From patchwork Fri Oct 30 15:49:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 11870169 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A02FBC00A89 for ; Fri, 30 Oct 2020 15:51:52 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 294DB206E9 for ; Fri, 30 Oct 2020 15:51:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="WFjCgVRm"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="XqTBWM/a" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 294DB206E9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Loo4G4Nb/Q7q6cJAvYgpT20hVh5dt0jvq7gKBv/JsMo=; b=WFjCgVRmvkRFSedjy4FCaNiPy HakNknsJJORft5eb5CuCSY3f25gOrisD96Z7iJYfcfRoGWdnvG5WkyGFA+qzdRfSwuWDuinXzjfAM BpI2KalKVxAHrprgJUU0Z3SWj2iOuc1hvFv+hxz33GpLaYfNoeq3HWB+J7tAcmMc5KWePn4UT0H4W U5coQj4XQ+nEJ9w4ve0vDb/fnekb/FCt37urEB7HJT32pAYiW60Cokqb+MH+A3jTMZbwBIVkDpwkm B7ouLmE/50YgkXpVjrlL4GpZvgPMs5ILK4BvK8tMQpEHPs1RE5IYFPEfbvOEzBMZ9VLmqIsGMA7v9 SVfuHKJdg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kYWgG-0003PO-92; Fri, 30 Oct 2020 15:51:08 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kYWeq-0002wi-EJ for linux-arm-kernel@lists.infradead.org; Fri, 30 Oct 2020 15:49:51 +0000 Received: from localhost.localdomain (HSI-KBW-46-223-126-90.hsi.kabel-badenwuerttemberg.de [46.223.126.90]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 678A0206E9; Fri, 30 Oct 2020 15:49:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604072979; bh=v4W+rSkvG9WdcPfSNfBGl6XjWSXTtC1rvveEB/jtQ0w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XqTBWM/aCsrmb4Tgi139hX/RSflNORGj9TBXdOTLU3VWg3oXN09auBrmiyxfD7l7s jP5NJCppEO2q8rAxXZgSlJP5r9YqZvxzDq+BRPp+fec+f8i1i7FravE+RhO6dmLMG2 4mf65FFZgvd5YsjohMNAZd1o4yHtKx2Zv0l9npvo= From: Arnd Bergmann To: Russell King , Christoph Hellwig Subject: [PATCH 5/9] ARM: oabi-compat: rework epoll_wait/epoll_pwait emulation Date: Fri, 30 Oct 2020 16:49:15 +0100 Message-Id: <20201030154919.1246645-5-arnd@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201030154919.1246645-1-arnd@kernel.org> References: <20201030154519.1245983-1-arnd@kernel.org> <20201030154919.1246645-1-arnd@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201030_114940_789766_C87DD093 X-CRM114-Status: GOOD ( 28.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, arnd@arndb.de, linus.walleij@linaro.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Arnd Bergmann The epoll_wait() system call wrapper is one of the remaining users of the set_fs() infrasturcture for Arm. Changing it to not require set_fs() is rather complex unfortunately. The approach I'm taking here is to allow architectures to override the code that copies the output to user space, and let the oabi-compat implementation check whether it is getting called from an EABI or OABI system call based on the thread_info->syscall value. The in_oabi_syscall() check here mirrors the in_compat_syscall() and in_x32_syscall() helpers for 32-bit compat implementations on other architectures. Overall, the amount of code goes down, at least with the newly added sys_oabi_epoll_pwait() helper getting removed again. The downside is added complexity in the source code for the native implementation. There should be no difference in runtime performance except for Arm kernels with CONFIG_OABI_COMPAT enabled that now have to go through an external function call to check which of the two variants to use. Signed-off-by: Arnd Bergmann --- arch/arm/include/asm/syscall.h | 11 +++++ arch/arm/kernel/sys_oabi-compat.c | 75 +++++++------------------------ arch/arm/tools/syscall.tbl | 4 +- fs/eventpoll.c | 5 +-- include/linux/eventpoll.h | 18 ++++++++ 5 files changed, 49 insertions(+), 64 deletions(-) diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index 89898497edd6..9efb7b3384e5 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -28,6 +28,17 @@ static inline int syscall_get_nr(struct task_struct *task, return task_thread_info(task)->syscall & ~__NR_OABI_SYSCALL_BASE; } +static inline bool __in_oabi_syscall(struct task_struct *task) +{ + return IS_ENABLED(CONFIG_OABI_COMPAT) && + (task_thread_info(task)->syscall & __NR_OABI_SYSCALL_BASE); +} + +static inline bool in_oabi_syscall(void) +{ + return __in_oabi_syscall(current); +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c index a2b1ae01e5bf..f9d8e5be6ba0 100644 --- a/arch/arm/kernel/sys_oabi-compat.c +++ b/arch/arm/kernel/sys_oabi-compat.c @@ -83,6 +83,8 @@ #include #include +#include + struct oldabi_stat64 { unsigned long long st_dev; unsigned int __pad1; @@ -264,70 +266,25 @@ asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd, return