cregit-Linux how code gets into the kernel

Release 4.15 kernel/trace/trace_uprobe.c

Directory: kernel/trace
/*
 * uprobes-based tracing 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
 *
 * Copyright (C) IBM Corporation, 2010-2012
 * Author:      Srikar Dronamraju <srikar@linux.vnet.ibm.com>
 */

#define pr_fmt(fmt)	"trace_kprobe: " fmt

#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/uprobes.h>
#include <linux/namei.h>
#include <linux/string.h>
#include <linux/rculist.h>

#include "trace_probe.h"


#define UPROBE_EVENT_SYSTEM	"uprobes"


struct uprobe_trace_entry_head {
	
struct trace_entry	ent;
	
unsigned long		vaddr[];
};


#define SIZEOF_TRACE_ENTRY(is_return)			\
	(sizeof(struct uprobe_trace_entry_head) +       \
         sizeof(unsigned long) * (is_return ? 2 : 1))


#define DATAOF_TRACE_ENTRY(entry, is_return)		\
	((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))


struct trace_uprobe_filter {
	
rwlock_t		rwlock;
	
int			nr_systemwide;
	
struct list_head	perf_events;
};

/*
 * uprobe event core functions
 */

struct trace_uprobe {
	
struct list_head		list;
	
struct trace_uprobe_filter	filter;
	
struct uprobe_consumer		consumer;
	
struct inode			*inode;
	
char				*filename;
	
unsigned long			offset;
	
unsigned long			nhit;
	
struct trace_probe		tp;
};


#define SIZEOF_TRACE_UPROBE(n)				\
	(offsetof(struct trace_uprobe, tp.args) +       \
        (sizeof(struct probe_arg) * (n)))

static int register_uprobe_event(struct trace_uprobe *tu);
static int unregister_uprobe_event(struct trace_uprobe *tu);

static DEFINE_MUTEX(uprobe_lock);
static LIST_HEAD(uprobe_list);


struct uprobe_dispatch_data {
	
struct trace_uprobe	*tu;
	
unsigned long		bp_addr;
};

static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
static int uretprobe_dispatcher(struct uprobe_consumer *con,
				unsigned long func, struct pt_regs *regs);

#ifdef CONFIG_STACK_GROWSUP



static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
	return addr - (n * sizeof(long));
}

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#else



static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
	return addr + (n * sizeof(long));
}

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#endif




static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
{
	unsigned long ret;
	unsigned long addr = user_stack_pointer(regs);

	addr = adjust_stack_addr(addr, n);

	if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
		return 0;

	return ret;
}


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/*
 * Uprobes-specific fetch functions
 */

#define DEFINE_FETCH_stack(type)					\
static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
                                         void *offset, void *dest)      \
{                                                                       \
        *(type *)dest = (type)get_user_stack_nth(regs,                  \
                                              ((unsigned long)offset)); \
}
DEFINE_BASIC_FETCH_FUNCS(stack)
/* No string on the stack entry */

#define fetch_stack_string	NULL

#define fetch_stack_string_size	NULL


#define DEFINE_FETCH_memory(type)					\
static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
                                          void *addr, void *dest)       \
{                                                                       \
        type retval;                                                    \
        void __user *vaddr = (void __force __user *) addr;              \
                                                                        \
        if (copy_from_user(&retval, vaddr, sizeof(type)))               \
                *(type *)dest = 0;                                      \
        else                                                            \
                *(type *) dest = retval;                                \
}
DEFINE_BASIC_FETCH_FUNCS(memory)
/*
 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 * length and relative data location.
 */

static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
					    void *addr, void *dest)
{
	long ret;
	u32 rloc = *(u32 *)dest;
	int maxlen  = get_rloc_len(rloc);
	u8 *dst = get_rloc_data(dest);
	void __user *src = (void __force __user *) addr;

	if (!maxlen)
		return;

	ret = strncpy_from_user(dst, src, maxlen);

	if (ret < 0) {	/* Failed to fetch string */
		((u8 *)get_rloc_data(dest))[0] = '\0';
		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));
	} else {
		*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));
	}
}


static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
						 void *addr, void *dest)
{
	int len;
	void __user *vaddr = (void __force __user *) addr;

	len = strnlen_user(vaddr, MAX_STRING_SIZE);

	if (len == 0 || len > MAX_STRING_SIZE)  /* Failed to check length */
		*(u32 *)dest = 0;
	else
		*(u32 *)dest = len;
}




static unsigned long translate_user_vaddr(void *file_offset)
{
	unsigned long base_addr;
	struct uprobe_dispatch_data *udd;

	udd = (void *) current->utask->vaddr;

	base_addr = udd->bp_addr - udd->tu->offset;
	return base_addr + (unsigned long)file_offset;
}


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Total53100.00%1100.00%




#define DEFINE_FETCH_file_offset(type)					\
static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs,    \
                                               void *offset, void *dest)\
{                                                                       \
        void *vaddr = (void *)translate_user_vaddr(offset);             \
                                                                        \
        FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest);               \
}
DEFINE_BASIC_FETCH_FUNCS(file_offset)
DEFINE_FETCH_file_offset(string)
DEFINE_FETCH_file_offset(string_size)

/* Fetch type information table */

static const struct fetch_type uprobes_fetch_type_table[] = {
	/* Special types */
	[FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
					sizeof(u32), 1, "__data_loc char[]"),
	[FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
					string_size, sizeof(u32), 0, "u32"),
	/* Basic types */
	ASSIGN_FETCH_TYPE(u8,  u8,  0),
	ASSIGN_FETCH_TYPE(u16, u16, 0),
	ASSIGN_FETCH_TYPE(u32, u32, 0),
	ASSIGN_FETCH_TYPE(u64, u64, 0),
	ASSIGN_FETCH_TYPE(s8,  u8,  1),
	ASSIGN_FETCH_TYPE(s16, u16, 1),
	ASSIGN_FETCH_TYPE(s32, u32, 1),
	ASSIGN_FETCH_TYPE(s64, u64, 1),
	ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),

	ASSIGN_FETCH_TYPE_END
};




static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
	rwlock_init(&filter->rwlock);
	filter->nr_systemwide = 0;
	INIT_LIST_HEAD(&filter->perf_events);
}


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static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
{
	return !filter->nr_systemwide && list_empty(&filter->perf_events);
}


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Oleg Nesterov26100.00%1100.00%


Total26100.00%1100.00%






static inline bool is_ret_probe(struct trace_uprobe *tu)
{
	return tu->consumer.ret_handler != NULL;
}


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Total21100.00%1100.00%



/*
 * Allocate new trace_uprobe and initialize it (including uprobes).
 */


static struct trace_uprobe *

alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
{
	struct trace_uprobe *tu;

	if (!event || !is_good_name(event))
		return ERR_PTR(-EINVAL);

	if (!group || !is_good_name(group))
		return ERR_PTR(-EINVAL);

	tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
	if (!tu)
		return ERR_PTR(-ENOMEM);

	tu->tp.call.class = &tu->tp.class;
	tu->tp.call.name = kstrdup(event, GFP_KERNEL);
	if (!tu->tp.call.name)
		goto error;

	tu->tp.class.system = kstrdup(group, GFP_KERNEL);
	if (!tu->tp.class.system)
		goto error;

	INIT_LIST_HEAD(&tu->list);
	INIT_LIST_HEAD(&tu->tp.files);
	tu->consumer.handler = uprobe_dispatcher;
	if (is_ret)
		tu->consumer.ret_handler = uretprobe_dispatcher;
	init_trace_uprobe_filter(&tu->filter);
	return tu;

error:
	kfree(tu->tp.call.name);
	kfree(tu);

	return ERR_PTR(-ENOMEM);
}


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Srikar Dronamraju18176.69%116.67%


Oleg Nesterov3113.14%350.00%


Namhyung Kim145.93%116.67%


Jovi Zhangwei104.24%116.67%


Total236100.00%6100.00%






static void free_trace_uprobe(struct trace_uprobe *tu)
{
	int i;

	for (i = 0; i < tu->tp.nr_args; i++)
		traceprobe_free_probe_arg(&tu->tp.args[i]);

	iput(tu->inode);
	kfree(tu->tp.call.class->system);
	kfree(tu->tp.call.name);
	kfree(tu->filename);
	kfree(tu);
}


Contributors
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Srikar Dronamraju7990.80%150.00%


Namhyung Kim89.20%150.00%


Total87100.00%2100.00%






static struct trace_uprobe *find_probe_event(const char *event, const char *group)
{
	struct trace_uprobe *tu;

	list_for_each_entry(tu, &uprobe_list, list)
		if (strcmp(trace_event_name(&tu->tp.call), event) == 0 &&
		    strcmp(tu->tp.call.class->system, group) == 0)
			return tu;

	return NULL;
}


Contributors
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Srikar Dronamraju6589.04%125.00%


