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Message-ID: <521AB43D.8090205@hitachi.com>
Date: Mon, 26 Aug 2013 10:49:49 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Ingo Molnar <mingo@...nel.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
linux-kernel@...r.kernel.org
Subject: Re: [Patch v2 1/3] kprobes: unify insn caches
(2013/08/23 20:04), Heiko Carstens wrote:
> The two insn caches (insn, and optinsn) each have an own mutex and
> alloc/free functions (get_[opt]insn_slot() / free_[opt]insn_slot()).
>
> Since there is the need for yet another insn cache which satifies
> dma allocations on s390, unify and simplify the current implementation:
>
> - Move the per insn cache mutex into struct kprobe_insn_cache.
> - Move the alloc/free functions to kprobe.h so they are simply
> wrappers for the generic __get_insn_slot/__free_insn_slot functions.
> The implementation is done with a DEFINE_INSN_CACHE_OPS() macro
> which provides the alloc/free functions for each cache if needed.
> - move the struct kprobe_insn_cache to kprobe.h which allows to generate
> architecture specific insn slot caches outside of the core kprobes
> code.
>
Looks Good for me :)
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Thank you!
> Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
> ---
> include/linux/kprobes.h | 32 +++++++++++++++++---
> kernel/kprobes.c | 75 +++++++++++++----------------------------------
> 2 files changed, 49 insertions(+), 58 deletions(-)
>
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index ca1d27a..077f653 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -264,10 +264,34 @@ extern void arch_arm_kprobe(struct kprobe *p);
> extern void arch_disarm_kprobe(struct kprobe *p);
> extern int arch_init_kprobes(void);
> extern void show_registers(struct pt_regs *regs);
> -extern kprobe_opcode_t *get_insn_slot(void);
> -extern void free_insn_slot(kprobe_opcode_t *slot, int dirty);
> extern void kprobes_inc_nmissed_count(struct kprobe *p);
>
> +struct kprobe_insn_cache {
> + struct mutex mutex;
> + struct list_head pages; /* list of kprobe_insn_page */
> + size_t insn_size; /* size of instruction slot */
> + int nr_garbage;
> +};
> +
> +extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
> +extern void __free_insn_slot(struct kprobe_insn_cache *c,
> + kprobe_opcode_t *slot, int dirty);
> +
> +#define DEFINE_INSN_CACHE_OPS(__name) \
> +extern struct kprobe_insn_cache kprobe_##__name##_slots; \
> + \
> +static inline kprobe_opcode_t *get_##__name##_slot(void) \
> +{ \
> + return __get_insn_slot(&kprobe_##__name##_slots); \
> +} \
> + \
> +static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
> +{ \
> + __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \
> +} \
> +
> +DEFINE_INSN_CACHE_OPS(insn);
> +
> #ifdef CONFIG_OPTPROBES
> /*
> * Internal structure for direct jump optimized probe
> @@ -287,13 +311,13 @@ extern void arch_optimize_kprobes(struct list_head *oplist);
> extern void arch_unoptimize_kprobes(struct list_head *oplist,
> struct list_head *done_list);
> extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
> -extern kprobe_opcode_t *get_optinsn_slot(void);
> -extern void free_optinsn_slot(kprobe_opcode_t *slot, int dirty);
> extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
> unsigned long addr);
>
> extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
>
> +DEFINE_INSN_CACHE_OPS(optinsn);
> +
> #ifdef CONFIG_SYSCTL
> extern int sysctl_kprobes_optimization;
> extern int proc_kprobes_optimization_handler(struct ctl_table *table,
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 6e33498..9e4912d 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -121,12 +121,6 @@ struct kprobe_insn_page {
> (offsetof(struct kprobe_insn_page, slot_used) + \
> (sizeof(char) * (slots)))
>
> -struct kprobe_insn_cache {
> - struct list_head pages; /* list of kprobe_insn_page */
> - size_t insn_size; /* size of instruction slot */
> - int nr_garbage;
> -};
> -
> static int slots_per_page(struct kprobe_insn_cache *c)
> {
> return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
> @@ -138,8 +132,8 @@ enum kprobe_slot_state {
> SLOT_USED = 2,
> };
>
> -static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
> -static struct kprobe_insn_cache kprobe_insn_slots = {
> +struct kprobe_insn_cache kprobe_insn_slots = {
> + .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
> .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
> .insn_size = MAX_INSN_SIZE,
> .nr_garbage = 0,
> @@ -150,10 +144,12 @@ static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
> * __get_insn_slot() - Find a slot on an executable page for an instruction.
> * We allocate an executable page if there's no room on existing ones.
> */
> -static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> +kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> {
> struct kprobe_insn_page *kip;
> + kprobe_opcode_t *slot = NULL;
>
> + mutex_lock(&c->mutex);
> retry:
> list_for_each_entry(kip, &c->pages, list) {
> if (kip->nused < slots_per_page(c)) {
> @@ -162,7 +158,8 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> if (kip->slot_used[i] == SLOT_CLEAN) {
> kip->slot_used[i] = SLOT_USED;
> kip->nused++;
> - return kip->insns + (i * c->insn_size);
> + slot = kip->insns + (i * c->insn_size);
> + goto out;
> }
> }
> /* kip->nused is broken. Fix it. */
> @@ -178,7 +175,7 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> /* All out of space. Need to allocate a new page. */
> kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
> if (!kip)
> - return NULL;
> + goto out;
>
> /*
> * Use module_alloc so this page is within +/- 2GB of where the
> @@ -188,7 +185,7 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> kip->insns = module_alloc(PAGE_SIZE);
> if (!kip->insns) {
> kfree(kip);
> - return NULL;
> + goto out;
> }
> INIT_LIST_HEAD(&kip->list);
> memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
> @@ -196,19 +193,10 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> kip->nused = 1;
> kip->ngarbage = 0;
> list_add(&kip->list, &c->pages);
> - return kip->insns;
> -}
> -
> -
> -kprobe_opcode_t __kprobes *get_insn_slot(void)
> -{
> - kprobe_opcode_t *ret = NULL;
> -
> - mutex_lock(&kprobe_insn_mutex);
> - ret = __get_insn_slot(&kprobe_insn_slots);
> - mutex_unlock(&kprobe_insn_mutex);
> -
> - return ret;
> + slot = kip->insns;
> +out:
> + mutex_unlock(&c->mutex);
> + return slot;
> }
>
> /* Return 1 if all garbages are collected, otherwise 0. */
> @@ -255,11 +243,12 @@ static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
> return 0;
> }
>
> -static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
> - kprobe_opcode_t *slot, int dirty)
> +void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
> + kprobe_opcode_t *slot, int dirty)
> {
> struct kprobe_insn_page *kip;
>
> + mutex_lock(&c->mutex);
> list_for_each_entry(kip, &c->pages, list) {
> long idx = ((long)slot - (long)kip->insns) /
> (c->insn_size * sizeof(kprobe_opcode_t));
> @@ -272,45 +261,23 @@ static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
> collect_garbage_slots(c);
> } else
> collect_one_slot(kip, idx);
> - return;
> + goto out;
> }
> }
> /* Could not free this slot. */
> WARN_ON(1);
> +out:
> + mutex_unlock(&c->mutex);
> }
>
> -void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
> -{
> - mutex_lock(&kprobe_insn_mutex);
> - __free_insn_slot(&kprobe_insn_slots, slot, dirty);
> - mutex_unlock(&kprobe_insn_mutex);
> -}
> #ifdef CONFIG_OPTPROBES
> /* For optimized_kprobe buffer */
> -static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
> -static struct kprobe_insn_cache kprobe_optinsn_slots = {
> +struct kprobe_insn_cache kprobe_optinsn_slots = {
> + .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
> .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
> /* .insn_size is initialized later */
> .nr_garbage = 0,
> };
> -/* Get a slot for optimized_kprobe buffer */
> -kprobe_opcode_t __kprobes *get_optinsn_slot(void)
> -{
> - kprobe_opcode_t *ret = NULL;
> -
> - mutex_lock(&kprobe_optinsn_mutex);
> - ret = __get_insn_slot(&kprobe_optinsn_slots);
> - mutex_unlock(&kprobe_optinsn_mutex);
> -
> - return ret;
> -}
> -
> -void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
> -{
> - mutex_lock(&kprobe_optinsn_mutex);
> - __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
> - mutex_unlock(&kprobe_optinsn_mutex);
> -}
> #endif
> #endif
>
>
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com
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