linux/kernel/kprobes.c
Prasanna S Panchamukhi 8b0914ea74 [PATCH] jprobes: allow a jprobe to coexist with muliple kprobes
Presently either multiple kprobes or only one jprobe could be inserted.
This patch removes the above limitation and allows one jprobe and multiple
kprobes to coexist at the same address.  However multiple jprobes cannot
coexist with multiple kprobes.  Currently I am working on the prototype to
allow multiple jprobes coexist with multiple kprobes.

Signed-off-by: Ananth N Mavinakayanhalli <amavin@redhat.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 09:45:25 -07:00

524 lines
13 KiB
C

/*
* Kernel Probes (KProbes)
* kernel/kprobes.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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, 2002, 2004
*
* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
* Probes initial implementation (includes suggestions from
* Rusty Russell).
* 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
* hlists and exceptions notifier as suggested by Andi Kleen.
* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
* interface to access function arguments.
* 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
* exceptions notifier to be first on the priority list.
* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
* <prasanna@in.ibm.com> added function-return probes.
*/
#include <linux/kprobes.h>
#include <linux/spinlock.h>
#include <linux/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
#include <asm/kdebug.h>
#define KPROBE_HASH_BITS 6
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
unsigned int kprobe_cpu = NR_CPUS;
static DEFINE_SPINLOCK(kprobe_lock);
static struct kprobe *curr_kprobe;
/* Locks kprobe: irqs must be disabled */
void lock_kprobes(void)
{
spin_lock(&kprobe_lock);
kprobe_cpu = smp_processor_id();
}
void unlock_kprobes(void)
{
kprobe_cpu = NR_CPUS;
spin_unlock(&kprobe_lock);
}
/* You have to be holding the kprobe_lock */
struct kprobe *get_kprobe(void *addr)
{
struct hlist_head *head;
struct hlist_node *node;
head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
hlist_for_each(node, head) {
struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
if (p->addr == addr)
return p;
}
return NULL;
}
/*
* Aggregate handlers for multiple kprobes support - these handlers
* take care of invoking the individual kprobe handlers on p->list
*/
static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *kp;
list_for_each_entry(kp, &p->list, list) {
if (kp->pre_handler) {
curr_kprobe = kp;
if (kp->pre_handler(kp, regs))
return 1;
}
curr_kprobe = NULL;
}
return 0;
}
static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
struct kprobe *kp;
list_for_each_entry(kp, &p->list, list) {
if (kp->post_handler) {
curr_kprobe = kp;
kp->post_handler(kp, regs, flags);
curr_kprobe = NULL;
}
}
return;
}
static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
int trapnr)
{
/*
* if we faulted "during" the execution of a user specified
* probe handler, invoke just that probe's fault handler
*/
if (curr_kprobe && curr_kprobe->fault_handler) {
if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr))
return 1;
}
return 0;
}
static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *kp = curr_kprobe;
if (curr_kprobe && kp->break_handler) {
if (kp->break_handler(kp, regs)) {
curr_kprobe = NULL;
return 1;
}
}
curr_kprobe = NULL;
return 0;
}
struct kprobe trampoline_p = {
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
.pre_handler = trampoline_probe_handler,
.post_handler = trampoline_post_handler
};
struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp)
{
struct hlist_node *node;
struct kretprobe_instance *ri;
hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
return ri;
return NULL;
}
static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp)
{
struct hlist_node *node;
struct kretprobe_instance *ri;
hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
return ri;
return NULL;
}
struct kretprobe_instance *get_rp_inst(void *sara)
{
struct hlist_head *head;
struct hlist_node *node;
struct task_struct *tsk;
struct kretprobe_instance *ri;
tsk = arch_get_kprobe_task(sara);
head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
hlist_for_each_entry(ri, node, head, hlist) {
if (ri->stack_addr == sara)
return ri;
}
return NULL;
}
void add_rp_inst(struct kretprobe_instance *ri)
{
struct task_struct *tsk;
/*
* Remove rp inst off the free list -
* Add it back when probed function returns
*/
hlist_del(&ri->uflist);
tsk = arch_get_kprobe_task(ri->stack_addr);
/* Add rp inst onto table */
INIT_HLIST_NODE(&ri->hlist);
hlist_add_head(&ri->hlist,
&kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]);
/* Also add this rp inst to the used list. */
INIT_HLIST_NODE(&ri->uflist);
hlist_add_head(&ri->uflist, &ri->rp->used_instances);
}
void recycle_rp_inst(struct kretprobe_instance *ri)
{
/* remove rp inst off the rprobe_inst_table */
hlist_del(&ri->hlist);
if (ri->rp) {
/* remove rp inst off the used list */
hlist_del(&ri->uflist);
/* put rp inst back onto the free list */
INIT_HLIST_NODE(&ri->uflist);
hlist_add_head(&ri->uflist, &ri->rp->free_instances);
} else
/* Unregistering */
kfree(ri);
}
struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk)
{
return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
}
struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk)
{
struct task_struct *tsk;
struct hlist_head *head;
struct hlist_node *node;
struct kretprobe_instance *ri;
head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];
hlist_for_each_entry(ri, node, head, hlist) {
tsk = arch_get_kprobe_task(ri->stack_addr);
if (tsk == tk)
return ri;
}
return NULL;
}
/*
* This function is called from do_exit or do_execv when task tk's stack is
* about to be recycled. Recycle any function-return probe instances
* associated with this task. These represent probed functions that have
* been called but may never return.
