From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Fengguang Wu <fengguang.wu@intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Subject: [PATCH 6/6 v2] kprobes/x86: Fix to support jprobes on ftrace-based kprobe
Date: Thu, 13 Sep 2012 23:00:18 -0400 [thread overview]
Message-ID: <20120914030233.080884371@goodmis.org> (raw)
In-Reply-To: 20120914030012.315074731@goodmis.org
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From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Fix kprobes/x86 to support jprobes on ftrace-based kprobes.
Because of -mfentry support of ftrace, ftrace is now put
on the beginning of function where jprobes are put.
Originally ftrace-based kprobes doesn't support jprobe
because it will change regs->ip and ftrace doesn't support
changing IP and ftrace itself doesn't conflict jprobe.
However, ftrace -mfentry support moves mcount call on the
top of functions where jprobes are put. This means that
jprobe always conflicts with ftrace-based kprobe and fails.
This patch allows ftrace-based kprobes to support jprobes
by allowing to modify regs->ip and kprobes breakpoint
handler also allows to skip singlestepping because there
is a ftrace call (not an original instruction).
Link: http://lkml.kernel.org/r/20120905143125.10329.90836.stgit@localhost.localdomain
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/x86/kernel/kprobes.c | 42 +++++++++++++++++++++++++++++-------------
kernel/kprobes.c | 3 ---
2 files changed, 29 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index f49f60c..b7c2a85 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -541,6 +541,8 @@ reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb
return 1;
}
+static void __kprobes skip_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb);
/*
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
* remain disabled throughout this function.
@@ -599,6 +601,12 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
} else if (kprobe_running()) {
p = __this_cpu_read(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
+#ifdef KPROBES_CAN_USE_FTRACE
+ if (kprobe_ftrace(p)) {
+ skip_singlestep(p, regs, kcb);
+ return 1;
+ }
+#endif
setup_singlestep(p, regs, kcb, 0);
return 1;
}
@@ -1053,6 +1061,21 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
}
#ifdef KPROBES_CAN_USE_FTRACE
+static void __kprobes skip_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ /*
+ * Emulate singlestep (and also recover regs->ip)
+ * as if there is a 5byte nop
+ */
+ regs->ip = (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);
+}
+
/* Ftrace callback handler for kprobes */
void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct pt_regs *regs)
@@ -1077,19 +1100,12 @@ void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
__this_cpu_write(current_kprobe, p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
- if (p->pre_handler)
- p->pre_handler(p, regs);
-
- if (unlikely(p->post_handler)) {
- /*
- * Emulate singlestep (and also recover regs->ip)
- * as if there is a 5byte nop
- */
- regs->ip = ip + MCOUNT_INSN_SIZE;
- kcb->kprobe_status = KPROBE_HIT_SSDONE;
- p->post_handler(p, regs, 0);
- }
- __this_cpu_write(current_kprobe, NULL);
+ if (!p->pre_handler || !p->pre_handler(p, regs))
+ skip_singlestep(p, regs, kcb);
+ /*
+ * If pre_handler returns !0, it sets regs->ip and
+ * resets current kprobe.
+ */
}
end:
local_irq_restore(flags);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 35b4315..098f396 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1418,9 +1418,6 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
/* Given address is not on the instruction boundary */
if ((unsigned long)p->addr != ftrace_addr)
return -EILSEQ;
- /* break_handler (jprobe) can not work with ftrace */
- if (p->break_handler)
- return -EINVAL;
p->flags |= KPROBE_FLAG_FTRACE;
#else /* !KPROBES_CAN_USE_FTRACE */
return -EINVAL;
--
1.7.10.4
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next prev parent reply other threads:[~2012-09-14 3:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-14 3:00 [PATCH 0/6 v2] [GIT PULL][3.7] tracing: cleanups and fixes Steven Rostedt
2012-09-14 3:00 ` [PATCH 1/6 v2] tracing: Skip printing "OK" if failed to disable event Steven Rostedt
2012-09-14 3:00 ` [PATCH 2/6 v2] trace: Stop compiling in trace_clock unconditionally Steven Rostedt
2012-09-14 3:00 ` [PATCH 3/6 v2] ftrace/x86: Adjust x86 regs.ip as like as x86-64 Steven Rostedt
2012-09-14 3:00 ` [PATCH 4/6 v2] kprobes/x86: Fix kprobes to collectly handle IP on ftrace Steven Rostedt
2012-09-14 3:00 ` [PATCH 5/6 v2] ftrace/x86-64: Allow to change RIP in handlers Steven Rostedt
2012-09-14 3:00 ` Steven Rostedt [this message]
2012-09-14 11:40 ` [PATCH 0/6 v2] [GIT PULL][3.7] tracing: cleanups and fixes Ingo Molnar
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