[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>
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 17e70b1..fddbac3 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -26,7 +26,6 @@
#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
-#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/preempt.h>
@@ -343,10 +342,11 @@
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 =
((struct fnptr *)kretprobe_trampoline)->ip;
+ spin_lock_irqsave(&kretprobe_lock, flags);
head = kretprobe_inst_table_head(current);
/*
@@ -386,7 +386,7 @@
regs->cr_iip = orig_ret_address;
reset_current_kprobe();
- unlock_kprobes();
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
preempt_enable_no_resched();
/*
@@ -397,6 +397,7 @@
return 1;
}
+/* Called with kretprobe_lock held */
void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
struct pt_regs *regs)
{
@@ -612,7 +613,6 @@
if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
(p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
ia64_psr(regs)->ss = 0;
- unlock_kprobes();
goto no_kprobe;
}
/* We have reentered the pre_kprobe_handler(), since
@@ -641,10 +641,8 @@
}
}
- lock_kprobes();
p = get_kprobe(addr);
if (!p) {
- unlock_kprobes();
if (!is_ia64_break_inst(regs)) {
/*
* The breakpoint instruction was removed right
@@ -707,7 +705,6 @@
goto out;
}
reset_current_kprobe();
- unlock_kprobes();
out:
preempt_enable_no_resched();
@@ -728,7 +725,6 @@
if (kcb->kprobe_status & KPROBE_HIT_SS) {
resume_execution(cur, regs);
reset_current_kprobe();
- unlock_kprobes();
preempt_enable_no_resched();
}
@@ -741,7 +737,7 @@
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
- preempt_disable();
+ rcu_read_lock();
switch(val) {
case DIE_BREAK:
if (pre_kprobes_handler(args))
@@ -757,7 +753,7 @@
default:
break;
}
- preempt_enable();
+ rcu_read_unlock();
return ret;
}