Namhyung Kim45.48%125.00%


Mathieu Desnoyers34.11%125.00%


Steven Rostedt11.37%125.00%


Total73100.00%4100.00%



/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */



static int unregister_trace_uprobe(struct trace_uprobe *tu)
{
	int ret;

	ret = unregister_uprobe_event(tu);
	if (ret)
		return ret;

	list_del(&tu->list);
	free_trace_uprobe(tu);
	return 0;
}


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Srikar Dronamraju2352.27%150.00%


Steven Rostedt2147.73%150.00%


Total44100.00%2100.00%



/* Register a trace_uprobe and probe_event */



static int register_trace_uprobe(struct trace_uprobe *tu)
{
	struct trace_uprobe *old_tu;
	int ret;

	mutex_lock(&uprobe_lock);

	/* register as an event */
	old_tu = find_probe_event(trace_event_name(&tu->tp.call),
			tu->tp.call.class->system);
	if (old_tu) {
		/* delete old event */
		ret = unregister_trace_uprobe(old_tu);
		if (ret)
			goto end;
	}

	ret = register_uprobe_event(tu);
	if (ret) {
		pr_warn("Failed to register probe event(%d)\n", ret);
		goto end;
	}

	list_add_tail(&tu->list, &uprobe_list);

end:
	mutex_unlock(&uprobe_lock);

	return ret;
}


Contributors
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Srikar Dronamraju9379.49%116.67%


Steven Rostedt1210.26%233.33%


Namhyung Kim86.84%116.67%


Mathieu Desnoyers32.56%116.67%


Joe Perches10.85%116.67%


Total117100.00%6100.00%



/*
 * Argument syntax:
 *  - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
 *
 *  - Remove uprobe: -:[GRP/]EVENT
 */



static int create_trace_uprobe(int argc, char **argv)
{
	struct trace_uprobe *tu;
	struct inode *inode;
	char *arg, *event, *group, *filename;
	char buf[MAX_EVENT_NAME_LEN];
	struct path path;
	unsigned long offset;
	bool is_delete, is_return;
	int i, ret;

	inode = NULL;
	ret = 0;
	is_delete = false;
	is_return = false;
	event = NULL;
	group = NULL;

	/* argc must be >= 1 */
	if (argv[0][0] == '-')
		is_delete = true;
	else if (argv[0][0] == 'r')
		is_return = true;
	else if (argv[0][0] != 'p') {
		pr_info("Probe definition must be started with 'p', 'r' or '-'.\n");
		return -EINVAL;
	}

	if (argv[0][1] == ':') {
		event = &argv[0][2];
		arg = strchr(event, '/');

		if (arg) {
			group = event;
			event = arg + 1;
			event[-1] = '\0';

			if (strlen(group) == 0) {
				pr_info("Group name is not specified\n");
				return -EINVAL;
			}
		}
		if (strlen(event) == 0) {
			pr_info("Event name is not specified\n");
			return -EINVAL;
		}
	}
	if (!group)
		group = UPROBE_EVENT_SYSTEM;

	if (is_delete) {
		int ret;

		if (!event) {
			pr_info("Delete command needs an event name.\n");
			return -EINVAL;
		}
		mutex_lock(&uprobe_lock);
		tu = find_probe_event(event, group);

		if (!tu) {
			mutex_unlock(&uprobe_lock);
			pr_info("Event %s/%s doesn't exist.\n", group, event);
			return -ENOENT;
		}
		/* delete an event */
		ret = unregister_trace_uprobe(tu);
		mutex_unlock(&uprobe_lock);
		return ret;
	}

	if (argc < 2) {
		pr_info("Probe point is not specified.\n");
		return -EINVAL;
	}
	/* Find the last occurrence, in case the path contains ':' too. */
	arg = strrchr(argv[1], ':');
	if (!arg) {
		ret = -EINVAL;
		goto fail_address_parse;
	}

	*arg++ = '\0';
	filename = argv[1];
	ret = kern_path(filename, LOOKUP_FOLLOW, &path);
	if (ret)
		goto fail_address_parse;

	inode = igrab(d_inode(path.dentry));
	path_put(&path);

	if (!inode || !S_ISREG(inode->i_mode)) {
		ret = -EINVAL;
		goto fail_address_parse;
	}

	ret = kstrtoul(arg, 0, &offset);
	if (ret)
		goto fail_address_parse;

	argc -= 2;
	argv += 2;

