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Date: Wed, 4 May 2022 13:28:42 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Max Filippov <jcmvbkbc@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
"Naveen N . Rao" <naveen.n.rao@...ux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
"David S . Miller" <davem@...emloft.net>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org,
Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH] kprobes: Fix build errors with CONFIG_KRETPROBES=n
Hello Max,
Can you test this patch? Since the other archs already implemented
kretprobe, I couldn't test it without modifying kernel.
Thank you,
On Wed, 4 May 2022 12:36:31 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:
> Max Filippov reported:
>
> When building kernel with CONFIG_KRETPROBES=n kernel/kprobes.c
> compilation fails with the following messages:
>
> kernel/kprobes.c: In function ‘recycle_rp_inst’:
> kernel/kprobes.c:1273:32: error: implicit declaration of function
> ‘get_kretprobe’
>
> kernel/kprobes.c: In function ‘kprobe_flush_task’:
> kernel/kprobes.c:1299:35: error: ‘struct task_struct’ has no member
> named ‘kretprobe_instances’
>
> This came from the commit d741bf41d7c7 ("kprobes: Remove
> kretprobe hash") which introduced get_kretprobe() and
> kretprobe_instances member in task_struct when CONFIG_KRETPROBES=y,
> but did not make recycle_rp_inst() and kprobe_flush_task()
> depending on CONFIG_KRETPORBES.
>
> Since those functions are only used for kretprobe, move those
> functions into #ifdef CONFIG_KRETPROBE area.
>
> Reported-by: Max Filippov <jcmvbkbc@...il.com>
> Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash")
> Cc: stable@...r.kernel.org
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
> include/linux/kprobes.h | 2 -
> kernel/kprobes.c | 144 +++++++++++++++++++++++------------------------
> 2 files changed, 72 insertions(+), 74 deletions(-)
>
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 157168769fc2..55041d2f884d 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -424,7 +424,7 @@ void unregister_kretprobe(struct kretprobe *rp);
> int register_kretprobes(struct kretprobe **rps, int num);
> void unregister_kretprobes(struct kretprobe **rps, int num);
>
> -#ifdef CONFIG_KRETPROBE_ON_RETHOOK
> +#if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
> #define kprobe_flush_task(tk) do {} while (0)
> #else
> void kprobe_flush_task(struct task_struct *tk);
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index dd58c0be9ce2..f214f8c088ed 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1257,79 +1257,6 @@ void kprobe_busy_end(void)
> preempt_enable();
> }
>
> -#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
> -static void free_rp_inst_rcu(struct rcu_head *head)
> -{
> - struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
> -
> - if (refcount_dec_and_test(&ri->rph->ref))
> - kfree(ri->rph);
> - kfree(ri);
> -}
> -NOKPROBE_SYMBOL(free_rp_inst_rcu);
> -
> -static void recycle_rp_inst(struct kretprobe_instance *ri)
> -{
> - struct kretprobe *rp = get_kretprobe(ri);
> -
> - if (likely(rp))
> - freelist_add(&ri->freelist, &rp->freelist);
> - else
> - call_rcu(&ri->rcu, free_rp_inst_rcu);
> -}
> -NOKPROBE_SYMBOL(recycle_rp_inst);
> -
> -/*
> - * This function is called from delayed_put_task_struct() when a task is
> - * dead and cleaned up to recycle any kretprobe instances associated with
> - * this task. These left over instances represent probed functions that
> - * have been called but will never return.
> - */
> -void kprobe_flush_task(struct task_struct *tk)
> -{
> - struct kretprobe_instance *ri;
> - struct llist_node *node;
> -
> - /* Early boot, not yet initialized. */
> - if (unlikely(!kprobes_initialized))
> - return;
> -
> - kprobe_busy_begin();
> -
> - node = __llist_del_all(&tk->kretprobe_instances);
> - while (node) {
> - ri = container_of(node, struct kretprobe_instance, llist);
> - node = node->next;
> -
> - recycle_rp_inst(ri);
> - }
> -
> - kprobe_busy_end();
> -}
> -NOKPROBE_SYMBOL(kprobe_flush_task);
> -
> -static inline void free_rp_inst(struct kretprobe *rp)
> -{
> - struct kretprobe_instance *ri;
> - struct freelist_node *node;
> - int count = 0;
> -
> - node = rp->freelist.head;
> - while (node) {
> - ri = container_of(node, struct kretprobe_instance, freelist);
> - node = node->next;
> -
> - kfree(ri);
> - count++;
> - }
> -
> - if (refcount_sub_and_test(count, &rp->rph->ref)) {
> - kfree(rp->rph);
> - rp->rph = NULL;
> - }
> -}
> -#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
> -
> /* Add the new probe to 'ap->list'. */
> static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
> {
> @@ -1928,6 +1855,77 @@ static struct notifier_block kprobe_exceptions_nb = {
> #ifdef CONFIG_KRETPROBES
>
> #if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
> +static void free_rp_inst_rcu(struct rcu_head *head)
> +{
> + struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
> +
> + if (refcount_dec_and_test(&ri->rph->ref))
> + kfree(ri->rph);
> + kfree(ri);
> +}
> +NOKPROBE_SYMBOL(free_rp_inst_rcu);
> +
> +static void recycle_rp_inst(struct kretprobe_instance *ri)
> +{
> + struct kretprobe *rp = get_kretprobe(ri);
> +
> + if (likely(rp))
> + freelist_add(&ri->freelist, &rp->freelist);
> + else
> + call_rcu(&ri->rcu, free_rp_inst_rcu);
> +}
> +NOKPROBE_SYMBOL(recycle_rp_inst);
> +
> +/*
> + * This function is called from delayed_put_task_struct() when a task is
> + * dead and cleaned up to recycle any kretprobe instances associated with
> + * this task. These left over instances represent probed functions that
> + * have been called but will never return.
> + */
> +void kprobe_flush_task(struct task_struct *tk)
> +{
> + struct kretprobe_instance *ri;
> + struct llist_node *node;
> +
> + /* Early boot, not yet initialized. */
> + if (unlikely(!kprobes_initialized))
> + return;
> +
> + kprobe_busy_begin();
> +
> + node = __llist_del_all(&tk->kretprobe_instances);
> + while (node) {
> + ri = container_of(node, struct kretprobe_instance, llist);
> + node = node->next;
> +
> + recycle_rp_inst(ri);
> + }
> +
> + kprobe_busy_end();
> +}
> +NOKPROBE_SYMBOL(kprobe_flush_task);
> +
> +static inline void free_rp_inst(struct kretprobe *rp)
> +{
> + struct kretprobe_instance *ri;
> + struct freelist_node *node;
> + int count = 0;
> +
> + node = rp->freelist.head;
> + while (node) {
> + ri = container_of(node, struct kretprobe_instance, freelist);
> + node = node->next;
> +
> + kfree(ri);
> + count++;
> + }
> +
> + if (refcount_sub_and_test(count, &rp->rph->ref)) {
> + kfree(rp->rph);
> + rp->rph = NULL;
> + }
> +}
> +
> /* This assumes the 'tsk' is the current task or the is not running. */
> static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
> struct llist_node **cur)
>
--
Masami Hiramatsu <mhiramat@...nel.org>
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