[linux-2.6-block.git] / kernel / trace / trace_probe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Common code for probe-based Dynamic events.
 *
 * This code was copied from kernel/trace/trace_kprobe.c written by
 * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 *
 * Updates to make this generic:
 * Copyright (C) IBM Corporation, 2010-2011
 * Author:     Srikar Dronamraju
 */
#define pr_fmt(fmt)	"trace_probe: " fmt

#include "trace_probe.h"

const char *reserved_field_names[] = {
	"common_type",
	"common_flags",
	"common_preempt_count",
	"common_pid",
	"common_tgid",
	FIELD_STRING_IP,
	FIELD_STRING_RETIP,
	FIELD_STRING_FUNC,
};

/* 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)			\
{									\
	trace_seq_printf(s, " %s=" fmt, name, *(type *)data);		\
	return !trace_seq_has_overflowed(s);				\
}									\
const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;				\
NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(tname));

DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
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")

/* Print type function for string type */
int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
				 void *data, void *ent)
{
	int len = *(u32 *)data >> 16;

	if (!len)
		trace_seq_printf(s, " %s=(fault)", name);
	else
		trace_seq_printf(s, " %s=\"%s\"", name,
				 (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\\\"";

#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);

static void free_deref_fetch_param(struct deref_fetch_param *data)
{
	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);
}
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;
};

#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)
{
	int i;

	if (!type)
		type = DEFAULT_FETCH_TYPE_STR;

	/* Special case: bitfield */
	if (*type == 'b') {
		unsigned long bs;

		type = strchr(type, '/');
		if (!type)
			goto fail;

		type++;
		if (kstrtoul(type, 0, &bs))
			goto fail;

		switch (bs) {
		case 8:
			return find_fetch_type("u8", ftbl);
		case 16:
			return find_fetch_type("u16", ftbl);
		case 32:
			return find_fetch_type("u32", ftbl);
		case 64:
			return find_fetch_type("u64", ftbl);
		default:
			goto fail;
		}
	}

	for (i = 0; ftbl[i].name; i++) {
		if (strcmp(type, ftbl[i].name) == 0)
			return &ftbl[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, long *offset)
{
	char *tmp;
	int ret;

	if (!offset)
		return -EINVAL;

	tmp = strpbrk(symbol, "+-");
	if (tmp) {
		ret = kstrtol(tmp, 0, offset);
		if (ret)
			return ret;
		*tmp = '\0';
	} else
		*offset = 0;

	return 0;
}

#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,
			    bool is_kprobe)
{
	int ret = 0;
	unsigned long param;

	if (strcmp(arg, "retval") == 0) {
		if (is_return)
			f->fn = t->fetch[FETCH_MTD_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;
		} 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;
			}
		} 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];
	} else
		ret = -EINVAL;

	return ret;
}

/* 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)
{
	unsigned long param;
	long offset;
	char *tmp;
	int ret = 0;

	switch (arg[0]) {
	case '$':
		ret = parse_probe_vars(arg + 1, t, f, 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;
			ret = 0;
		}
		break;

	case '@':	/* memory, file-offset or symbol */
		if (isdigit(arg[1])) {
			ret = kstrtoul(arg + 1, 0, &param);
			if (ret)
				break;

			f->fn = t->fetch[FETCH_MTD_memory];
			f->data = (void *)param;
		} else if (arg[1] == '+') {
			/* kprobes don't support file offsets */
			if (is_kprobe)
				return -EINVAL;

			ret = kstrtol(arg + 2, 0, &offset);
			if (ret)
				break;

			f->fn = t->fetch[FETCH_MTD_file_offset];
			f->data = (void *)offset;
		} else {
			/* uprobes don't support symbols */
			if (!is_kprobe)
				return -EINVAL;

			ret = traceprobe_split_symbol_offset(arg + 1, &offset);
			if (ret)
				break;

			f->data = alloc_symbol_cache(arg + 1, offset);
			if (f->data)
				f->fn = t->fetch[FETCH_MTD_symbol];
		}
		break;

	case '+':	/* deref memory */
		arg++;	/* Skip '+', because kstrtol() rejects it. */
	case '-':
		tmp = strchr(arg, '(');
		if (!tmp)
			break;

		*tmp = '\0';
		ret = kstrtol(arg, 0, &offset);

		if (ret)
			break;

		arg = tmp + 1;
		tmp = strrchr(arg, ')');

		if (tmp) {
			struct deref_fetch_param	*dprm;
			const struct fetch_type		*t2;

			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);
			if (ret)
				kfree(dprm);
			else {
				f->fn = t->fetch[FETCH_MTD_deref];
				f->data = (void *)dprm;
			}
		}
		break;
	}
	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;
}

#define BYTES_TO_BITS(nb)	((BITS_PER_LONG * (nb)) / sizeof(long))

/* 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 bitfield_fetch_param *bprm;
	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 != '@')
		return -EINVAL;

	bf = tail + 1;
	bo = simple_strtoul(bf, &tail, 0);

	if (tail == bf || *tail != '/')
		return -EINVAL;

	bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
	bprm->low_shift = bprm->hi_shift + bo;

	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)
{
	const char *t;
	int ret;

	if (strlen(arg) > MAX_ARGSTR_LEN) {
		pr_info("Argument is too long.: %s\n",  arg);
		return -ENOSPC;
	}
	parg->comm = kstrdup(arg, GFP_KERNEL);
	if (!parg->comm) {
		pr_info("Failed to allocate memory for command '%s'.\n", arg);
		return -ENOMEM;
	}
	t = strchr(parg->comm, ':');
	if (t) {
		arg[t - parg->comm] = '\0';
		t++;
	}
	/*
	 * 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, ftbl);
	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);

	if (ret >= 0) {
		parg->fetch_size.fn = get_fetch_size_function(parg->type,
							      parg->fetch.fn,
							      ftbl);
		parg->fetch_size.data = parg->fetch.data;
	}

	return ret;
}

/* Return 1 if name is reserved or already used by another argument */
int traceprobe_conflict_field_name(const char *name,
			       struct probe_arg *args, int narg)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
		if (strcmp(reserved_field_names[i], name) == 0)
			return 1;

	for (i = 0; i < narg; i++)
		if (strcmp(args[i].name, name) == 0)
			return 1;

	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->name);
	kfree(arg->comm);
}

static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
			   bool is_return)
{
	int i;
	int pos = 0;

	const char *fmt, *arg;

	if (!is_return) {
		fmt = "(%lx)";
		arg = "REC->" FIELD_STRING_IP;
	} else {
		fmt = "(%lx <- %lx)";
		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);
	}

	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);
	}

#undef LEN_OR_ZERO

	/* return the length of print_fmt */
	return pos;
}

int set_print_fmt(struct trace_probe *tp, bool is_return)
{
	int len;
	char *print_fmt;

	/* First: called with 0 length to calculate the needed length */
	len = __set_print_fmt(tp, NULL, 0, is_return);
	print_fmt = kmalloc(len + 1, GFP_KERNEL);
	if (!print_fmt)
		return -ENOMEM;

	/* Second: actually write the @print_fmt */
	__set_print_fmt(tp, print_fmt, len + 1, is_return);
	tp->call.print_fmt = print_fmt;

	return 0;
}
Commit	Line	Data
bcea3f96	1	// SPDX-License-Identifier: GPL-2.0
8ab83f56 SD	2	/*
	3	* Common code for probe-based Dynamic events.
	4	*
8ab83f56 SD	5	* This code was copied from kernel/trace/trace_kprobe.c written by
	6	* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
	7	*
	8	* Updates to make this generic:
	9	* Copyright (C) IBM Corporation, 2010-2011
	10	* Author: Srikar Dronamraju
	11	*/
72576341	12	#define pr_fmt(fmt) "trace_probe: " fmt
8ab83f56 SD	13
	14	#include "trace_probe.h"
	15
	16	const char *reserved_field_names[] = {
	17	"common_type",
	18	"common_flags",
	19	"common_preempt_count",
	20	"common_pid",
	21	"common_tgid",
	22	FIELD_STRING_IP,
	23	FIELD_STRING_RETIP,
	24	FIELD_STRING_FUNC,
	25	};
	26
8ab83f56	27	/* Printing in basic type function template */
17ce3dc7 MH	28	#define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt) \
17ce3dc7 MH	29	int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq s, const char name, \
3da0f180	30	void data, void ent) \
8ab83f56	31	{ \
d2b0191a SRRH	32	trace_seq_printf(s, " %s=" fmt, name, (type )data); \
d2b0191a SRRH	33	return !trace_seq_has_overflowed(s); \
8ab83f56	34	} \
17ce3dc7 MH	35	const char PRINT_TYPE_FMT_NAME(tname)[] = fmt; \
17ce3dc7 MH	36	NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(tname));
8ab83f56	37
bdca79c2 MH	38	DEFINE_BASIC_PRINT_TYPE_FUNC(u8, u8, "%u")
	39	DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
	40	DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
	41	DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
17ce3dc7 MH	42	DEFINE_BASIC_PRINT_TYPE_FUNC(s8, s8, "%d")
	43	DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
	44	DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
	45	DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
	46	DEFINE_BASIC_PRINT_TYPE_FUNC(x8, u8, "0x%x")
	47	DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
	48	DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
	49	DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
8ab83f56	50
8ab83f56	51	/* Print type function for string type */
3da0f180 MH	52	int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq s, const char name,
3da0f180 MH	53	void data, void ent)
8ab83f56 SD	54	{
	55	int len = (u32 )data >> 16;
	56
	57	if (!len)
d2b0191a	58	trace_seq_printf(s, " %s=(fault)", name);
8ab83f56	59	else
d2b0191a SRRH	60	trace_seq_printf(s, " %s=\"%s\"", name,
	61	(const char *)get_loc_data(data, ent));
	62	return !trace_seq_has_overflowed(s);
8ab83f56	63	}
3da0f180	64	NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
8ab83f56	65
b26c74e1	66	const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
8ab83f56	67
8ab83f56 SD	68	#define CHECK_FETCH_FUNCS(method, fn) \
	69	(((FETCH_FUNC_NAME(method, u8) == fn) \|\| \
	70	(FETCH_FUNC_NAME(method, u16) == fn) \|\| \
	71	(FETCH_FUNC_NAME(method, u32) == fn) \|\| \
	72	(FETCH_FUNC_NAME(method, u64) == fn) \|\| \
	73	(FETCH_FUNC_NAME(method, string) == fn) \|\| \
	74	(FETCH_FUNC_NAME(method, string_size) == fn)) \
	75	&& (fn != NULL))
	76
	77	/* Data fetch function templates */
	78	#define DEFINE_FETCH_reg(type) \
3da0f180	79	void FETCH_FUNC_NAME(reg, type)(struct pt_regs regs, void offset, void *dest) \
8ab83f56 SD	80	{ \
	81	(type )dest = (type)regs_get_register(regs, \
	82	(unsigned int)((unsigned long)offset)); \
3da0f180 MH	83	} \
3da0f180 MH	84	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
8ab83f56 SD	85	DEFINE_BASIC_FETCH_FUNCS(reg)
