| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20231007110229.70b21d0d7610bdf304b5e355@kernel.org>
Date: Sat, 7 Oct 2023 11:02:29 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: "wuqiang.matt" <wuqiang.matt@...edance.com>
Cc: linux-trace-kernel@...r.kernel.org, davem@...emloft.net,
anil.s.keshavamurthy@...el.com, naveen.n.rao@...ux.ibm.com,
rostedt@...dmis.org, peterz@...radead.org,
akpm@...ux-foundation.org, sander@...nheule.net,
ebiggers@...gle.com, dan.j.williams@...el.com, jpoimboe@...nel.org,
linux-kernel@...r.kernel.org, lkp@...el.com, mattwu@....com
Subject: Re: [PATCH v9 3/5] kprobes: kretprobe scalability improvement with
objpool
On Tue, 5 Sep 2023 09:52:53 +0800
"wuqiang.matt" <wuqiang.matt@...edance.com> wrote:
> kretprobe is using freelist to manage return-instances, but freelist,
> as LIFO queue based on singly linked list, scales badly and reduces
> the overall throughput of kretprobed routines, especially for high
> contention scenarios.
>
> Here's a typical throughput test of sys_prctl (counts in 10 seconds,
> measured with perf stat -a -I 10000 -e syscalls:sys_enter_prctl):
>
> OS: Debian 10 X86_64, Linux 6.5rc7 with freelist
> HW: XEON 8336C x 2, 64 cores/128 threads, DDR4 3200MT/s
>
> 1T 2T 4T 8T 16T 24T
> 24150045 29317964 15446741 12494489 18287272 18287272
> 32T 48T 64T 72T 96T 128T
> 16200682 1620068 11645677 11269858 10470118 9931051
>
> This patch introduces objpool to kretprobe and rethook, with orginal
> freelist replaced and brings near-linear scalability to kretprobed
> routines. Tests of kretprobe throughput show the biggest ratio as
> 166.7x of the original freelist. Here's the comparison:
>
> 1T 2T 4T 8T 16T
> native: 41186213 82336866 164250978 328662645 658810299
> freelist: 24150045 29317964 15446741 12494489 18287272
> objpool: 24663700 49410571 98544977 197725940 396294399
> 32T 48T 64T 96T 128T
> native: 1330338351 1969957941 2512291791 1514690434 2671040914
> freelist: 16200682 13737658 11645677 10470118 9931051
> objpool: 78673470 1177354156 1514690434 1604472348 1655086824
>
> Tests on 96-core ARM64 system output similarly, but with the biggest
> ratio up to 454.8x:
>
> OS: Debian 10 AARCH64, Linux 6.5rc7
> HW: Kunpeng-920 96 cores/2 sockets/4 NUMA nodes, DDR4 2933 MT/s
>
> 1T 2T 4T 8T 16T
> native: . 30066096 13733813 126194076 257447289 505800181
> freelist: 16152090 11064397 11124068 7215768 5663013
> objpool: 13733813 27749031 56540679 112291770 223482778
> 24T 32T 48T 64T 96T
> native: 763305277 1015925192 1521075123 2033009392 3021013752
> freelist: 5015810 4602893 3766792 3382478 2945292
> objpool: 334605663 448310646 675018951 903449904 1339693418
>
This looks good to me (and I have tested with updated objpool)
Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Wuqiang, can you update the above number with the simplified
objpool? I got better number (always 80% of the native performance)
with 128 node/probe.
