From: Masami Hiramatsu <mhiramat@kernel.org>
To: linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>
Cc: 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, mhiramat@kernel.org
Subject: [PATCH v5 15/21] kprobes: Free kretprobe_instance with rcu callback
Date: Sat, 29 Aug 2020 22:02:47 +0900 [thread overview]
Message-ID: <159870616685.1229682.11978742048709542226.stgit@devnote2> (raw)
In-Reply-To: <159870598914.1229682.15230803449082078353.stgit@devnote2>
Free kretprobe_instance with rcu callback instead of directly
freeing the object in the kretprobe handler context.
This will make kretprobe run safer in NMI context.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v3:
- Stick the rcu_head with hlist_node in kretprobe_instance
- Make recycle_rp_inst() static
---
include/linux/kprobes.h | 6 ++++--
kernel/kprobes.c | 25 ++++++-------------------
2 files changed, 10 insertions(+), 21 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index c6a913e608b7..663be8debf25 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -156,7 +156,10 @@ struct kretprobe {
};
struct kretprobe_instance {
- struct hlist_node hlist;
+ union {
+ struct hlist_node hlist;
+ struct rcu_head rcu;
+ };
struct kretprobe *rp;
kprobe_opcode_t *ret_addr;
struct task_struct *task;
@@ -395,7 +398,6 @@ int register_kretprobes(struct kretprobe **rps, int num);
void unregister_kretprobes(struct kretprobe **rps, int num);
void kprobe_flush_task(struct task_struct *tk);
-void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
int disable_kprobe(struct kprobe *kp);
int enable_kprobe(struct kprobe *kp);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 211138225fa5..0676868f1ac2 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1223,8 +1223,7 @@ void kprobes_inc_nmissed_count(struct kprobe *p)
}
NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
-void recycle_rp_inst(struct kretprobe_instance *ri,
- struct hlist_head *head)
+static void recycle_rp_inst(struct kretprobe_instance *ri)
{
struct kretprobe *rp = ri->rp;
@@ -1236,8 +1235,7 @@ void recycle_rp_inst(struct kretprobe_instance *ri,
hlist_add_head(&ri->hlist, &rp->free_instances);
raw_spin_unlock(&rp->lock);
} else
- /* Unregistering */
- hlist_add_head(&ri->hlist, head);
+ kfree_rcu(ri, rcu);
}
NOKPROBE_SYMBOL(recycle_rp_inst);
@@ -1313,7 +1311,7 @@ void kprobe_busy_end(void)
void kprobe_flush_task(struct task_struct *tk)
{
struct kretprobe_instance *ri;
- struct hlist_head *head, empty_rp;
+ struct hlist_head *head;
struct hlist_node *tmp;
unsigned long hash, flags = 0;
@@ -1323,19 +1321,14 @@ void kprobe_flush_task(struct task_struct *tk)
kprobe_busy_begin();
- INIT_HLIST_HEAD(&empty_rp);
hash = hash_ptr(tk, KPROBE_HASH_BITS);
head = &kretprobe_inst_table[hash];
kretprobe_table_lock(hash, &flags);
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task == tk)
- recycle_rp_inst(ri, &empty_rp);
+ recycle_rp_inst(ri);
}
kretprobe_table_unlock(hash, &flags);
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
kprobe_busy_end();
}
@@ -1936,13 +1929,12 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
void *frame_pointer)
{
struct kretprobe_instance *ri = NULL, *last = NULL;
- struct hlist_head *head, empty_rp;
+ struct hlist_head *head;
struct hlist_node *tmp;
unsigned long flags;
kprobe_opcode_t *correct_ret_addr = NULL;
bool skipped = false;
- INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags);
/*
@@ -2011,7 +2003,7 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
__this_cpu_write(current_kprobe, prev);
}
- recycle_rp_inst(ri, &empty_rp);
+ recycle_rp_inst(ri);
if (ri == last)
break;
@@ -2019,11 +2011,6 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
kretprobe_hash_unlock(current, &flags);
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
-
return (unsigned long)correct_ret_addr;
}
NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
next prev parent reply other threads:[~2020-08-29 13:04 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 ` Masami Hiramatsu [this message]
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
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
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