[deliverable/linux.git] / kernel / trace / trace_probe.c

/*
 * Common code for probe-based Dynamic events.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * 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
 */

#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(type, fmt)				\
__kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,	\
						const char *name,	\
						void *data, void *ent)	\
{									\
	return trace_seq_printf(s, " %s=" fmt, name, *(type *)data);	\
}									\
const char PRINT_TYPE_FMT_NAME(type)[] = fmt;

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

/* Print type function for string type */
__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));
}

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)						\
__kprobes 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));	\
}
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)					\
__kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,	\
					  void *dummy, void *dest)	\
{									\
	*(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

/* 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)					\
__kprobes 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;					\
}
DEFINE_BASIC_FETCH_FUNCS(deref)
DEFINE_FETCH_deref(string)

__kprobes 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;
}

static __kprobes 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);
}

static __kprobes 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);
}

/* Bitfield fetch function */
struct bitfield_fetch_param {
	struct fetch_param	orig;
	unsigned char		hi_shift;
	unsigned char		low_shift;
};

#define DEFINE_FETCH_bitfield(type)					\
__kprobes 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;						\
}

DEFINE_BASIC_FETCH_FUNCS(bitfield)
#define fetch_bitfield_string		NULL
#define fetch_bitfield_string_size	NULL

static __kprobes 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 __kprobes 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);
}

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 __kprobes void fetch_kernel_stack_address(struct pt_regs *regs,
						 void *dummy, void *dest)
{
	*(unsigned long *)dest = kernel_stack_pointer(regs);
}

static __kprobes void fetch_user_stack_address(struct pt_regs *regs,
					       void *dummy, void *dest)
{
	*(unsigned long *)dest = user_stack_pointer(regs);
}

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)
{
	char *tmp;
	int ret;

	if (!offset)
		return -EINVAL;

	tmp = strchr(symbol, '+');
	if (tmp) {
		/* skip sign because kstrtoul doesn't accept '+' */
		ret = kstrtoul(tmp + 1, 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
		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;

	ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
	BUG_ON(ftbl == NULL);

	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 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 {
			/* 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);
			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;

	ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
	BUG_ON(ftbl == NULL);

	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++;
	}
	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);

	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);
}

int traceprobe_command(const char *buf, int (*createfn)(int, char **))
{
	char **argv;
	int argc, ret;

	argc = 0;
	ret = 0;
	argv = argv_split(GFP_KERNEL, buf, &argc);
	if (!argv)
		return -ENOMEM;

	if (argc)
		ret = createfn(argc, argv);

	argv_free(argv);

	return ret;
}

#define WRITE_BUFSIZE  4096

ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
				size_t count, loff_t *ppos,
				int (*createfn)(int, char **))
{
	char *kbuf, *tmp;
	int ret = 0;
	size_t done = 0;
	size_t size;

	kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
	if (!kbuf)
		return -ENOMEM;

	while (done < count) {
		size = count - done;

		if (size >= WRITE_BUFSIZE)
			size = WRITE_BUFSIZE - 1;

		if (copy_from_user(kbuf, buffer + done, size)) {
			ret = -EFAULT;
			goto out;
		}
		kbuf[size] = '\0';
		tmp = strchr(kbuf, '\n');

		if (tmp) {
			*tmp = '\0';
			size = tmp - kbuf + 1;
		} else if (done + size < count) {
			pr_warning("Line length is too long: "
				   "Should be less than %d.", WRITE_BUFSIZE);
			ret = -EINVAL;
			goto out;
		}
		done += size;
		/* Remove comments */
		tmp = strchr(kbuf, '#');

		if (tmp)
			*tmp = '\0';

		ret = traceprobe_command(kbuf, createfn);
		if (ret)
			goto out;
	}
	ret = done;

out:
	kfree(kbuf);

	return ret;
}

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
8ab83f56 SD	1	/*
	2	* Common code for probe-based Dynamic events.
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	* GNU General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public License
	14	* along with this program; if not, write to the Free Software
	15	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	16	*
	17	* This code was copied from kernel/trace/trace_kprobe.c written by
	18	* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
	19	*
	20	* Updates to make this generic:
	21	* Copyright (C) IBM Corporation, 2010-2011
	22	* Author: Srikar Dronamraju
	23	*/
	24
	25	#include "trace_probe.h"
	26
	27	const char *reserved_field_names[] = {
	28	"common_type",
	29	"common_flags",
	30	"common_preempt_count",
	31	"common_pid",
	32	"common_tgid",
	33	FIELD_STRING_IP,
	34	FIELD_STRING_RETIP,
	35	FIELD_STRING_FUNC,
	36	};
	37
8ab83f56	38	/* Printing in basic type function template */
50eb2672	39	#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt) \
b26c74e1	40	__kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, \
8ab83f56	41	const char *name, \
50eb2672	42	void data, void ent) \
8ab83f56	43	{ \
50eb2672	44	return trace_seq_printf(s, " %s=" fmt, name, (type )data); \
8ab83f56	45	} \
b26c74e1	46	const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
8ab83f56	47
50eb2672 NK	48	DEFINE_BASIC_PRINT_TYPE_FUNC(u8 , "0x%x")
	49	DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "0x%x")
	50	DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "0x%x")
	51	DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "0x%Lx")
	52	DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d")
	53	DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
	54	DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
	55	DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
8ab83f56	56
8ab83f56	57	/* Print type function for string type */
b26c74e1	58	__kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
8ab83f56 SD	59	const char *name,
	60	void data, void ent)
	61	{
	62	int len = (u32 )data >> 16;
	63
	64	if (!len)
	65	return trace_seq_printf(s, " %s=(fault)", name);
	66	else
	67	return trace_seq_printf(s, " %s=\"%s\"", name,
	68	(const char *)get_loc_data(data, ent));
	69	}
	70
b26c74e1	71	const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
8ab83f56	72
8ab83f56 SD	73	#define CHECK_FETCH_FUNCS(method, fn) \
	74	(((FETCH_FUNC_NAME(method, u8) == fn) \|\| \
	75	(FETCH_FUNC_NAME(method, u16) == fn) \|\| \
	76	(FETCH_FUNC_NAME(method, u32) == fn) \|\| \
	77	(FETCH_FUNC_NAME(method, u64) == fn) \|\| \
	78	(FETCH_FUNC_NAME(method, string) == fn) \|\| \
	79	(FETCH_FUNC_NAME(method, string_size) == fn)) \
	80	&& (fn != NULL))
	81
	82	/* Data fetch function templates */
	83	#define DEFINE_FETCH_reg(type) \
b26c74e1	84	__kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, \
8ab83f56 SD	85	void offset, void dest) \
	86	{ \
	87	(type )dest = (type)regs_get_register(regs, \
	88	(unsigned int)((unsigned long)offset)); \
	89	}
	90	DEFINE_BASIC_FETCH_FUNCS(reg)
	91	/* No string on the register */
	92	#define fetch_reg_string NULL
	93	#define fetch_reg_string_size NULL
	94
8ab83f56	95	#define DEFINE_FETCH_retval(type) \
b26c74e1	96	__kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \
8ab83f56 SD	97	void dummy, void dest) \
	98	{ \
	99	(type )dest = (type)regs_return_value(regs); \
	100	}
	101	DEFINE_BASIC_FETCH_FUNCS(retval)
	102	/* No string on the retval */
	103	#define fetch_retval_string NULL
	104	#define fetch_retval_string_size NULL
	105
8ab83f56 SD	106	/* Dereference memory access function */
	107	struct deref_fetch_param {
	108	struct fetch_param orig;
	109	long offset;
3925f4a5 HL	110	fetch_func_t fetch;
3925f4a5 HL	111	fetch_func_t fetch_size;
8ab83f56 SD	112	};
