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kprobes: Remove kretprobe hash

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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) <peterz@infradead.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870620431.1229682.16325792502413731312.stgit@devnote2
This commit is contained in:
Peter Zijlstra 2020-08-29 22:03:24 +09:00 • committed by Ingo Molnar
parent 476c5818c3
commit d741bf41d7
5 changed files with 99 additions and 171 deletions
Download patch file Download diff file Expand all files Collapse all files

19
include/linux/kprobes.h
View file

@ -27,6 +27,7 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/ftrace.h>
#include <linux/refcount.h>
#include <asm/kprobes.h>
#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)

4
include/linux/sched.h
View file

@ -1315,6 +1315,10 @@ struct task_struct {
struct callback_head mce_kill_me;
#endif
#ifdef CONFIG_KRETPROBES
struct llist_head kretprobe_instances;
#endif
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.