From: Vasily Gorbik <gor@linux.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Josef Bacik <jbacik@fb.com>, linux-kernel@vger.kernel.org
Subject: User stacktrace garbage when USER_STACKTRACE_SUPPORT is not enabled
Date: Wed, 31 Mar 2021 13:52:45 +0200
Message-ID: <your-ad-here.call-01617191565-ext-9692@work.hours> (raw)
Hi Steven,
At least on s390 since commit cbc3b92ce037 ("tracing: Set kernel_stack's
caller size properly") kernel stack trace contains 8 garbage values in the end.
I assume those are supposed to be filled by ftrace_trace_userstack, which is
only implemented on x86.
sshd-804 [050] 1997.252608: kernel_stack: <stack trace>
=> trampoline_probe_handler (549628c94)
=> kprobe_handler (549629260)
=> kprobe_exceptions_notify (549629370)
=> notify_die (549686e5e)
=> illegal_op (54960d440)
=> __do_pgm_check (54a106b08)
=> pgm_check_handler (54a112cc8)
=> kretprobe_trampoline (549629438)
=> kretprobe_trampoline (549629436)
=> do_syscall (549611ee6)
=> __do_syscall (54a106ccc)
=> system_call (54a112b5a)
=> 769010000000322
=> 22125e4d8
=> 22125e8f8
=> e000054100040100
=> _end (3220000000c)
=> 2
=> 20f892ec00000002
=> 20f898b800000002
kernel/trace/trace_entries.h:
159 #define FTRACE_STACK_ENTRIES 8
160
161 FTRACE_ENTRY(kernel_stack, stack_entry,
162
163 TRACE_STACK,
164
165 F_STRUCT(
166 __field( int, size )
167 __array( unsigned long, caller, FTRACE_STACK_ENTRIES )
168 ),
Is there any reason to keep those 8 extra values in the caller array if
CONFIG_USER_STACKTRACE_SUPPORT is not enabled? Any advice how to fix that
gracefully? It seems to work if I simply set FTRACE_STACK_ENTRIES to 0 when
CONFIG_USER_STACKTRACE_SUPPORT is not enabled.
next reply index
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-31 11:52 Vasily Gorbik [this message]
2021-03-31 14:37 ` Steven Rostedt
2021-03-31 20:51 ` Vasily Gorbik
2021-03-31 21:09 ` Steven Rostedt
2021-03-31 22:02 ` Vasily Gorbik
2021-03-31 22:27 ` Steven Rostedt
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=your-ad-here.call-01617191565-ext-9692@work.hours \
--to=gor@linux.ibm.com \
--cc=jbacik@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.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
LKML Archive on lore.kernel.org
Archives are clonable:
git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
linux-kernel@vger.kernel.org
public-inbox-index lkml
Example config snippet for mirrors
Newsgroup available over NNTP:
nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git