From d741bf41d7c7db4898bacfcb020353cddc032fd8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Sat, 29 Aug 2020 22:03:24 +0900 Subject: kprobes: Remove kretprobe hash The kretprobe hash is mostly superfluous, replace it with a per-task variable. This gets rid of the task hash and it's related locking. Note that this may change the kprobes module-exported API for kretprobe handlers. If any out-of-tree kretprobe user uses ri->rp, use get_kretprobe(ri) instead. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Masami Hiramatsu Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/159870620431.1229682.16325792502413731312.stgit@devnote2 --- include/linux/kprobes.h | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'include/linux/kprobes.h') diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 5c8c271fa1e9..00cf4421efd5 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -27,6 +27,7 @@ #include #include #include +#include #include #ifdef CONFIG_KPROBES @@ -144,6 +145,11 @@ static inline int kprobe_ftrace(struct kprobe *p) * ignored, due to maxactive being too low. * */ +struct kretprobe_holder { + struct kretprobe *rp; + refcount_t ref; +}; + struct kretprobe { struct kprobe kp; kretprobe_handler_t handler; @@ -152,17 +158,18 @@ struct kretprobe { int nmissed; size_t data_size; struct hlist_head free_instances; + struct kretprobe_holder *rph; raw_spinlock_t lock; }; struct kretprobe_instance { union { + struct llist_node llist; struct hlist_node hlist; struct rcu_head rcu; }; - struct kretprobe *rp; + struct kretprobe_holder *rph; kprobe_opcode_t *ret_addr; - struct task_struct *task; void *fp; char data[]; }; @@ -221,6 +228,14 @@ unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, return ret; } +static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) +{ + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), + "Kretprobe is accessed from instance under preemptive context"); + + return READ_ONCE(ri->rph->rp); +} + #else /* CONFIG_KRETPROBES */ static inline void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) -- cgit