Commit-ID: a5b7e1a89b820f2b9b23634ca4c59b555e8d9a0d
Gitweb: http://git.kernel.org/tip/a5b7e1a89b820f2b9b23634ca4c59b555e8d9a0d
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 21 Jul 2015 15:40:23 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 31 Jul 2015 10:38:05 +0200
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@xxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Acked-by: Anton Arapov <arapov@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150721134023.GA4776@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/uprobes.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 93d939c8..7e61c8c 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
--
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