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kprobes: support per-kprobe disabling

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Add disable_kprobe() and enable_kprobe() to disable/enable kprobes
temporarily.

disable_kprobe() asynchronously disables probe handlers of specified
kprobe.  So, after calling it, some handlers can be called at a while.
enable_kprobe() enables specified kprobe.

aggr_pre_handler and aggr_post_handler check disabled probes.  On the
other hand aggr_break_handler and aggr_fault_handler don't check it
because these handlers will be called while executing pre or post handlers
and usually those help error handling.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Masami Hiramatsu
2009-04-06 19:01:02 -07:00
committed by Linus Torvalds
parent e579abeb58
commit de5bd88d5a
3 changed files with 193 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

171
kernel/kprobes.c
View File

@@ -328,7 +328,7 @@ static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
struct kprobe *kp;
list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->pre_handler && !kprobe_gone(kp)) {
if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp);
if (kp->pre_handler(kp, regs))
return 1;
@@ -344,7 +344,7 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
struct kprobe *kp;
list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->post_handler && !kprobe_gone(kp)) {
if (kp->post_handler && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp);
kp->post_handler(kp, regs, flags);
reset_kprobe_instance();
@@ -523,6 +523,7 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
*/
static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
{
BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
if (p->break_handler) {
if (ap->break_handler)
return -EEXIST;
@@ -532,6 +533,13 @@ static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
list_add_rcu(&p->list, &ap->list);
if (p->post_handler && !ap->post_handler)
ap->post_handler = aggr_post_handler;
if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
ap->flags &= ~KPROBE_FLAG_DISABLED;
if (!kprobes_all_disarmed)
/* Arm the breakpoint again. */
arch_arm_kprobe(ap);
}
return 0;
}
@@ -592,20 +600,36 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
* freed by unregister_kprobe.
*/
return ret;
/* Clear gone flag to prevent allocating new slot again. */
ap->flags &= ~KPROBE_FLAG_GONE;
/*
* If the old_p has gone, its breakpoint has been disarmed.
* We have to arm it again after preparing real kprobes.
* Clear gone flag to prevent allocating new slot again, and
* set disabled flag because it is not armed yet.
*/
if (!kprobes_all_disarmed)
arch_arm_kprobe(ap);
ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
| KPROBE_FLAG_DISABLED;
}
copy_kprobe(ap, p);
return add_new_kprobe(ap, p);
}
/* Try to disable aggr_kprobe, and return 1 if succeeded.*/
static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
{
struct kprobe *kp;
list_for_each_entry_rcu(kp, &p->list, list) {
if (!kprobe_disabled(kp))
/*
* There is an active probe on the list.
* We can't disable aggr_kprobe.
*/
return 0;
}
p->flags |= KPROBE_FLAG_DISABLED;
return 1;
}
static int __kprobes in_kprobes_functions(unsigned long addr)
{
struct kprobe_blackpoint *kb;
@@ -664,7 +688,9 @@ int __kprobes register_kprobe(struct kprobe *p)
return -EINVAL;
}
p->flags = 0;
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
p->flags &= KPROBE_FLAG_DISABLED;
/*
* Check if are we probing a module.
*/
@@ -709,7 +735,7 @@ int __kprobes register_kprobe(struct kprobe *p)
hlist_add_head_rcu(&p->hlist,
&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
if (!kprobes_all_disarmed)
if (!kprobes_all_disarmed && !kprobe_disabled(p))
arch_arm_kprobe(p);
out_unlock_text:
@@ -724,6 +750,26 @@ out:
}
EXPORT_SYMBOL_GPL(register_kprobe);
/* Check passed kprobe is valid and return kprobe in kprobe_table. */
static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
{
struct kprobe *old_p, *list_p;
old_p = get_kprobe(p->addr);
if (unlikely(!old_p))
return NULL;
if (p != old_p) {
