kernel_stack_nth(regs,		\
-				(unsigned int)((unsigned long)offset));	\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
-
-DEFINE_BASIC_FETCH_FUNCS(stack)
-/* No string on the stack entry */
-#define fetch_stack_string	NULL
-#define fetch_stack_string_size	NULL
-
-#define DEFINE_FETCH_memory(type)					\
-static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,		\
-					  void *addr, void *dest)	\
-{									\
-	type retval;							\
-	if (probe_kernel_address(addr, retval))				\
-		*(type *)dest = 0;					\
-	else								\
-		*(type *)dest = retval;					\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
-
-DEFINE_BASIC_FETCH_FUNCS(memory)
-/*
- * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
- * length and relative data location.
- */
-static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
-					    void *addr, void *dest)
-{
-	int maxlen = get_rloc_len(*(u32 *)dest);
-	u8 *dst = get_rloc_data(dest);
-	long ret;
-
-	if (!maxlen)
-		return;
-
-	/*
-	 * Try to get string again, since the string can be changed while
-	 * probing.
-	 */
-	ret = strncpy_from_unsafe(dst, addr, maxlen);
-
-	if (ret < 0) {	/* Failed to fetch string */
-		dst[0] = '\0';
-		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
-	} else {
-		*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
-	}
-}
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
-
-/* Return the length of string -- including null terminal byte */
-static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
-						 void *addr, void *dest)
-{
-	mm_segment_t old_fs;
-	int ret, len = 0;
-	u8 c;
-
-	old_fs = get_fs();
-	set_fs(KERNEL_DS);
-	pagefault_disable();
-
-	do {
-		ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
-		len++;
-	} while (c && ret == 0 && len < MAX_STRING_SIZE);
-
-	pagefault_enable();
-	set_fs(old_fs);
-
-	if (ret < 0)	/* Failed to check the length */
-		*(u32 *)dest = 0;
-	else
-		*(u32 *)dest = len;
-}
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
-
-#define DEFINE_FETCH_symbol(type)					\
-void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
-{									\
-	struct symbol_cache *sc = data;					\
-	if (sc->addr)							\
-		fetch_memory_##type(regs, (void *)sc->addr, dest);	\
-	else								\
-		*(type *)dest = 0;					\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
-
-DEFINE_BASIC_FETCH_FUNCS(symbol)
-DEFINE_FETCH_symbol(string)
-DEFINE_FETCH_symbol(string_size)
-
-/* kprobes don't support file_offset fetch methods */
-#define fetch_file_offset_u8		NULL
-#define fetch_file_offset_u16		NULL
-#define fetch_file_offset_u32		NULL
-#define fetch_file_offset_u64		NULL
-#define fetch_file_offset_string	NULL
-#define fetch_file_offset_string_size	NULL
-
-/* Fetch type information table */
-static const struct fetch_type kprobes_fetch_type_table[] = {
-	/* Special types */
-	[FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
-					sizeof(u32), 1, "__data_loc char[]"),
-	[FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
-					string_size, sizeof(u32), 0, "u32"),
-	/* Basic types */
-	ASSIGN_FETCH_TYPE(u8,  u8,  0),
-	ASSIGN_FETCH_TYPE(u16, u16, 0),
-	ASSIGN_FETCH_TYPE(u32, u32, 0),
-	ASSIGN_FETCH_TYPE(u64, u64, 0),
-	ASSIGN_FETCH_TYPE(s8,  u8,  1),
-	ASSIGN_FETCH_TYPE(s16, u16, 1),
-	ASSIGN_FETCH_TYPE(s32, u32, 1),
-	ASSIGN_FETCH_TYPE(s64, u64, 1),
-	ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
-	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
-	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
-	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
-
-	ASSIGN_FETCH_TYPE_END
-};
-
 /*
  * Allocate new trace_probe and initialize it (including kprobes).
  */
@@ -458,14 +280,11 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 /* Internal register function - just handle k*probes and flags */
 static int __register_trace_kprobe(struct trace_kprobe *tk)
 {
-	int i, ret;
+	int ret;
 
 	if (trace_probe_is_registered(&tk->tp))
 		return -EINVAL;
 
-	for (i = 0; i < tk->tp.nr_args; i++)
-		traceprobe_update_arg(&tk->tp.args[i]);
-
 	/* Set/clear disabled flag according to tp->flag */
 	if (trace_probe_is_enabled(&tk->tp))
 		tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
@@ -798,8 +617,7 @@ static int create_trace_kprobe(int argc, char **argv)
 
 		/* Parse fetch argument */
 		ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
-						is_return, true,
-						kprobes_fetch_type_table);
+						 is_return, true);
 		if (ret) {
 			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 			goto error;
@@ -953,6 +771,133 @@ static const struct file_operations kprobe_profile_ops = {
 	.release        = seq_release,
 };
 
+/* Kprobe specific fetch functions */
+
+/* Return the length of string -- including null terminal byte */
+static nokprobe_inline void
+fetch_store_strlen(unsigned long addr, void *dest)
+{
+	mm_segment_t old_fs;
+	int ret, len = 0;
+	u8 c;
+
+	old_fs = get_fs();
+	set_fs(KERNEL_DS);
+	pagefault_disable();
+
+	do {
+		ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
+		len++;
+	} while (c && ret == 0 && len < MAX_STRING_SIZE);
+
+	pagefault_enable();
+	set_fs(old_fs);
+
+	if (ret < 0)	/* Failed to check the length */
+		*(u32 *)dest = 0;
+	else
+		*(u32 *)dest = len;
+}
+
+/*
+ * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
+ * length and relative data location.
+ */
+static nokprobe_inline void
+fetch_store_string(unsigned long addr, void *dest)
+{
+	int maxlen = get_rloc_len(*(u32 *)dest);
+	u8 *dst = get_rloc_data(dest);
+	long ret;
+
+	if (!maxlen)
+		return;
+
+	/*
+	 * Try to get string again, since the string can be changed while
+	 * probing.
+	 */
+	ret = strncpy_from_unsafe(dst, (void *)addr, maxlen);
+
+	if (ret < 0) {	/* Failed to fetch string */
+		dst[0] = '\0';
+		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
+	} else {
+		*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
+	}
+}
+
+/* Note that we don't verify it, since the code does not come from user space */
+static int
+process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
+		   bool pre)
+{
+	unsigned long val;
+	int ret;
+
+	/* 1st stage: get value from context */
+	switch (code->op) {
+	case FETCH_OP_REG:
+		val = regs_get_register(regs, code->param);
+		break;
+	case FETCH_OP_STACK:
+		val = regs_get_kernel_stack_nth(regs, code->param);
+		break;
+	case FETCH_OP_STACKP:
+		val = kernel_stack_pointer(regs);
+		break;
+	case FETCH_OP_RETVAL:
+		val = regs_return_value(regs);
+		break;
+	case FETCH_OP_IMM:
+		val = code->immediate;
+		break;
+	case FETCH_OP_COMM:
+		val = (unsigned long)current->comm;
+		break;
+	default:
+		return -EILSEQ;
+	}
+	code++;
+
+	/* 2nd stage: dereference memory if needed */
+	while (code->op == FETCH_OP_DEREF) {
+		ret = probe_kernel_read(&val, (void *)val + code->offset,
+					sizeof(val));
+		if (ret)
+			return ret;
+		code++;
+	}
+
+	/* 3rd stage: store value to buffer */
+	switch (code->op) {
+	case FETCH_OP_ST_RAW:
+		fetch_store_raw(val, code, dest);
+		break;
+	case FETCH_OP_ST_MEM:
+		probe_kernel_read(dest, (void *)val + code->offset, code->size);
+		break;
+	case FETCH_OP_ST_STRING:
+		if (pre)
+			fetch_store_strlen(val + code->offset, dest);
+		else
+			fetch_store_string(val + code->offset, dest);
+		break;
+	default:
+		return -EILSEQ;
+	}
+	code++;
+
+	/* 4th stage: modify stored value if needed */
+	if (code->op == FETCH_OP_MOD_BF) {
+		fetch_apply_bitfield(code, dest);
+		code++;
+	}
+
+	return code->op == FETCH_OP_END ? 0 : -EILSEQ;
+}
+NOKPROBE_SYMBOL(process_fetch_insn)
+
 /* Kprobe handler */
 static nokprobe_inline void
 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index be98a58416a9..52b4931864d6 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -73,176 +73,41 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
 
 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
 
-#define CHECK_FETCH_FUNCS(method, fn)			\
-	(((FETCH_FUNC_NAME(method, u8) == fn) ||	\
-	  (FETCH_FUNC_NAME(method, u16) == fn) ||	\
-	  (FETCH_FUNC_NAME(method, u32) == fn) ||	\
-	  (FETCH_FUNC_NAME(method, u64) == fn) ||	\
-	  (FETCH_FUNC_NAME(method, string) == fn) ||	\
-	  (FETCH_FUNC_NAME(method, string_size) == fn)) \
-	 && (fn != NULL))
-
-/* Data fetch function templates */
-#define DEFINE_FETCH_reg(type)						\
-void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest)	\
-{									\
-	*(type *)dest = (type)regs_get_register(regs,			\
-				(unsigned int)((unsigned long)offset));	\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
-DEFINE_BASIC_FETCH_FUNCS(reg)
-/* No string on the register */
-#define fetch_reg_string	NULL
-#define fetch_reg_string_size	NULL
-
-#define DEFINE_FETCH_retval(type)					\
-void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,		\
-				   void *dummy, void *dest)		\
-{									\
-	*(type *)dest = (type)regs_return_value(regs);			\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
-DEFINE_BASIC_FETCH_FUNCS(retval)
-/* No string on the retval */
-#define fetch_retval_string		NULL
-#define fetch_retval_string_size	NULL
-
-/* Dereference memory access function */
-struct deref_fetch_param {
-	struct fetch_param	orig;
-	long			offset;
-	fetch_func_t		fetch;
-	fetch_func_t		fetch_size;
-};
-
-#define DEFINE_FETCH_deref(type)					\
-void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,			\
-				  void *data, void *dest)		\
-{									\
-	struct deref_fetch_param *dprm = data;				\
-	unsigned long addr;						\
-	call_fetch(&dprm->orig, regs, &addr);				\
-	if (addr) {							\
-		addr += dprm->offset;					\
-		dprm->fetch(regs, (void *)addr, dest);			\
-	} else								\
-		*(type *)dest = 0;					\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
-DEFINE_BASIC_FETCH_FUNCS(deref)
-DEFINE_FETCH_deref(string)
-
-void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
-					 void *data, void *dest)
-{
-	struct deref_fetch_param *dprm = data;
-	unsigned long addr;
-
-	call_fetch(&dprm->orig, regs, &addr);
-	if (addr && dprm->fetch_size) {
-		addr += dprm->offset;
-		dprm->fetch_size(regs, (void *)addr, dest);
-	} else
-		*(string_size *)dest = 0;
-}
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
-
-static void update_deref_fetch_param(struct deref_fetch_param *data)
-{
-	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
-		update_deref_fetch_param(data->orig.data);
-	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
-		update_symbol_cache(data->orig.data);
-}
-NOKPROBE_SYMBOL(update_deref_fetch_param);
+/*
+ * Kprobes-specific fetch functions
+ */
 
-static void free_deref_fetch_param(struct deref_fetch_param *data)
+/* dummy template */
+static int
+process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs,
+		   void *dest, bool pre)
 {
-	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
-		free_deref_fetch_param(data->orig.data);
-	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
-		free_symbol_cache(data->orig.data);
-	kfree(data);
+	return 0;
 }
-NOKPROBE_SYMBOL(free_deref_fetch_param);
 
-/* Bitfield fetch function */
-struct bitfield_fetch_param {
-	struct fetch_param	orig;
-	unsigned char		hi_shift;
-	unsigned char		low_shift;
+/* Fetch type information table */
+static const struct fetch_type probe_fetch_types[] = {
+	/* Special types */
+	__ASSIGN_FETCH_TYPE("string", string, string, sizeof(u32), 1,
+			    "__data_loc char[]"),
+	/* Basic types */
+	ASSIGN_FETCH_TYPE(u8,  u8,  0),
+	ASSIGN_FETCH_TYPE(u16, u16, 0),
+	ASSIGN_FETCH_TYPE(u32, u32, 0),
+	ASSIGN_FETCH_TYPE(u64, u64, 0),
+	ASSIGN_FETCH_TYPE(s8,  u8,  1),
+	ASSIGN_FETCH_TYPE(s16, u16, 1),
+	ASSIGN_FETCH_TYPE(s32, u32, 1),
+	ASSIGN_FETCH_TYPE(s64, u64, 1),
+	ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
+	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
+	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
+	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
+
+	ASSIGN_FETCH_TYPE_END
 };
 
-#define DEFINE_FETCH_bitfield(type)					\
-void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs,		\
-				     void *data, void *dest)		\
-{									\
-	struct bitfield_fetch_param *bprm = data;			\
-	type buf = 0;							\
-	call_fetch(&bprm->orig, regs, &buf);				\
-	if (buf) {							\
-		buf <<= bprm->hi_shift;					\
-		buf >>= bprm->low_shift;				\
-	}								\
-	*(type *)dest = buf;						\
-}									\
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
-DEFINE_BASIC_FETCH_FUNCS(bitfield)
-#define fetch_bitfield_string		NULL
-#define fetch_bitfield_string_size	NULL
-
-static void
-update_bitfield_fetch_param(struct bitfield_fetch_param *data)
-{
-	/*
-	 * Don't check the bitfield itself, because this must be the
-	 * last fetch function.
-	 */
-	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
-		update_deref_fetch_param(data->orig.data);
-	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
-		update_symbol_cache(data->orig.data);
-}
-
-static void
-free_bitfield_fetch_param(struct bitfield_fetch_param *data)
-{
-	/*
-	 * Don't check the bitfield itself, because this must be the
-	 * last fetch function.
-	 */
-	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
-		free_deref_fetch_param(data->orig.data);
-	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
-		free_symbol_cache(data->orig.data);
-
-	kfree(data);
-}
-
-void FETCH_FUNC_NAME(comm, string)(struct pt_regs *regs,
-					  void *data, void *dest)
-{
-	int maxlen = get_rloc_len(*(u32 *)dest);
-	u8 *dst = get_rloc_data(dest);
-	long ret;
-
-	if (!maxlen)
-		return;
-
-	ret = strlcpy(dst, current->comm, maxlen);
-	*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
-}
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string));
-
-void FETCH_FUNC_NAME(comm, string_size)(struct pt_regs *regs,
-					       void *data, void *dest)
-{
-	*(u32 *)dest = strlen(current->comm) + 1;
-}
-NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string_size));
-
-static const struct fetch_type *find_fetch_type(const char *type,
-						const struct fetch_type *ftbl)
+static const struct fetch_type *find_fetch_type(const char *type)
 {
 	int i;
 
@@ -263,58 +128,27 @@ static const struct fetch_type *find_fetch_type(const char *type,
 
 		switch (bs) {
 		case 8:
-			return find_fetch_type("u8", ftbl);
+			return find_fetch_type("u8");
 		case 16:
-			return find_fetch_type("u16", ftbl);
+			return find_fetch_type("u16");
 		case 32:
-			return find_fetch_type("u32", ftbl);
+			return find_fetch_type("u32");
 		case 64:
-			return find_fetch_type("u64", ftbl);
+			return find_fetch_type("u64");
 		default:
 			goto fail;
 		}
 	}
 
