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kprobes/x86: Disable preemption in ftrace-based jprobes

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Disable preemption in ftrace-based jprobe handlers as
described in Documentation/kprobes.txt:

  "Probe handlers are run with preemption disabled."

This will fix jprobes behavior when CONFIG_PREEMPT=y.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/150581530024.32348.9863783558598926771.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2017-09-19 19:01:40 +09:00 committed by Ingo Molnar
parent 9a09f261a4
commit 5bb4fc2d86
1 changed files with 14 additions and 9 deletions
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23
arch/x86/kernel/kprobes/ftrace.c
View File

@ -26,7 +26,7 @@
#include "common.h"
static nokprobe_inline
int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
void __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb, unsigned long orig_ip)
{
/*
@ -41,20 +41,21 @@ int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
__this_cpu_write(current_kprobe, NULL);
if (orig_ip)
regs->ip = orig_ip;
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;
if (kprobe_ftrace(p)) {
__skip_singlestep(p, regs, kcb, 0);
preempt_enable_no_resched();
return 1;
}
return 0;
}
NOKPROBE_SYMBOL(skip_singlestep);
/* Ftrace callback handler for kprobes */
/* Ftrace callback handler for kprobes -- called under preepmt disabed */
void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct pt_regs *regs)
{
@ -77,13 +78,17 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
regs->ip = ip + sizeof(kprobe_opcode_t);
/* To emulate trap based kprobes, preempt_disable here */
preempt_disable();
__this_cpu_write(current_kprobe, p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
if (!p->pre_handler || !p->pre_handler(p, regs))
if (!p->pre_handler || !p->pre_handler(p, regs)) {
__skip_singlestep(p, regs, kcb, orig_ip);
preempt_enable_no_resched();
}
/*
* If pre_handler returns !0, it sets regs->ip and
* resets current kprobe.
* resets current kprobe, and keep preempt count +1.
*/
}
end: