From: peterz@infradead.org
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, Eddy_Wu@trendmicro.com,
x86@kernel.org, davem@davemloft.net, rostedt@goodmis.org,
naveen.n.rao@linux.ibm.com, anil.s.keshavamurthy@intel.com,
linux-arch@vger.kernel.org, cameron@moodycamel.com,
oleg@redhat.com, will@kernel.org, paulmck@kernel.org
Subject: Re: [PATCH v5 00/21] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless
Date: Wed, 2 Sep 2020 11:36:13 +0200 [thread overview]
Message-ID: <20200902093613.GY1362448@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200902171755.b126672093a3c5d1b3a62a4f@kernel.org>
On Wed, Sep 02, 2020 at 05:17:55PM +0900, Masami Hiramatsu wrote:
> > Ok, but then lockdep will yell at you if you have that enabled and run
> > the unoptimized things.
>
> Oh, does it warn for all spinlock things in kprobes if it is unoptimized?
> Hmm, it has to be noted in the documentation.
Lockdep will warn about spinlocks used in NMI context that are also used
outside NMI context.
Now, for the kretprobe that kprobe_busy flag prevents the actual
recursion self-deadlock, but lockdep isn't smart enough to see that.
One way around this might be to use SINGLE_DEPTH_NESTING for locks when
we use them from INT3 context. That way they'll have a different class
and lockdep will not see the recursion.
pre_handler_kretprobe() is always called from INT3, right?
Something like the below might then work...
---
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 287b263c9cb9..b78f4fe08e86 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1255,11 +1255,11 @@ __acquires(hlist_lock)
NOKPROBE_SYMBOL(kretprobe_hash_lock);
static void kretprobe_table_lock(unsigned long hash,
- unsigned long *flags)
+ unsigned long *flags, int nesting)
__acquires(hlist_lock)
{
raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
- raw_spin_lock_irqsave(hlist_lock, *flags);
+ raw_spin_lock_irqsave_nested(hlist_lock, *flags, nesting);
}
NOKPROBE_SYMBOL(kretprobe_table_lock);
@@ -1326,7 +1326,7 @@ void kprobe_flush_task(struct task_struct *tk)
INIT_HLIST_HEAD(&empty_rp);
hash = hash_ptr(tk, KPROBE_HASH_BITS);
head = &kretprobe_inst_table[hash];
- kretprobe_table_lock(hash, &flags);
+ kretprobe_table_lock(hash, &flags, 0);
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task == tk)
recycle_rp_inst(ri, &empty_rp);
@@ -1361,7 +1361,7 @@ static void cleanup_rp_inst(struct kretprobe *rp)
/* No race here */
for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
- kretprobe_table_lock(hash, &flags);
+ kretprobe_table_lock(hash, &flags, 0);
head = &kretprobe_inst_table[hash];
hlist_for_each_entry_safe(ri, next, head, hlist) {
if (ri->rp == rp)
@@ -1950,7 +1950,7 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
/* TODO: consider to only swap the RA after the last pre_handler fired */
hash = hash_ptr(current, KPROBE_HASH_BITS);
- raw_spin_lock_irqsave(&rp->lock, flags);
+ raw_spin_lock_irqsave_nested(&rp->lock, flags, SINGLE_DEPTH_NESTING);
if (!hlist_empty(&rp->free_instances)) {
ri = hlist_entry(rp->free_instances.first,
struct kretprobe_instance, hlist);
@@ -1961,7 +1961,7 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
ri->task = current;
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
- raw_spin_lock_irqsave(&rp->lock, flags);
+ raw_spin_lock_irqsave_nested(&rp->lock, flags, SINGLE_DEPTH_NESTING);
hlist_add_head(&ri->hlist, &rp->free_instances);
raw_spin_unlock_irqrestore(&rp->lock, flags);
return 0;
@@ -1971,7 +1971,7 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
/* XXX(hch): why is there no hlist_move_head? */
INIT_HLIST_NODE(&ri->hlist);