-	for (i = 0; ftbl[i].name; i++) {
-		if (strcmp(type, ftbl[i].name) == 0)
-			return &ftbl[i];
+	for (i = 0; probe_fetch_types[i].name; i++) {
+		if (strcmp(type, probe_fetch_types[i].name) == 0)
+			return &probe_fetch_types[i];
 	}
 
 fail:
 	return NULL;
 }
 
-/* Special function : only accept unsigned long */
-static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
-{
-	*(unsigned long *)dest = kernel_stack_pointer(regs);
-}
-NOKPROBE_SYMBOL(fetch_kernel_stack_address);
-
-static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
-{
-	*(unsigned long *)dest = user_stack_pointer(regs);
-}
-NOKPROBE_SYMBOL(fetch_user_stack_address);
-
-static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
-					    fetch_func_t orig_fn,
-					    const struct fetch_type *ftbl)
-{
-	int i;
-
-	if (type != &ftbl[FETCH_TYPE_STRING])
-		return NULL;	/* Only string type needs size function */
-
-	for (i = 0; i < FETCH_MTD_END; i++)
-		if (type->fetch[i] == orig_fn)
-			return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
-
-	WARN_ON(1);	/* This should not happen */
-
-	return NULL;
-}
-
 /* Split symbol and offset. */
 int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
 {
@@ -341,7 +175,7 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 
 static int parse_probe_vars(char *arg, const struct fetch_type *t,
-			    struct fetch_param *f, bool is_return,
+			    struct fetch_insn *code, bool is_return,
 			    bool is_kprobe)
 {
 	int ret = 0;
@@ -349,33 +183,24 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 
 	if (strcmp(arg, "retval") == 0) {
 		if (is_return)
-			f->fn = t->fetch[FETCH_MTD_retval];
+			code->op = FETCH_OP_RETVAL;
 		else
 			ret = -EINVAL;
 	} else if (strncmp(arg, "stack", 5) == 0) {
 		if (arg[5] == '\0') {
-			if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
-				return -EINVAL;
-
-			if (is_kprobe)
-				f->fn = fetch_kernel_stack_address;
-			else
-				f->fn = fetch_user_stack_address;
+			code->op = FETCH_OP_STACKP;
 		} else if (isdigit(arg[5])) {
 			ret = kstrtoul(arg + 5, 10, &param);
 			if (ret || (is_kprobe && param > PARAM_MAX_STACK))
 				ret = -EINVAL;
 			else {
-				f->fn = t->fetch[FETCH_MTD_stack];
-				f->data = (void *)param;
+				code->op = FETCH_OP_STACK;
+				code->param = (unsigned int)param;
 			}
 		} else
 			ret = -EINVAL;
 	} else if (strcmp(arg, "comm") == 0) {
-		if (strcmp(t->name, "string") != 0 &&
-		    strcmp(t->name, "string_size") != 0)
-			return -EINVAL;
-		f->fn = t->fetch[FETCH_MTD_comm];
+		code->op = FETCH_OP_COMM;
 	} else
 		ret = -EINVAL;
 
@@ -383,10 +208,12 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 }
 
 /* Recursive argument parser */
-static int parse_probe_arg(char *arg, const struct fetch_type *t,
-		     struct fetch_param *f, bool is_return, bool is_kprobe,
-		     const struct fetch_type *ftbl)
+static int
+parse_probe_arg(char *arg, const struct fetch_type *type,
+		struct fetch_insn **pcode, struct fetch_insn *end,
+		bool is_return, bool is_kprobe)
 {
+	struct fetch_insn *code = *pcode;
 	unsigned long param;
 	long offset;
 	char *tmp;
@@ -394,14 +221,15 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 
 	switch (arg[0]) {
 	case '$':
-		ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
+		ret = parse_probe_vars(arg + 1, type, code,
+					is_return, is_kprobe);
 		break;
 
 	case '%':	/* named register */
 		ret = regs_query_register_offset(arg + 1);
 		if (ret >= 0) {
-			f->fn = t->fetch[FETCH_MTD_reg];
-			f->data = (void *)(unsigned long)ret;
+			code->op = FETCH_OP_REG;
+			code->param = (unsigned int)ret;
 			ret = 0;
 		}
 		break;
@@ -411,9 +239,9 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 			ret = kstrtoul(arg + 1, 0, &param);
 			if (ret)
 				break;
-
-			f->fn = t->fetch[FETCH_MTD_memory];
-			f->data = (void *)param;
+			/* load address */
+			code->op = FETCH_OP_IMM;
+			code->immediate = param;
 		} else if (arg[1] == '+') {
 			/* kprobes don't support file offsets */
 			if (is_kprobe)
@@ -423,8 +251,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 			if (ret)
 				break;
 
-			f->fn = t->fetch[FETCH_MTD_file_offset];
-			f->data = (void *)offset;
+			code->op = FETCH_OP_FOFFS;
+			code->immediate = (unsigned long)offset;  // imm64?
 		} else {
 			/* uprobes don't support symbols */
 			if (!is_kprobe)
@@ -434,10 +262,19 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 			if (ret)
 				break;
 
-			f->data = alloc_symbol_cache(arg + 1, offset);
-			if (f->data)
-				f->fn = t->fetch[FETCH_MTD_symbol];
+			code->op = FETCH_OP_IMM;
+			code->immediate =
+				(unsigned long)kallsyms_lookup_name(arg + 1);
+			if (!code->immediate)
+				return -ENOENT;
+			code->immediate += offset;
 		}
+		/* These are fetching from memory */
+		if (++code == end)
+			return -E2BIG;
+		*pcode = code;
+		code->op = FETCH_OP_DEREF;
+		code->offset = offset;
 		break;
 
 	case '+':	/* deref memory */
@@ -445,11 +282,10 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 	case '-':
 		tmp = strchr(arg, '(');
 		if (!tmp)
-			break;
+			return -EINVAL;
 
 		*tmp = '\0';
 		ret = kstrtol(arg, 0, &offset);
-
 		if (ret)
 			break;
 
@@ -457,36 +293,28 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 		tmp = strrchr(arg, ')');
 
 		if (tmp) {
-			struct deref_fetch_param	*dprm;
-			const struct fetch_type		*t2;
+			const struct fetch_type *t2 = find_fetch_type(NULL);
 
-			t2 = find_fetch_type(NULL, ftbl);
 			*tmp = '\0';
-			dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
-
-			if (!dprm)
-				return -ENOMEM;
-
-			dprm->offset = offset;
-			dprm->fetch = t->fetch[FETCH_MTD_memory];
-			dprm->fetch_size = get_fetch_size_function(t,
-							dprm->fetch, ftbl);
-			ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
-							is_kprobe, ftbl);
+			ret = parse_probe_arg(arg, t2, &code, end, is_return,
+					      is_kprobe);
 			if (ret)
-				kfree(dprm);
-			else {
-				f->fn = t->fetch[FETCH_MTD_deref];
-				f->data = (void *)dprm;
-			}
+				break;
+			if (code->op == FETCH_OP_COMM)
+				return -EINVAL;
+			if (++code == end)
+				return -E2BIG;
+			*pcode = code;
+
+			code->op = FETCH_OP_DEREF;
+			code->offset = offset;
 		}
 		break;
 	}
-	if (!ret && !f->fn) {	/* Parsed, but do not find fetch method */
-		pr_info("%s type has no corresponding fetch method.\n", t->name);
+	if (!ret && code->op == FETCH_OP_NOP) {
+		/* Parsed, but do not find fetch method */
 		ret = -EINVAL;
 	}
-
 	return ret;
 }
 
@@ -495,22 +323,15 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 /* Bitfield type needs to be parsed into a fetch function */
 static int __parse_bitfield_probe_arg(const char *bf,
 				      const struct fetch_type *t,
-				      struct fetch_param *f)
+				      struct fetch_insn **pcode)
 {
-	struct bitfield_fetch_param *bprm;
+	struct fetch_insn *code = *pcode;
 	unsigned long bw, bo;
 	char *tail;
 
 	if (*bf != 'b')
 		return 0;
 
-	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
-	if (!bprm)
-		return -ENOMEM;
-
-	bprm->orig = *f;
-	f->fn = t->fetch[FETCH_MTD_bitfield];
-	f->data = (void *)bprm;
 	bw = simple_strtoul(bf + 1, &tail, 0);	/* Use simple one */
 
 	if (bw == 0 || *tail != '@')
@@ -521,18 +342,24 @@ static int __parse_bitfield_probe_arg(const char *bf,
 
 	if (tail == bf || *tail != '/')
 		return -EINVAL;
+	code++;
+	if (code->op != FETCH_OP_NOP)
+		return -E2BIG;
+	*pcode = code;
 
-	bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
-	bprm->low_shift = bprm->hi_shift + bo;
+	code->op = FETCH_OP_MOD_BF;
+	code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
+	code->rshift = BYTES_TO_BITS(t->size) - bw;
+	code->basesize = t->size;
 
 	return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 }
 
 /* String length checking wrapper */
 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-		struct probe_arg *parg, bool is_return, bool is_kprobe,
-		const struct fetch_type *ftbl)
+		struct probe_arg *parg, bool is_return, bool is_kprobe)
 {
+	struct fetch_insn *code, *tmp = NULL;
 	const char *t;
 	int ret;
 
@@ -556,25 +383,70 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 	 */
 	if (!t && strcmp(arg, "$comm") == 0)
 		t = "string";
-	parg->type = find_fetch_type(t, ftbl);
+	parg->type = find_fetch_type(t);
 	if (!parg->type) {
 		pr_info("Unsupported type: %s\n", t);
 		return -EINVAL;
 	}
 	parg->offset = *size;
 	*size += parg->type->size;
-	ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
-			      is_kprobe, ftbl);
 
-	if (ret >= 0 && t != NULL)
-		ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
+	code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
+	if (!code)
+		return -ENOMEM;
+	code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
+
+	ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
+			      is_return, is_kprobe);
+	if (ret)
+		goto fail;
 
-	if (ret >= 0) {
-		parg->fetch_size.fn = get_fetch_size_function(parg->type,
-							      parg->fetch.fn,
-							      ftbl);
-		parg->fetch_size.data = parg->fetch.data;
+	/* Store operation */
+	if (!strcmp(parg->type->name, "string")) {
+		if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM) {
+			pr_info("string only accepts memory or address.\n");
+			ret = -EINVAL;
+			goto fail;
+		}
+		if (code->op == FETCH_OP_IMM) {
+			code++;
+			if (code->op != FETCH_OP_NOP) {
+				ret = -E2BIG;
+				goto fail;
+			}
+		}
+		code->op = FETCH_OP_ST_STRING;	/* In DEREF case, replace it */
+		parg->dynamic = true;
+	} else if (code->op == FETCH_OP_DEREF) {
+		code->op = FETCH_OP_ST_MEM;
+		code->size = parg->type->size;
+	} else {
+		code++;
+		if (code->op != FETCH_OP_NOP) {
+			ret = -E2BIG;
+			goto fail;
+		}
+		code->op = FETCH_OP_ST_RAW;
+		code->size = parg->type->size;
 	}
+	/* Modify operation */
+	if (t != NULL) {
+		ret = __parse_bitfield_probe_arg(t, parg->type, &code);
+		if (ret)
+			goto fail;
+	}
+	code++;
+	code->op = FETCH_OP_END;
+
+	/* Shrink down the code buffer */
+	parg->code = kzalloc(sizeof(*code) * (code - tmp + 1), GFP_KERNEL);
+	if (!parg->code)
+		ret = -ENOMEM;
+	else
+		memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));
+
+fail:
+	kfree(tmp);
 
 	return ret;
 }
@@ -596,25 +468,9 @@ int traceprobe_conflict_field_name(const char *name,
 	return 0;
 }
 
-void traceprobe_update_arg(struct probe_arg *arg)
-{
-	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
-		update_bitfield_fetch_param(arg->fetch.data);
-	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
-		update_deref_fetch_param(arg->fetch.data);
-	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
-		update_symbol_cache(arg->fetch.data);
-}
-
 void traceprobe_free_probe_arg(struct probe_arg *arg)
 {
-	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
-		free_bitfield_fetch_param(arg->fetch.data);
-	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
-		free_deref_fetch_param(arg->fetch.data);
-	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
-		free_symbol_cache(arg->fetch.data);
-
+	kfree(arg->code);
 	kfree(arg->name);
 	kfree(arg->comm);
 }
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index a1490e279658..b22792a6f889 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -91,25 +91,50 @@ 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 */
@@ -118,13 +143,6 @@ 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 */
@@ -154,66 +172,12 @@ 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,					\
@@ -221,17 +185,6 @@ 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)			\
@@ -243,44 +196,9 @@ ASSIGN_FETCH_FUNC(file_offset, ftype),			\
 
 #define ASSIGN_FETCH_TYPE_END {}
 
-#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);
-#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;
-}
-#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 +230,6 @@ 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)
 {
@@ -343,8 +255,7 @@ find_event_file_link(struct trace_probe *tp, struct trace_event_file *file)
 }
 
 extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-		   struct probe_arg *parg, bool is_return, bool is_kprobe,
-		   const struct fetch_type *ftbl);
+		   struct probe_arg *parg, bool is_return, bool is_kprobe);
 
 extern int traceprobe_conflict_field_name(const char *name,
 			       struct probe_arg *args, int narg);
@@ -354,18 +265,72 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
 
 extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset);
 
+/* traceprobe fetch helper  */
+static nokprobe_inline void
+fetch_store_raw(unsigned long val, struct fetch_insn *code, void *buf)
+{
+	switch (code->size) {
+	case 1:
+		*(u8 *)buf = (u8)val;
+		break;
+	case 2:
+		*(u16 *)buf = (u16)val;
+		break;
+	case 4:
+		*(u32 *)buf = (u32)val;
+		break;
+	case 8:
+		//TBD: 32bit signed
+		*(u64 *)buf = (u64)val;
+		break;
+	default:
+		*(unsigned long *)buf = val;
+	}
+}
+
+static nokprobe_inline void
+fetch_apply_bitfield(struct fetch_insn *code, void *buf)
+{
+	switch (code->basesize) {
+	case 1:
+		*(u8 *)buf <<= code->lshift;
+		*(u8 *)buf >>= code->rshift;
+		break;
+	case 2:
+		*(u16 *)buf <<= code->lshift;
+		*(u16 *)buf >>= code->rshift;
+		break;
+	case 4:
+		*(u32 *)buf <<= code->lshift;
+		*(u32 *)buf >>= code->rshift;
+		break;
+	case 8:
+		*(u64 *)buf <<= code->lshift;
+		*(u64 *)buf >>= code->rshift;
+		break;
+	}
+}
+
+/* Define this for each callsite */
+static int
+process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs,
+		   void *dest, bool pre);
+
 /* Sum up total data length for dynamic arraies (strings) */
 static nokprobe_inline int
 __get_data_size(struct trace_probe *tp, struct pt_regs *regs)
 {
+	struct probe_arg *arg;
 	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);
+	for (i = 0; i < tp->nr_args; i++) {
+		arg = tp->args + i;
+		if (unlikely(arg->dynamic)) {
+			process_fetch_insn(arg->code, regs, &len, true);
 			ret += len;
 		}
+	}
 
 	return ret;
 }
@@ -375,30 +340,31 @@ static nokprobe_inline void
 store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
 		 u8 *data, int maxlen)
 {
-	int i;
+	struct probe_arg *arg;
 	u32 end = tp->size;
 	u32 *dl;	/* Data (relative) location */
+	int i;
 
 	for (i = 0; i < tp->nr_args; i++) {
-		if (unlikely(tp->args[i].fetch_size.fn)) {
+		arg = tp->args + i;
+		if (unlikely(arg->dynamic)) {
 			/*
 			 * 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);
+			dl = (u32 *)(data + arg->offset);
+			*dl = make_data_rloc(maxlen, end - arg->offset);
 			/* Then try to fetch string or dynamic array data */
-			call_fetch(&tp->args[i].fetch, regs, dl);
+			process_fetch_insn(arg->code, regs, dl, false);
 			/* 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);
+			*dl = convert_rloc_to_loc(*dl, ent_size + arg->offset);
 		} else
 			/* Just fetching data normally */
-			call_fetch(&tp->args[i].fetch, regs,
-				   data + tp->args[i].offset);
+			process_fetch_insn(arg->code, regs, data + arg->offset,
+					   false);
 	}
 }
 
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 968bd403d68c..84692f564062 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -109,37 +109,19 @@ static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
 /*
  * Uprobes-specific fetch functions
  */
-#define DEFINE_FETCH_stack(type)					\
-static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,		\
-					 void *offset, void *dest)	\
-{									\
-	*(type *)dest = (type)get_user_stack_nth(regs,			\
-					      ((unsigned long)offset)); \
-}
-DEFINE_BASIC_FETCH_FUNCS(stack)
-/* No string on the stack entry */
-#define fetch_stack_string	NULL
-#define fetch_stack_string_size	NULL
-
-#define DEFINE_FETCH_memory(type)					\
-static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,		\
-					  void *addr, void *dest)	\
-{									\
-	type retval;							\
-	void __user *vaddr = (void __force __user *) addr;		\
-									\
-	if (copy_from_user(&retval, vaddr, sizeof(type)))		\
-		*(type *)dest = 0;					\
-	else								\
-		*(type *) dest = retval;				\
+static nokprobe_inline int
+probe_user_read(void *dest, void *src, size_t size)
+{
+	void __user *vaddr = (void __force __user *)src;
+
+	return copy_from_user(dest, vaddr, size);
 }
-DEFINE_BASIC_FETCH_FUNCS(memory)
 /*
  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
  * length and relative data location.
  */
-static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
-					    void *addr, void *dest)
+static nokprobe_inline void
+fetch_store_string(unsigned long addr, void *dest)
 {
 	long ret;
 	u32 rloc = *(u32 *)dest;
@@ -160,8 +142,9 @@ static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
 	}
 }
 
