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[S390] kprobes: activation and deactivation

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Replace set_current_kprobe/reset_current_kprobe/save_previous_kprobe/
restore_previous_kprobe with a simpler scheme push_kprobe/pop_kprobe.
The mini kprobes stack can store up to two active kprobes.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2011-01-05 12:47:20 +01:00 committed by Martin Schwidefsky
parent ba640a5915
commit b9599798f9
1 changed files with 27 additions and 32 deletions
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59
arch/s390/kernel/kprobes.c
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@ -214,25 +214,29 @@ static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb,
regs->psw.addr = ip | PSW_ADDR_AMODE;
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
/*
* Activate a kprobe by storing its pointer to current_kprobe. The
* previous kprobe is stored in kcb->prev_kprobe. A stack of up to
* two kprobes can be active, see KPROBE_REENTER.
*/
static void __kprobes push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.kp = __get_cpu_var(current_kprobe);
kcb->prev_kprobe.status = kcb->kprobe_status;
__get_cpu_var(current_kprobe) = p;
}
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
/*
* Deactivate a kprobe by backing up to the previous state. If the
* current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL,
* for any other state prev_kprobe.kp will be NULL.
*/
static void __kprobes pop_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
}
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = p;
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
@ -261,14 +265,16 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
/* We have reentered the kprobe_handler(), since
* another probe was hit while within the handler.
* We here save the original kprobes variables and
* just single step on the instruction of the new probe
* without calling any user handlers.
/*
* We have hit a kprobe while another is still
* active. This can happen in the pre and post
* handler. Single step the instruction of the
* new probe but do not call any handler function
* of this secondary kprobe.
* push_kprobe and pop_kprobe saves and restores
* the currently active kprobe.
*/
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
push_kprobe(kcb, p);
kprobes_inc_nmissed_count(p);
enable_singlestep(kcb, regs,
(unsigned long) p->ainsn.insn);
@ -294,7 +300,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
goto no_kprobe;
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p, regs, kcb);
push_kprobe(kcb, p);
if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;
@ -395,7 +401,7 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
reset_current_kprobe();
pop_kprobe(get_kprobe_ctlblk());
kretprobe_hash_unlock(current, &flags);
preempt_enable_no_resched();
@ -457,14 +463,7 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
}
resume_execution(cur, regs);
/*Restore back the original saved kprobes variables and continue. */
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
goto out;
}
reset_current_kprobe();
out:
pop_kprobe(kcb);
preempt_enable_no_resched();
/*
@ -499,11 +498,7 @@ static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
* normal page fault.
*/
disable_singlestep(kcb, regs, (unsigned long) cur->addr);
if (kcb->kprobe_status == KPROBE_REENTER)
restore_previous_kprobe(kcb);
else {
reset_current_kprobe();
}
pop_kprobe(kcb);
preempt_enable_no_resched();
break;
case KPROBE_HIT_ACTIVE: