tracing/kprobes: Support "string" type

  +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)

  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) are supported.

		  (u8/u16/u32/u64/s8/s16/s32/s64) and string are supported.

  (*) only for return probe.

  (**) this is useful for fetching a field of data structures.

#include <linux/ptrace.h>

#include <linux/perf_event.h>

#include <linux/stringify.h>

#include <linux/limits.h>

#include <linux/uaccess.h>

#include <asm/bitsperlong.h>

#include "trace.h"

#define MAX_TRACE_ARGS 128

#define MAX_ARGSTR_LEN 63

#define MAX_EVENT_NAME_LEN 64

#define MAX_STRING_SIZE PATH_MAX

#define KPROBE_EVENT_SYSTEM "kprobes"

/* Reserved field names */

};

/* Printing function type */

typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *);

typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *,

				 void *);

#define PRINT_TYPE_FUNC_NAME(type)	print_type_##type

#define PRINT_TYPE_FMT_NAME(type)	print_type_format_##type

/* Printing  in basic type function template */

#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)			\

static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,	\

						const char *name, void *data)\

						const char *name,	\

						void *data, void *ent)\

{									\

	return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\

}									\

DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)

DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)

/* data_rloc: data relative location, compatible with u32 */

#define make_data_rloc(len, roffs)	\

	(((u32)(len) << 16) | ((u32)(roffs) & 0xffff))

#define get_rloc_len(dl)	((u32)(dl) >> 16)

#define get_rloc_offs(dl)	((u32)(dl) & 0xffff)

static inline void *get_rloc_data(u32 *dl)

{

	return (u8 *)dl + get_rloc_offs(*dl);

}

/* For data_loc conversion */

static inline void *get_loc_data(u32 *dl, void *ent)

{

	return (u8 *)ent + get_rloc_offs(*dl);

}

/*

 * Convert data_rloc to data_loc:

 *  data_rloc stores the offset from data_rloc itself, but data_loc

 *  stores the offset from event entry.

 */

#define convert_rloc_to_loc(dl, offs)	((u32)(dl) + (offs))

/* For defining macros, define string/string_size types */

typedef u32 string;

typedef u32 string_size;

/* Print type function for string type */

static __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,

						  const char *name,

						  void *data, void *ent)

{

	int len = *(u32 *)data >> 16;

	if (!len)

		return trace_seq_printf(s, " %s=(fault)", name);

	else

		return trace_seq_printf(s, " %s=\"%s\"", name,

					(const char *)get_loc_data(data, ent));

}

static const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";

/* Data fetch function type */

typedef	void (*fetch_func_t)(struct pt_regs *, void *, void *);

	return fprm->fn(regs, fprm->data, dest);

}

#define FETCH_FUNC_NAME(kind, type)	fetch_##kind##_##type

#define FETCH_FUNC_NAME(method, type)	fetch_##method##_##type

/*

 * 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(kind)  \

DEFINE_FETCH_##kind(u8)			\

DEFINE_FETCH_##kind(u16)		\

DEFINE_FETCH_##kind(u32)		\

DEFINE_FETCH_##kind(u64)

#define CHECK_BASIC_FETCH_FUNCS(kind, fn)	\

	((FETCH_FUNC_NAME(kind, u8) == fn) ||	\

	 (FETCH_FUNC_NAME(kind, u16) == fn) ||	\

	 (FETCH_FUNC_NAME(kind, u32) == fn) ||	\

	 (FETCH_FUNC_NAME(kind, u64) == fn))

#define DEFINE_BASIC_FETCH_FUNCS(method) \

DEFINE_FETCH_##method(u8)		\

DEFINE_FETCH_##method(u16)		\

DEFINE_FETCH_##method(u32)		\

DEFINE_FETCH_##method(u64)

#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)						\

				(unsigned int)((unsigned long)offset));	\

}

DEFINE_BASIC_FETCH_FUNCS(reg)

/* No string on the register */

#define fetch_reg_string NULL

#define fetch_reg_string_size NULL

#define DEFINE_FETCH_stack(type)					\

static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\

				(unsigned int)((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_retval(type)					\

static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\

	*(type *)dest = (type)regs_return_value(regs);			\

}

DEFINE_BASIC_FETCH_FUNCS(retval)

/* No string on the retval */

#define fetch_retval_string NULL

#define fetch_retval_string_size NULL

#define DEFINE_FETCH_memory(type)					\

static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\

		*(type *)dest = retval;					\

}

DEFINE_BASIC_FETCH_FUNCS(memory)

/*

 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max

 * length and relative data location.

 */

static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,

						      void *addr, void *dest)

{

	long ret;

	int maxlen = get_rloc_len(*(u32 *)dest);

	u8 *dst = get_rloc_data(dest);

	u8 *src = addr;

	mm_segment_t old_fs = get_fs();

	if (!maxlen)

		return;

	/*

	 * Try to get string again, since the string can be changed while

	 * probing.

