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powerpc: kprobes: Use generic kretprobe trampoline handler 

Use the generic kretprobe trampoline handler. Don't use
framepointer verification.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870610825.1229682.2090635992093223399.stgit@devnote2
This commit is contained in:
Masami Hiramatsu 2020-08-29 22:01:48 +09:00 committed by Ingo Molnar
parent 16ff6f7ac9
commit b6c5a58dd8
1 changed files with 3 additions and 50 deletions
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53
arch/powerpc/kernel/kprobes.c
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@ -218,6 +218,7 @@ bool arch_kprobe_on_func_entry(unsigned long offset)
void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->link;
ri->fp = NULL;
/* Replace the return addr with trampoline addr */
regs->link = (unsigned long)kretprobe_trampoline;
@ -396,50 +397,9 @@ asm(".global kretprobe_trampoline\n"
*/
static int 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;
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 than 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)
ri->rp->handler(ri, regs);
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);
unsigned long orig_ret_address;
orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
/*
* We get here through one of two paths:
* 1. by taking a trap -> kprobe_handler() -> here
@ -458,13 +418,6 @@ static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
regs->nip = orig_ret_address - 4;
regs->link = 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 0;
}
NOKPROBE_SYMBOL(trampoline_probe_handler);