* <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/slab.h>
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <asm-generic/sections.h>
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;
+DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */
+DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */
+static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
+#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
/*
* kprobe->ainsn.insn points to the copy of the instruction to be
* single-stepped. x86_64, POWER4 and above have no-exec support and
}
}
}
+#endif
-/* Locks kprobe: irqs must be disabled */
-void __kprobes lock_kprobes(void)
+/* We have preemption disabled.. so it is safe to use __ versions */
+static inline void set_kprobe_instance(struct kprobe *kp)
{
- spin_lock(&kprobe_lock);
- kprobe_cpu = smp_processor_id();
+ __get_cpu_var(kprobe_instance) = kp;
}
-void __kprobes unlock_kprobes(void)
+static inline void reset_kprobe_instance(void)
{
- kprobe_cpu = NR_CPUS;
- spin_unlock(&kprobe_lock);
+ __get_cpu_var(kprobe_instance) = NULL;
}
-/* You have to be holding the kprobe_lock */
+/*
+ * This routine is called either:
+ * - under the kprobe_mutex - during kprobe_[un]register()
+ * OR
+ * - with preemption disabled - from arch/xxx/kernel/kprobes.c
+ */
struct kprobe __kprobes *get_kprobe(void *addr)
{
struct hlist_head *head;
struct hlist_node *node;
+ struct kprobe *p;
head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
- hlist_for_each(node, head) {
- struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
+ hlist_for_each_entry_rcu(p, node, head, hlist) {
if (p->addr == addr)
return p;
}
{
struct kprobe *kp;
- list_for_each_entry(kp, &p->list, list) {
+ list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->pre_handler) {
- curr_kprobe = kp;
+ set_kprobe_instance(kp);
if (kp->pre_handler(kp, regs))
return 1;
}
- curr_kprobe = NULL;
+ reset_kprobe_instance();
}
return 0;
}
{
struct kprobe *kp;
- list_for_each_entry(kp, &p->list, list) {
+ list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->post_handler) {
- curr_kprobe = kp;
+ set_kprobe_instance(kp);
kp->post_handler(kp, regs, flags);
- curr_kprobe = NULL;
+ reset_kprobe_instance();
}
}
return;
static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
int trapnr)
{
+ struct kprobe *cur = __get_cpu_var(kprobe_instance);
+
/*
* 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))
+ if (cur && cur->fault_handler) {
+ if (cur->fault_handler(cur, regs, trapnr))
return 1;
}
return 0;
static int __kprobes 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;
- }
+ struct kprobe *cur = __get_cpu_var(kprobe_instance);
+ int ret = 0;
+
+ if (cur && cur->break_handler) {
+ if (cur->break_handler(cur, regs))
+ ret = 1;
}
- curr_kprobe = NULL;
- return 0;
+ reset_kprobe_instance();
+ return ret;
+}
+
+/* Walks the list and increments nmissed count for multiprobe case */
+void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
+{
+ struct kprobe *kp;
+ if (p->pre_handler != aggr_pre_handler) {
+ p->nmissed++;
+ } else {
+ list_for_each_entry_rcu(kp, &p->list, list)
+ kp->nmissed++;
+ }
+ return;
}
+/* Called with kretprobe_lock held */
struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp)
{
struct hlist_node *node;
return NULL;
}
+/* Called with kretprobe_lock held */
static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe
*rp)
{
return NULL;
}
+/* Called with kretprobe_lock held */
void __kprobes add_rp_inst(struct kretprobe_instance *ri)
{
/*
hlist_add_head(&ri->uflist, &ri->rp->used_instances);
}
+/* Called with kretprobe_lock held */
void __kprobes recycle_rp_inst(struct kretprobe_instance *ri)
{
/* remove rp inst off the rprobe_inst_table */
}
/*
- * This function is called from exit_thread or flush_thread when task tk's
- * stack is being recycled so that we can recycle any function-return probe
- * instances associated with this task. These left over instances represent
- * probed functions that have been called but will never return.
+ * This function is called from finish_task_switch when task tk becomes dead,
+ * so that we can recycle any function-return probe instances associated
+ * with this task. These left over instances represent probed functions
+ * that have been called but will never return.
*/
void __kprobes kprobe_flush_task(struct task_struct *tk)
{
struct hlist_node *node, *tmp;
unsigned long flags = 0;
- spin_lock_irqsave(&kprobe_lock, flags);
- head = kretprobe_inst_table_head(current);
+ spin_lock_irqsave(&kretprobe_lock, flags);
+ head = kretprobe_inst_table_head(tk);
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
if (ri->task == tk)
recycle_rp_inst(ri);
}
- 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 __kprobes 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;
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
}
static inline void free_rp_inst(struct kretprobe *rp)
struct kprobe *kp;
if (p->break_handler) {
- list_for_each_entry(kp, &old_p->list, list) {
+ list_for_each_entry_rcu(kp, &old_p->list, list) {
if (kp->break_handler)
return -EEXIST;
}
- list_add_tail(&p->list, &old_p->list);
+ list_add_tail_rcu(&p->list, &old_p->list);
} else
- list_add(&p->list, &old_p->list);
+ list_add_rcu(&p->list, &old_p->list);
return 0;
}
ap->break_handler = aggr_break_handler;
INIT_LIST_HEAD(&ap->list);
- list_add(&p->list, &ap->list);
+ list_add_rcu(&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)]);
+ hlist_replace_rcu(&p->hlist, &ap->hlist);
}
/*
* This is the second or subsequent kprobe at the address - handle
* the intricacies
- * TODO: Move kcalloc outside the spinlock
*/
static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
struct kprobe *p)
copy_kprobe(old_p, p);
ret = add_new_kprobe(old_p, p);
} else {
- ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
+ ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
if (!ap)
return -ENOMEM;
add_aggr_kprobe(ap, old_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);
-}
-
static int __kprobes in_kprobes_functions(unsigned long addr)
{
if (addr >= (unsigned long)__kprobes_text_start
return 0;
}
-int __kprobes register_kprobe(struct kprobe *p)
+static int __kprobes __register_kprobe(struct kprobe *p,
+ unsigned long called_from)
{
int ret = 0;
- unsigned long flags = 0;
struct kprobe *old_p;
+ struct module *probed_mod;
- if ((ret = in_kprobes_functions((unsigned long) p->addr)) != 0)
- return ret;
- if ((ret = arch_prepare_kprobe(p)) != 0)
- goto rm_kprobe;
+ if ((!kernel_text_address((unsigned long) p->addr)) ||
+ in_kprobes_functions((unsigned long) p->addr))
+ return -EINVAL;
+
+ p->mod_refcounted = 0;
+ /* Check are we probing a module */
+ if ((probed_mod = module_text_address((unsigned long) p->addr))) {
+ struct module *calling_mod = module_text_address(called_from);
+ /* We must allow modules to probe themself and
+ * in this case avoid incrementing the module refcount,
+ * so as to allow unloading of self probing modules.
