mirror of https://gitee.com/openkylin/linux.git
121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
/*
|
|
* Dynamic Ftrace based Kprobes Optimization
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
* Copyright (C) Hitachi Ltd., 2012
|
|
* Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
|
|
* IBM Corporation
|
|
*/
|
|
#include <linux/kprobes.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/preempt.h>
|
|
#include <linux/ftrace.h>
|
|
|
|
/*
|
|
* This is called from ftrace code after invoking registered handlers to
|
|
* disambiguate regs->nip changes done by jprobes and livepatch. We check if
|
|
* there is an active jprobe at the provided address (mcount location).
|
|
*/
|
|
int __is_active_jprobe(unsigned long addr)
|
|
{
|
|
if (!preemptible()) {
|
|
struct kprobe *p = raw_cpu_read(current_kprobe);
|
|
return (p && (unsigned long)p->addr == addr) ? 1 : 0;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static nokprobe_inline
|
|
int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
|
|
struct kprobe_ctlblk *kcb, unsigned long orig_nip)
|
|
{
|
|
/*
|
|
* Emulate singlestep (and also recover regs->nip)
|
|
* as if there is a nop
|
|
*/
|
|
regs->nip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
|
|
if (unlikely(p->post_handler)) {
|
|
kcb->kprobe_status = KPROBE_HIT_SSDONE;
|
|
p->post_handler(p, regs, 0);
|
|
}
|
|
__this_cpu_write(current_kprobe, NULL);
|
|
if (orig_nip)
|
|
regs->nip = orig_nip;
|
|
return 1;
|
|
}
|
|
|
|
int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
|
|
struct kprobe_ctlblk *kcb)
|
|
{
|
|
if (kprobe_ftrace(p))
|
|
return __skip_singlestep(p, regs, kcb, 0);
|
|
else
|
|
return 0;
|
|
}
|
|
NOKPROBE_SYMBOL(skip_singlestep);
|
|
|
|
/* Ftrace callback handler for kprobes */
|
|
void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
|
|
struct ftrace_ops *ops, struct pt_regs *regs)
|
|
{
|
|
struct kprobe *p;
|
|
struct kprobe_ctlblk *kcb;
|
|
|
|
preempt_disable();
|
|
|
|
p = get_kprobe((kprobe_opcode_t *)nip);
|
|
if (unlikely(!p) || kprobe_disabled(p))
|
|
goto end;
|
|
|
|
kcb = get_kprobe_ctlblk();
|
|
if (kprobe_running()) {
|
|
kprobes_inc_nmissed_count(p);
|
|
} else {
|
|
unsigned long orig_nip = regs->nip;
|
|
|
|
/*
|
|
* On powerpc, NIP is *before* this instruction for the
|
|
* pre handler
|
|
*/
|
|
regs->nip -= MCOUNT_INSN_SIZE;
|
|
|
|
__this_cpu_write(current_kprobe, p);
|
|
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
if (!p->pre_handler || !p->pre_handler(p, regs))
|
|
__skip_singlestep(p, regs, kcb, orig_nip);
|
|
else {
|
|
/*
|
|
* If pre_handler returns !0, it sets regs->nip and
|
|
* resets current kprobe. In this case, we should not
|
|
* re-enable preemption.
|
|
*/
|
|
return;
|
|
}
|
|
}
|
|
end:
|
|
preempt_enable_no_resched();
|
|
}
|
|
NOKPROBE_SYMBOL(kprobe_ftrace_handler);
|
|
|
|
int arch_prepare_kprobe_ftrace(struct kprobe *p)
|
|
{
|
|
p->ainsn.insn = NULL;
|
|
p->ainsn.boostable = -1;
|
|
return 0;
|
|
}
|