[PATCH 4.19.y 3/3] ia64: kprobes: Fix to pass correct trampoline address to the handler

From: Masami Hiramatsu
Date: Tue Apr 26 2022 - 10:26:35 EST

commit a7fe2378454cf46cd5e2776d05e72bbe8f0a468c upstream.

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.

Link: https://lkml.kernel.org/r/163163042696.489837.12551102356265354730.stgit@devnote2

Fixes: e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler")
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: X86 ML <x86@xxxxxxxxxx>
Cc: Daniel Xu <dxu@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Abhishek Sagar <sagar.abhishek@xxxxxxxxx>
Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
Cc: Paul McKenney <paulmck@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
arch/ia64/kernel/kprobes.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index aa41bd5cf9b7..7fc0806bbdc9 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -424,7 +424,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
struct hlist_node *tmp;
unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address =
- ((struct fnptr *)kretprobe_trampoline)->ip;
+ (unsigned long)dereference_function_descriptor(kretprobe_trampoline);

kretprobe_hash_lock(current, &head, &flags);
@@ -500,7 +500,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
ri->ret_addr = (kprobe_opcode_t *)regs->b0;

/* 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 */
@@ -1030,14 +1030,14 @@ 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;