kprobes: kretprobe user entry-handler
Provide support to add an optional user defined callback to be run at
function entry of a kretprobe'd function. Also modify the kprobe smoke
tests to include an entry-handler during the kretprobe sanity test.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d0493ea..7a86e64 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -699,6 +699,12 @@
struct kretprobe_instance, uflist);
ri->rp = rp;
ri->task = current;
+
+ if (rp->entry_handler && rp->entry_handler(ri, regs)) {
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ return 0;
+ }
+
arch_prepare_kretprobe(ri, regs);
/* XXX(hch): why is there no hlist_move_head? */
@@ -745,7 +751,8 @@
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);
+ inst = kmalloc(sizeof(struct kretprobe_instance) +
+ rp->data_size, GFP_KERNEL);
if (inst == NULL) {
free_rp_inst(rp);
return -ENOMEM;
diff --git a/kernel/test_kprobes.c b/kernel/test_kprobes.c
index 88cdb10..06b6395 100644
--- a/kernel/test_kprobes.c
+++ b/kernel/test_kprobes.c
@@ -135,6 +135,12 @@
#ifdef CONFIG_KRETPROBES
static u32 krph_val;
+static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+ krph_val = (rand1 / div_factor);
+ return 0;
+}
+
static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long ret = regs_return_value(regs);
@@ -144,13 +150,19 @@
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in kretprobe handler\n");
}
+ if (krph_val == 0) {
+ handler_errors++;
+ printk(KERN_ERR "Kprobe smoke test failed: "
+ "call to kretprobe entry handler failed\n");
+ }
- krph_val = (rand1 / div_factor);
+ krph_val = rand1;
return 0;
}
static struct kretprobe rp = {
.handler = return_handler,
+ .entry_handler = entry_handler,
.kp.symbol_name = "kprobe_target"
};
@@ -167,7 +179,7 @@
ret = kprobe_target(rand1);
unregister_kretprobe(&rp);
- if (krph_val == 0) {
+ if (krph_val != rand1) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kretprobe handler not called\n");
handler_errors++;