	/* setup a probe */
	if (!event) {
		char *tail;
		char *ptr;

		tail = kstrdup(kbasename(filename), GFP_KERNEL);
		if (!tail) {
			ret = -ENOMEM;
			goto fail_address_parse;
		}

		ptr = strpbrk(tail, ".-_");
		if (ptr)
			*ptr = '\0';

		snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
		event = buf;
		kfree(tail);
	}

	tu = alloc_trace_uprobe(group, event, argc, is_return);
	if (IS_ERR(tu)) {
		pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
		ret = PTR_ERR(tu);
		goto fail_address_parse;
	}
	tu->offset = offset;
	tu->inode = inode;
	tu->filename = kstrdup(filename, GFP_KERNEL);

	if (!tu->filename) {
		pr_info("Failed to allocate filename.\n");
		ret = -ENOMEM;
		goto error;
	}

	/* parse arguments */
	ret = 0;
	for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
		struct probe_arg *parg = &tu->tp.args[i];

		/* Increment count for freeing args in error case */
		tu->tp.nr_args++;

		/* Parse argument name */
		arg = strchr(argv[i], '=');
		if (arg) {
			*arg++ = '\0';
			parg->name = kstrdup(argv[i], GFP_KERNEL);
		} else {
			arg = argv[i];
			/* If argument name is omitted, set "argN" */
			snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
			parg->name = kstrdup(buf, GFP_KERNEL);
		}

		if (!parg->name) {
			pr_info("Failed to allocate argument[%d] name.\n", i);
			ret = -ENOMEM;
			goto error;
		}

		if (!is_good_name(parg->name)) {
			pr_info("Invalid argument[%d] name: %s\n", i, parg->name);
			ret = -EINVAL;
			goto error;
		}

		if (traceprobe_conflict_field_name(parg->name, tu->tp.args, i)) {
			pr_info("Argument[%d] name '%s' conflicts with "
				"another field.\n", i, argv[i]);
			ret = -EINVAL;
			goto error;
		}

		/* Parse fetch argument */
		ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
						 is_return, false,
						 uprobes_fetch_type_table);
		if (ret) {
			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
			goto error;
		}
	}

	ret = register_trace_uprobe(tu);
	if (ret)
		goto error;
	return 0;

error:
	free_trace_uprobe(tu);
	return ret;

fail_address_parse:
	iput(inode);

	pr_info("Failed to parse address or file.\n");

	return ret;
}


Contributors
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Srikar Dronamraju82386.45%17.14%


Oleg Nesterov545.67%428.57%


Namhyung Kim293.05%214.29%


Jovi Zhang212.21%17.14%


Jovi Zhangwei70.74%17.14%


Steven Rostedt60.63%17.14%


Andy Shevchenko50.53%17.14%


David Howells30.32%17.14%


Kenny Yu20.21%17.14%


Stephen Rothwell20.21%17.14%


Total952100.00%14100.00%






static int cleanup_all_probes(void)
{
	struct trace_uprobe *tu;
	int ret = 0;

	mutex_lock(&uprobe_lock);
	while (!list_empty(&uprobe_list)) {
		tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
		ret = unregister_trace_uprobe(tu);
		if (ret)
			break;
	}
	mutex_unlock(&uprobe_lock);
	return ret;
}


Contributors
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Srikar Dronamraju5477.14%150.00%


Steven Rostedt1622.86%150.00%


Total70100.00%2100.00%



/* Probes listing interfaces */



static void *probes_seq_start(struct seq_file *m, loff_t *pos)
{
	mutex_lock(&uprobe_lock);
	return seq_list_start(&uprobe_list, *pos);
}


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Srikar Dronamraju32100.00%1100.00%


Total32100.00%1100.00%






static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
	return seq_list_next(v, &uprobe_list, pos);
}


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Srikar Dronamraju31100.00%1100.00%


Total31100.00%1100.00%






static void probes_seq_stop(struct seq_file *m, void *v)
{
	mutex_unlock(&uprobe_lock);
}


Contributors
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Srikar Dronamraju21100.00%1100.00%


Total21100.00%1100.00%






static int probes_seq_show(struct seq_file *m, void *v)
{
	struct trace_uprobe *tu = v;
	char c = is_ret_probe(tu) ? 'r' : 'p';
	int i;

	seq_printf(m, "%c:%s/%s", c, tu->tp.call.class->system,
			trace_event_name(&tu->tp.call));
	seq_printf(m, " %s:", tu->filename);

	/* Don't print "0x  (null)" when offset is 0 */
	if (tu->offset) {
		seq_printf(m, "0x%p", (void *)tu->offset);
	} else {
		switch (sizeof(void *)) {
		case 4:
			seq_printf(m, "0x00000000");
			break;
		case 8:
		default:
			seq_printf(m, "0x0000000000000000");
			break;
		}
	}

	for (i = 0; i