[RFC PATCH 12/14] sh: kprobes: Use generic kretprobe trampoline handler

From: Masami Hiramatsu
Date: Wed Aug 26 2020 - 09:50:17 EST


Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
arch/sh/kernel/kprobes.c | 59 +++-------------------------------------------
1 file changed, 4 insertions(+), 55 deletions(-)

diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index 318296f48f1a..118927ab63af 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -204,6 +204,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->pr;
+ ri->fp = NULL;

/* Replace the return addr with trampoline addr */
regs->pr = (unsigned long)kretprobe_trampoline;
@@ -302,62 +303,10 @@ static void __used kretprobe_trampoline_holder(void)
*/
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
- struct kretprobe_instance *ri = NULL;
- struct hlist_head *head, empty_rp;
- struct hlist_node *tmp;
- unsigned long flags, orig_ret_address = 0;
- unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+ regs->pc = __kretprobe_trampoline_handler(regs,
+ (unsigned long)&kretprobe_trampoline, NULL);

- INIT_HLIST_HEAD(&empty_rp);
- kretprobe_hash_lock(current, &head, &flags);
-
- /*
- * It is possible to have multiple instances associated with a given
- * task either because an multiple functions in the call path
- * have a return probe installed on them, and/or more then one return
- * return probe was registered for a target function.
- *
- * We can handle this because:
- * - instances are always inserted at the head of the list
- * - when multiple return probes are registered for the same
- * function, the first instance's ret_addr will point to the
- * real return address, and all the rest will point to
- * kretprobe_trampoline
- */
- hlist_for_each_entry_safe(ri, tmp, head, hlist) {
- if (ri->task != current)
- /* another task is sharing our hash bucket */
- continue;
-
- if (ri->rp && ri->rp->handler) {
- __this_cpu_write(current_kprobe, &ri->rp->kp);
- ri->rp->handler(ri, regs);
- __this_cpu_write(current_kprobe, NULL);
- }
-
- orig_ret_address = (unsigned long)ri->ret_addr;
- recycle_rp_inst(ri, &empty_rp);
-
- if (orig_ret_address != trampoline_address)
- /*
- * This is the real return address. Any other
- * instances associated with this task are for
- * other calls deeper on the call stack
- */
- break;
- }
-
- kretprobe_assert(ri, orig_ret_address, trampoline_address);
-
- regs->pc = orig_ret_address;
- kretprobe_hash_unlock(current, &flags);
-
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
-
- return orig_ret_address;
+ return 1;
}

static int __kprobes post_kprobe_handler(struct pt_regs *regs)