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authorSrikar Dronamraju <srikar@linux.vnet.ibm.com>2012-03-30 23:56:46 +0530
committerIngo Molnar <mingo@kernel.org>2012-03-31 11:50:02 +0200
commit682968e0c425c60f0dde37977e5beb2b12ddc4cc (patch)
tree875eb289aa0e08189b2cf7dc99ee522f91e647e7 /kernel/fork.c
parentd4b3b6384f98f8692ad0209891ccdbc7e78bbefe (diff)
uprobes/core: Optimize probe hits with the help of a counter
Maintain a per-mm counter: number of uprobes that are inserted on this process address space. This counter can be used at probe hit time to determine if we need a lookup in the uprobes rbtree. Everytime a probe gets inserted successfully, the probe count is incremented and everytime a probe gets removed, the probe count is decremented. The new uprobe_munmap hook ensures the count is correct on a unmap or remap of a region. We expect that once a uprobe_munmap() is called, the vma goes away. So uprobe_unregister() finding a probe to unregister would either mean unmap event hasnt occurred yet or a mmap event on the same executable file occured after a unmap event. Additionally, uprobe_mmap hook now also gets called: a. on every executable vma that is COWed at fork. b. a vma of interest is newly mapped; breakpoint insertion also happens at the required address. On process creation, make sure the probes count in the child is set correctly. Special cases that are taken care include: a. mremap b. VM_DONTCOPY vmas on fork() c. insertion/removal races in the parent during fork(). Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com> Cc: Linux-mm <linux-mm@kvack.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Anton Arapov <anton@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20120330182646.10018.85805.sendpatchset@srdronam.in.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 3133b9da59d5..26a8f5c25805 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -421,6 +421,9 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
if (retval)
goto out;
+
+ if (file && uprobe_mmap(tmp))
+ goto out;
}
/* a new mm has just been created */
arch_dup_mmap(oldmm, mm);