list_for_each_entry_rcu(list_p, &old_p->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid;
return NULL;
}
valid:
return old_p;
}
/*
* Unregister a kprobe without a scheduler synchronization.
*/
@@ -731,18 +777,10 @@ static int __kprobes __unregister_kprobe_top(struct kprobe *p)
{
struct kprobe *old_p, *list_p;
old_p = get_kprobe(p->addr);
if (unlikely(!old_p))
old_p = __get_valid_kprobe(p);
if (old_p == NULL)
return -EINVAL;
if (p != old_p) {
list_for_each_entry_rcu(list_p, &old_p->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid_p;
return -EINVAL;
}
valid_p:
if (old_p == p ||
(old_p->pre_handler == aggr_pre_handler &&
list_is_singular(&old_p->list))) {
@@ -751,7 +789,7 @@ valid_p:
* enabled and not gone - otherwise, the breakpoint would
* already have been removed. We save on flushing icache.
*/
if (!kprobes_all_disarmed && !kprobe_gone(old_p)) {
if (!kprobes_all_disarmed && !kprobe_disabled(old_p)) {
mutex_lock(&text_mutex);
arch_disarm_kprobe(p);
mutex_unlock(&text_mutex);
@@ -769,6 +807,11 @@ valid_p:
}
noclean:
list_del_rcu(&p->list);
if (!kprobe_disabled(old_p)) {
try_to_disable_aggr_kprobe(old_p);
if (!kprobes_all_disarmed && kprobe_disabled(old_p))
arch_disarm_kprobe(old_p);
}
}
return 0;
}
@@ -1078,6 +1121,7 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
static void __kprobes kill_kprobe(struct kprobe *p)
{
struct kprobe *kp;
p->flags |= KPROBE_FLAG_GONE;
if (p->pre_handler == aggr_pre_handler) {
/*
@@ -1219,12 +1263,18 @@ static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
else
kprobe_type = "k";
if (sym)
seq_printf(pi, "%p %s %s+0x%x %s %s\n", p->addr, kprobe_type,
sym, offset, (modname ? modname : " "),
(kprobe_gone(p) ? "[GONE]" : ""));
seq_printf(pi, "%p %s %s+0x%x %s %s%s\n",
p->addr, kprobe_type, sym, offset,
(modname ? modname : " "),
(kprobe_gone(p) ? "[GONE]" : ""),
((kprobe_disabled(p) && !kprobe_gone(p)) ?
"[DISABLED]" : ""));
else
seq_printf(pi, "%p %s %p %s\n", p->addr, kprobe_type, p->addr,
(kprobe_gone(p) ? "[GONE]" : ""));
seq_printf(pi, "%p %s %p %s%s\n",
p->addr, kprobe_type, p->addr,
(kprobe_gone(p) ? "[GONE]" : ""),
((kprobe_disabled(p) && !kprobe_gone(p)) ?
"[DISABLED]" : ""));
}
static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
@@ -1289,6 +1339,71 @@ static struct file_operations debugfs_kprobes_operations = {
.release = seq_release,
};
/* Disable one kprobe */
int __kprobes disable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Check whether specified probe is valid. */
p = __get_valid_kprobe(kp);
if (unlikely(p == NULL)) {
ret = -EINVAL;
goto out;
}
/* If the probe is already disabled (or gone), just return */
if (kprobe_disabled(kp))
goto out;
kp->flags |= KPROBE_FLAG_DISABLED;
if (p != kp)
/* When kp != p, p is always enabled. */
try_to_disable_aggr_kprobe(p);
if (!kprobes_all_disarmed && kprobe_disabled(p))
arch_disarm_kprobe(p);
out:
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(disable_kprobe);
/* Enable one kprobe */
int __kprobes enable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Check whether specified probe is valid. */
p = __get_valid_kprobe(kp);
if (unlikely(p == NULL)) {
ret = -EINVAL;
goto out;
}
if (kprobe_gone(kp)) {
/* This kprobe has gone, we couldn't enable it. */
ret = -EINVAL;
goto out;
}
if (!kprobes_all_disarmed && kprobe_disabled(p))
arch_arm_kprobe(p);
p->flags &= ~KPROBE_FLAG_DISABLED;
if (p != kp)
kp->flags &= ~KPROBE_FLAG_DISABLED;
out:
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(enable_kprobe);
static void __kprobes arm_all_kprobes(void)
{
struct hlist_head *head;
@@ -1306,7 +1421,7 @@ static void __kprobes arm_all_kprobes(void)
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, node, head, hlist)
if (!kprobe_gone(p))
if (!kprobe_disabled(p))
arch_arm_kprobe(p);
}
mutex_unlock(&text_mutex);
@@ -1338,7 +1453,7 @@ static void __kprobes disarm_all_kprobes(void)
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, node, head, hlist) {
if (!arch_trampoline_kprobe(p) && !kprobe_gone(p))
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
arch_disarm_kprobe(p);
}
}