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authorAnanth N Mavinakayanahalli2005-11-07 01:00:14 -0800
committerLinus Torvalds2005-11-07 07:53:46 -0800
commit991a51d83a3d9bebfafdd1e692cf310899d60791 (patch)
tree4cc6eaa2a868838e59c7737da9868f2358f2bb19 /arch/i386
parent3516a46042508a495fac13c2e73530d936ebe015 (diff)
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes
Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. 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>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/kprobes.c22
1 files changed, 7 insertions, 15 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index 99565a66915d..ad469299267a 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -31,7 +31,6 @@
#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
-#include <linux/spinlock.h>
#include <linux/preempt.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
@@ -123,6 +122,7 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
regs->eip = (unsigned long)&p->ainsn.insn;
}
+/* Called with kretprobe_lock held */
void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
struct pt_regs *regs)
{
@@ -168,15 +168,12 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
}
/* Check we're not actually recursing */
if (kprobe_running()) {
- /* We *are* holding lock here, so this is safe.
- Disarm the probe we just hit, and ignore it. */
p = get_kprobe(addr);
if (p) {
if (kcb->kprobe_status == KPROBE_HIT_SS &&
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
regs->eflags &= ~TF_MASK;
regs->eflags |= kcb->kprobe_saved_eflags;
- unlock_kprobes();
goto no_kprobe;
}
/* We have reentered the kprobe_handler(), since
@@ -197,14 +194,11 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
goto ss_probe;
}
}
- /* If it's not ours, can't be delete race, (we hold lock). */
goto no_kprobe;
}
- lock_kprobes();
p = get_kprobe(addr);
if (!p) {
- unlock_kprobes();
if (regs->eflags & VM_MASK) {
/* We are in virtual-8086 mode. Return 0 */
goto no_kprobe;
@@ -268,9 +262,10 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
struct kretprobe_instance *ri = NULL;
struct hlist_head *head;
struct hlist_node *node, *tmp;
- unsigned long orig_ret_address = 0;
+ unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
+ spin_lock_irqsave(&kretprobe_lock, flags);
head = kretprobe_inst_table_head(current);
/*
@@ -310,7 +305,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
regs->eip = orig_ret_address;
reset_current_kprobe();
- unlock_kprobes();
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
preempt_enable_no_resched();
/*
@@ -395,7 +390,7 @@ static void __kprobes resume_execution(struct kprobe *p,
/*
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled thoroughout this function. And we hold kprobe lock.
+ * remain disabled thoroughout this function.
*/
static inline int post_kprobe_handler(struct pt_regs *regs)
{
@@ -419,7 +414,6 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
goto out;
}
reset_current_kprobe();
- unlock_kprobes();
out:
preempt_enable_no_resched();
@@ -434,7 +428,6 @@ out:
return 1;
}
-/* Interrupts disabled, kprobe_lock held. */
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
@@ -448,7 +441,6 @@ static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
regs->eflags |= kcb->kprobe_old_eflags;
reset_current_kprobe();
- unlock_kprobes();
preempt_enable_no_resched();
}
return 0;
@@ -463,7 +455,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
- preempt_disable();
+ rcu_read_lock();
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
@@ -482,7 +474,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
default:
break;
}
- preempt_enable();
+ rcu_read_unlock();
return ret;
}