	86	/* No string on the register */
	87	#define fetch_reg_string NULL
	88	#define fetch_reg_string_size NULL
	89
8ab83f56	90	#define DEFINE_FETCH_retval(type) \
3da0f180 MH	91	void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \
3da0f180 MH	92	void dummy, void dest) \
8ab83f56 SD	93	{ \
8ab83f56 SD	94	(type )dest = (type)regs_return_value(regs); \
3da0f180 MH	95	} \
3da0f180 MH	96	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
8ab83f56 SD	97	DEFINE_BASIC_FETCH_FUNCS(retval)
	98	/* No string on the retval */
	99	#define fetch_retval_string NULL
	100	#define fetch_retval_string_size NULL
	101
8ab83f56 SD	102	/* Dereference memory access function */
	103	struct deref_fetch_param {
	104	struct fetch_param orig;
	105	long offset;
3925f4a5 HL	106	fetch_func_t fetch;
3925f4a5 HL	107	fetch_func_t fetch_size;
8ab83f56 SD	108	};
	109
	110	#define DEFINE_FETCH_deref(type) \
3da0f180 MH	111	void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
3da0f180 MH	112	void data, void dest) \
8ab83f56 SD	113	{ \
	114	struct deref_fetch_param *dprm = data; \
	115	unsigned long addr; \
	116	call_fetch(&dprm->orig, regs, &addr); \
	117	if (addr) { \
	118	addr += dprm->offset; \
3925f4a5	119	dprm->fetch(regs, (void *)addr, dest); \
8ab83f56 SD	120	} else \
8ab83f56 SD	121	(type )dest = 0; \
3da0f180 MH	122	} \
3da0f180 MH	123	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
8ab83f56 SD	124	DEFINE_BASIC_FETCH_FUNCS(deref)
8ab83f56 SD	125	DEFINE_FETCH_deref(string)
3925f4a5	126
3da0f180 MH	127	void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
3da0f180 MH	128	void data, void dest)
3925f4a5 HL	129	{
	130	struct deref_fetch_param *dprm = data;
	131	unsigned long addr;
	132
	133	call_fetch(&dprm->orig, regs, &addr);
	134	if (addr && dprm->fetch_size) {
	135	addr += dprm->offset;
	136	dprm->fetch_size(regs, (void *)addr, dest);
	137	} else
	138	(string_size )dest = 0;
	139	}
3da0f180	140	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
8ab83f56	141
3da0f180	142	static void update_deref_fetch_param(struct deref_fetch_param *data)
8ab83f56 SD	143	{
	144	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	145	update_deref_fetch_param(data->orig.data);
	146	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	147	update_symbol_cache(data->orig.data);
	148	}
3da0f180	149	NOKPROBE_SYMBOL(update_deref_fetch_param);
8ab83f56	150
3da0f180	151	static void free_deref_fetch_param(struct deref_fetch_param *data)
8ab83f56 SD	152	{
	153	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	154	free_deref_fetch_param(data->orig.data);
	155	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	156	free_symbol_cache(data->orig.data);
	157	kfree(data);
	158	}
3da0f180	159	NOKPROBE_SYMBOL(free_deref_fetch_param);
8ab83f56 SD	160
	161	/* Bitfield fetch function */
	162	struct bitfield_fetch_param {
	163	struct fetch_param orig;
	164	unsigned char hi_shift;
	165	unsigned char low_shift;
	166	};
	167
	168	#define DEFINE_FETCH_bitfield(type) \
3da0f180 MH	169	void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \
3da0f180 MH	170	void data, void dest) \
8ab83f56 SD	171	{ \
	172	struct bitfield_fetch_param *bprm = data; \
	173	type buf = 0; \
	174	call_fetch(&bprm->orig, regs, &buf); \
	175	if (buf) { \
	176	buf <<= bprm->hi_shift; \
	177	buf >>= bprm->low_shift; \
	178	} \
	179	(type )dest = buf; \
3da0f180 MH	180	} \
3da0f180 MH	181	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
8ab83f56 SD	182	DEFINE_BASIC_FETCH_FUNCS(bitfield)
