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authorOleg Nesterov <oleg@redhat.com>2015-07-21 15:40:23 +0200
committerIngo Molnar <mingo@kernel.org>2015-07-31 10:38:05 +0200
commita5b7e1a89b820f2b9b23634ca4c59b555e8d9a0d (patch)
tree6c15eed109c9cc8982f428dc2d8a6b56b7aeb5fc /kernel/events
parent5eeb50de42fd3251845d03c556db012267c72b3f (diff)
uprobes: Change prepare_uretprobe() to (try to) flush the dead frames
Change prepare_uretprobe() to flush the !arch_uretprobe_is_alive() return_instance's. This is not needed correctness-wise, but can help to avoid the failure caused by MAX_URETPROBE_DEPTH. Note: in this case arch_uretprobe_is_alive() can be false positive, the stack can grow after longjmp(). Unfortunately, the kernel can't 100% solve this problem, but see the next patch. Tested-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Anton Arapov <arapov@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150721134023.GA4776@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/uprobes.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 93d939c80cd9..7e61c8ca27e0 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1511,6 +1511,16 @@ static unsigned long get_trampoline_vaddr(void)
return trampoline_vaddr;
}
+static void cleanup_return_instances(struct uprobe_task *utask, struct pt_regs *regs)
+{
+ struct return_instance *ri = utask->return_instances;
+ while (ri && !arch_uretprobe_is_alive(ri, regs)) {
+ ri = free_ret_instance(ri);
+ utask->depth--;
+ }
+ utask->return_instances = ri;
+}
+
static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
{
struct return_instance *ri;
@@ -1541,6 +1551,9 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
if (orig_ret_vaddr == -1)
goto fail;
+ /* drop the entries invalidated by longjmp() */
+ cleanup_return_instances(utask, regs);
+
/*
* We don't want to keep trampoline address in stack, rather keep the
* original return address of first caller thru all the consequent