- kretprobe_table_lock(hash, &flags);
+ kretprobe_table_lock(hash, &flags, SINGLE_DEPTH_NESTING);
hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
kretprobe_table_unlock(hash, &flags);
} else {
next prev parent reply other threads:[~2020-09-02 9:36 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-29 12:59 [PATCH v5 00/21] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 01/21] kprobes: Add generic kretprobe trampoline handler Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 02/21] x86/kprobes: Use " Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 03/21] arm: kprobes: " Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 04/21] arm64: " Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 05/21] arc: " Masami Hiramatsu
2020-08-29 13:00 ` [PATCH v5 06/21] csky: " Masami Hiramatsu
2020-08-29 13:01 ` [PATCH v5 07/21] ia64: " Masami Hiramatsu
2020-08-29 13:01 ` [PATCH v5 08/21] mips: " Masami Hiramatsu
2020-08-29 13:01 ` [PATCH v5 09/21] parisc: " Masami Hiramatsu
2020-08-29 13:01 ` [PATCH v5 10/21] powerpc: " Masami Hiramatsu
2020-08-29 13:02 ` [PATCH v5 11/21] s390: " Masami Hiramatsu
2020-08-29 13:02 ` [PATCH v5 12/21] sh: " Masami Hiramatsu
2020-08-29 13:02 ` [PATCH v5 13/21] sparc: " Masami Hiramatsu
2020-08-29 13:02 ` [PATCH v5 14/21] kprobes: Remove NMI context check Masami Hiramatsu
[not found] ` <20201030213831.04e81962@oasis.local.home>
2020-11-02 5:11 ` Masami Hiramatsu
2020-11-02 5:53 ` Masami Hiramatsu
2020-11-02 7:02 ` Masami Hiramatsu
2020-11-02 14:27 ` Steven Rostedt
2020-11-03 5:39 ` Masami Hiramatsu
2020-11-03 16:09 ` Steven Rostedt
2020-11-04 2:08 ` Masami Hiramatsu
2020-11-04 14:47 ` Steven Rostedt
2020-11-05 5:15 ` Masami Hiramatsu
2020-08-29 13:02 ` [PATCH v5 15/21] kprobes: Free kretprobe_instance with rcu callback Masami Hiramatsu
2020-08-29 13:03 ` [PATCH v5 16/21] kprobes: Make local used functions static Masami Hiramatsu
2020-08-29 13:03 ` [PATCH v5 17/21] llist: Add nonatomic __llist_add() and __llist_dell_all() Masami Hiramatsu
2020-10-12 16:24 ` Ingo Molnar
2020-10-14 0:24 ` Masami Hiramatsu
2020-08-29 13:03 ` [PATCH v5 18/21] kprobes: Remove kretprobe hash Masami Hiramatsu
2020-08-29 13:03 ` [PATCH v5 19/21] asm-generic/atomic: Add try_cmpxchg() fallbacks Masami Hiramatsu
2020-10-12 16:25 ` Ingo Molnar
2020-08-29 13:03 ` [PATCH v5 20/21] freelist: Lock less freelist Masami Hiramatsu
2020-08-29 13:03 ` [PATCH v5 21/21] kprobes: Replace rp->free_instance with freelist Masami Hiramatsu
2020-09-01 19:08 ` [PATCH v5 00/21] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless Peter Zijlstra
2020-09-02 0:37 ` Masami Hiramatsu
2020-09-02 7:02 ` peterz
2020-09-02 8:17 ` Masami Hiramatsu
2020-09-02 9:36 ` peterz [this message]
2020-09-02 13:19 ` Masami Hiramatsu
2020-09-02 13:42 ` peterz
2020-09-03 1:39 ` Masami Hiramatsu
2020-09-03 2:02 ` Masami Hiramatsu
2020-09-07 17:44 ` Frank Ch. Eigler
2020-09-08 2:55 ` Masami Hiramatsu
2020-09-08 10:37 ` peterz
2020-09-08 11:15 ` Eddy_Wu
2020-09-08 11:33 ` peterz
2020-09-08 15:09 ` Masami Hiramatsu
2020-09-09 5:28 ` Masami Hiramatsu
2020-09-11 2:32 ` Masami Hiramatsu
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=20200902093613.GY1362448@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=Eddy_Wu@trendmicro.com \
--cc=anil.s.keshavamurthy@intel.com \
--cc=cameron@moodycamel.com \
--cc=davem@davemloft.net \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@kernel.org \
--cc=naveen.n.rao@linux.ibm.com \
--cc=oleg@redhat.com \
--cc=paulmck@kernel.org \
--cc=rostedt@goodmis.org \
--cc=will@kernel.org \
--cc=x86@kernel.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).