	183	#define fetch_bitfield_string NULL
	184	#define fetch_bitfield_string_size NULL
	185
fbc1963d	186	static void
8ab83f56 SD	187	update_bitfield_fetch_param(struct bitfield_fetch_param *data)
	188	{
	189	/*
	190	* Don't check the bitfield itself, because this must be the
	191	* last fetch function.
	192	*/
	193	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	194	update_deref_fetch_param(data->orig.data);
	195	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	196	update_symbol_cache(data->orig.data);
	197	}
	198
fbc1963d	199	static void
8ab83f56 SD	200	free_bitfield_fetch_param(struct bitfield_fetch_param *data)
	201	{
	202	/*
	203	* Don't check the bitfield itself, because this must be the
	204	* last fetch function.
	205	*/
	206	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	207	free_deref_fetch_param(data->orig.data);
	208	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	209	free_symbol_cache(data->orig.data);
	210
	211	kfree(data);
	212	}
	213
35abb67d OS	214	void FETCH_FUNC_NAME(comm, string)(struct pt_regs *regs,
	215	void data, void dest)
	216	{
	217	int maxlen = get_rloc_len((u32 )dest);
	218	u8 *dst = get_rloc_data(dest);
	219	long ret;
	220
	221	if (!maxlen)
	222	return;
	223
	224	ret = strlcpy(dst, current->comm, maxlen);
	225	(u32 )dest = make_data_rloc(ret, get_rloc_offs((u32 )dest));
	226	}
	227	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string));
	228
	229	void FETCH_FUNC_NAME(comm, string_size)(struct pt_regs *regs,
	230	void data, void dest)
	231	{
	232	(u32 )dest = strlen(current->comm) + 1;
	233	}
	234	NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string_size));
	235
34fee3a1 NK	236	static const struct fetch_type find_fetch_type(const char type,
34fee3a1 NK	237	const struct fetch_type *ftbl)
8ab83f56 SD	238	{
	239	int i;
	240
	241	if (!type)
	242	type = DEFAULT_FETCH_TYPE_STR;
	243
	244	/* Special case: bitfield */
	245	if (*type == 'b') {
	246	unsigned long bs;
	247
	248	type = strchr(type, '/');
	249	if (!type)
	250	goto fail;
	251
	252	type++;
bcd83ea6	253	if (kstrtoul(type, 0, &bs))
8ab83f56 SD	254	goto fail;
	255
	256	switch (bs) {
	257	case 8:
34fee3a1	258	return find_fetch_type("u8", ftbl);
8ab83f56	259	case 16:
34fee3a1	260	return find_fetch_type("u16", ftbl);
8ab83f56	261	case 32:
34fee3a1	262	return find_fetch_type("u32", ftbl);
8ab83f56	263	case 64:
34fee3a1	264	return find_fetch_type("u64", ftbl);
8ab83f56 SD	265	default:
	266	goto fail;
	267	}
	268	}
	269
34fee3a1 NK	270	for (i = 0; ftbl[i].name; i++) {
	271	if (strcmp(type, ftbl[i].name) == 0)
	272	return &ftbl[i];
	273	}
8ab83f56 SD	274
	275	fail:
	276	return NULL;
	277	}
	278
	279	/* Special function : only accept unsigned long */
3da0f180	280	static void fetch_kernel_stack_address(struct pt_regs regs, void dummy, void *dest)
8ab83f56 SD	281	{
	282	(unsigned long )dest = kernel_stack_pointer(regs);
	283	}
3da0f180	284	NOKPROBE_SYMBOL(fetch_kernel_stack_address);
8ab83f56	285
3da0f180	286	static void fetch_user_stack_address(struct pt_regs regs, void dummy, void *dest)
b079d374 NK	287	{
	288	(unsigned long )dest = user_stack_pointer(regs);
	289	}
3da0f180	290	NOKPROBE_SYMBOL(fetch_user_stack_address);
b079d374	291
8ab83f56	292	static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
34fee3a1 NK	293	fetch_func_t orig_fn,
34fee3a1 NK	294	const struct fetch_type *ftbl)
8ab83f56 SD	295	{
	296	int i;
	297
34fee3a1	298	if (type != &ftbl[FETCH_TYPE_STRING])
