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authorPrasanna S Panchamukhi <prasanna@in.ibm.com>2005-06-23 00:09:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 09:45:24 -0700
commitea32c65cc2d2294c04e9f81d0578a6f51febfdbf (patch)
treeb301766bcc903f982b0ae85b5edffe9477a65408 /kernel
parent89cb14c0dd0e4a7d0315d19f449389c4d49237ee (diff)
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[PATCH] kprobes: Temporary disarming of reentrant probe
In situations where a kprobes handler calls a routine which has a probe on it, then kprobes_handler() disarms the new probe forever. This patch removes the above limitation by temporarily disarming the new probe. When the another probe hits while handling the old probe, the kprobes_handler() saves previous kprobes state and handles the new probe without calling the new kprobes registered handlers. kprobe_post_handler() restores back the previous kprobes state and the normal execution continues. However on x86_64 architecture, re-rentrancy is provided only through pre_handler(). If a routine having probe is referenced through post_handler(), then the probes on that routine are disarmed forever, since the exception stack is gets changed after the processor single steps the instruction of the new probe. This patch includes generic changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kprobes.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index dd42e71..456eced 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -335,6 +335,7 @@ int register_kprobe(struct kprobe *p)
}
spin_lock_irqsave(&kprobe_lock, flags);
old_p = get_kprobe(p->addr);
+ p->nmissed = 0;
if (old_p) {
ret = register_aggr_kprobe(old_p, p);
goto out;