From da1816b1caeccdff04531e763bb35d7caa3ed19f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 29 Dec 2012 17:49:11 +0100 Subject: uprobes: Teach handler_chain() to filter out the probed task Currrently the are 2 problems with pre-filtering: 1. It is not possible to add/remove a task (mm) after uprobe_register() 2. A forked child inherits all breakpoints and uprobe_consumer can not control this. This patch does the first step to improve the filtering. handler_chain() removes the breakpoints installed by this uprobe from current->mm if all handlers return UPROBE_HANDLER_REMOVE. Note that handler_chain() relies on ->register_rwsem to avoid the race with uprobe_register/unregister which can add/del a consumer, or even remove and then insert the new uprobe at the same address. Perhaps we will add uprobe_apply_mm(uprobe, mm, is_register) and teach copy_mm() to do filter(UPROBE_FILTER_FORK), but I think this change makes sense anyway. Note: instead of checking the retcode from uc->handler, we could add uc->filter(UPROBE_FILTER_BPHIT). But I think this is not optimal to call 2 hooks in a row. This buys nothing, and if handler/filter do something nontrivial they will probably do the same work twice. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- include/linux/uprobes.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux') diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index c2df6934fdc6..95d0002efda5 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -35,6 +35,9 @@ struct inode; # include #endif +#define UPROBE_HANDLER_REMOVE 1 +#define UPROBE_HANDLER_MASK 1 + enum uprobe_filter_ctx { UPROBE_FILTER_REGISTER, UPROBE_FILTER_UNREGISTER, -- cgit v1.2.3