	 */

	set_fs(KERNEL_DS);

	pagefault_disable();

	do

		ret = __copy_from_user_inatomic(dst++, src++, 1);

	while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);

	dst[-1] = '\0';

	pagefault_enable();

	set_fs(old_fs);

	if (ret < 0) {	/* Failed to fetch string */

		((u8 *)get_rloc_data(dest))[0] = '\0';

		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));

	} else

		*(u32 *)dest = make_data_rloc(src - (u8 *)addr,

					      get_rloc_offs(*(u32 *)dest));

}

/* Return the length of string -- including null terminal byte */

static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,

							void *addr, void *dest)

{

	int ret, len = 0;

	u8 c;

	mm_segment_t 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;

}

/* Memory fetching by symbol */

struct symbol_cache {

		*(type *)dest = 0;					\

}

DEFINE_BASIC_FETCH_FUNCS(symbol)

DEFINE_FETCH_symbol(string)

DEFINE_FETCH_symbol(string_size)

/* Dereference memory access function */

struct deref_fetch_param {

		*(type *)dest = 0;					\

}

DEFINE_BASIC_FETCH_FUNCS(deref)

DEFINE_FETCH_deref(string)

DEFINE_FETCH_deref(string_size)

static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)

{

	if (CHECK_BASIC_FETCH_FUNCS(deref, data->orig.fn))

	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))

		free_deref_fetch_param(data->orig.data);

	else if (CHECK_BASIC_FETCH_FUNCS(symbol, data->orig.fn))

	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))

		free_symbol_cache(data->orig.data);

	kfree(data);

}

#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)

#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)

#define ASSIGN_FETCH_FUNC(kind, type)	\

	.kind = FETCH_FUNC_NAME(kind, type)

/* Fetch types */

enum {

	FETCH_MTD_reg = 0,

	FETCH_MTD_stack,

	FETCH_MTD_retval,

	FETCH_MTD_memory,

	FETCH_MTD_symbol,

	FETCH_MTD_deref,

	FETCH_MTD_END,

};

#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)	\

	{.name = #ptype,			\

	 .size = sizeof(ftype),			\

#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,					\

	 .is_signed = sign,				\

	 .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(memory, ftype),			\

ASSIGN_FETCH_FUNC(symbol, ftype),			\

ASSIGN_FETCH_FUNC(deref, ftype),			\

	  }						\

	}

#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)			\

	__ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)

#define FETCH_TYPE_STRING 0

#define FETCH_TYPE_STRSIZE 1

/* Fetch type information table */

static const struct fetch_type {

	const char	*name;		/* Name of type */

	int		is_signed;	/* Signed flag */

	print_type_func_t	print;	/* Print functions */

	const char	*fmt;		/* Fromat string */

	const char	*fmttype;	/* Name in format file */

	/* Fetch functions */

	fetch_func_t	reg;

	fetch_func_t	stack;

	fetch_func_t	retval;

	fetch_func_t	memory;

	fetch_func_t	symbol;

	fetch_func_t	deref;

	fetch_func_t	fetch[FETCH_MTD_END];

} 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),

	*(unsigned long *)dest = kernel_stack_pointer(regs);

}

static fetch_func_t get_fetch_size_function(const struct fetch_type *type,

					    fetch_func_t orig_fn)

{

	int i;

	if (type != &fetch_type_table[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 fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];

	WARN_ON(1);	/* This should not happen */

	return NULL;

}

/**

 * Kprobe event core functions

 */

struct probe_arg {

	struct fetch_param	fetch;

	struct fetch_param	fetch_size;

	unsigned int		offset;	/* Offset from argument entry */

	const char		*name;	/* Name of this argument */

	const char		*comm;	/* Command of this argument */

static void free_probe_arg(struct probe_arg *arg)

{

	if (CHECK_BASIC_FETCH_FUNCS(deref, arg->fetch.fn))

	if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))

		free_deref_fetch_param(arg->fetch.data);

	else if (CHECK_BASIC_FETCH_FUNCS(symbol, arg->fetch.fn))

	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))

		free_symbol_cache(arg->fetch.data);

	kfree(arg->name);

	kfree(arg->comm);

	if (strcmp(arg, "retval") == 0) {

		if (is_return)

			f->fn = t->retval;

			f->fn = t->fetch[FETCH_MTD_retval];

		else

			ret = -EINVAL;

	} else if (strncmp(arg, "stack", 5) == 0) {

			if (ret || param > PARAM_MAX_STACK)

				ret = -EINVAL;

			else {

				f->fn = t->stack;

				f->fn = t->fetch[FETCH_MTD_stack];

				f->data = (void *)param;

			}

		} else

	case '%':	/* named register */

		ret = regs_query_register_offset(arg + 1);

		if (ret >= 0) {

			f->fn = t->reg;

			f->fn = t->fetch[FETCH_MTD_reg];

			f->data = (void *)(unsigned long)ret;

			ret = 0;