*/
void kprobe_flush_task(struct task_struct *tk)
{
unsigned long flags = 0;
spin_lock_irqsave(&kprobe_lock, flags);
arch_kprobe_flush_task(tk);
spin_unlock_irqrestore(&kprobe_lock, flags);
}
/*
* This kprobe pre_handler is registered with every kretprobe. When probe
* hits it will set up the return probe.
*/
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe *rp = container_of(p, struct kretprobe, kp);
/*TODO: consider to only swap the RA after the last pre_handler fired */
arch_prepare_kretprobe(rp, regs);
return 0;
}
static inline void free_rp_inst(struct kretprobe *rp)
{
struct kretprobe_instance *ri;
while ((ri = get_free_rp_inst(rp)) != NULL) {
hlist_del(&ri->uflist);
kfree(ri);
}
}
/*
* Keep all fields in the kprobe consistent
*/
static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
{
memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
}
/*
* Add the new probe to old_p->list. Fail if this is the
* second jprobe at the address - two jprobes can't coexist
*/
static int add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
{
struct kprobe *kp;
if (p->break_handler) {
list_for_each_entry(kp, &old_p->list, list) {
if (kp->break_handler)
return -EEXIST;
}
list_add_tail(&p->list, &old_p->list);
} else
list_add(&p->list, &old_p->list);
return 0;
}
/*
* Fill in the required fields of the "manager kprobe". Replace the
* earlier kprobe in the hlist with the manager kprobe
*/
static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
{
copy_kprobe(p, ap);
ap->addr = p->addr;
ap->pre_handler = aggr_pre_handler;
ap->post_handler = aggr_post_handler;
ap->fault_handler = aggr_fault_handler;
ap->break_handler = aggr_break_handler;
INIT_LIST_HEAD(&ap->list);
list_add(&p->list, &ap->list);
INIT_HLIST_NODE(&ap->hlist);
hlist_del(&p->hlist);
hlist_add_head(&ap->hlist,
&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
}
/*
* This is the second or subsequent kprobe at the address - handle
* the intricacies
* TODO: Move kcalloc outside the spinlock
*/
static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p)
{
int ret = 0;
struct kprobe *ap;
if (old_p->pre_handler == aggr_pre_handler) {
copy_kprobe(old_p, p);
ret = add_new_kprobe(old_p, p);
} else {
ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
if (!ap)
return -ENOMEM;
add_aggr_kprobe(ap, old_p);
copy_kprobe(ap, p);
ret = add_new_kprobe(ap, p);
}
return ret;
}
/* kprobe removal house-keeping routines */
static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
{
arch_disarm_kprobe(p);
hlist_del(&p->hlist);
spin_unlock_irqrestore(&kprobe_lock, flags);
arch_remove_kprobe(p);
}
static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
struct kprobe *p, unsigned long flags)
{
list_del(&p->list);
if (list_empty(&old_p->list)) {
cleanup_kprobe(old_p, flags);
kfree(old_p);
} else
spin_unlock_irqrestore(&kprobe_lock, flags);
}
int register_kprobe(struct kprobe *p)
{
int ret = 0;
unsigned long flags = 0;
struct kprobe *old_p;
if ((ret = arch_prepare_kprobe(p)) != 0) {
goto rm_kprobe;
}
spin_lock_irqsave(&kprobe_lock, flags);
old_p = get_kprobe(p->addr);