-static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
-						 void *addr, void *dest)
+/* Return the length of string -- including null terminal byte */
+static nokprobe_inline void
+fetch_store_strlen(unsigned long addr, void *dest)
 {
 	int len;
 	void __user *vaddr = (void __force __user *) addr;
@@ -174,7 +157,7 @@ static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 		*(u32 *)dest = len;
 }
 
-static unsigned long translate_user_vaddr(void *file_offset)
+static unsigned long translate_user_vaddr(unsigned long file_offset)
 {
 	unsigned long base_addr;
 	struct uprobe_dispatch_data *udd;
@@ -182,44 +165,79 @@ static unsigned long translate_user_vaddr(void *file_offset)
 	udd = (void *) current->utask->vaddr;
 
 	base_addr = udd->bp_addr - udd->tu->offset;
-	return base_addr + (unsigned long)file_offset;
+	return base_addr + file_offset;
 }
 
-#define DEFINE_FETCH_file_offset(type)					\
-static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs,	\
-					       void *offset, void *dest)\
-{									\
-	void *vaddr = (void *)translate_user_vaddr(offset);		\
-									\
-	FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest);		\
+/* Note that we don't verify it, since the code does not come from user space */
+static int
+process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
+		   bool pre)
+{
+	unsigned long val;
+	int ret;
+
+	/* 1st stage: get value from context */
+	switch (code->op) {
+	case FETCH_OP_REG:
+		val = regs_get_register(regs, code->param);
+		break;
+	case FETCH_OP_STACK:
+		val = get_user_stack_nth(regs, code->param);
+		break;
+	case FETCH_OP_STACKP:
+		val = user_stack_pointer(regs);
+		break;
+	case FETCH_OP_RETVAL:
+		val = regs_return_value(regs);
+		break;
+	case FETCH_OP_IMM:
+		val = code->immediate;
+		break;
+	case FETCH_OP_FOFFS:
+		val = translate_user_vaddr(code->immediate);
+		break;
+	default:
+		return -EILSEQ;
+	}
+	code++;
+
+	/* 2nd stage: dereference memory if needed */
+	while (code->op == FETCH_OP_DEREF) {
+		ret = probe_user_read(&val, (void *)val + code->offset,
+				      sizeof(val));
+		if (ret)
+			return ret;
+		code++;
+	}
+
+	/* 3rd stage: store value to buffer */
+	switch (code->op) {
+	case FETCH_OP_ST_RAW:
+		fetch_store_raw(val, code, dest);
+		break;
+	case FETCH_OP_ST_MEM:
+		probe_user_read(dest, (void *)val + code->offset, code->size);
+		break;
+	case FETCH_OP_ST_STRING:
+		if (pre)
+			fetch_store_strlen(val + code->offset, dest);
+		else
+			fetch_store_string(val + code->offset, dest);
+		break;
+	default:
+		return -EILSEQ;
+	}
+	code++;
+
+	/* 4th stage: modify stored value if needed */
+	if (code->op == FETCH_OP_MOD_BF) {
+		fetch_apply_bitfield(code, dest);
+		code++;
+	}
+
+	return code->op == FETCH_OP_END ? 0 : -EILSEQ;
 }
-DEFINE_BASIC_FETCH_FUNCS(file_offset)
-DEFINE_FETCH_file_offset(string)
-DEFINE_FETCH_file_offset(string_size)
-
-/* Fetch type information table */
-static const struct fetch_type uprobes_fetch_type_table[] = {
-	/* Special types */
-	[FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
-					sizeof(u32), 1, "__data_loc char[]"),
-	[FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
-					string_size, sizeof(u32), 0, "u32"),
-	/* Basic types */
-	ASSIGN_FETCH_TYPE(u8,  u8,  0),
-	ASSIGN_FETCH_TYPE(u16, u16, 0),
-	ASSIGN_FETCH_TYPE(u32, u32, 0),
-	ASSIGN_FETCH_TYPE(u64, u64, 0),
-	ASSIGN_FETCH_TYPE(s8,  u8,  1),
-	ASSIGN_FETCH_TYPE(s16, u16, 1),
-	ASSIGN_FETCH_TYPE(s32, u32, 1),
-	ASSIGN_FETCH_TYPE(s64, u64, 1),
-	ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
-	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
-	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
-	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
-
-	ASSIGN_FETCH_TYPE_END
-};
+NOKPROBE_SYMBOL(process_fetch_insn)
 
 static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
 {
@@ -538,8 +556,7 @@ static int create_trace_uprobe(int argc, char **argv)
 
 		/* Parse fetch argument */
 		ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
-						 is_return, false,
-						 uprobes_fetch_type_table);
+						 is_return, false);
 		if (ret) {
 			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 			goto error;

[RFC PATCH 5/8] tracing: probeevent: Add symbol type

[Masami Hiramatsu]

Add "symbol" type to probeevent, which is an alias of u32 or u64
(depends on BITS_PER_LONG). This shows the result value in
symbol+offset style. This type is only available with kprobe
events.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Documentation/trace/kprobetrace.txt |    3 +++
 kernel/trace/trace_probe.c          |    8 ++++++++
 kernel/trace/trace_probe.h          |   12 +++++++++---
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 1a3a3d6bc2a8..d49381f2e411 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -62,6 +62,7 @@ respectively. 'x' prefix implies it is unsigned. Traced arguments are shown
 in decimal ('s' and 'u') or hexadecimal ('x'). Without type casting, 'x32'
 or 'x64' is used depends on the architecture (e.g. x86-32 uses x32, and
 x86-64 uses x64).
+
 String type is a special type, which fetches a "null-terminated" string from
 kernel space. This means it will fail and store NULL if the string container
 has been paged out.
@@ -70,6 +71,8 @@ offset, and container-size (usually 32). The syntax is;
 
  b<bit-width>@<bit-offset>/<container-size>
 
+Symbol type('symbol') is an alias of u32 or u64 type (depends on BITS_PER_LONG)
+which shows given pointer in "symbol+offset" style.
 For $comm, the default type is "string"; any other type is invalid.
 
 
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 52b4931864d6..f56dfadd29d5 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -58,6 +58,13 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
 DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
 
+int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
+{
+	trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
+	return !trace_seq_has_overflowed(s);
+}
+const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";
+
 /* Print type function for string type */
 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
 {
@@ -103,6 +110,7 @@ static const struct fetch_type probe_fetch_types[] = {
 	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
+	ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),
 
 	ASSIGN_FETCH_TYPE_END
 };
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index b22792a6f889..2234586b9942 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -171,6 +171,7 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x32);
 DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
 
 DECLARE_BASIC_PRINT_TYPE_FUNC(string);
+DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
 
 /* Default (unsigned long) fetch type */
 #define __DEFAULT_FETCH_TYPE(t) x##t
@@ -178,6 +179,10 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(string);
 #define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
 #define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
 
+#define __ADDR_FETCH_TYPE(t) u##t
+#define _ADDR_FETCH_TYPE(t) __ADDR_FETCH_TYPE(t)
+#define ADDR_FETCH_TYPE _ADDR_FETCH_TYPE(BITS_PER_LONG)
+
 #define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)	\
 	{.name = _name,				\
 	 .size = _size,					\
@@ -186,13 +191,14 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(string);
 	 .fmt = PRINT_TYPE_FMT_NAME(ptype),		\
 	 .fmttype = _fmttype,				\
 	}
-
+#define _ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)	\
+	__ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, #_fmttype)
 #define ASSIGN_FETCH_TYPE(ptype, ftype, sign)			\
-	__ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)
+	_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, ptype)
 
 /* If ptype is an alias of atype, use this macro (show atype in format) */
 #define ASSIGN_FETCH_TYPE_ALIAS(ptype, atype, ftype, sign)		\
-	__ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #atype)
+	_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, atype)
 
 #define ASSIGN_FETCH_TYPE_END {}
 

[RFC PATCH 6/8] x86: ptrace: Add function argument access API

[Masami Hiramatsu]

Add regs_get_argument() which returns N th argument of the
function call.
Note that this chooses most probably assignment, in some case
it can be incorrect (e.g. passing data structure or floating
point etc.)