+ */
+ if (calling_mod && (calling_mod != probed_mod)) {
+ if (unlikely(!try_module_get(probed_mod)))
+ return -EINVAL;
+ p->mod_refcounted = 1;
+ } else
+ probed_mod = NULL;
+ }
- spin_lock_irqsave(&kprobe_lock, flags);
- old_p = get_kprobe(p->addr);
p->nmissed = 0;
+ mutex_lock(&kprobe_mutex);
+ old_p = get_kprobe(p->addr);
if (old_p) {
ret = register_aggr_kprobe(old_p, p);
goto out;
}
- arch_copy_kprobe(p);
+ if ((ret = arch_prepare_kprobe(p)) != 0)
+ goto out;
+
INIT_HLIST_NODE(&p->hlist);
- hlist_add_head(&p->hlist,
+ hlist_add_head_rcu(&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);
+ mutex_unlock(&kprobe_mutex);
+
+ if (ret && probed_mod)
+ module_put(probed_mod);
return ret;
}
+int __kprobes register_kprobe(struct kprobe *p)
+{
+ return __register_kprobe(p,
+ (unsigned long)__builtin_return_address(0));
+}
+
void __kprobes unregister_kprobe(struct kprobe *p)
{
- unsigned long flags;
- struct kprobe *old_p;
+ struct module *mod;
+ struct kprobe *old_p, *list_p;
+ int cleanup_p;
- spin_lock_irqsave(&kprobe_lock, flags);
+ mutex_lock(&kprobe_mutex);
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);
+ if (unlikely(!old_p)) {
+ mutex_unlock(&kprobe_mutex);
+ return;
+ }
+ 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;
+ mutex_unlock(&kprobe_mutex);
+ return;
+ }
+valid_p:
+ if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) &&
+ (p->list.next == &old_p->list) &&
+ (p->list.prev == &old_p->list))) {
+ /* Only probe on the hash list */
+ arch_disarm_kprobe(p);
+ hlist_del_rcu(&old_p->hlist);
+ cleanup_p = 1;
+ } else {
+ list_del_rcu(&p->list);
+ cleanup_p = 0;
+ }
+
+ mutex_unlock(&kprobe_mutex);
+
+ synchronize_sched();
+ if (p->mod_refcounted &&
+ (mod = module_text_address((unsigned long)p->addr)))
+ module_put(mod);
+
+ if (cleanup_p) {
+ if (p != old_p) {
+ list_del_rcu(&p->list);
+ kfree(old_p);
+ }
+ arch_remove_kprobe(p);
+ }
}
static struct notifier_block kprobe_exceptions_nb = {
jp->kp.pre_handler = setjmp_pre_handler;
jp->kp.break_handler = longjmp_break_handler;
- return register_kprobe(&jp->kp);
+ return __register_kprobe(&jp->kp,
+ (unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_jprobe(struct jprobe *jp)
#ifdef ARCH_SUPPORTS_KRETPROBES
+/*
+ * This kprobe pre_handler is registered with every kretprobe. When probe
+ * hits it will set up the return probe.
+ */
+static int __kprobes pre_handler_kretprobe(struct kprobe *p,
+ struct pt_regs *regs)
+{
+ struct kretprobe *rp = container_of(p, struct kretprobe, kp);
+ unsigned long flags = 0;
+
+ /*TODO: consider to only swap the RA after the last pre_handler fired */
+ spin_lock_irqsave(&kretprobe_lock, flags);
+ arch_prepare_kretprobe(rp, regs);
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ return 0;
+}
+
int __kprobes register_kretprobe(struct kretprobe *rp)
{
int ret = 0;
rp->nmissed = 0;
/* Establish function entry probe point */
- if ((ret = register_kprobe(&rp->kp)) != 0)
+ if ((ret = __register_kprobe(&rp->kp,
+ (unsigned long)__builtin_return_address(0))) != 0)
free_rp_inst(rp);
return ret;
}
unregister_kprobe(&rp->kp);
/* No race here */
- spin_lock_irqsave(&kprobe_lock, flags);
- free_rp_inst(rp);
+ spin_lock_irqsave(&kretprobe_lock, flags);
while ((ri = get_used_rp_inst(rp)) != NULL) {
ri->rp = NULL;
hlist_del(&ri->uflist);
}
- spin_unlock_irqrestore(&kprobe_lock, flags);
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ free_rp_inst(rp);
}
static int __init init_kprobes(void)
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff