Commit 0f94eb63 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar

kprobes/x86: Boost probes when reentering

Integrate prepare_singlestep() into setup_singlestep() to boost
up reenter probes, if possible.
Signed-off-by: default avatarMasami 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: default avatarIngo Molnar <mingo@elte.hu>
parent b2be84df
...@@ -406,18 +406,6 @@ static void __kprobes restore_btf(void) ...@@ -406,18 +406,6 @@ static void __kprobes restore_btf(void)
update_debugctlmsr(current->thread.debugctlmsr); 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, void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs) struct pt_regs *regs)
{ {
...@@ -430,19 +418,38 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, ...@@ -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, 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 !defined(CONFIG_PREEMPT)
if (p->ainsn.boostable == 1 && !p->post_handler) { if (p->ainsn.boostable == 1 && !p->post_handler) {
/* Boost up -- we can execute copied instructions directly */ /* 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; regs->ip = (unsigned long)p->ainsn.insn;
preempt_enable_no_resched(); preempt_enable_no_resched();
return; return;
} }
#endif #endif
prepare_singlestep(p, regs); if (reenter) {
kcb->kprobe_status = KPROBE_HIT_SS; 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, ...@@ -456,11 +463,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
switch (kcb->kprobe_status) { switch (kcb->kprobe_status) {
case KPROBE_HIT_SSDONE: case KPROBE_HIT_SSDONE:
case KPROBE_HIT_ACTIVE: case KPROBE_HIT_ACTIVE:
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p); kprobes_inc_nmissed_count(p);
prepare_singlestep(p, regs); setup_singlestep(p, regs, kcb, 1);
kcb->kprobe_status = KPROBE_REENTER;
break; break;
case KPROBE_HIT_SS: case KPROBE_HIT_SS:
/* A probe has been hit in the codepath leading up to, or just /* 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) ...@@ -535,13 +539,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
* more here. * more here.
*/ */
if (!p->pre_handler || !p->pre_handler(p, regs)) if (!p->pre_handler || !p->pre_handler(p, regs))
setup_singlestep(p, regs, kcb); setup_singlestep(p, regs, kcb, 0);
return 1; return 1;
} }
} else if (kprobe_running()) { } else if (kprobe_running()) {
p = __get_cpu_var(current_kprobe); p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) { if (p->break_handler && p->break_handler(p, regs)) {
setup_singlestep(p, regs, kcb); setup_singlestep(p, regs, kcb, 0);
return 1; return 1;
} }
} /* else: not a kprobe fault; let the kernel handle it */ } /* else: not a kprobe fault; let the kernel handle it */
......
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