From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Josef Bacik <jbacik@fb.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Howard McLauchlan <hmclauchlan@fb.com>
Subject: [PATCH 2/5] tracing/uprobe: Add support for overlayfs
Date: Wed, 11 Apr 2018 21:54:01 -0400 [thread overview]
Message-ID: <20180412015440.633150795@goodmis.org> (raw)
In-Reply-To: 20180412015359.244491749@goodmis.org
[-- Attachment #1: 0002-tracing-uprobe-Add-support-for-overlayfs.patch --]
[-- Type: text/plain, Size: 2037 bytes --]
From: Howard McLauchlan <hmclauchlan@fb.com>
uprobes cannot successfully attach to binaries located in a directory
mounted with overlayfs.
To verify, create directories for mounting overlayfs
(upper,lower,work,merge), move some binary into merge/ and use readelf
to obtain some known instruction of the binary. I used /bin/true and the
entry instruction(0x13b0):
$ mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work merge
$ cd /sys/kernel/debug/tracing
$ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events
$ echo 1 > events/uprobes/true_entry/enable
This returns 'bash: echo: write error: Input/output error' and dmesg
tells us 'event trace: Could not enable event true_entry'
This change makes create_trace_uprobe() look for the real inode of a
dentry. In the case of normal filesystems, this simplifies to just
returning the inode. In the case of overlayfs(and similar fs) we will
obtain the underlying dentry and corresponding inode, upon which uprobes
can successfully register.
Running the example above with the patch applied, we can see that the
uprobe is enabled and will output to trace as expected.
Link: http://lkml.kernel.org/r/20180410231030.2720-1-hmclauchlan@fb.com
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_uprobe.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 268029ae1be6..8b86d76c55ee 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -446,7 +446,7 @@ static int create_trace_uprobe(int argc, char **argv)
if (ret)
goto fail_address_parse;
- inode = igrab(d_inode(path.dentry));
+ inode = igrab(d_real_inode(path.dentry));
path_put(&path);
if (!inode || !S_ISREG(inode->i_mode)) {
--
2.16.3
next prev parent reply other threads:[~2018-04-12 1:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 1:53 [PATCH 0/5] [GIT PULL] tracing: A few last minute clean up and fixes Steven Rostedt
2018-04-12 1:54 ` Steven Rostedt [this message]
2018-04-12 1:54 ` [PATCH 3/5] trace_uprobe: Use %lx to display offset Steven Rostedt
2018-04-12 1:54 ` [PATCH 4/5] trace_uprobe: Simplify probes_seq_show() Steven Rostedt
2018-04-12 1:54 ` [PATCH 5/5] tracing: Enforce passing in filter=NULL to create_filter() Steven Rostedt
2018-04-12 17:53 ` [PATCH 0/5] [GIT PULL] tracing: A few last minute clean up and fixes Linus Torvalds
2018-04-12 17:58 ` Linus Torvalds
2018-04-12 18:28 ` Steven Rostedt
2018-04-12 19:00 ` Konstantin Ryabitsev
2018-04-12 19:46 ` Steven Rostedt
2018-04-12 19:55 ` Konstantin Ryabitsev
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180412015440.633150795@goodmis.org \
--to=rostedt@goodmis.org \
--cc=akpm@linux-foundation.org \
--cc=hmclauchlan@fb.com \
--cc=jbacik@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@kernel.org \
--cc=srikar@linux.vnet.ibm.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).