This is expected to be called from kprobes or ftrace with regs
where the top of stack is the return address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/Kconfig                  |    7 +++++++
 arch/x86/Kconfig              |    1 +
 arch/x86/include/asm/ptrace.h |   38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index a26d6f8ab967..91e839bdcab9 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -258,6 +258,13 @@ config HAVE_REGS_AND_STACK_ACCESS_API
 	  declared in asm/ptrace.h
 	  For example the kprobes-based event tracer needs this API.
 
+config HAVE_FUNCTION_ARG_ACCESS_API
+	bool
+	help
+	  This symbol should be selected by an architecure if it supports
+	  the API needed to access function arguments from pt_regs,
+	  declared in asm/ptrace.h
+
 config HAVE_CLK
 	bool
 	help
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 423e4b64e683..c63883665a53 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -172,6 +172,7 @@ config X86
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_RCU_TABLE_FREE
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_FUNCTION_ARG_ACCESS_API
 	select HAVE_RELIABLE_STACKTRACE		if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
 	select HAVE_STACK_VALIDATION		if X86_64
 	select HAVE_SYSCALL_TRACEPOINTS
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 14131dd06b29..f0688ec22b15 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -251,6 +251,44 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 		return 0;
 }
 
+/**
+ * regs_get_kernel_argument() - get Nth function argument in kernel
+ * @regs:	pt_regs of that context
+ * @n:		function argument number (start from 0)
+ *
+ * regs_get_argument() returns @n th argument of the function call.
+ * Note that this chooses most probably assignment, in some case
+ * it can be incorrect.
+ * This is expected to be called from kprobes or ftrace with regs
+ * where the top of stack is the return address.
+ */
+static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
+						     unsigned int n)
+{
+	const static unsigned int argument_offs[] = {
+#ifdef __i386__
+		offsetof(struct pt_regs, ax),
+		offsetof(struct pt_regs, cx),
+		offsetof(struct pt_regs, dx),
+#define NR_REG_ARGUMENTS 3
+#else
+		offsetof(struct pt_regs, di),
+		offsetof(struct pt_regs, si),
+		offsetof(struct pt_regs, dx),
+		offsetof(struct pt_regs, cx),
+		offsetof(struct pt_regs, r8),
+		offsetof(struct pt_regs, r9),
+#define NR_REG_ARGUMENTS 6
+#endif
+	};
+
+	if (n >= NR_REG_ARGUMENTS) {
+		n -= NR_REG_ARGUMENTS - 1;
+		return regs_get_kernel_stack_nth(regs, n);
+	} else
+		return regs_get_register(regs, argument_offs[n]);
+}
+
 #define arch_has_single_step()	(1)
 #ifdef CONFIG_X86_DEBUGCTLMSR
 #define arch_has_block_step()	(1)

[RFC PATCH 7/8] tracing: probeevent: Add $argN for accessing function args

[Masami Hiramatsu]

Add $argN special fetch variable for accessing function
arguments. This allows user to trace the Nth argument easily
at the function entry.

Note that this returns most probably assignment of registers
and stacks. In some case, it may not work well. If you need
to access correct registers or stacks you should use perf-probe.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Documentation/trace/kprobetrace.txt |   10 ++++++----
 kernel/trace/trace_kprobe.c         |   18 +++++++++++++-----
 kernel/trace/trace_probe.c          |   36 ++++++++++++++++++++++-------------
 kernel/trace/trace_probe.h          |    9 ++++++++-
 kernel/trace/trace_uprobe.c         |    2 +-
 5 files changed, 51 insertions(+), 24 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index d49381f2e411..ec34640becbd 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -43,16 +43,18 @@ Synopsis of kprobe_events
   @SYM[+|-offs]	: Fetch memory at SYM +|- offs (SYM should be a data symbol)
   $stackN	: Fetch Nth entry of stack (N >= 0)
   $stack	: Fetch stack address.
-  $retval	: Fetch return value.(*)
+  $argN		: Fetch the Nth function argument.(*1)
+  $retval	: Fetch return value.(*2)
   $comm		: Fetch current task comm.
-  +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
+  +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(*3)
   NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
   FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
 		  (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types
 		  (x8/x16/x32/x64), "string" and bitfield are supported.
 
-  (*) only for return probe.
-  (**) this is useful for fetching a field of data structures.
+  (*1) only for the probe on function entry (offset = 0)
+  (*2) only for return probe.
+  (*3) this is useful for fetching a field of data structures.
 
 Types
 -----
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1d0554c6bb34..cab5efe0a66c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -457,13 +457,15 @@ static int create_trace_kprobe(int argc, char **argv)
 	unsigned long offset = 0;
 	void *addr = NULL;
 	char buf[MAX_EVENT_NAME_LEN];
+	unsigned int flags = TPARG_FL_KERNEL;
 
 	/* argc must be >= 1 */
 	if (argv[0][0] == 'p')
 		is_return = false;
-	else if (argv[0][0] == 'r')
+	else if (argv[0][0] == 'r') {
 		is_return = true;
-	else if (argv[0][0] == '-')
+		flags |= TPARG_FL_RETURN;
+	} else if (argv[0][0] == '-')
 		is_delete = true;
 	else {
 		pr_info("Probe definition must be started with 'p', 'r' or"
@@ -546,8 +548,9 @@ static int create_trace_kprobe(int argc, char **argv)
 			pr_info("Failed to parse either an address or a symbol.\n");
 			return ret;
 		}
-		if (offset && is_return &&
-		    !kprobe_on_func_entry(NULL, symbol, offset)) {
+		if (kprobe_on_func_entry(NULL, symbol, offset))
+			flags |= TPARG_FL_FENTRY;
+		if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {
 			pr_info("Given offset is not valid for return probe.\n");
 			return -EINVAL;
 		}
@@ -617,7 +620,7 @@ static int create_trace_kprobe(int argc, char **argv)
 
 		/* Parse fetch argument */
 		ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
-						 is_return, true);
+						 flags);
 		if (ret) {
 			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 			goto error;
@@ -855,6 +858,11 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 	case FETCH_OP_COMM:
 		val = (unsigned long)current->comm;
 		break;
+#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
+	case FETCH_OP_ARG:
+		val = regs_get_kernel_argument(regs, code->param);
+		break;
+#endif
 	default:
 		return -EILSEQ;
 	}
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index f56dfadd29d5..491a640a1a3e 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -183,14 +183,13 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 
 static int parse_probe_vars(char *arg, const struct fetch_type *t,
-			    struct fetch_insn *code, bool is_return,
-			    bool is_kprobe)
+			    struct fetch_insn *code, unsigned int flags)
 {
 	int ret = 0;
 	unsigned long param;
 
 	if (strcmp(arg, "retval") == 0) {
-		if (is_return)
+		if (flags & TPARG_FL_RETURN)
 			code->op = FETCH_OP_RETVAL;
 		else
 			ret = -EINVAL;
@@ -199,7 +198,8 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 			code->op = FETCH_OP_STACKP;
 		} else if (isdigit(arg[5])) {
 			ret = kstrtoul(arg + 5, 10, &param);
-			if (ret || (is_kprobe && param > PARAM_MAX_STACK))
+			if (ret || ((flags & TPARG_FL_KERNEL) &&
+				    param > PARAM_MAX_STACK))
 				ret = -EINVAL;
 			else {
 				code->op = FETCH_OP_STACK;
@@ -209,6 +209,18 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 			ret = -EINVAL;
 	} else if (strcmp(arg, "comm") == 0) {
 		code->op = FETCH_OP_COMM;
+#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
+	} else if (((flags & TPARG_FL_MASK) ==
+		    (TPARG_FL_KERNEL | TPARG_FL_FENTRY)) &&
+		   strncmp(arg, "arg", 3) == 0) {
+		if (!isdigit(arg[3]))
+			return -EINVAL;
+		ret = kstrtoul(arg + 3, 10, &param);
+		if (ret || param > PARAM_MAX_STACK)
+			return -EINVAL;
+		code->op = FETCH_OP_ARG;
+		code->param = (unsigned int)param;
+#endif
 	} else
 		ret = -EINVAL;
 