(*) https://lore.kernel.org/all/20231003003923.eabc33bb3f4ffb8eac71f2af@kernel.org/
Thank you,
> Signed-off-by: wuqiang.matt <wuqiang.matt@...edance.com>
> ---
> include/linux/kprobes.h | 11 ++---
> include/linux/rethook.h | 16 ++-----
> kernel/kprobes.c | 93 +++++++++++++++++------------------------
> kernel/trace/fprobe.c | 32 ++++++--------
> kernel/trace/rethook.c | 90 ++++++++++++++++++---------------------
> 5 files changed, 98 insertions(+), 144 deletions(-)
>
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 85a64cb95d75..365eb092e9c4 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -26,8 +26,7 @@
> #include <linux/rcupdate.h>
> #include <linux/mutex.h>
> #include <linux/ftrace.h>
> -#include <linux/refcount.h>
> -#include <linux/freelist.h>
> +#include <linux/objpool.h>
> #include <linux/rethook.h>
> #include <asm/kprobes.h>
>
> @@ -141,7 +140,7 @@ static inline bool kprobe_ftrace(struct kprobe *p)
> */
> struct kretprobe_holder {
> struct kretprobe *rp;
> - refcount_t ref;
> + struct objpool_head pool;
> };
>
> struct kretprobe {
> @@ -154,7 +153,6 @@ struct kretprobe {
> #ifdef CONFIG_KRETPROBE_ON_RETHOOK
> struct rethook *rh;
> #else
> - struct freelist_head freelist;
> struct kretprobe_holder *rph;
> #endif
> };
> @@ -165,10 +163,7 @@ struct kretprobe_instance {
> #ifdef CONFIG_KRETPROBE_ON_RETHOOK
> struct rethook_node node;
> #else
> - union {
> - struct freelist_node freelist;
> - struct rcu_head rcu;
> - };
> + struct rcu_head rcu;
> struct llist_node llist;
> struct kretprobe_holder *rph;
> kprobe_opcode_t *ret_addr;
> diff --git a/include/linux/rethook.h b/include/linux/rethook.h
> index 26b6f3c81a76..ce69b2b7bc35 100644
> --- a/include/linux/rethook.h
> +++ b/include/linux/rethook.h
> @@ -6,11 +6,10 @@
> #define _LINUX_RETHOOK_H
>
> #include <linux/compiler.h>
> -#include <linux/freelist.h>
> +#include <linux/objpool.h>
> #include <linux/kallsyms.h>
> #include <linux/llist.h>
> #include <linux/rcupdate.h>
> -#include <linux/refcount.h>
>
> struct rethook_node;
>
> @@ -30,14 +29,12 @@ typedef void (*rethook_handler_t) (struct rethook_node *, void *, unsigned long,
> struct rethook {
> void *data;
> rethook_handler_t handler;
> - struct freelist_head pool;
> - refcount_t ref;
> + struct objpool_head pool;
> struct rcu_head rcu;
> };
>
> /**
> * struct rethook_node - The rethook shadow-stack entry node.
> - * @freelist: The freelist, linked to struct rethook::pool.
> * @rcu: The rcu_head for deferred freeing.
> * @llist: The llist, linked to a struct task_struct::rethooks.
> * @rethook: The pointer to the struct rethook.
> @@ -48,20 +45,16 @@ struct rethook {
> * on each entry of the shadow stack.
> */
> struct rethook_node {
> - union {
> - struct freelist_node freelist;
> - struct rcu_head rcu;
> - };
> + struct rcu_head rcu;
> struct llist_node llist;
> struct rethook *rethook;
> unsigned long ret_addr;
> unsigned long frame;
> };
>
> -struct rethook *rethook_alloc(void *data, rethook_handler_t handler);
> +struct rethook *rethook_alloc(void *data, rethook_handler_t handler, int size, int num);
> void rethook_stop(struct rethook *rh);
> void rethook_free(struct rethook *rh);
> -void rethook_add_node(struct rethook *rh, struct rethook_node *node);
> struct rethook_node *rethook_try_get(struct rethook *rh);
> void rethook_recycle(struct rethook_node *node);
> void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount);
> @@ -98,4 +91,3 @@ void rethook_flush_task(struct task_struct *tk);
> #endif
>
> #endif
> -
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index ca385b61d546..075a632e6c7c 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1877,13 +1877,27 @@ static struct notifier_block kprobe_exceptions_nb = {
