Since the int3 itself disables the local_irq and kprobes
keeps it disabled while the single step has done, the
kernel preemption never happen while processing a kprobe.
This means that we don't need to disable/enable preemption.
Also, this changes kprobe_int3_handler to use goto-out style.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
---
arch/x86/kernel/kprobes/core.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 060641e..6b4d9bd 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -506,7 +506,6 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
* stepping.
*/
regs->ip = (unsigned long)p->ainsn.insn;
- preempt_enable_no_resched();
return;
}
#endif
@@ -574,13 +573,6 @@ int kprobe_int3_handler(struct pt_regs *regs)
struct kprobe_ctlblk *kcb;
addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
- /*
- * We don't want to be preempted for the entire
- * duration of kprobe processing. We conditionally
- * re-enable preemption at the end of this function,
- * and also in reenter_kprobe() and setup_singlestep().
- */
- preempt_disable();
kcb = get_kprobe_ctlblk();
p = get_kprobe(addr);
@@ -588,7 +580,7 @@ int kprobe_int3_handler(struct pt_regs *regs)
if (p) {
if (kprobe_running()) {
if (reenter_kprobe(p, regs, kcb))
- return 1;
+ goto handled;
} else {
set_current_kprobe(p, regs, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
@@ -603,7 +595,7 @@ int kprobe_int3_handler(struct pt_regs *regs)
*/
if (!p->pre_handler || !p->pre_handler(p, regs))
setup_singlestep(p, regs, kcb, 0);
- return 1;
+ goto handled;
}
} else if (*addr != BREAKPOINT_INSTRUCTION) {
/*
@@ -616,19 +608,20 @@ int kprobe_int3_handler(struct pt_regs *regs)
* the original instruction.
*/
regs->ip = (unsigned long)addr;
- preempt_enable_no_resched();
- return 1;
+ goto handled;
} else if (kprobe_running()) {
p = __this_cpu_read(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
if (!skip_singlestep(p, regs, kcb))
setup_singlestep(p, regs, kcb, 0);
- return 1;
+ goto handled;
}
} /* else: not a kprobe fault; let the kernel handle it */
- preempt_enable_no_resched();
return 0;
+
+handled:
+ return 1;
}
NOKPROBE_SYMBOL(kprobe_int3_handler);
@@ -893,7 +886,6 @@ int kprobe_debug_handler(struct pt_regs *regs)
}
reset_current_kprobe();
out:
- preempt_enable_no_resched();
/*
* if somebody else is singlestepping across a probe point, flags
@@ -928,7 +920,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
restore_previous_kprobe(kcb);
else
reset_current_kprobe();
- preempt_enable_no_resched();
break;
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
@@ -1062,7 +1053,6 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
kcb->jprobes_stack,
MIN_STACK_SIZE(kcb->jprobe_saved_sp));
- preempt_enable_no_resched();
return 1;
}
return 0;
--
To unsubscribe from this list: send the line "unsubscribe linux-arch" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