@@ -219,7 +231,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 static int
 parse_probe_arg(char *arg, const struct fetch_type *type,
 		struct fetch_insn **pcode, struct fetch_insn *end,
-		bool is_return, bool is_kprobe)
+		unsigned int flags)
 {
 	struct fetch_insn *code = *pcode;
 	unsigned long param;
@@ -229,8 +241,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
 
 	switch (arg[0]) {
 	case '$':
-		ret = parse_probe_vars(arg + 1, type, code,
-					is_return, is_kprobe);
+		ret = parse_probe_vars(arg + 1, type, code, flags);
 		break;
 
 	case '%':	/* named register */
@@ -252,7 +263,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
 			code->immediate = param;
 		} else if (arg[1] == '+') {
 			/* kprobes don't support file offsets */
-			if (is_kprobe)
+			if (flags & TPARG_FL_KERNEL)
 				return -EINVAL;
 
 			ret = kstrtol(arg + 2, 0, &offset);
@@ -263,7 +274,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
 			code->immediate = (unsigned long)offset;  // imm64?
 		} else {
 			/* uprobes don't support symbols */
-			if (!is_kprobe)
+			if (!(flags & TPARG_FL_KERNEL))
 				return -EINVAL;
 
 			ret = traceprobe_split_symbol_offset(arg + 1, &offset);
@@ -304,8 +315,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
 			const struct fetch_type *t2 = find_fetch_type(NULL);
 
 			*tmp = '\0';
-			ret = parse_probe_arg(arg, t2, &code, end, is_return,
-					      is_kprobe);
+			ret = parse_probe_arg(arg, t2, &code, end, flags);
 			if (ret)
 				break;
 			if (code->op == FETCH_OP_COMM)
@@ -365,7 +375,7 @@ static int __parse_bitfield_probe_arg(const char *bf,
 
 /* String length checking wrapper */
 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-		struct probe_arg *parg, bool is_return, bool is_kprobe)
+		struct probe_arg *parg, unsigned int flags)
 {
 	struct fetch_insn *code, *tmp = NULL;
 	const char *t;
@@ -405,7 +415,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 	code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
 
 	ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
-			      is_return, is_kprobe);
+			      flags);
 	if (ret)
 		goto fail;
 
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 2234586b9942..c23aa7e20502 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -35,6 +35,7 @@
 #include <linux/stringify.h>
 #include <linux/limits.h>
 #include <linux/uaccess.h>
+#include <linux/bitops.h>
 #include <asm/bitsperlong.h>
 
 #include "trace.h"
@@ -103,6 +104,7 @@ enum fetch_op {
 	FETCH_OP_RETVAL,	/* Return value */
 	FETCH_OP_IMM,		/* Immediate : .immediate */
 	FETCH_OP_COMM,		/* Current comm */
+	FETCH_OP_ARG,		/* Function argument : .param */
 	FETCH_OP_FOFFS,		/* File offset: .immediate */
 	// Stage 2 (dereference) op
 	FETCH_OP_DEREF,		/* Dereference: .offset */
@@ -260,8 +262,13 @@ find_event_file_link(struct trace_probe *tp, struct trace_event_file *file)
 	return NULL;
 }
 
+#define TPARG_FL_RETURN BIT(0)
+#define TPARG_FL_KERNEL BIT(1)
+#define TPARG_FL_FENTRY BIT(2)
+#define TPARG_FL_MASK	GENMASK(2, 0)
+
 extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-		   struct probe_arg *parg, bool is_return, bool is_kprobe);
+		   struct probe_arg *parg, unsigned int flags);
 
 extern int traceprobe_conflict_field_name(const char *name,
 			       struct probe_arg *args, int narg);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 84692f564062..d6479af1e6ac 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -556,7 +556,7 @@ static int create_trace_uprobe(int argc, char **argv)
 
 		/* Parse fetch argument */
 		ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
-						 is_return, false);
+					is_return ? TPARG_FL_RETURN : 0);
 		if (ret) {
 			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 			goto error;

[RFC PATCH 8/8] tracing: probeevent: Add an array for basic types

[Masami Hiramatsu]

Add an array for basic types. This allows user to get arraied
basic types from memory address.
The array type syntax is

	TYPE[N]

Where TYPE is one of basic type (u8/16/32/64,s8/16/32/64, and
x8/16/32/64) and N is a fixed value.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Documentation/trace/kprobetrace.txt |    7 ++
 kernel/trace/trace_kprobe.c         |   17 +++++
 kernel/trace/trace_probe.c          |  111 ++++++++++++++++++++++++++---------
 kernel/trace/trace_probe.h          |   29 ++++++++-
 kernel/trace/trace_uprobe.c         |   17 +++++
 5 files changed, 144 insertions(+), 37 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index ec34640becbd..17d3e1a97d85 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -65,6 +65,13 @@ in decimal ('s' and 'u') or hexadecimal ('x'). Without type casting, 'x32'
 or 'x64' is used depends on the architecture (e.g. x86-32 uses x32, and
 x86-64 uses x64).
 
+These value types can be an array. To record array data, you can add '[N]'
+(where N is a fixed number, less than 64) to the base type.
+E.g. 'x16[4]' means an array of x16 (2bytes hex) with 4 elements.
+Note that the array can be applied to memory type fetchargs, you can not
+apply it to registers/stack-entries etc. (for example, '$stack1:x8[8]' is
+wrong, but '+8($stack):x8[8]' is OK.)
+
 String type is a special type, which fetches a "null-terminated" string from
 kernel space. This means it will fail and store NULL if the string container
 has been paged out.
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index cab5efe0a66c..45e00de573d3 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -835,8 +835,9 @@ static int
 process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		   bool pre)
 {
+	struct fetch_insn *s3 = NULL;
 	unsigned long val;
-	int ret;
+	int ret, i = 0;
 
 	/* 1st stage: get value from context */
 	switch (code->op) {
@@ -877,6 +878,8 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		code++;
 	}
 
+stage3:
+	s3 = code;
 	/* 3rd stage: store value to buffer */
 	switch (code->op) {
 	case FETCH_OP_ST_RAW:
@@ -902,6 +905,16 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		code++;
 	}
 
+	/* the last stage: Loop on array */
+	if (code->op == FETCH_OP_LP_ARRAY) {
+		if (++i < code->param) {
+			code = s3;
+			val += s3->size;
+			dest += s3->size;
+			goto stage3;
+		}
+	}
+
 	return code->op == FETCH_OP_END ? 0 : -EILSEQ;
 }
 NOKPROBE_SYMBOL(process_fetch_insn)
@@ -1248,7 +1261,7 @@ static int register_kprobe_event(struct trace_kprobe *tk)
 		call->event.funcs = &kprobe_funcs;
 		call->class->define_fields = kprobe_event_define_fields;
 	}
-	if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
+	if (traceprobe_set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
 		return -ENOMEM;
 	ret = register_trace_event(&call->event);
 	if (!ret) {
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 491a640a1a3e..ae96f98506f0 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -378,8 +378,8 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 		struct probe_arg *parg, unsigned int flags)
 {
 	struct fetch_insn *code, *tmp = NULL;
-	const char *t;
-	int ret;
+	char *t, *t2;
+	int ret, len;
 
 	if (strlen(arg) > MAX_ARGSTR_LEN) {
 		pr_info("Argument is too long.: %s\n",  arg);
@@ -390,24 +390,40 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 		pr_info("Failed to allocate memory for command '%s'.\n", arg);
 		return -ENOMEM;
 	}
-	t = strchr(parg->comm, ':');
+	t = strchr(arg, ':');
 	if (t) {
-		arg[t - parg->comm] = '\0';
-		t++;
+		*t = '\0';
+		t2 = strchr(++t, '[');
+		if (t2) {
+			*t2 = '\0';
+			parg->count = simple_strtoul(t2 + 1, &t2, 0);
+			if (strcmp(t2, "]") || parg->count == 0)
+				return -EINVAL;
+		}
 	}
 	/*
 	 * The default type of $comm should be "string", and it can't be
 	 * dereferenced.
 	 */
 	if (!t && strcmp(arg, "$comm") == 0)
-		t = "string";
-	parg->type = find_fetch_type(t);
+		parg->type = find_fetch_type("string");
+	else
+		parg->type = find_fetch_type(t);
 	if (!parg->type) {
 		pr_info("Unsupported type: %s\n", t);
 		return -EINVAL;
 	}
 	parg->offset = *size;
-	*size += parg->type->size;
+	*size += parg->type->size * (parg->count ?: 1);
+
+	if (parg->count) {
+		len = strlen(parg->type->fmttype) + 6;
+		parg->fmt = kmalloc(len, GFP_KERNEL);
+		if (!parg->fmt)
+			return -ENOMEM;
+		snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
+			 parg->count);
+	}
 
 	code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
 	if (!code)
@@ -453,6 +469,21 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 		if (ret)
 			goto fail;
 	}
+	/* Loop(Array) operation */
+	if (parg->count) {
+		if (code->op != FETCH_OP_ST_MEM) {
+			pr_info("array only accepts memory or address\n");
+			ret = -EINVAL;
+			goto fail;
+		}
+		code++;
+		if (code->op != FETCH_OP_NOP) {
+			ret = -E2BIG;
+			goto fail;
+		}
+		code->op = FETCH_OP_LP_ARRAY;
+		code->param = parg->count;
+	}
 	code++;
 	code->op = FETCH_OP_END;
 