> #ifdef CONFIG_KRETPROBES
>
> #if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
> +
> +/* callbacks for objpool of kretprobe instances */
> +static int kretprobe_init_inst(void *nod, void *context)
> +{
> + struct kretprobe_instance *ri = nod;
> +
> + ri->rph = context;
> + return 0;
> +}
> +static int kretprobe_fini_pool(struct objpool_head *head, void *context)
> +{
> + kfree(context);
> + return 0;
> +}
> +
> static void free_rp_inst_rcu(struct rcu_head *head)
> {
> struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
> + struct kretprobe_holder *rph = ri->rph;
>
> - if (refcount_dec_and_test(&ri->rph->ref))
> - kfree(ri->rph);
> - kfree(ri);
> + objpool_drop(ri, &rph->pool);
> }
> NOKPROBE_SYMBOL(free_rp_inst_rcu);
>
> @@ -1892,7 +1906,7 @@ static void recycle_rp_inst(struct kretprobe_instance *ri)
> struct kretprobe *rp = get_kretprobe(ri);
>
> if (likely(rp))
> - freelist_add(&ri->freelist, &rp->freelist);
> + objpool_push(ri, &rp->rph->pool);
> else
> call_rcu(&ri->rcu, free_rp_inst_rcu);
> }
> @@ -1929,23 +1943,12 @@ 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++;
> - }
> + struct kretprobe_holder *rph = rp->rph;
>
> - if (refcount_sub_and_test(count, &rp->rph->ref)) {
> - kfree(rp->rph);
> - rp->rph = NULL;
> - }
> + if (!rph)
> + return;
> + rp->rph = NULL;
> + objpool_fini(&rph->pool);
> }
>
> /* This assumes the 'tsk' is the current task or the is not running. */
> @@ -2087,19 +2090,17 @@ NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
> static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
> {
> struct kretprobe *rp = container_of(p, struct kretprobe, kp);
> + struct kretprobe_holder *rph = rp->rph;
> struct kretprobe_instance *ri;
> - struct freelist_node *fn;
>
> - fn = freelist_try_get(&rp->freelist);
> - if (!fn) {
> + ri = objpool_pop(&rph->pool);
> + if (!ri) {
> rp->nmissed++;
> return 0;
> }
>
> - ri = container_of(fn, struct kretprobe_instance, freelist);
> -
> if (rp->entry_handler && rp->entry_handler(ri, regs)) {
> - freelist_add(&ri->freelist, &rp->freelist);
> + objpool_push(ri, &rph->pool);
> return 0;
> }
>
> @@ -2193,7 +2194,6 @@ int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long o
> int register_kretprobe(struct kretprobe *rp)
> {
> int ret;
> - struct kretprobe_instance *inst;
> int i;
> void *addr;
>
> @@ -2227,20 +2227,12 @@ int register_kretprobe(struct kretprobe *rp)
> rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
>
> #ifdef CONFIG_KRETPROBE_ON_RETHOOK
> - rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler);
> - if (!rp->rh)
> - return -ENOMEM;
> + rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler,
> + sizeof(struct kretprobe_instance) +
> + rp->data_size, rp->maxactive);
> + if (IS_ERR(rp->rh))
> + return PTR_ERR(rp->rh);
>
> - for (i = 0; i < rp->maxactive; i++) {
> - inst = kzalloc(sizeof(struct kretprobe_instance) +
> - rp->data_size, GFP_KERNEL);
> - if (inst == NULL) {
> - rethook_free(rp->rh);
> - rp->rh = NULL;
> - return -ENOMEM;
> - }
> - rethook_add_node(rp->rh, &inst->node);
> - }
> rp->nmissed = 0;
> /* Establish function entry probe point */
> ret = register_kprobe(&rp->kp);
> @@ -2249,25 +2241,18 @@ int register_kretprobe(struct kretprobe *rp)
> rp->rh = NULL;
> }
> #else /* !CONFIG_KRETPROBE_ON_RETHOOK */
> - rp->freelist.head = NULL;
> rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
> if (!rp->rph)
> return -ENOMEM;
>
> - rp->rph->rp = rp;
> - for (i = 0; i < rp->maxactive; i++) {
> - inst = kzalloc(sizeof(struct kretprobe_instance) +
> - rp->data_size, GFP_KERNEL);
> - if (inst == NULL) {
> - refcount_set(&rp->rph->ref, i);
> - free_rp_inst(rp);
> - return -ENOMEM;
> - }
> - inst->rph = rp->rph;
