Re: [PATCH] kernel: kprobe: move all *kretprobe* generic implementationto CONFIG_KRETPROBES enabled area

From: Masami Hiramatsu
Date: Tue Feb 04 2014 - 02:17:44 EST


(2014/02/04 14:16), Chen Gang wrote:
> When CONFIG_KRETPROBES disabled, all *kretprobe* generic implementation
> are useless, so need move them to CONFIG_KPROBES enabled area.
>
> Now, *kretprobe* generic implementation are all implemented in 2 files:
>
> - in "include/linux/kprobes.h":
>
> move inline kretprobe*() to CONFIG_KPROBES area and dummy outside.
> move some *kprobe() declarations which kretprobe*() call, to front.
> not touch kretprobe_blacklist[] which is architecture's variable.
>
> - in "kernel/kprobes.c":
>
> move all kretprobe* to CONFIG_KPROBES area and dummy outside.
> define kretprobe_flush_task() to let kprobe_flush_task() call.
> define init_kretprobes() to let init_kprobes() call.
>
> The patch passes compiling (get "kernel/kprobes.o" and "kernel/built-
> in.o") under avr32 and x86_64 allmodconfig, and passes building (get
> bzImage and Modpost modules) under x86_64 defconfig.

Thanks for the fix! and I have some comments below.

> Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx>
> ---
> include/linux/kprobes.h | 58 +++++----
> kernel/kprobes.c | 328 +++++++++++++++++++++++++++---------------------
> 2 files changed, 222 insertions(+), 164 deletions(-)
>
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 925eaf2..c0d1212 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -223,10 +223,36 @@ static inline int kprobes_built_in(void)
> return 1;
> }
>
> +int disable_kprobe(struct kprobe *kp);
> +int enable_kprobe(struct kprobe *kp);
> +
> +void dump_kprobe(struct kprobe *kp);
> +
> +extern struct kretprobe_blackpoint kretprobe_blacklist[];
> +
> #ifdef CONFIG_KRETPROBES
> extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
> struct pt_regs *regs);
> extern int arch_trampoline_kprobe(struct kprobe *p);
> +static inline void kretprobe_assert(struct kretprobe_instance *ri,
> + unsigned long orig_ret_address, unsigned long trampoline_address)
> +{
> + if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> + printk(KERN_ERR
> + "kretprobe BUG!: Processing kretprobe %p @ %p\n",
> + ri->rp, ri->rp->kp.addr);
> + BUG();
> + }
> +}
> +static inline int disable_kretprobe(struct kretprobe *rp)
> +{
> + return disable_kprobe(&rp->kp);
> +}
> +static inline int enable_kretprobe(struct kretprobe *rp)
> +{
> + return enable_kprobe(&rp->kp);
> +}
> +
> #else /* CONFIG_KRETPROBES */
> static inline void arch_prepare_kretprobe(struct kretprobe *rp,
> struct pt_regs *regs)
> @@ -236,19 +262,20 @@ static inline int arch_trampoline_kprobe(struct kprobe *p)
> {
> return 0;
> }
> -#endif /* CONFIG_KRETPROBES */
> -
> -extern struct kretprobe_blackpoint kretprobe_blacklist[];
> -
> static inline void kretprobe_assert(struct kretprobe_instance *ri,
> unsigned long orig_ret_address, unsigned long trampoline_address)
> {
> - if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> - printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
> - ri->rp, ri->rp->kp.addr);
> - BUG();
> - }
> }
> +static inline int disable_kretprobe(struct kretprobe *rp)
> +{
> + return 0;
> +}
> +static inline int enable_kretprobe(struct kretprobe *rp)
> +{
> + return 0;
> +}

No, these should returns -EINVAL or -ENOSYS, since these are user API.
Anyway, I don't think those inlined functions to be changed, because
most of them are internal functions. If CONFIG_KRETPROBES=n, it just
be ignored.

So, I think you don't need to change kprobes.h.


> +
> +#endif /* CONFIG_KRETPROBES */
>
> #ifdef CONFIG_KPROBES_SANITY_TEST
> extern int init_test_probes(void);
> @@ -379,11 +406,6 @@ 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);
> -
> -void dump_kprobe(struct kprobe *kp);
> -
> #else /* !CONFIG_KPROBES: */
>
> static inline int kprobes_built_in(void)
> @@ -459,14 +481,6 @@ static inline int enable_kprobe(struct kprobe *kp)
> return -ENOSYS;
> }
> #endif /* CONFIG_KPROBES */
> -static inline int disable_kretprobe(struct kretprobe *rp)
> -{
> - return disable_kprobe(&rp->kp);
> -}
> -static inline int enable_kretprobe(struct kretprobe *rp)
> -{
> - return enable_kprobe(&rp->kp);
> -}
> static inline int disable_jprobe(struct jprobe *jp)
> {
> return disable_kprobe(&jp->kp);
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index ceeadfc..e305a81 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
[...]
> @@ -1936,8 +1955,44 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
> return 0;
> }
>
> +void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
> + struct hlist_head *head)
> +{
> +}
> +
> +void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
> + struct hlist_head **head, unsigned long *flags)
> +__acquires(hlist_lock)
> +{
> +}
> +
> +void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
> + unsigned long *flags)
> +__releases(hlist_lock)
> +{
> +}
> +

> +static void __kprobes kretprobe_flush_task(struct task_struct *tk)
> +{
> +}
> +
> +static void __init init_kretprobes(void)
> +{
> +}

These should be macros, as I did for optprobe functions
with !CONFIG_OPTPROBES.

Other parts looks good to me!;)

Thank you!


--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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