Subject: [RFC PATCH 07/11] kprobes: introduces macros for allocing early kprobe resources.

From: [email-masked] (Wang Nan)
Date: Wed, 7 Jan 2015 18:45:40 +0800

On 2015/1/7 15:35, Wang Nan wrote:
> Introduces macros to genearte common early kprobe related resource
> allocator.
> 
> All early kprobe related resources are statically allocated during
> linking for each early kprobe slot. For each type of resource, a bitmap
> is used to track allocation. __DEFINE_EKPROBE_ALLOC_OPS defines alloc
> and free handler for them. The range of the resource and the bitmap
> should be provided for allocaing and freeing. DEFINE_EKPROBE_ALLOC_OPS
> defines bitmap and the array used by it.
> 
> Signed-off-by: Wang Nan <[email-masked]>
> ---
>  include/linux/kprobes.h | 69 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index b0265f9..9a18188 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -270,6 +270,75 @@ extern void show_registers(struct pt_regs *regs);
>  extern void kprobes_inc_nmissed_count(struct kprobe *p);
>  extern bool arch_within_kprobe_blacklist(unsigned long addr);
>  
> +#ifdef CONFIG_EARLY_KPROBES
> +
> +#define NR_EARLY_KPROBES_SLOTS	CONFIG_NR_EARLY_KPROBES_SLOTS
> +#define ALIGN_UP(v, a)	(((v) + ((a) - 1)) & ~((a) - 1))
> +#define EARLY_KPROBES_BITMAP_SZ	ALIGN_UP(NR_EARLY_KPROBES_SLOTS, BITS_PER_LONG)
> +
> +#define __ek_in_range(v, s, e)	(((v) >= (s)) && ((v) < (e)))
> +#define __ek_buf_sz(s, e)	((void *)(e) - (void *)(s))
> +#define __ek_elem_sz_b(s, e)	(__ek_buf_sz(s, e) / NR_EARLY_KPROBES_SLOTS)
> +#define __ek_elem_sz(s, e)	(__ek_elem_sz_b(s, e) / sizeof(s[0]))
> +#define __ek_elem_idx(v, s, e)	(__ek_buf_sz(s, v) / __ek_elem_sz_b(s, e))
> +#define __ek_get_elem(i, s, e)	(&((s)[__ek_elem_sz(s, e) * (i)]))
> +#define __DEFINE_EKPROBE_ALLOC_OPS(__t, __name)				\
> +static inline __t *__ek_alloc_##__name(__t *__s, __t *__e, unsigned long *__b)\
> +{									\
> +	int __i = find_next_zero_bit(__b, NR_EARLY_KPROBES_SLOTS, 0);	\
> +	if (__i >= NR_EARLY_KPROBES_SLOTS)				\
> +		return NULL;						\
> +	set_bit(__i, __b);						\
> +	return __ek_get_elem(__i, __s, __e);				\
> +}									\
> +static inline int __ek_free_##__name(__t *__v, __t *__s, __t *__e, unsigned long *__b)	\
> +{									\
> +	if (!__ek_in_range(__v, __s, __e))				\
> +		return 0;						\
> +	clear_bit(__ek_elem_idx(__v, __s, __e), __b);			\
> +	return 1;							\
> +}
> +
> +#define DEFINE_EKPROBE_ALLOC_OPS(__t, __name, __static)			\
> +__static __t __ek_##__name##_slots[NR_EARLY_KPROBES_SLOTS];		\
> +__static unsigned long __ek_##__name##_bitmap[EARLY_KPROBES_BITMAP_SZ];	\
> +__DEFINE_EKPROBE_ALLOC_OPS(__t, __name)					\
> +static inline __t *ek_alloc_##__name(void)				\
> +{									\
> +	return __ek_alloc_##__name(&((__ek_##__name##_slots)[0]),	\
> +			&((__ek_##__name##_slots)[NR_EARLY_KPROBES_SLOTS]),\
> +			(__ek_##__name##_bitmap));			\
> +}									\
> +static inline int ek_free_##__name(__t *__s)				\
> +{									\
> +	return __ek_free_##__name(__s, &((__ek_##__name##_slots)[0]),	\
> +			&((__ek_##__name##_slots)[NR_EARLY_KPROBES_SLOTS]),\
> +			(__ek_##__name##_bitmap));			\
> +}
> +
> +
> +#else
> +#define __DEFINE_EKPROBE_ALLOC_OPS(__t, __name)				\
> +static inline __t *__ek_alloc_##__name(__t *__s, __t *__e, unsigned long *__b)\
> +{									\
> +	return NULL;							\
> +}									\
> +static inline int __ek_free_##__name(__t *__v, __t *__s, __t *__e, unsigned long *__b)\
> +{									\
> +	return 0;							\
> +}
> +
> +#define DEFINE_EKPROBE_ALLOC_OPS(__t, __name, __static)			\
> +static inline __t *ek_alloc_##__name(void)				\
> +{									\
> +	return NULL;							\
> +}									\
> +static inline void ek_free_##__name(__t *__s)				\
> +{									\
> +}
> +

Sorry, here is a small problem. Should be:
static inline int ek_free_##__name(__t *__s)				\
{									\
	return 0;							\
}

> +#endif
> +
>  struct kprobe_insn_cache {
>  	struct mutex mutex;
>  	void *(*alloc)(void);	/* allocate insn page */
>