	113
	114	#define DEFINE_FETCH_deref(type) \
b26c74e1	115	__kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
8ab83f56 SD	116	void data, void dest) \
	117	{ \
	118	struct deref_fetch_param *dprm = data; \
	119	unsigned long addr; \
	120	call_fetch(&dprm->orig, regs, &addr); \
	121	if (addr) { \
	122	addr += dprm->offset; \
3925f4a5	123	dprm->fetch(regs, (void *)addr, dest); \
8ab83f56 SD	124	} else \
	125	(type )dest = 0; \
	126	}
	127	DEFINE_BASIC_FETCH_FUNCS(deref)
	128	DEFINE_FETCH_deref(string)
3925f4a5 HL	129
	130	__kprobes void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
	131	void data, void dest)
	132	{
	133	struct deref_fetch_param *dprm = data;
	134	unsigned long addr;
	135
	136	call_fetch(&dprm->orig, regs, &addr);
	137	if (addr && dprm->fetch_size) {
	138	addr += dprm->offset;
	139	dprm->fetch_size(regs, (void *)addr, dest);
	140	} else
	141	(string_size )dest = 0;
	142	}
8ab83f56 SD	143
	144	static __kprobes void update_deref_fetch_param(struct deref_fetch_param *data)
	145	{
	146	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	147	update_deref_fetch_param(data->orig.data);
	148	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	149	update_symbol_cache(data->orig.data);
	150	}
	151
	152	static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
	153	{
	154	if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
	155	free_deref_fetch_param(data->orig.data);
	156	else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
	157	free_symbol_cache(data->orig.data);
	158	kfree(data);
	159	}
	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) \
b26c74e1	169	__kprobes void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \
8ab83f56 SD	170	void data, void dest) \
	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; \
	180	}
	181
	182	DEFINE_BASIC_FETCH_FUNCS(bitfield)
	183	#define fetch_bitfield_string NULL
	184	#define fetch_bitfield_string_size NULL
	185
	186	static __kprobes void
	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
	199	static __kprobes void
	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
34fee3a1 NK	214	static const struct fetch_type find_fetch_type(const char type,
34fee3a1 NK	215	const struct fetch_type *ftbl)
8ab83f56 SD	216	{
	217	int i;
	218
	219	if (!type)
	220	type = DEFAULT_FETCH_TYPE_STR;
	221
	222	/* Special case: bitfield */
	223	if (*type == 'b') {
	224	unsigned long bs;
	225
	226	type = strchr(type, '/');
	227	if (!type)
	228	goto fail;
	229
	230	type++;
bcd83ea6	231	if (kstrtoul(type, 0, &bs))
8ab83f56 SD	232	goto fail;
	233
	234	switch (bs) {
	235	case 8:
34fee3a1	236	return find_fetch_type("u8", ftbl);
8ab83f56	237	case 16:
34fee3a1	238	return find_fetch_type("u16", ftbl);
8ab83f56	239	case 32:
34fee3a1	240	return find_fetch_type("u32", ftbl);
8ab83f56	241	case 64:
34fee3a1	242	return find_fetch_type("u64", ftbl);
8ab83f56 SD	243	default:
	244	goto fail;
	245	}
	246	}
	247
34fee3a1 NK	248	for (i = 0; ftbl[i].name; i++) {
	249	if (strcmp(type, ftbl[i].name) == 0)
	250	return &ftbl[i];
	251	}
8ab83f56 SD	252
	253	fail:
	254	return NULL;
	255	}
	256
	257	/* Special function : only accept unsigned long */
b079d374 NK	258	static __kprobes void fetch_kernel_stack_address(struct pt_regs *regs,
b079d374 NK	259	void dummy, void dest)
8ab83f56 SD	260	{
	261	(unsigned long )dest = kernel_stack_pointer(regs);
	262	}
	263
b079d374 NK	264	static __kprobes void fetch_user_stack_address(struct pt_regs *regs,
	265	void dummy, void dest)
	266	{
	267	(unsigned long )dest = user_stack_pointer(regs);
	268	}
	269
8ab83f56	270	static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
34fee3a1 NK	271	fetch_func_t orig_fn,
34fee3a1 NK	272	const struct fetch_type *ftbl)
8ab83f56 SD	273	{
	274	int i;
	275
34fee3a1	276	if (type != &ftbl[FETCH_TYPE_STRING])
8ab83f56 SD	277	return NULL; /* Only string type needs size function */
	278
	279	for (i = 0; i < FETCH_MTD_END; i++)
	280	if (type->fetch[i] == orig_fn)
34fee3a1	281	return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
8ab83f56 SD	282
	283	WARN_ON(1); /* This should not happen */
	284
	285	return NULL;
	286	}
	287
	288	/* Split symbol and offset. */
	289	int traceprobe_split_symbol_offset(char symbol, unsigned long offset)
	290	{
	291	char *tmp;
	292	int ret;
	293
	294	if (!offset)
	295	return -EINVAL;
	296
	297	tmp = strchr(symbol, '+');
	298	if (tmp) {
bcd83ea6 DW	299	/* skip sign because kstrtoul doesn't accept '+' */
bcd83ea6 DW	300	ret = kstrtoul(tmp + 1, 0, offset);
8ab83f56 SD	301	if (ret)
	302	return ret;
	303
	304	*tmp = '\0';
	305	} else
	306	*offset = 0;
	307
	308	return 0;
	309	}
	310
	311	#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
	312
	313	static int parse_probe_vars(char arg, const struct fetch_type t,
b079d374 NK	314	struct fetch_param *f, bool is_return,
b079d374 NK	315	bool is_kprobe)
8ab83f56 SD	316	{
	317	int ret = 0;
	318	unsigned long param;
	319
	320	if (strcmp(arg, "retval") == 0) {
	321	if (is_return)
	322	f->fn = t->fetch[FETCH_MTD_retval];
	323	else
	324	ret = -EINVAL;
	325	} else if (strncmp(arg, "stack", 5) == 0) {
	326	if (arg[5] == '\0') {
b079d374 NK	327	if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
	328	return -EINVAL;
	329
	330	if (is_kprobe)
	331	f->fn = fetch_kernel_stack_address;
8ab83f56	332	else
b079d374	333	f->fn = fetch_user_stack_address;
8ab83f56	334	} else if (isdigit(arg[5])) {
bcd83ea6	335	ret = kstrtoul(arg + 5, 10, &param);
b079d374	336	if (ret \|\| (is_kprobe && param > PARAM_MAX_STACK))
8ab83f56 SD	337	ret = -EINVAL;
	338	else {
	339	f->fn = t->fetch[FETCH_MTD_stack];
	340	f->data = (void *)param;
	341	}
	342	} else
	343	ret = -EINVAL;
	344	} else
	345	ret = -EINVAL;
	346
	347	return ret;
	348	}
	349
	350	/* Recursive argument parser */
	351	static int parse_probe_arg(char arg, const struct fetch_type t,
f3f096cf	352	struct fetch_param *f, bool is_return, bool is_kprobe)
8ab83f56	353	{
34fee3a1	354	const struct fetch_type *ftbl;
8ab83f56 SD	355	unsigned long param;
	356	long offset;
	357	char *tmp;
34fee3a1	358	int ret = 0;
8ab83f56	359
34fee3a1 NK	360	ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
34fee3a1 NK	361	BUG_ON(ftbl == NULL);
f3f096cf	362
8ab83f56 SD	363	switch (arg[0]) {
8ab83f56 SD	364	case '$':
b079d374	365	ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
8ab83f56 SD	366	break;
	367
	368	case '%': /* named register */
	369	ret = regs_query_register_offset(arg + 1);
	370	if (ret >= 0) {
	371	f->fn = t->fetch[FETCH_MTD_reg];
	372	f->data = (void *)(unsigned long)ret;
	373	ret = 0;
	374	}
	375	break;
	376
	377	case '@': /* memory or symbol */
	378	if (isdigit(arg[1])) {
bcd83ea6	379	ret = kstrtoul(arg + 1, 0, &param);
8ab83f56 SD	380	if (ret)
	381	break;
	382
	383	f->fn = t->fetch[FETCH_MTD_memory];
	384	f->data = (void *)param;
	385	} else {
b079d374 NK	386	/* uprobes don't support symbols */
	387	if (!is_kprobe)
	388	return -EINVAL;
	389
8ab83f56 SD	390	ret = traceprobe_split_symbol_offset(arg + 1, &offset);
	391	if (ret)
	392	break;
	393
	394	f->data = alloc_symbol_cache(arg + 1, offset);
	395	if (f->data)
	396	f->fn = t->fetch[FETCH_MTD_symbol];
	397	}
	398	break;
	399
	400	case '+': /* deref memory */
bcd83ea6	401	arg++; /* Skip '+', because kstrtol() rejects it. */
8ab83f56 SD	402	case '-':
	403	tmp = strchr(arg, '(');
	404	if (!tmp)
	405	break;
	406
	407	*tmp = '\0';
bcd83ea6	408	ret = kstrtol(arg, 0, &offset);
8ab83f56 SD	409
	410	if (ret)
	411	break;
	412
	413	arg = tmp + 1;
	414	tmp = strrchr(arg, ')');
	415
	416	if (tmp) {
	417	struct deref_fetch_param *dprm;
	418	const struct fetch_type *t2;
	419
34fee3a1	420	t2 = find_fetch_type(NULL, ftbl);