8ab83f56 SD	299	return NULL; /* Only string type needs size function */
	300
	301	for (i = 0; i < FETCH_MTD_END; i++)
	302	if (type->fetch[i] == orig_fn)
34fee3a1	303	return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
8ab83f56 SD	304
	305	WARN_ON(1); /* This should not happen */
	306
	307	return NULL;
	308	}
	309
	310	/* Split symbol and offset. */
c5d343b6	311	int traceprobe_split_symbol_offset(char symbol, long offset)
8ab83f56 SD	312	{
	313	char *tmp;
	314	int ret;
	315
	316	if (!offset)
	317	return -EINVAL;
	318
c5d343b6	319	tmp = strpbrk(symbol, "+-");
8ab83f56	320	if (tmp) {
c5d343b6	321	ret = kstrtol(tmp, 0, offset);
8ab83f56 SD	322	if (ret)
8ab83f56 SD	323	return ret;
8ab83f56 SD	324	*tmp = '\0';
	325	} else
	326	*offset = 0;
	327
	328	return 0;
	329	}
	330
	331	#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
	332
	333	static int parse_probe_vars(char arg, const struct fetch_type t,
b079d374 NK	334	struct fetch_param *f, bool is_return,
b079d374 NK	335	bool is_kprobe)
8ab83f56 SD	336	{
	337	int ret = 0;
	338	unsigned long param;
	339
	340	if (strcmp(arg, "retval") == 0) {
	341	if (is_return)
	342	f->fn = t->fetch[FETCH_MTD_retval];
	343	else
	344	ret = -EINVAL;
	345	} else if (strncmp(arg, "stack", 5) == 0) {
	346	if (arg[5] == '\0') {
b079d374 NK	347	if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
	348	return -EINVAL;
	349
	350	if (is_kprobe)
	351	f->fn = fetch_kernel_stack_address;
8ab83f56	352	else
b079d374	353	f->fn = fetch_user_stack_address;
8ab83f56	354	} else if (isdigit(arg[5])) {
bcd83ea6	355	ret = kstrtoul(arg + 5, 10, &param);
b079d374	356	if (ret \|\| (is_kprobe && param > PARAM_MAX_STACK))
8ab83f56 SD	357	ret = -EINVAL;
	358	else {
	359	f->fn = t->fetch[FETCH_MTD_stack];
	360	f->data = (void *)param;
	361	}
	362	} else
	363	ret = -EINVAL;
35abb67d OS	364	} else if (strcmp(arg, "comm") == 0) {
	365	if (strcmp(t->name, "string") != 0 &&
	366	strcmp(t->name, "string_size") != 0)
	367	return -EINVAL;
	368	f->fn = t->fetch[FETCH_MTD_comm];
8ab83f56 SD	369	} else
	370	ret = -EINVAL;
	371
	372	return ret;
	373	}
	374
	375	/* Recursive argument parser */
	376	static int parse_probe_arg(char arg, const struct fetch_type t,
d9a16d3a SR	377	struct fetch_param *f, bool is_return, bool is_kprobe,
d9a16d3a SR	378	const struct fetch_type *ftbl)
8ab83f56 SD	379	{
	380	unsigned long param;
	381	long offset;
	382	char *tmp;
34fee3a1	383	int ret = 0;
8ab83f56	384
8ab83f56 SD	385	switch (arg[0]) {
8ab83f56 SD	386	case '$':
b079d374	387	ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
8ab83f56 SD	388	break;
	389
	390	case '%': /* named register */
	391	ret = regs_query_register_offset(arg + 1);
	392	if (ret >= 0) {
	393	f->fn = t->fetch[FETCH_MTD_reg];
	394	f->data = (void *)(unsigned long)ret;
	395	ret = 0;
	396	}
	397	break;
	398
b7e0bf34	399	case '@': /* memory, file-offset or symbol */
8ab83f56	400	if (isdigit(arg[1])) {
bcd83ea6	401	ret = kstrtoul(arg + 1, 0, &param);
8ab83f56 SD	402	if (ret)
	403	break;
	404
	405	f->fn = t->fetch[FETCH_MTD_memory];
	406	f->data = (void *)param;
b7e0bf34 NK	407	} else if (arg[1] == '+') {
	408	/* kprobes don't support file offsets */
	409	if (is_kprobe)
	410	return -EINVAL;
	411
	412	ret = kstrtol(arg + 2, 0, &offset);
	413	if (ret)
	414	break;
	415
	416	f->fn = t->fetch[FETCH_MTD_file_offset];
	417	f->data = (void *)offset;
8ab83f56	418	} else {
b079d374 NK	419	/* uprobes don't support symbols */
	420	if (!is_kprobe)
	421	return -EINVAL;
	422
8ab83f56 SD	423	ret = traceprobe_split_symbol_offset(arg + 1, &offset);
	424	if (ret)
	425	break;
	426
	427	f->data = alloc_symbol_cache(arg + 1, offset);
	428	if (f->data)
	429	f->fn = t->fetch[FETCH_MTD_symbol];
	430	}
	431	break;
	432
	433	case '+': /* deref memory */
bcd83ea6	434	arg++; /* Skip '+', because kstrtol() rejects it. */
8ab83f56 SD	435	case '-':
	436	tmp = strchr(arg, '(');
	437	if (!tmp)
	438	break;
	439
	440	*tmp = '\0';
bcd83ea6	441	ret = kstrtol(arg, 0, &offset);
8ab83f56 SD	442
	443	if (ret)
	444	break;
	445
	446	arg = tmp + 1;
	447	tmp = strrchr(arg, ')');
	448
	449	if (tmp) {
	450	struct deref_fetch_param *dprm;
	451	const struct fetch_type *t2;
	452
34fee3a1	453	t2 = find_fetch_type(NULL, ftbl);
8ab83f56 SD	454	*tmp = '\0';
	455	dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
	456
	457	if (!dprm)
	458	return -ENOMEM;
	459
	460	dprm->offset = offset;
3925f4a5 HL	461	dprm->fetch = t->fetch[FETCH_MTD_memory];
	462	dprm->fetch_size = get_fetch_size_function(t,
	463	dprm->fetch, ftbl);
f3f096cf	464	ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
d9a16d3a	465	is_kprobe, ftbl);
8ab83f56 SD	466	if (ret)
	467	kfree(dprm);
	468	else {
	469	f->fn = t->fetch[FETCH_MTD_deref];
	470	f->data = (void *)dprm;
	471	}
	472	}
	473	break;
	474	}
	475	if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
	476	pr_info("%s type has no corresponding fetch method.\n", t->name);
	477	ret = -EINVAL;
	478	}
	479
	480	return ret;
	481	}
	482
	483	#define BYTES_TO_BITS(nb) ((BITS_PER_LONG * (nb)) / sizeof(long))
	484
	485	/* Bitfield type needs to be parsed into a fetch function */
	486	static int __parse_bitfield_probe_arg(const char *bf,
	487	const struct fetch_type *t,
	488	struct fetch_param *f)
	489	{
	490	struct bitfield_fetch_param *bprm;
	491	unsigned long bw, bo;
	492	char *tail;
	493
	494	if (*bf != 'b')
	495	return 0;
	496
	497	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
	498	if (!bprm)
	499	return -ENOMEM;
	500
	501	bprm->orig = *f;
	502	f->fn = t->fetch[FETCH_MTD_bitfield];
	503	f->data = (void *)bprm;
	504	bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */
	505
	506	if (bw == 0 \|\| *tail != '@')
	507	return -EINVAL;
	508
	509	bf = tail + 1;
	510	bo = simple_strtoul(bf, &tail, 0);
	511
	512	if (tail == bf \|\| *tail != '/')
	513	return -EINVAL;
	514
	515	bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
	516	bprm->low_shift = bprm->hi_shift + bo;
	517
	518	return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
	519	}
	520
	521	/* String length checking wrapper */
	522	int traceprobe_parse_probe_arg(char arg, ssize_t size,
d9a16d3a SR	523	struct probe_arg *parg, bool is_return, bool is_kprobe,
d9a16d3a SR	524	const struct fetch_type *ftbl)
8ab83f56 SD	525	{
	526	const char *t;
	527	int ret;
	528
	529	if (strlen(arg) > MAX_ARGSTR_LEN) {
	530	pr_info("Argument is too long.: %s\n", arg);
	531	return -ENOSPC;
	532	}
	533	parg->comm = kstrdup(arg, GFP_KERNEL);
	534	if (!parg->comm) {
	535	pr_info("Failed to allocate memory for command '%s'.\n", arg);
	536	return -ENOMEM;
	537	}
	538	t = strchr(parg->comm, ':');
	539	if (t) {
	540	arg[t - parg->comm] = '\0';
	541	t++;
	542	}
35abb67d OS	543	/*
	544	* The default type of $comm should be "string", and it can't be
	545	* dereferenced.
	546	*/
	547	if (!t && strcmp(arg, "$comm") == 0)
	548	t = "string";
34fee3a1	549	parg->type = find_fetch_type(t, ftbl);
8ab83f56 SD	550	if (!parg->type) {
	551	pr_info("Unsupported type: %s\n", t);
	552	return -EINVAL;
	553	}
	554	parg->offset = *size;
	555	*size += parg->type->size;
d9a16d3a SR	556	ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
d9a16d3a SR	557	is_kprobe, ftbl);
8ab83f56 SD	558
	559	if (ret >= 0 && t != NULL)
	560	ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
	561
	562	if (ret >= 0) {
	563	parg->fetch_size.fn = get_fetch_size_function(parg->type,
34fee3a1 NK	564	parg->fetch.fn,
34fee3a1 NK	565	ftbl);
8ab83f56 SD	566	parg->fetch_size.data = parg->fetch.data;
	567	}
	568
	569	return ret;
	570	}
	571
	572	/* Return 1 if name is reserved or already used by another argument */
	573	int traceprobe_conflict_field_name(const char *name,
	574	struct probe_arg *args, int narg)
	575	{
	576	int i;
	577
	578	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
	579	if (strcmp(reserved_field_names[i], name) == 0)
	580	return 1;
	581
	582	for (i = 0; i < narg; i++)
	583	if (strcmp(args[i].name, name) == 0)
	584	return 1;
	585
	586	return 0;
	587	}
	588
	589	void traceprobe_update_arg(struct probe_arg *arg)
	590	{
	591	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
	592	update_bitfield_fetch_param(arg->fetch.data);
	593	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
	594	update_deref_fetch_param(arg->fetch.data);
	595	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
	596	update_symbol_cache(arg->fetch.data);
	597	}
	598
	599	void traceprobe_free_probe_arg(struct probe_arg *arg)
	600	{
	601	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
	602	free_bitfield_fetch_param(arg->fetch.data);
	603	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
	604	free_deref_fetch_param(arg->fetch.data);
	605	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
	606	free_symbol_cache(arg->fetch.data);
	607
	608	kfree(arg->name);
	609	kfree(arg->comm);
	610	}
	611
5bf652aa NK	612	static int __set_print_fmt(struct trace_probe tp, char buf, int len,
	613	bool is_return)
	614	{
	615	int i;
	616	int pos = 0;
	617
	618	const char fmt, arg;
	619
	620	if (!is_return) {
	621	fmt = "(%lx)";
	622	arg = "REC->" FIELD_STRING_IP;
	623	} else {
	624	fmt = "(%lx <- %lx)";
	625	arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
	626	}
	627
	628	/* When len=0, we just calculate the needed length */
	629	#define LEN_OR_ZERO (len ? len - pos : 0)
	630
	631	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
	632
	633	for (i = 0; i < tp->nr_args; i++) {
	634	pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
	635	tp->args[i].name, tp->args[i].type->fmt);
	636	}
	637
	638	pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
	639
	640	for (i = 0; i < tp->nr_args; i++) {
	641	if (strcmp(tp->args[i].type->name, "string") == 0)
	642	pos += snprintf(buf + pos, LEN_OR_ZERO,
	643	", __get_str(%s)",
	644	tp->args[i].name);
	645	else
	646	pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
	647	tp->args[i].name);
	648	}
	649
	650	#undef LEN_OR_ZERO
	651
	652	/* return the length of print_fmt */
	653	return pos;
	654	}
	655
	656	int set_print_fmt(struct trace_probe *tp, bool is_return)
	657	{
	658	int len;
	659	char *print_fmt;
	660
	661	/* First: called with 0 length to calculate the needed length */
	662	len = __set_print_fmt(tp, NULL, 0, is_return);
	663	print_fmt = kmalloc(len + 1, GFP_KERNEL);
	664	if (!print_fmt)
	665	return -ENOMEM;
	666
	667	/* Second: actually write the @print_fmt */
	668	__set_print_fmt(tp, print_fmt, len + 1, is_return);
	669	tp->call.print_fmt = print_fmt;
	670
	671	return 0;
	672	}