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[tip:perf/probes] kprobes/x86: Boost probes when reentering
- From: tip-bot for Masami Hiramatsu <mhiramat at redhat dot com>
- To: linux-tip-commits at vger dot kernel dot org
- Cc: mingo at redhat dot com, andersk at ksplice dot com, fweisbec at gmail dot com, dle-develop at lists dot sourceforge dot net, rostedt at goodmis dot org, compudj at krystal dot dyndns dot org, jbaron at redhat dot com, tglx at linutronix dot de, mhiramat at redhat dot com, systemtap at sources dot redhat dot com, linux-kernel at vger dot kernel dot org, hpa at zytor dot com, jkenisto at us dot ibm dot com, andi at firstfloor dot org, tabbott at ksplice dot com, hch at infradead dot org, ananth at in dot ibm dot com, srikar at linux dot vnet dot ibm dot com, mingo at elte dot hu
- Date: Thu, 25 Feb 2010 19:29:01 GMT
- Subject: [tip:perf/probes] kprobes/x86: Boost probes when reentering
- Git-commit-id: 0f94eb634ef7af736dee5639aac1c2fe9635d089
- References: <20100225133423.6725.12071.stgit@localhost6.localdomain6>
- Reply-to: mingo at redhat dot com, andersk at ksplice dot com, fweisbec at gmail dot com, dle-develop at lists dot sourceforge dot net, rostedt at goodmis dot org, compudj at krystal dot dyndns dot org, jbaron at redhat dot com, tglx at linutronix dot de, mhiramat at redhat dot com, systemtap at sources dot redhat dot com, linux-kernel at vger dot kernel dot org, hpa at zytor dot com, jkenisto at us dot ibm dot com, andi at firstfloor dot org, tabbott at ksplice dot com, hch at infradead dot org, ananth at in dot ibm dot com, srikar at linux dot vnet dot ibm dot com, mingo at elte dot hu
Commit-ID: 0f94eb634ef7af736dee5639aac1c2fe9635d089
Gitweb: http://git.kernel.org/tip/0f94eb634ef7af736dee5639aac1c2fe9635d089
Author: Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Thu, 25 Feb 2010 08:34:23 -0500
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 25 Feb 2010 17:49:25 +0100
kprobes/x86: Boost probes when reentering
Integrate prepare_singlestep() into setup_singlestep() to boost
up reenter probes, if possible.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133423.6725.12071.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/kprobes.c | 48 ++++++++++++++++++++++++--------------------
1 files changed, 26 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 15177cd..c69bb65 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -406,18 +406,6 @@ static void __kprobes restore_btf(void)
update_debugctlmsr(current->thread.debugctlmsr);
}
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
-{
- clear_btf();
- regs->flags |= X86_EFLAGS_TF;
- regs->flags &= ~X86_EFLAGS_IF;
- /* single step inline if the instruction is an int3 */
- if (p->opcode == BREAKPOINT_INSTRUCTION)
- regs->ip = (unsigned long)p->addr;
- else
- regs->ip = (unsigned long)p->ainsn.insn;
-}
-
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
@@ -430,19 +418,38 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
}
static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
- struct kprobe_ctlblk *kcb)
+ struct kprobe_ctlblk *kcb, int reenter)
{
#if !defined(CONFIG_PREEMPT)
if (p->ainsn.boostable == 1 && !p->post_handler) {
/* Boost up -- we can execute copied instructions directly */
- reset_current_kprobe();
+ if (!reenter)
+ reset_current_kprobe();
+ /*
+ * Reentering boosted probe doesn't reset current_kprobe,
+ * nor set current_kprobe, because it doesn't use single
+ * stepping.
+ */
regs->ip = (unsigned long)p->ainsn.insn;
preempt_enable_no_resched();
return;
}
#endif
- prepare_singlestep(p, regs);
- kcb->kprobe_status = KPROBE_HIT_SS;
+ if (reenter) {
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_REENTER;
+ } else
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ /* Prepare real single stepping */
+ clear_btf();
+ regs->flags |= X86_EFLAGS_TF;
+ regs->flags &= ~X86_EFLAGS_IF;
+ /* single step inline if the instruction is an int3 */
+ if (p->opcode == BREAKPOINT_INSTRUCTION)
+ regs->ip = (unsigned long)p->addr;
+ else
+ regs->ip = (unsigned long)p->ainsn.insn;
}
/*
@@ -456,11 +463,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
switch (kcb->kprobe_status) {
case KPROBE_HIT_SSDONE:
case KPROBE_HIT_ACTIVE:
- save_previous_kprobe(kcb);
- set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p);
- prepare_singlestep(p, regs);
- kcb->kprobe_status = KPROBE_REENTER;
+ setup_singlestep(p, regs, kcb, 1);
break;
case KPROBE_HIT_SS:
/* A probe has been hit in the codepath leading up to, or just
@@ -535,13 +539,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
* more here.
*/
if (!p->pre_handler || !p->pre_handler(p, regs))
- setup_singlestep(p, regs, kcb);
+ setup_singlestep(p, regs, kcb, 0);
return 1;
}
} else if (kprobe_running()) {
p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
- setup_singlestep(p, regs, kcb);
+ setup_singlestep(p, regs, kcb, 0);
return 1;
}
} /* else: not a kprobe fault; let the kernel handle it */