8ab83f56 SD	421	*tmp = '\0';
	422	dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
	423
	424	if (!dprm)
	425	return -ENOMEM;
	426
	427	dprm->offset = offset;
3925f4a5 HL	428	dprm->fetch = t->fetch[FETCH_MTD_memory];
	429	dprm->fetch_size = get_fetch_size_function(t,
	430	dprm->fetch, ftbl);
f3f096cf SD	431	ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
f3f096cf SD	432	is_kprobe);
8ab83f56 SD	433	if (ret)
	434	kfree(dprm);
	435	else {
	436	f->fn = t->fetch[FETCH_MTD_deref];
	437	f->data = (void *)dprm;
	438	}
	439	}
	440	break;
	441	}
	442	if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
	443	pr_info("%s type has no corresponding fetch method.\n", t->name);
	444	ret = -EINVAL;
	445	}
	446
	447	return ret;
	448	}
	449
	450	#define BYTES_TO_BITS(nb) ((BITS_PER_LONG * (nb)) / sizeof(long))
	451
	452	/* Bitfield type needs to be parsed into a fetch function */
	453	static int __parse_bitfield_probe_arg(const char *bf,
	454	const struct fetch_type *t,
	455	struct fetch_param *f)
	456	{
	457	struct bitfield_fetch_param *bprm;
	458	unsigned long bw, bo;
	459	char *tail;
	460
	461	if (*bf != 'b')
	462	return 0;
	463
	464	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
	465	if (!bprm)
	466	return -ENOMEM;
	467
	468	bprm->orig = *f;
	469	f->fn = t->fetch[FETCH_MTD_bitfield];
	470	f->data = (void *)bprm;
	471	bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */
	472
	473	if (bw == 0 \|\| *tail != '@')
	474	return -EINVAL;
	475
	476	bf = tail + 1;
	477	bo = simple_strtoul(bf, &tail, 0);
	478
	479	if (tail == bf \|\| *tail != '/')
	480	return -EINVAL;
	481
	482	bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
	483	bprm->low_shift = bprm->hi_shift + bo;
	484
	485	return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
	486	}
	487
	488	/* String length checking wrapper */
	489	int traceprobe_parse_probe_arg(char arg, ssize_t size,
f3f096cf	490	struct probe_arg *parg, bool is_return, bool is_kprobe)
8ab83f56	491	{
34fee3a1	492	const struct fetch_type *ftbl;
8ab83f56 SD	493	const char *t;
	494	int ret;
	495
34fee3a1 NK	496	ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
	497	BUG_ON(ftbl == NULL);
	498
8ab83f56 SD	499	if (strlen(arg) > MAX_ARGSTR_LEN) {
	500	pr_info("Argument is too long.: %s\n", arg);
	501	return -ENOSPC;
	502	}
	503	parg->comm = kstrdup(arg, GFP_KERNEL);
	504	if (!parg->comm) {
	505	pr_info("Failed to allocate memory for command '%s'.\n", arg);
	506	return -ENOMEM;
	507	}
	508	t = strchr(parg->comm, ':');
	509	if (t) {
	510	arg[t - parg->comm] = '\0';
	511	t++;
	512	}
34fee3a1	513	parg->type = find_fetch_type(t, ftbl);
8ab83f56 SD	514	if (!parg->type) {
	515	pr_info("Unsupported type: %s\n", t);
	516	return -EINVAL;
	517	}
	518	parg->offset = *size;
	519	*size += parg->type->size;
f3f096cf	520	ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);
8ab83f56 SD	521
	522	if (ret >= 0 && t != NULL)
	523	ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
	524
	525	if (ret >= 0) {
	526	parg->fetch_size.fn = get_fetch_size_function(parg->type,
34fee3a1 NK	527	parg->fetch.fn,
34fee3a1 NK	528	ftbl);
8ab83f56 SD	529	parg->fetch_size.data = parg->fetch.data;
	530	}
	531
	532	return ret;
	533	}
	534
	535	/* Return 1 if name is reserved or already used by another argument */
	536	int traceprobe_conflict_field_name(const char *name,
	537	struct probe_arg *args, int narg)
	538	{
	539	int i;
	540
	541	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
	542	if (strcmp(reserved_field_names[i], name) == 0)
	543	return 1;
	544
	545	for (i = 0; i < narg; i++)
	546	if (strcmp(args[i].name, name) == 0)
	547	return 1;
	548
	549	return 0;
	550	}
	551
	552	void traceprobe_update_arg(struct probe_arg *arg)
	553	{
	554	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
	555	update_bitfield_fetch_param(arg->fetch.data);
	556	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
	557	update_deref_fetch_param(arg->fetch.data);
	558	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
	559	update_symbol_cache(arg->fetch.data);
	560	}
	561
	562	void traceprobe_free_probe_arg(struct probe_arg *arg)
	563	{
	564	if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
	565	free_bitfield_fetch_param(arg->fetch.data);
	566	else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
	567	free_deref_fetch_param(arg->fetch.data);
	568	else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
	569	free_symbol_cache(arg->fetch.data);
	570
	571	kfree(arg->name);
	572	kfree(arg->comm);
	573	}
	574
	575	int traceprobe_command(const char buf, int (createfn)(int, char **))
	576	{
	577	char **argv;
	578	int argc, ret;
	579
	580	argc = 0;
	581	ret = 0;
	582	argv = argv_split(GFP_KERNEL, buf, &argc);
	583	if (!argv)
	584	return -ENOMEM;
	585
	586	if (argc)
	587	ret = createfn(argc, argv);
	588
	589	argv_free(argv);
	590
	591	return ret;
	592	}
593
594	#define WRITE_BUFSIZE 4096
595
596	ssize_t traceprobe_probes_write(struct file file, const char __user buffer,
597	size_t count, loff_t *ppos,
598	int (createfn)(int, char *))
599	{
600	char kbuf, tmp;
601	int ret = 0;
602	size_t done = 0;
603	size_t size;
604
605	kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
606	if (!kbuf)
607	return -ENOMEM;
608
609	while (done < count) {
610	size = count - done;
611
612	if (size >= WRITE_BUFSIZE)
613	size = WRITE_BUFSIZE - 1;
614
615	if (copy_from_user(kbuf, buffer + done, size)) {
616	ret = -EFAULT;
617	goto out;
618	}
619	kbuf[size] = '\0';
620	tmp = strchr(kbuf, '\n');
621
622	if (tmp) {
623	*tmp = '\0';
624	size = tmp - kbuf + 1;
625	} else if (done + size < count) {
626	pr_warning("Line length is too long: "
627	"Should be less than %d.", WRITE_BUFSIZE);
628	ret = -EINVAL;
629	goto out;
630	}
631	done += size;
632	/* Remove comments */
633	tmp = strchr(kbuf, '#');
634
635	if (tmp)
636	*tmp = '\0';
637
638	ret = traceprobe_command(kbuf, createfn);
639	if (ret)
640	goto out;
641	}
642	ret = done;
643
644	out:
645	kfree(kbuf);
646
647	return ret;
648	}
5bf652aa NK	649
	650	static int __set_print_fmt(struct trace_probe tp, char buf, int len,
	651	bool is_return)
	652	{
	653	int i;
	654	int pos = 0;
	655
	656	const char fmt, arg;
	657
	658	if (!is_return) {
	659	fmt = "(%lx)";
	660	arg = "REC->" FIELD_STRING_IP;
	661	} else {
	662	fmt = "(%lx <- %lx)";
	663	arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
	664	}
	665
	666	/* When len=0, we just calculate the needed length */
	667	#define LEN_OR_ZERO (len ? len - pos : 0)
	668
	669	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
	670
	671	for (i = 0; i < tp->nr_args; i++) {
	672	pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
	673	tp->args[i].name, tp->args[i].type->fmt);
	674	}
	675
	676	pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
	677
	678	for (i = 0; i < tp->nr_args; i++) {
	679	if (strcmp(tp->args[i].type->name, "string") == 0)
	680	pos += snprintf(buf + pos, LEN_OR_ZERO,
	681	", __get_str(%s)",
	682	tp->args[i].name);
	683	else
	684	pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
	685	tp->args[i].name);
	686	}
	687
	688	#undef LEN_OR_ZERO
	689
	690	/* return the length of print_fmt */
	691	return pos;
	692	}
	693
	694	int set_print_fmt(struct trace_probe *tp, bool is_return)
	695	{
	696	int len;
	697	char *print_fmt;
	698
	699	/* First: called with 0 length to calculate the needed length */
	700	len = __set_print_fmt(tp, NULL, 0, is_return);
	701	print_fmt = kmalloc(len + 1, GFP_KERNEL);
	702	if (!print_fmt)
	703	return -ENOMEM;
	704
	705	/* Second: actually write the @print_fmt */
	706	__set_print_fmt(tp, print_fmt, len + 1, is_return);
	707	tp->call.print_fmt = print_fmt;
	708
	709	return 0;
	710	}