@@ -491,14 +522,17 @@ void traceprobe_free_probe_arg(struct probe_arg *arg)
 	kfree(arg->code);
 	kfree(arg->name);
 	kfree(arg->comm);
+	kfree(arg->fmt);
 }
 
+/* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 			   bool is_return)
 {
-	int i;
+	struct probe_arg *parg;
+	int i, j;
 	int pos = 0;
-
 	const char *fmt, *arg;
 
 	if (!is_return) {
@@ -509,35 +543,51 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 		arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 	}
 
-	/* When len=0, we just calculate the needed length */
-#define LEN_OR_ZERO (len ? len - pos : 0)
-
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 
 	for (i = 0; i < tp->nr_args; i++) {
-		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
-				tp->args[i].name, tp->args[i].type->fmt);
+		parg = tp->args + i;
+		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=", parg->name);
+		if (parg->count) {
+			pos += snprintf(buf + pos, LEN_OR_ZERO, "{%s",
+					parg->type->fmt);
+			for (j = 1; j < parg->count; j++)
+				pos += snprintf(buf + pos, LEN_OR_ZERO, ",%s",
+						parg->type->fmt);
+			pos += snprintf(buf + pos, LEN_OR_ZERO, "}");
+		} else
+			pos += snprintf(buf + pos, LEN_OR_ZERO, "%s",
+					parg->type->fmt);
 	}
 
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 
 	for (i = 0; i < tp->nr_args; i++) {
-		if (strcmp(tp->args[i].type->name, "string") == 0)
+		parg = tp->args + i;
+		if (parg->count) {
+			if (strcmp(parg->type->name, "string") == 0)
+				fmt = ", __get_str(%s[%d])";
+			else
+				fmt = ", REC->%s[%d]";
+			for (j = 0; j < parg->count; j++)
+				pos += snprintf(buf + pos, LEN_OR_ZERO,
+						fmt, parg->name, j);
+		} else {
+			if (strcmp(parg->type->name, "string") == 0)
+				fmt = ", __get_str(%s)";
+			else
+				fmt = ", REC->%s";
 			pos += snprintf(buf + pos, LEN_OR_ZERO,
-					", __get_str(%s)",
-					tp->args[i].name);
-		else
-			pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
-					tp->args[i].name);
+					fmt, parg->name);
+		}
 	}
 
-#undef LEN_OR_ZERO
-
 	/* return the length of print_fmt */
 	return pos;
 }
+#undef LEN_OR_ZERO
 
-int set_print_fmt(struct trace_probe *tp, bool is_return)
+int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return)
 {
 	int len;
 	char *print_fmt;
@@ -563,11 +613,16 @@ int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	/* Set argument names as fields */
 	for (i = 0; i < tp->nr_args; i++) {
 		struct probe_arg *parg = &tp->args[i];
-
-		ret = trace_define_field(event_call, parg->type->fmttype,
-					 parg->name,
+		const char *fmt = parg->type->fmttype;
+		int size = parg->type->size;
+
+		if (parg->fmt)
+			fmt = parg->fmt;
+		if (parg->count)
+			size *= parg->count;
+		ret = trace_define_field(event_call, fmt, parg->name,
 					 offset + parg->offset,
-					 parg->type->size,
+					 parg->type->size * parg->count,
 					 parg->type->is_signed,
 					 FILTER_OTHER);
 		if (ret)
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index c23aa7e20502..62e68e4ef80b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -114,6 +114,8 @@ enum fetch_op {
 	FETCH_OP_ST_STRING,	/* String: .offset, .size */
 	// Stage 4 (modify) op
 	FETCH_OP_MOD_BF,	/* Bitfield: .basesize, .lshift, .rshift */
+	// Stage 5 (loop) op
+	FETCH_OP_LP_ARRAY,	/* Array: .param = loop count */
 	FETCH_OP_END,
 };
 
@@ -203,13 +205,16 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
 	_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, atype)
 
 #define ASSIGN_FETCH_TYPE_END {}
+#define MAX_ARRAY_LEN	64
 
 struct probe_arg {
 	struct fetch_insn	*code;
 	bool			dynamic;/* Dynamic array (string) is used */
 	unsigned int		offset;	/* Offset from argument entry */
+	unsigned int		count;	/* Array count */
 	const char		*name;	/* Name of this argument */
 	const char		*comm;	/* Command of this argument */
+	char			*fmt;	/* Format string if needed */
 	const struct fetch_type	*type;	/* Type of this argument */
 };
 
@@ -385,16 +390,30 @@ static inline int
 print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
 		 u8 *data, void *field)
 {
-	int i;
+	void *p;
+	int i, j;
 
 	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;
+		struct probe_arg *a = args + i;
+
+		trace_seq_printf(s, " %s=", a->name);
+		if (likely(!a->count)) {
+			if (!a->type->print(s, data + a->offset, field))
+				return -ENOMEM;
+			continue;
+		}
+		trace_seq_putc(s, '{');
+		p = data + a->offset;
+		for (j = 0; j < a->count; j++) {
+			if (!a->type->print(s, p, field))
+				return -ENOMEM;
+			trace_seq_putc(s, j == a->count - 1 ? '}' : ',');
+			p += a->type->size;
+		}
 	}
 	return 0;
 }
 
-extern int set_print_fmt(struct trace_probe *tp, bool is_return);
+extern int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return);
 extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 					size_t offset, struct trace_probe *tp);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index d6479af1e6ac..6fc7ea0159d4 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -173,8 +173,9 @@ static int
 process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		   bool pre)
 {
+	struct fetch_insn *s3 = NULL;
 	unsigned long val;
-	int ret;
+	int ret, i = 0;
 
 	/* 1st stage: get value from context */
 	switch (code->op) {
@@ -210,6 +211,8 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		code++;
 	}
 
+stage3:
+	s3 = code;
 	/* 3rd stage: store value to buffer */
 	switch (code->op) {
 	case FETCH_OP_ST_RAW:
@@ -235,6 +238,16 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 		code++;
 	}
 
+	/* the last stage: Loop on array */
+	if (code->op == FETCH_OP_LP_ARRAY) {
+		if (++i < code->param) {
+			code = s3;
+			val += s3->size;
+			dest += s3->size;
+			goto stage3;
+		}
+	}
+
 	return code->op == FETCH_OP_END ? 0 : -EILSEQ;
 }
 NOKPROBE_SYMBOL(process_fetch_insn)
@@ -1303,7 +1316,7 @@ static int register_uprobe_event(struct trace_uprobe *tu)
 	call->event.funcs = &uprobe_funcs;
 	call->class->define_fields = uprobe_event_define_fields;
 
-	if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
+	if (traceprobe_set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
 		return -ENOMEM;
 
 	ret = register_trace_event(&call->event);

Re: [RFC PATCH 0/8] tracing: probeevent: Improve fetcharg features

[Steven Rostedt]

On Wed, 14 Feb 2018 00:35:45 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Hi,
> 
> This series improves probeevent variable fetcharg framework,
> 
> - Rewrite fetcharg framework with fetch_insn, switch-case based
>   instead of function pointer. (maybe good for retpoline)
> - Add "symbol" type support, which shows symbol+offset instead of
>   address value.
> - Add "$argN" fetcharg, which fetches function parameters.
>   (currently only for x86-64)
> - Add array type support for basic types (except for string),
>   which enables to get fixed length array from probeevents.
> 
> All ideas came from Steve's function event tracer. Thanks Steve!

You're welcome ;-)

> 
> I'll add string (pointer) array support and testcases for these
> features in the next version.
> 

Just to let you know I'm trying to catch up with some internal work and
may not be able to look at these for a few days.

Hopefully others will be able to review them.

-- Steve