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Date: Fri, 23 Aug 2013 17:54:08 +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 0/3] kprobes: add new dma insn slot cache for s390
(2013/08/23 17:09), Heiko Carstens wrote:
> On Fri, Aug 23, 2013 at 01:31:23PM +0900, Masami Hiramatsu wrote:
>> (2013/08/22 14:52), Heiko Carstens wrote:
>>> Therefore I need to different insn slot caches, where the slots are either
>>> allocated with __get_free_page(GFP_KERNEL | GFP_DMA) (for the kernel image)
>>> or module_alloc(PAGE_SIZE) for modules.
>>>
>>> I can't have a single cache which satifies both areas.
>>
>> Oh, I see.
>> Indeed, that enough reason to add a new cache... By the way, is there
>> any way to implement it without new kconfig like DMAPROBE and dma flag?
>> AFAICS, since such flag is strongly depends on the s390 arch, I don't
>> like to put it in kernel/kprobes.c.
>>
>> Perhaps, we can make insn slot more generic, e.g. create new slot type
>> with passing page allocator.
>
> Something like below?
> (only compile tested and on top of the previous patches).
Yes! this is exactly what I thought :)
> I'm not sure, since that would expose struct kprobe_insn_cache.
That is OK, since it is required for some arch.
Could you update the series with this change?
Thank you!
>
> arch/Kconfig | 7 -------
> arch/s390/Kconfig | 1 -
> arch/s390/kernel/kprobes.c | 20 ++++++++++++++++++
> include/linux/kprobes.h | 14 ++++++++-----
> kernel/kprobes.c | 51 ++++++++++++++++------------------------------
> 5 files changed, 47 insertions(+), 46 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 7010d68..1feb169 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -76,13 +76,6 @@ config OPTPROBES
> depends on KPROBES && HAVE_OPTPROBES
> depends on !PREEMPT
>
> -config DMAPROBES
> - bool
> - help
> - Architectures may want to put kprobes instruction slots into
> - the dma memory region. E.g. s390 has the kernel image in the
> - dma memory region but the module area far away.
> -
> config KPROBES_ON_FTRACE
> def_bool y
> depends on KPROBES && HAVE_KPROBES_ON_FTRACE
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index ce389a9..8a4cae7 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -96,7 +96,6 @@ config S390
> select ARCH_WANT_IPC_PARSE_VERSION
> select BUILDTIME_EXTABLE_SORT
> select CLONE_BACKWARDS2
> - select DMAPROBES if KPROBES
> select GENERIC_CLOCKEVENTS
> select GENERIC_CPU_DEVICES if !SMP
> select GENERIC_SMP_IDLE_THREAD
> diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
> index bc1071c..cb7ac9e 100644
> --- a/arch/s390/kernel/kprobes.c
> +++ b/arch/s390/kernel/kprobes.c
> @@ -37,6 +37,26 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = { };
>
> +DEFINE_INSN_CACHE_OPS(dmainsn);
> +
> +static void *alloc_dmainsn_page(void)
> +{
> + return (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
> +}
> +
> +static void free_dmainsn_page(void *page)
> +{
> + free_page((unsigned long)page);
> +}
> +
> +struct kprobe_insn_cache kprobe_dmainsn_slots = {
> + .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
> + .alloc = alloc_dmainsn_page,
> + .free = free_dmainsn_page,
> + .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
> + .insn_size = MAX_INSN_SIZE,
> +};
> +
> static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
> {
> switch (insn[0] >> 8) {
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index a5290f6..4e96827 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -266,7 +266,15 @@ extern int arch_init_kprobes(void);
> extern void show_registers(struct pt_regs *regs);
> extern void kprobes_inc_nmissed_count(struct kprobe *p);
>
> -struct kprobe_insn_cache;
> +struct kprobe_insn_cache {
> + struct mutex mutex;
> + void *(*alloc)(void); /* allocate insn page */
> + void (*free)(void *); /* free insn page */
> + 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);
> @@ -321,10 +329,6 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
>
> #endif /* CONFIG_OPTPROBES */
>
> -#ifdef CONFIG_DMAPROBES
> -DEFINE_INSN_CACHE_OPS(dmainsn);
> -#endif
> -
> #ifdef CONFIG_KPROBES_ON_FTRACE
> extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *ops, struct pt_regs *regs);
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 3b8b073..a0d367a 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -112,9 +112,9 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
> struct kprobe_insn_page {
> struct list_head list;
> kprobe_opcode_t *insns; /* Page of instruction slots */
> + struct kprobe_insn_cache *cache;
> int nused;
> int ngarbage;
> - bool dma_alloc;
> char slot_used[];
> };
>
> @@ -122,14 +122,6 @@ struct kprobe_insn_page {
> (offsetof(struct kprobe_insn_page, slot_used) + \
> (sizeof(char) * (slots)))
>
> -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;
> - bool dma_alloc;
> -};
> -
> static int slots_per_page(struct kprobe_insn_cache *c)
> {
> return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
> @@ -141,12 +133,23 @@ enum kprobe_slot_state {
> SLOT_USED = 2,
> };
>
> +static void *alloc_insn_page(void)
> +{
> + return module_alloc(PAGE_SIZE);
> +}
> +
> +static void free_insn_page(void *page)
> +{
> + module_free(NULL, page);
> +}
> +
> struct kprobe_insn_cache kprobe_insn_slots = {
> .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
> + .alloc = alloc_insn_page,
> + .free = free_insn_page,
> .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
> .insn_size = MAX_INSN_SIZE,
> .nr_garbage = 0,
> - .dma_alloc = false,
> };
> static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
>
> @@ -192,10 +195,7 @@ kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> * kernel image and loaded module images reside. This is required
> * so x86_64 can correctly handle the %rip-relative fixups.
> */
> - if (c->dma_alloc)
> - kip->insns = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
> - else
> - kip->insns = module_alloc(PAGE_SIZE);
> + kip->insns = c->alloc();
> if (!kip->insns) {
> kfree(kip);
> goto out;
> @@ -205,7 +205,7 @@ kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
> kip->slot_used[0] = SLOT_USED;
> kip->nused = 1;
> kip->ngarbage = 0;
> - kip->dma_alloc = c->dma_alloc;
> + kip->cache = c;
> list_add(&kip->list, &c->pages);
> slot = kip->insns;
> out:
> @@ -227,10 +227,7 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
> */
> if (!list_is_singular(&kip->list)) {
> list_del(&kip->list);
> - if (kip->dma_alloc)
> - free_page((unsigned long)kip->insns);
> - else
> - module_free(NULL, kip->insns);
> + kip->cache->free(kip->insns);
> kfree(kip);
> }
> return 1;
> @@ -291,23 +288,11 @@ out:
> /* For optimized_kprobe buffer */
> struct kprobe_insn_cache kprobe_optinsn_slots = {
> .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
> + .alloc = alloc_insn_page,
> + .free = free_insn_page,
> .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
> /* .insn_size is initialized later */
> .nr_garbage = 0,
> - .dma_alloc = false,
> -};
> -#endif
> -#ifdef CONFIG_DMAPROBES
> -/*
> - * Special buffer for architectures which require insn slots
> - * to be in the GFP_DMA memory range.
> - */
> -struct kprobe_insn_cache kprobe_dmainsn_slots = {
> - .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
> - .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
> - .insn_size = MAX_INSN_SIZE,
> - .nr_garbage = 0,
> - .dma_alloc = true,
> };
> #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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