> - freelist_add(&inst->freelist, &rp->freelist);
> + if (objpool_init(&rp->rph->pool, rp->maxactive, rp->data_size +
> + sizeof(struct kretprobe_instance), GFP_KERNEL,
> + rp->rph, kretprobe_init_inst, kretprobe_fini_pool)) {
> + kfree(rp->rph);
> + rp->rph = NULL;
> + return -ENOMEM;
> }
> - refcount_set(&rp->rph->ref, i);
> -
> + rp->rph->rp = rp;
> rp->nmissed = 0;
> /* Establish function entry probe point */
> ret = register_kprobe(&rp->kp);
> diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> index 3b21f4063258..f5bf98e6b2ac 100644
> --- a/kernel/trace/fprobe.c
> +++ b/kernel/trace/fprobe.c
> @@ -187,9 +187,9 @@ static void fprobe_init(struct fprobe *fp)
>
> static int fprobe_init_rethook(struct fprobe *fp, int num)
> {
> - int i, size;
> + int size;
>
> - if (num < 0)
> + if (num <= 0)
> return -EINVAL;
>
> if (!fp->exit_handler) {
> @@ -202,29 +202,21 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
> size = fp->nr_maxactive;
> else
> size = num * num_possible_cpus() * 2;
> - if (size < 0)
> + if (size <= 0)
> return -E2BIG;
>
> - fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
> - if (!fp->rethook)
> - return -ENOMEM;
> - for (i = 0; i < size; i++) {
> - struct fprobe_rethook_node *node;
> -
> - node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL);
> - if (!node) {
> - rethook_free(fp->rethook);
> - fp->rethook = NULL;
> - return -ENOMEM;
> - }
> - rethook_add_node(fp->rethook, &node->node);
> - }
> + /* Initialize rethook */
> + fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler,
> + sizeof(struct fprobe_rethook_node), size);
> + if (IS_ERR(fp->rethook))
> + return PTR_ERR(fp->rethook);
> +
> return 0;
> }
>
> static void fprobe_fail_cleanup(struct fprobe *fp)
> {
> - if (fp->rethook) {
> + if (!IS_ERR_OR_NULL(fp->rethook)) {
> /* Don't need to cleanup rethook->handler because this is not used. */
> rethook_free(fp->rethook);
> fp->rethook = NULL;
> @@ -379,14 +371,14 @@ int unregister_fprobe(struct fprobe *fp)
> if (!fprobe_is_registered(fp))
> return -EINVAL;
>
> - if (fp->rethook)
> + if (!IS_ERR_OR_NULL(fp->rethook))
> rethook_stop(fp->rethook);
>
> ret = unregister_ftrace_function(&fp->ops);
> if (ret < 0)
> return ret;
>
> - if (fp->rethook)
> + if (!IS_ERR_OR_NULL(fp->rethook))
> rethook_free(fp->rethook);
>
> ftrace_free_filter(&fp->ops);
> diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> index 5eb9b598f4e9..13c8e6773892 100644
> --- a/kernel/trace/rethook.c
> +++ b/kernel/trace/rethook.c
> @@ -9,6 +9,7 @@
> #include <linux/rethook.h>
> #include <linux/slab.h>
> #include <linux/sort.h>
> +#include <linux/smp.h>
>
> /* Return hook list (shadow stack by list) */
>
> @@ -36,21 +37,7 @@ void rethook_flush_task(struct task_struct *tk)
> static void rethook_free_rcu(struct rcu_head *head)
> {
> struct rethook *rh = container_of(head, struct rethook, rcu);
> - struct rethook_node *rhn;
> - struct freelist_node *node;
> - int count = 1;
> -
> - node = rh->pool.head;
> - while (node) {
> - rhn = container_of(node, struct rethook_node, freelist);
> - node = node->next;
> - kfree(rhn);
> - count++;
> - }
> -
> - /* The rh->ref is the number of pooled node + 1 */
> - if (refcount_sub_and_test(count, &rh->ref))
> - kfree(rh);
> + objpool_fini(&rh->pool);
> }
>
> /**
> @@ -83,54 +70,62 @@ void rethook_free(struct rethook *rh)
> call_rcu(&rh->rcu, rethook_free_rcu);
> }
>
> +static int rethook_init_node(void *nod, void *context)
> +{
> + struct rethook_node *node = nod;
> +
> + node->rethook = context;
> + return 0;
> +}
> +
> +static int rethook_fini_pool(struct objpool_head *head, void *context)
> +{
> + kfree(context);
> + return 0;
> +}
> +
> /**
> * rethook_alloc() - Allocate struct rethook.