p->nmissed = 0;
if (old_p) {
ret = register_aggr_kprobe(old_p, p);
goto out;
}
arch_copy_kprobe(p);
INIT_HLIST_NODE(&p->hlist);
hlist_add_head(&p->hlist,
&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
arch_arm_kprobe(p);
out:
spin_unlock_irqrestore(&kprobe_lock, flags);
rm_kprobe:
if (ret == -EEXIST)
arch_remove_kprobe(p);
return ret;
}
void unregister_kprobe(struct kprobe *p)
{
unsigned long flags;
struct kprobe *old_p;
spin_lock_irqsave(&kprobe_lock, flags);
old_p = get_kprobe(p->addr);
if (old_p) {
if (old_p->pre_handler == aggr_pre_handler)
cleanup_aggr_kprobe(old_p, p, flags);
else
cleanup_kprobe(p, flags);
} else
spin_unlock_irqrestore(&kprobe_lock, flags);
}
static struct notifier_block kprobe_exceptions_nb = {
.notifier_call = kprobe_exceptions_notify,
.priority = 0x7fffffff /* we need to notified first */
};
int register_jprobe(struct jprobe *jp)
{
/* Todo: Verify probepoint is a function entry point */
jp->kp.pre_handler = setjmp_pre_handler;
jp->kp.break_handler = longjmp_break_handler;
return register_kprobe(&jp->kp);
}
void unregister_jprobe(struct jprobe *jp)
{
unregister_kprobe(&jp->kp);
}
#ifdef ARCH_SUPPORTS_KRETPROBES
int register_kretprobe(struct kretprobe *rp)
{
int ret = 0;
struct kretprobe_instance *inst;
int i;
rp->kp.pre_handler = pre_handler_kretprobe;
/* Pre-allocate memory for max kretprobe instances */
if (rp->maxactive <= 0) {
#ifdef CONFIG_PREEMPT
rp->maxactive = max(10, 2 * NR_CPUS);
#else
rp->maxactive = NR_CPUS;
#endif
}
INIT_HLIST_HEAD(&rp->used_instances);
INIT_HLIST_HEAD(&rp->free_instances);
for (i = 0; i < rp->maxactive; i++) {
inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
if (inst == NULL) {
free_rp_inst(rp);
return -ENOMEM;
}
INIT_HLIST_NODE(&inst->uflist);
hlist_add_head(&inst->uflist, &rp->free_instances);
}
rp->nmissed = 0;
/* Establish function entry probe point */
if ((ret = register_kprobe(&rp->kp)) != 0)
free_rp_inst(rp);
return ret;
}
#else /* ARCH_SUPPORTS_KRETPROBES */
int register_kretprobe(struct kretprobe *rp)
{
return -ENOSYS;
}
#endif /* ARCH_SUPPORTS_KRETPROBES */
void unregister_kretprobe(struct kretprobe *rp)
{
unsigned long flags;
struct kretprobe_instance *ri;
unregister_kprobe(&rp->kp);
/* No race here */
spin_lock_irqsave(&kprobe_lock, flags);
free_rp_inst(rp);
while ((ri = get_used_rp_inst(rp)) != NULL) {
ri->rp = NULL;
hlist_del(&ri->uflist);
}
spin_unlock_irqrestore(&kprobe_lock, flags);
}
static int __init init_kprobes(void)
{
int i, err = 0;
/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
INIT_HLIST_HEAD(&kprobe_table[i]);
INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
}
err = register_die_notifier(&kprobe_exceptions_nb);
/* Register the trampoline probe for return probe */
register_kprobe(&trampoline_p);
return err;
}
__initcall(init_kprobes);
EXPORT_SYMBOL_GPL(register_kprobe);
EXPORT_SYMBOL_GPL(unregister_kprobe);
EXPORT_SYMBOL_GPL(register_jprobe);
EXPORT_SYMBOL_GPL(unregister_jprobe);
EXPORT_SYMBOL_GPL(jprobe_return);
EXPORT_SYMBOL_GPL(register_kretprobe);
EXPORT_SYMBOL_GPL(unregister_kretprobe);