From: Masami Hiramatsu mhiramat@kernel.org
commit c85c9a2c6e368dc94907e63babb18a9788e5c9b6 upstream.
Commit 36dadef23fcc ("kprobes: Init kprobes in early_initcall") moved the kprobe setup in early_initcall(), which includes kprobe jump optimization. The kprobes jump optimizer involves synchronize_rcu_tasks() which depends on the ksoftirqd and rcu_spawn_tasks_*(). However, since those are setup in core_initcall(), kprobes jump optimizer can not run at the early_initcall().
To avoid this issue, make the kprobe optimization disabled in the early_initcall() and enables it in subsys_initcall().
Note that non-optimized kprobes is still available after early_initcall(). Only jump optimization is delayed.
Link: https://lkml.kernel.org/r/161365856280.719838.12423085451287256713.stgit@dev...
Fixes: 36dadef23fcc ("kprobes: Init kprobes in early_initcall") Cc: Ingo Molnar mingo@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: RCU rcu@vger.kernel.org Cc: Michael Ellerman mpe@ellerman.id.au Cc: Andrew Morton akpm@linux-foundation.org Cc: Daniel Axtens dja@axtens.net Cc: Frederic Weisbecker frederic@kernel.org Cc: Neeraj Upadhyay neeraju@codeaurora.org Cc: Joel Fernandes joel@joelfernandes.org Cc: Michal Hocko mhocko@suse.com Cc: "Theodore Y . Ts'o" tytso@mit.edu Cc: Oleksiy Avramchenko oleksiy.avramchenko@sonymobile.com Cc: stable@vger.kernel.org Reported-by: Paul E. McKenney paulmck@kernel.org Reported-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Reported-by: Uladzislau Rezki urezki@gmail.com Acked-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/kprobes.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-)
--- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -861,7 +861,6 @@ out: cpus_read_unlock(); }
-#ifdef CONFIG_SYSCTL static void optimize_all_kprobes(void) { struct hlist_head *head; @@ -887,6 +886,7 @@ out: mutex_unlock(&kprobe_mutex); }
+#ifdef CONFIG_SYSCTL static void unoptimize_all_kprobes(void) { struct hlist_head *head; @@ -2497,18 +2497,14 @@ static int __init init_kprobes(void) } }
-#if defined(CONFIG_OPTPROBES) -#if defined(__ARCH_WANT_KPROBES_INSN_SLOT) - /* Init kprobe_optinsn_slots */ - kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; -#endif - /* By default, kprobes can be optimized */ - kprobes_allow_optimization = true; -#endif - /* By default, kprobes are armed */ kprobes_all_disarmed = false;
+#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT) + /* Init kprobe_optinsn_slots for allocation */ + kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; +#endif + err = arch_init_kprobes(); if (!err) err = register_die_notifier(&kprobe_exceptions_nb); @@ -2523,6 +2519,21 @@ static int __init init_kprobes(void) } early_initcall(init_kprobes);
+#if defined(CONFIG_OPTPROBES) +static int __init init_optprobes(void) +{ + /* + * Enable kprobe optimization - this kicks the optimizer which + * depends on synchronize_rcu_tasks() and ksoftirqd, that is + * not spawned in early initcall. So delay the optimization. + */ + optimize_all_kprobes(); + + return 0; +} +subsys_initcall(init_optprobes); +#endif + #ifdef CONFIG_DEBUG_FS static void report_probe(struct seq_file *pi, struct kprobe *p, const char *sym, int offset, char *modname, struct kprobe *pp)