[PATCH -tip v11 12/27] ia64: kprobes: Fix to pass correct trampoline address to the handler

[Masami Hiramatsu <mhiramat@xxxxxxxxxx>]

The following commit:

   Commit e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler")

Passed the wrong trampoline address to __kretprobe_trampoline_handler(): it
passes the descriptor address instead of function entry address.

Pass the right parameter.

Also use correct symbol dereference function to get the function address
from 'kretprobe_trampoline' - an IA64 special.

Fixes: e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 Changes in v9:
  - Update changelog according to Ingo's suggestion.
  - Add Cc: stable tag.
 Changes in v5:
  - Fix a compile error typo.
---
 arch/ia64/kernel/kprobes.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 441ed04b1037..d4048518a1d7 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -398,7 +398,8 @@ static void kretprobe_trampoline(void)
 
 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-	regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);
+	regs->cr_iip = __kretprobe_trampoline_handler(regs,
+		dereference_function_descriptor(kretprobe_trampoline), NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
@@ -414,7 +415,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
+	regs->b0 = (unsigned long)dereference_function_descriptor(kretprobe_trampoline);
 }
 
 /* Check the instruction in the slot is break */
@@ -902,14 +903,14 @@ static struct kprobe trampoline_p = {
 int __init arch_init_kprobes(void)
 {
 	trampoline_p.addr =
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
+		dereference_function_descriptor(kretprobe_trampoline);
 	return register_kprobe(&trampoline_p);
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
 	if (p->addr ==
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
+		dereference_function_descriptor(kretprobe_trampoline))
 		return 1;
 
 	return 0;