lkml.org 
[lkml]   [2017]   [Sep]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] uprobe: Warn if unable to install breakpoint
Date
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> writes:

> When we try to install a uprobe breakpoint in uprobe_mmap(), we ignore
> all errors encountered in the process per this comment at the top of
> the function:
> /*
> * Called from mmap_region/vma_adjust with mm->mmap_sem acquired.
> *
> * Currently we ignore all errors and always return 0, the callers
> * can't handle the failure anyway.
> */
>
> However, this is very confusing for users since no probe hits are
> recorded nor is an error logged in dmesg.
>
> Fix this by logging an error in dmesg so that users can discover that
> there was an issue with the uprobe. To facilitate use of uprobe_warn(),
> we move that function to the top of the file.
>
> With this patch, we see a message similar to this in dmesg:
> [ 201.449213] uprobe: uprobe_t:9740 failed to setup probe at 0x95c (-524)
>
> Reported-by: Anton Blanchard <anton@samba.org>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> ---
> kernel/events/uprobes.c | 21 ++++++++++++++-------
> 1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 0e137f98a50c..587c591a535c 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -112,6 +112,12 @@ struct xol_area {
> unsigned long vaddr; /* Page(s) of instruction slots */
> };
>
> +static void uprobe_warn(struct task_struct *t, const char *msg)
> +{
> + pr_warn("uprobe: %s:%d failed to %s\n",
> + current->comm, current->pid, msg);

That should probably be ratelimited no?

cheers

\
 
 \ /
  Last update: 2017-09-01 07:10    [W:0.036 / U:7.796 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site