From: Alexei Starovoitov <ast@kernel.org>
To: <davem@davemloft.net>
Cc: <daniel@iogearbox.net>, <peterz@infradead.org>,
<jannh@google.com>, <paulmck@linux.ibm.com>,
<will.deacon@arm.com>, <mingo@redhat.com>,
<netdev@vger.kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled
Date: Mon, 28 Jan 2019 17:21:52 -0800 [thread overview]
Message-ID: <20190129012152.251061-1-ast@kernel.org> (raw)
From: Peter Zijlstra <peterz@infradead.org>
Introduce cant_sleep() macro for annotation of functions that cannot sleep.
Use it in BPF_PROG_RUN to catch execution of BPF programs
in preemptable context.
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
include/linux/filter.h | 2 +-
include/linux/kernel.h | 14 ++++++++++++--
kernel/sched/core.c | 28 ++++++++++++++++++++++++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index e4b473f85b46..7e87863617b3 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -533,7 +533,7 @@ struct sk_filter {
struct bpf_prog *prog;
};
-#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi)
+#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); })
#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 8f0e68e250a7..a8868a32098c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -245,8 +245,10 @@ extern int _cond_resched(void);
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
- void ___might_sleep(const char *file, int line, int preempt_offset);
- void __might_sleep(const char *file, int line, int preempt_offset);
+extern void ___might_sleep(const char *file, int line, int preempt_offset);
+extern void __might_sleep(const char *file, int line, int preempt_offset);
+extern void __cant_sleep(const char *file, int line, int preempt_offset);
+
/**
* might_sleep - annotation for functions that can sleep
*
@@ -259,6 +261,13 @@ extern int _cond_resched(void);
*/
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
+/**
+ * cant_sleep - annotation for functions that cannot sleep
+ *
+ * this macro will print a stack trace if it is executed with preemption enabled
+ */
+# define cant_sleep() \
+ do { __cant_sleep(__FILE__, __LINE__, 0); } while (0)
# define sched_annotate_sleep() (current->task_state_change = 0)
#else
static inline void ___might_sleep(const char *file, int line,
@@ -266,6 +275,7 @@ extern int _cond_resched(void);
static inline void __might_sleep(const char *file, int line,
int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
+# define cant_sleep() do { } while (0)
# define sched_annotate_sleep() do { } while (0)
#endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a674c7db2f29..1dcbff62f973 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6149,6 +6149,34 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
}
EXPORT_SYMBOL(___might_sleep);
+
+void __cant_sleep(const char *file, int line, int preempt_offset)
+{
+ static unsigned long prev_jiffy;
+
+ if (irqs_disabled())
+ return;
+
+ if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
+ return;
+
+ if (preempt_count() > preempt_offset)
+ return;
+
+ if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
+ return;
+ prev_jiffy = jiffies;
+
+ printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
+ printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
+ in_atomic(), irqs_disabled(),
+ current->pid, current->comm);
+
+ debug_show_held_locks(current);
+ dump_stack();
+ add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+}
+EXPORT_SYMBOL_GPL(__cant_sleep);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
--
2.20.0
next reply other threads:[~2019-01-29 1:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-29 1:21 Alexei Starovoitov [this message]
2019-01-29 7:00 ` [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled Song Liu
2019-01-31 22:29 ` Daniel Borkmann
2019-02-19 20:58 ` Daniel Borkmann
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=20190129012152.251061-1-ast@kernel.org \
--to=ast@kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=jannh@google.com \
--cc=kernel-team@fb.com \
--cc=mingo@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=paulmck@linux.ibm.com \
--cc=peterz@infradead.org \
--cc=will.deacon@arm.com \
/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).