do_epoll_ctl(epfd, op, fd, &kernel, false); } -static long do_oabi_epoll_wait(int epfd, struct oabi_epoll_event __user *events, - int maxevents, int timeout) +struct epoll_event __user * +epoll_put_uevent(__poll_t revents, __u64 data, + struct epoll_event __user *uevent) { - struct epoll_event *kbuf; - struct oabi_epoll_event e; - mm_segment_t fs; - long ret, err, i; + if (in_oabi_syscall()) { + struct oabi_epoll_event __user *oevent = (void __user *)uevent; - if (maxevents <= 0 || - maxevents > (INT_MAX/sizeof(*kbuf)) || - maxevents > (INT_MAX/sizeof(*events))) - return -EINVAL; - if (!access_ok(events, sizeof(*events) * maxevents)) - return -EFAULT; - kbuf = kmalloc_array(maxevents, sizeof(*kbuf), GFP_KERNEL); - if (!kbuf) - return -ENOMEM; - fs = get_fs(); - set_fs(KERNEL_DS); - ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout); - set_fs(fs); - err = 0; - for (i = 0; i < ret; i++) { - e.events = kbuf[i].events; - e.data = kbuf[i].data; - err = __copy_to_user(events, &e, sizeof(e)); - if (err) - break; - events++; - } - kfree(kbuf); - return err ? -EFAULT : ret; -} + if (__put_user(revents, &oevent->events) || + __put_user(data, &oevent->data)) + return NULL; -SYSCALL_DEFINE4(oabi_epoll_wait, int, epfd, - struct oabi_epoll_event __user *, events, - int, maxevents, int, timeout) -{ - return do_oabi_epoll_wait(epfd, events, maxevents, timeout); -} - -/* - * Implement the event wait interface for the eventpoll file. It is the kernel - * part of the user space epoll_pwait(2). - */ -SYSCALL_DEFINE6(oabi_epoll_pwait, int, epfd, - struct oabi_epoll_event __user *, events, int, maxevents, - int, timeout, const sigset_t __user *, sigmask, - size_t, sigsetsize) -{ - int error; - - /* - * If the caller wants a certain signal mask to be set during the wait, - * we apply it here. - */ - error = set_user_sigmask(sigmask, sigsetsize); - if (error) - return error; + return (void __user *)(oevent+1); + } - error = do_oabi_epoll_wait(epfd, events, maxevents, timeout); - restore_saved_sigmask_unless(error == -EINTR); + if (__put_user(revents, &uevent->events) || + __put_user(data, &uevent->data)) + return NULL; - return error; + return uevent+1; } struct oabi_sembuf { diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index 330cf0aa04c4..2dd99f86e8a5 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -266,7 +266,7 @@ 249 common lookup_dcookie sys_lookup_dcookie 250 common epoll_create sys_epoll_create 251 common epoll_ctl sys_epoll_ctl sys_oabi_epoll_ctl -252 common epoll_wait sys_epoll_wait sys_oabi_epoll_wait +252 common epoll_wait sys_epoll_wait 253 common remap_file_pages sys_remap_file_pages # 254 for set_thread_area # 255 for get_thread_area @@ -360,7 +360,7 @@ 343 common vmsplice sys_vmsplice 344 common move_pages sys_move_pages 345 common getcpu sys_getcpu -346 common epoll_pwait sys_epoll_pwait sys_oabi_epoll_pwait +346 common epoll_pwait sys_epoll_pwait 347 common kexec_load sys_kexec_load 348 common utimensat sys_utimensat_time32 349 common signalfd sys_signalfd diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 4df61129566d..a21e8dbbe567 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1743,8 +1743,8 @@ static __poll_t ep_send_events_proc(struct eventpoll *ep, struct list_head *head if (!revents) continue; - if (__put_user(revents, &uevent->events) || - __put_user(epi->event.data, &uevent->data)) { + uevent = epoll_put_uevent(revents, epi->event.data, uevent); + if (!uevent) { list_add(&epi->rdllink, head); ep_pm_stay_awake(epi); if (!esed->res) @@ -1752,7 +1752,6 @@ static __poll_t ep_send_events_proc(struct eventpoll *ep, struct list_head *head return 0; } esed->res++; - uevent++; if (epi->event.events & EPOLLONESHOT) epi->event.events &= EP_PRIVATE_BITS; else if (!(epi->event.events & EPOLLET)) { diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h index 8f000fada5a4..d1f13147ed69 100644 --- a/include/linux/eventpoll.h +++ b/include/linux/eventpoll.h @@ -77,4 +77,22 @@ static inline void eventpoll_release(struct file *file) {} #endif +#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT) +/* ARM OABI has an incompatible struct layout and needs a special handler */ +extern struct epoll_event __user * +epoll_put_uevent(__poll_t revents, __u64 data, + struct epoll_event __user *uevent); +#else +static inline struct epoll_event __user * +epoll_put_uevent(__poll_t revents, __u64 data, + struct epoll_event __user *uevent) +{ + if (__put_user(revents, &uevent->events) || + __put_user(data, &uevent->data)) + return NULL; + + return uevent+1; +} +#endif + #endif /* #ifndef _LINUX_EVENTPOLL_H */