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[PATCH] kprobes: Allow multiple kprobes at the same address

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Allow registration of multiple kprobes at an address in an architecture
agnostic way.  Corresponding handlers will be invoked in a sequence.  But,
a kprobe and a jprobe can't (yet) co-exist at the same address.

Signed-off-by: Ananth N Mavinakayanahalli <amavin@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ananth N Mavinakayanahalli 2005-05-05 16:15:42 -07:00 committed by Linus Torvalds
parent 04dea5f932
commit 64f562c6df
2 changed files with 134 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/kprobes.h
View File

@ -43,6 +43,9 @@ typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
struct kprobe {
struct hlist_node hlist;
/* list of kprobes for multi-handler support */
struct list_head list;
/* location of the probe point */
kprobe_opcode_t *addr;

144
kernel/kprobes.c
View File

@ -44,6 +44,7 @@ static struct hlist_head kprobe_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)
@ -73,22 +74,139 @@ struct kprobe *get_kprobe(void *addr)
return NULL;
}
/*
* Aggregate handlers for multiple kprobes support - these handlers
* take care of invoking the individual kprobe handlers on p->list
*/
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;
kp->pre_handler(kp, regs);
curr_kprobe = NULL;
}
}
return 0;
}
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;
}
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;
}
/*
* 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)
{
ap->addr = p->addr;
ap->opcode = p->opcode;
memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn));
ap->pre_handler = aggr_pre_handler;
ap->post_handler = aggr_post_handler;
ap->fault_handler = aggr_fault_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->break_handler || p->break_handler) {
ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */
} else if (old_p->pre_handler == aggr_pre_handler) {
list_add(&p->list, &old_p->list);
} else {
ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
if (!ap)
return -ENOMEM;
add_aggr_kprobe(ap, old_p);
list_add(&p->list, &ap->list);
}
return ret;
}
/* kprobe removal house-keeping routines */
static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
{
*p->addr = p->opcode;
hlist_del(&p->hlist);
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
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);
INIT_HLIST_NODE(&p->hlist);
if (get_kprobe(p->addr)) {
ret = -EEXIST;
old_p = get_kprobe(p->addr);
if (old_p) {
ret = register_aggr_kprobe(old_p, p);
goto out;
}
arch_copy_kprobe(p);
arch_copy_kprobe(p);
INIT_HLIST_NODE(&p->hlist);
hlist_add_head(&p->hlist,
&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
@ -107,17 +225,17 @@ int register_kprobe(struct kprobe *p)
void unregister_kprobe(struct kprobe *p)
{
unsigned long flags;
struct kprobe *old_p;
spin_lock_irqsave(&kprobe_lock, flags);
if (!get_kprobe(p->addr)) {
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);
return;
}
*p->addr = p->opcode;
hlist_del(&p->hlist);
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
spin_unlock_irqrestore(&kprobe_lock, flags);
arch_remove_kprobe(p);
}
static struct notifier_block kprobe_exceptions_nb = {