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[PATCH] Kprobes: preempt_disable/enable() simplification

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Reorganize the preempt_disable/enable calls to eliminate the extra preempt
depth.  Changes based on Paul McKenney's review suggestions for the kprobes
RCU changeset.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ananth N Mavinakayanahalli
2005-11-07 01:00:14 -08:00
committed by Linus Torvalds
parent 991a51d83a
commit d217d5450f
7 changed files with 80 additions and 61 deletions
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25
arch/i386/kernel/kprobes.c
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@@ -153,7 +153,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
int ret = 0;
kprobe_opcode_t *addr = NULL;
unsigned long *lp;
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
struct kprobe_ctlblk *kcb;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
/* Check if the application is using LDT entry for its code segment and
* calculate the address by reading the base address from the LDT entry.
@@ -221,11 +228,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
goto no_kprobe;
}
/*
* This preempt_disable() matches the preempt_enable_no_resched()
* in post_kprobe_handler()
*/
preempt_disable();
set_current_kprobe(p, regs, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
@@ -239,6 +241,7 @@ ss_probe:
return 1;
no_kprobe:
preempt_enable_no_resched();
return ret;
}
@@ -310,8 +313,8 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we have handled unlocking
* and re-enabling preemption
* kprobe_handler() that we don't want the post_handler
* to run (and have re-enabled preemption)
*/
return 1;
}
@@ -455,7 +458,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
rcu_read_lock();
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
@@ -467,14 +469,16 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
break;
case DIE_GPF:
case DIE_PAGE_FAULT:
/* kprobe_running() needs smp_processor_id() */
preempt_disable();
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
preempt_enable();
break;
default:
break;
}
rcu_read_unlock();
return ret;
}
@@ -537,6 +541,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
*regs = kcb->jprobe_saved_regs;
memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
MIN_STACK_SIZE(stack_addr));
preempt_enable_no_resched();
return 1;
}
return 0;