From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2A98189902 for ; Mon, 30 Sep 2024 09:40:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727689247; cv=none; b=npIat5qAlsr2vjWe6a/JN2UTh2hUHskkjTdsSdkCEVRU1md9q2Q2fwG+bV7rz+k7uDRE3QJdbsc9v8ZHsXAOAPVj5kGHAVW6PqaMFKHISEX3373i+Oml9zf7s18SwKddy3fLx4gVfP7H+aetKLUifPD0DQC8eVdekLNhJO1tovo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727689247; c=relaxed/simple; bh=cvR51nrfsAexTy67HhXjj6ohzaXX0/38qIkbN+szIoQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c1CZ002DZBxl1W8x3G0NrX76I21aaMAOSDe8NaVJ6B75y7fSnIOcXeL7AO406iw8ekXAaEx6NuE1fDDGDSI3n61SfLeDEyWip40gd/eiBNYRJWpdeKphnX8Cjy6cq18haROIoWaO27heTAlSo+Iu5RV0iI96DA5oUt+n/8Hcd+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=dSYm9uxq; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dSYm9uxq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1727689244; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=v0E+qKNNngUa/s7lIUGOnbui4nnSmqw78cj0HvRaCzg=; b=dSYm9uxqFso3aQIbmjejzJ4fOSYhedixNmUM06d9ugEh9eBidkFai/KC03DbK1uDhKnXQX S6mL7ARFuhSnuGUcFXsk7T6/5NOdCIz1PZ8PV8+jmlNPMATMVMFf4M+mJKUNigLKzJIIL9 8Yls30gThjh0JOpnn+XjQX9M9W4bvpI= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-607-HttAFN4iNH-QDBGEmmn92w-1; Mon, 30 Sep 2024 05:40:38 -0400 X-MC-Unique: HttAFN4iNH-QDBGEmmn92w-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (unknown [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1E7CC19030B9; Mon, 30 Sep 2024 09:40:36 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.88]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id E8354195419F; Mon, 30 Sep 2024 09:40:29 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 30 Sep 2024 11:40:22 +0200 (CEST) Date: Mon, 30 Sep 2024 11:40:15 +0200 From: Oleg Nesterov To: Jiri Olsa Cc: Peter Zijlstra , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCHv5 bpf-next 02/13] uprobe: Add support for session consumer Message-ID: <20240930094014.GB18499@redhat.com> References: <20240929205717.3813648-1-jolsa@kernel.org> <20240929205717.3813648-3-jolsa@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240929205717.3813648-3-jolsa@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Jiri, LGTM. But I'm afraid you need to send v6, sorry ;) This change has some (trivial) conflicts in prepare_uretprobe() with the cleanups I sent yesterday, and Peter is going to queue them. See https://lore.kernel.org/all/20240929144201.GA9429@redhat.com/ Oleg. On 09/29, Jiri Olsa wrote: > > This change allows the uprobe consumer to behave as session which > means that 'handler' and 'ret_handler' callbacks are connected in > a way that allows to: > > - control execution of 'ret_handler' from 'handler' callback > - share data between 'handler' and 'ret_handler' callbacks > > The session concept fits to our common use case where we do filtering > on entry uprobe and based on the result we decide to run the return > uprobe (or not). > > It's also convenient to share the data between session callbacks. > > To achive this we are adding new return value the uprobe consumer > can return from 'handler' callback: > > UPROBE_HANDLER_IGNORE > - Ignore 'ret_handler' callback for this consumer. > > And store cookie and pass it to 'ret_handler' when consumer has both > 'handler' and 'ret_handler' callbacks defined. > > We store shared data in the return_consumer object array as part of > the return_instance object. This way the handle_uretprobe_chain can > find related return_consumer and its shared data. > > We also store entry handler return value, for cases when there are > multiple consumers on single uprobe and some of them are ignored and > some of them not, in which case the return probe gets installed and > we need to have a way to find out which consumer needs to be ignored. > > The tricky part is when consumer is registered 'after' the uprobe > entry handler is hit. In such case this consumer's 'ret_handler' gets > executed as well, but it won't have the proper data pointer set, > so we can filter it out. > > Suggested-by: Oleg Nesterov > Signed-off-by: Jiri Olsa > --- > include/linux/uprobes.h | 21 +++++- > kernel/events/uprobes.c | 148 +++++++++++++++++++++++++++++++--------- > 2 files changed, 137 insertions(+), 32 deletions(-) > > diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h > index bb265a632b91..dbaf04189548 100644 > --- a/include/linux/uprobes.h > +++ b/include/linux/uprobes.h > @@ -23,8 +23,17 @@ struct inode; > struct notifier_block; > struct page; > > +/* > + * Allowed return values from uprobe consumer's handler callback > + * with following meaning: > + * > + * UPROBE_HANDLER_REMOVE > + * - Remove the uprobe breakpoint from current->mm. > + * UPROBE_HANDLER_IGNORE > + * - Ignore ret_handler callback for this consumer. > + */ > #define UPROBE_HANDLER_REMOVE 1 > -#define UPROBE_HANDLER_MASK 1 > +#define UPROBE_HANDLER_IGNORE 2 > > #define MAX_URETPROBE_DEPTH 64 > > @@ -44,6 +53,8 @@ struct uprobe_consumer { > bool (*filter)(struct uprobe_consumer *self, struct mm_struct *mm); > > struct list_head cons_node; > + > + __u64 id; /* set when uprobe_consumer is registered */ > }; > > #ifdef CONFIG_UPROBES > @@ -83,14 +94,22 @@ struct uprobe_task { > unsigned int depth; > }; > > +struct return_consumer { > + __u64 cookie; > + __u64 id; > +}; > + > struct return_instance { > struct uprobe *uprobe; > unsigned long func; > unsigned long stack; /* stack pointer */ > unsigned long orig_ret_vaddr; /* original return address */ > bool chained; /* true, if instance is nested */ > + int consumers_cnt; > > struct return_instance *next; /* keep as stack */ > + > + struct return_consumer consumers[] __counted_by(consumers_cnt); > }; > > enum rp_check { > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 2ba93f8a31aa..76fe535c9b3c 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -65,7 +65,7 @@ struct uprobe { > struct rcu_head rcu; > loff_t offset; > loff_t ref_ctr_offset; > - unsigned long flags; > + unsigned long flags; /* "unsigned long" so bitops work */ > > /* > * The generic code assumes that it has two members of unknown type > @@ -825,8 +825,11 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, > > static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) > { > + static atomic64_t id; > + > down_write(&uprobe->consumer_rwsem); > list_add_rcu(&uc->cons_node, &uprobe->consumers); > + uc->id = (__u64) atomic64_inc_return(&id); > up_write(&uprobe->consumer_rwsem); > } > > @@ -1797,6 +1800,34 @@ static struct uprobe_task *get_utask(void) > return current->utask; > } > > +static size_t ri_size(int consumers_cnt) > +{ > + struct return_instance *ri; > + > + return sizeof(*ri) + sizeof(ri->consumers[0]) * consumers_cnt; > +} > + > +#define DEF_CNT 4 > + > +static struct return_instance *alloc_return_instance(void) > +{ > + struct return_instance *ri; > + > + ri = kzalloc(ri_size(DEF_CNT), GFP_KERNEL); > + if (!ri) > + return ZERO_SIZE_PTR; > + > + ri->consumers_cnt = DEF_CNT; > + return ri; > +} > + > +static struct return_instance *dup_return_instance(struct return_instance *old) > +{ > + size_t size = ri_size(old->consumers_cnt); > + > + return kmemdup(old, size, GFP_KERNEL); > +} > + > static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) > { > struct uprobe_task *n_utask; > @@ -1809,11 +1840,10 @@ static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) > > p = &n_utask->return_instances; > for (o = o_utask->return_instances; o; o = o->next) { > - n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); > + n = dup_return_instance(o); > if (!n) > return -ENOMEM; > > - *n = *o; > /* > * uprobe's refcnt has to be positive at this point, kept by > * utask->return_instances items; return_instances can't be > @@ -1906,39 +1936,35 @@ static void cleanup_return_instances(struct uprobe_task *utask, bool chained, > utask->return_instances = ri; > } > > -static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) > +static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs, > + struct return_instance *ri) > { > - struct return_instance *ri; > struct uprobe_task *utask; > unsigned long orig_ret_vaddr, trampoline_vaddr; > bool chained; > > if (!get_xol_area()) > - return; > + goto free; > > utask = get_utask(); > if (!utask) > - return; > + goto free; > > if (utask->depth >= MAX_URETPROBE_DEPTH) { > printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" > " nestedness limit pid/tgid=%d/%d\n", > current->pid, current->tgid); > - return; > + goto free; > } > > /* we need to bump refcount to store uprobe in utask */ > if (!try_get_uprobe(uprobe)) > - return; > - > - ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); > - if (!ri) > - goto fail; > + goto free; > > trampoline_vaddr = uprobe_get_trampoline_vaddr(); > orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); > if (orig_ret_vaddr == -1) > - goto fail; > + goto put; > > /* drop the entries invalidated by longjmp() */ > chained = (orig_ret_vaddr == trampoline_vaddr); > @@ -1956,7 +1982,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) > * attack from user-space. > */ > uprobe_warn(current, "handle tail call"); > - goto fail; > + goto put; > } > orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; > } > @@ -1971,9 +1997,10 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) > utask->return_instances = ri; > > return; > -fail: > - kfree(ri); > +put: > put_uprobe(uprobe); > +free: > + kfree(ri); > } > > /* Prepare to single-step probed instruction out of line. */ > @@ -2125,35 +2152,91 @@ static struct uprobe *find_active_uprobe_rcu(unsigned long bp_vaddr, int *is_swb > return uprobe; > } > > +static struct return_instance* > +push_consumer(struct return_instance *ri, int idx, __u64 id, __u64 cookie) > +{ > + if (unlikely(ri == ZERO_SIZE_PTR)) > + return ri; > + > + if (unlikely(idx >= ri->consumers_cnt)) { > + struct return_instance *old_ri = ri; > + > + ri->consumers_cnt += DEF_CNT; > + ri = krealloc(old_ri, ri_size(old_ri->consumers_cnt), GFP_KERNEL); > + if (!ri) { > + kfree(old_ri); > + return ZERO_SIZE_PTR; > + } > + } > + > + ri->consumers[idx].id = id; > + ri->consumers[idx].cookie = cookie; > + return ri; > +} > + > +static struct return_consumer * > +return_consumer_find(struct return_instance *ri, int *iter, int id) > +{ > + struct return_consumer *ric; > + int idx = *iter; > + > + for (ric = &ri->consumers[idx]; idx < ri->consumers_cnt; idx++, ric++) { > + if (ric->id == id) { > + *iter = idx + 1; > + return ric; > + } > + } > + return NULL; > +} > + > +static bool ignore_ret_handler(int rc) > +{ > + return rc == UPROBE_HANDLER_REMOVE || rc == UPROBE_HANDLER_IGNORE; > +} > + > static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) > { > struct uprobe_consumer *uc; > - int remove = UPROBE_HANDLER_REMOVE; > - bool need_prep = false; /* prepare return uprobe, when needed */ > - bool has_consumers = false; > + bool has_consumers = false, remove = true; > + struct return_instance *ri = NULL; > + int push_idx = 0; > > current->utask->auprobe = &uprobe->arch; > > list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node, > srcu_read_lock_held(&uprobes_srcu)) { > + bool session = uc->handler && uc->ret_handler; > + __u64 cookie = 0; > int rc = 0; > > if (uc->handler) { > - rc = uc->handler(uc, regs, NULL); > - WARN(rc & ~UPROBE_HANDLER_MASK, > + rc = uc->handler(uc, regs, &cookie); > + WARN(rc < 0 || rc > 2, > "bad rc=0x%x from %ps()\n", rc, uc->handler); > } > > - if (uc->ret_handler) > - need_prep = true; > - > - remove &= rc; > + remove &= rc == UPROBE_HANDLER_REMOVE; > has_consumers = true; > + > + if (!uc->ret_handler || ignore_ret_handler(rc)) > + continue; > + > + if (!ri) > + ri = alloc_return_instance(); > + > + if (session) > + ri = push_consumer(ri, push_idx++, uc->id, cookie); > } > current->utask->auprobe = NULL; > > - if (need_prep && !remove) > - prepare_uretprobe(uprobe, regs); /* put bp at return */ > + if (!ZERO_OR_NULL_PTR(ri)) { > + /* > + * The push_idx value has the final number of return consumers, > + * and ri->consumers_cnt has number of allocated consumers. > + */ > + ri->consumers_cnt = push_idx; > + prepare_uretprobe(uprobe, regs, ri); > + } > > if (remove && has_consumers) { > down_read(&uprobe->register_rwsem); > @@ -2172,14 +2255,17 @@ static void > handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) > { > struct uprobe *uprobe = ri->uprobe; > + struct return_consumer *ric; > struct uprobe_consumer *uc; > - int srcu_idx; > + int srcu_idx, ric_idx = 0; > > srcu_idx = srcu_read_lock(&uprobes_srcu); > list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node, > srcu_read_lock_held(&uprobes_srcu)) { > - if (uc->ret_handler) > - uc->ret_handler(uc, ri->func, regs, NULL); > + if (uc->ret_handler) { > + ric = return_consumer_find(ri, &ric_idx, uc->id); > + uc->ret_handler(uc, ri->func, regs, ric ? &ric->cookie : NULL); > + } > } > srcu_read_unlock(&uprobes_srcu, srcu_idx); > } > -- > 2.46.1 >