> * @data: a data to pass the @handler when hooking the return.
> - * @handler: the return hook callback function.
> + * @handler: the return hook callback function, must NOT be NULL
> + * @size: node size: rethook node and additional data
> + * @num: number of rethook nodes to be preallocated
> *
> * Allocate and initialize a new rethook with @data and @handler.
> - * Return NULL if memory allocation fails or @handler is NULL.
> + * Return pointer of new rethook, or error codes for failures.
> + *
> * Note that @handler == NULL means this rethook is going to be freed.
> */
> -struct rethook *rethook_alloc(void *data, rethook_handler_t handler)
> +struct rethook *rethook_alloc(void *data, rethook_handler_t handler,
> + int size, int num)
> {
> - struct rethook *rh = kzalloc(sizeof(struct rethook), GFP_KERNEL);
> + struct rethook *rh;
>
> - if (!rh || !handler) {
> - kfree(rh);
> - return NULL;
> - }
> + if (!handler || num <= 0 || size < sizeof(struct rethook_node))
> + return ERR_PTR(-EINVAL);
> +
> + rh = kzalloc(sizeof(struct rethook), GFP_KERNEL);
> + if (!rh)
> + return ERR_PTR(-ENOMEM);
>
> rh->data = data;
> rh->handler = handler;
> - rh->pool.head = NULL;
> - refcount_set(&rh->ref, 1);
>
> + /* initialize the objpool for rethook nodes */
> + if (objpool_init(&rh->pool, num, size, GFP_KERNEL, rh,
> + rethook_init_node, rethook_fini_pool)) {
> + kfree(rh);
> + return ERR_PTR(-ENOMEM);
> + }
> return rh;
> }
>
> -/**
> - * rethook_add_node() - Add a new node to the rethook.
> - * @rh: the struct rethook.
> - * @node: the struct rethook_node to be added.
> - *
> - * Add @node to @rh. User must allocate @node (as a part of user's
> - * data structure.) The @node fields are initialized in this function.
> - */
> -void rethook_add_node(struct rethook *rh, struct rethook_node *node)
> -{
> - node->rethook = rh;
> - freelist_add(&node->freelist, &rh->pool);
> - refcount_inc(&rh->ref);
> -}
> -
> static void free_rethook_node_rcu(struct rcu_head *head)
> {
> struct rethook_node *node = container_of(head, struct rethook_node, rcu);
> + struct rethook *rh = node->rethook;
>
> - if (refcount_dec_and_test(&node->rethook->ref))
> - kfree(node->rethook);
> - kfree(node);
> + objpool_drop(node, &rh->pool);
> }
>
> /**
> @@ -145,7 +140,7 @@ void rethook_recycle(struct rethook_node *node)
> lockdep_assert_preemption_disabled();
>
> if (likely(READ_ONCE(node->rethook->handler)))
> - freelist_add(&node->freelist, &node->rethook->pool);
> + objpool_push(node, &node->rethook->pool);
> else
> call_rcu(&node->rcu, free_rethook_node_rcu);
> }
> @@ -161,7 +156,6 @@ NOKPROBE_SYMBOL(rethook_recycle);
> struct rethook_node *rethook_try_get(struct rethook *rh)
> {
> rethook_handler_t handler = READ_ONCE(rh->handler);
> - struct freelist_node *fn;
>
> lockdep_assert_preemption_disabled();
>
> @@ -178,11 +172,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh)
> if (unlikely(!rcu_is_watching()))
> return NULL;
>
> - fn = freelist_try_get(&rh->pool);
> - if (!fn)
> - return NULL;
> -
> - return container_of(fn, struct rethook_node, freelist);
> + return (struct rethook_node *)objpool_pop(&rh->pool);
> }
> NOKPROBE_SYMBOL(rethook_try_get);
>
> --
> 2.40.1
>
--
Masami Hiramatsu (Google) <mhiramat@...nel.org>
Powered by blists - more mailing lists