		}

			ret = strict_strtoul(arg + 1, 0, &param);

			if (ret)

				break;

			f->fn = t->memory;

			f->fn = t->fetch[FETCH_MTD_memory];

			f->data = (void *)param;

		} else {

			ret = split_symbol_offset(arg + 1, &offset);

				break;

			f->data = alloc_symbol_cache(arg + 1, offset);

			if (f->data)

				f->fn = t->symbol;

				f->fn = t->fetch[FETCH_MTD_symbol];

		}

		break;

	case '+':	/* deref memory */

			if (ret)

				kfree(dprm);

			else {

				f->fn = t->deref;

				f->fn = t->fetch[FETCH_MTD_deref];

				f->data = (void *)dprm;

			}

		}

		break;

	}

	if (!ret && !f->fn)

	if (!ret && !f->fn) {	/* Parsed, but do not find fetch method */

		pr_info("%s type has no corresponding fetch method.\n",

			t->name);

		ret = -EINVAL;

	}

	return ret;

}

			   struct probe_arg *parg, int is_return)

{

	const char *t;

	int ret;

	if (strlen(arg) > MAX_ARGSTR_LEN) {

		pr_info("Argument is too long.: %s\n",  arg);

	}

	parg->offset = tp->size;

	tp->size += parg->type->size;

	return __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);

	ret = __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);

	if (ret >= 0) {

		parg->fetch_size.fn = get_fetch_size_function(parg->type,

							      parg->fetch.fn);

		parg->fetch_size.data = parg->fetch.data;

	}

	return ret;

}

/* Return 1 if name is reserved or already used by another argument */

	.release        = seq_release,

};

/* Sum up total data length for dynamic arraies (strings) */

static __kprobes 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 __kprobes 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);

	}

}

/* Kprobe handler */

static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)

{

	struct kprobe_trace_entry_head *entry;

	struct ring_buffer_event *event;

	struct ring_buffer *buffer;

	u8 *data;

	int size, i, pc;

	int size, dsize, pc;

	unsigned long irq_flags;

	struct ftrace_event_call *call = &tp->call;

	local_save_flags(irq_flags);

	pc = preempt_count();

	size = sizeof(*entry) + tp->size;

	dsize = __get_data_size(tp, regs);

	size = sizeof(*entry) + tp->size + dsize;

	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,

						  size, irq_flags, pc);

	entry = ring_buffer_event_data(event);

	entry->ip = (unsigned long)kp->addr;

	data = (u8 *)&entry[1];

	for (i = 0; i < tp->nr_args; i++)

		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);

	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

	if (!filter_current_check_discard(buffer, call, entry, event))

		trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);

	struct kretprobe_trace_entry_head *entry;

	struct ring_buffer_event *event;

	struct ring_buffer *buffer;

	u8 *data;

	int size, i, pc;

	int size, pc, dsize;

	unsigned long irq_flags;

	struct ftrace_event_call *call = &tp->call;

	local_save_flags(irq_flags);

	pc = preempt_count();

	size = sizeof(*entry) + tp->size;

	dsize = __get_data_size(tp, regs);

	size = sizeof(*entry) + tp->size + dsize;

	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,

						  size, irq_flags, pc);

	entry = ring_buffer_event_data(event);

	entry->func = (unsigned long)tp->rp.kp.addr;

	entry->ret_ip = (unsigned long)ri->ret_addr;

	data = (u8 *)&entry[1];

	for (i = 0; i < tp->nr_args; i++)

		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);

	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

	if (!filter_current_check_discard(buffer, call, entry, event))

		trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);

	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))

					     data + tp->args[i].offset, field))

			goto partial;

	if (!trace_seq_puts(s, "\n"))

	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))

					     data + tp->args[i].offset, field))

			goto partial;

	if (!trace_seq_puts(s, "\n"))

	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);

	/* Set argument names as fields */

	for (i = 0; i < tp->nr_args; i++) {

		ret = trace_define_field(event_call, tp->args[i].type->name,

		ret = trace_define_field(event_call, tp->args[i].type->fmttype,

					 tp->args[i].name,

					 sizeof(field) + tp->args[i].offset,

					 tp->args[i].type->size,

	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);

	/* Set argument names as fields */

	for (i = 0; i < tp->nr_args; i++) {

		ret = trace_define_field(event_call, tp->args[i].type->name,

		ret = trace_define_field(event_call, tp->args[i].type->fmttype,

					 tp->args[i].name,

					 sizeof(field) + tp->args[i].offset,

					 tp->args[i].type->size,

	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)

			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);

	}

	struct ftrace_event_call *call = &tp->call;

	struct kprobe_trace_entry_head *entry;

	struct hlist_head *head;

	u8 *data;

	int size, __size, i;

	int size, __size, dsize;

	int rctx;

	__size = sizeof(*entry) + tp->size;

	dsize = __get_data_size(tp, regs);