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Thu, 1 Oct 2020 14:12:54 +0000 (UTC) Received: from threadripper.lan ([46.223.126.90]) by mrelayeu.kundenserver.de (mreue108 [212.227.15.145]) with ESMTPA (Nemesis) id 1MZTua-1jsYXD0BPy-00WXhu; Thu, 01 Oct 2020 16:12:53 +0200 From: Arnd Bergmann To: Russell King , Christoph Hellwig Cc: Alexander Viro , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, Arnd Bergmann Subject: [PATCH v3 05/10] ARM: oabi-compat: rework epoll_wait/epoll_pwait emulation Date: Thu, 1 Oct 2020 16:12:28 +0200 Message-Id: <20201001141233.119343-6-arnd@arndb.de> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201001141233.119343-1-arnd@arndb.de> References: <20201001141233.119343-1-arnd@arndb.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:XIaaingPpec+a6Y9LnJdFRwLVmXn4q8tvLz+Ns67E/nR1D/CxZu 2f3ZnnElaftMX2cx8jyMBlmpalu7G5S/I031cpRt14OJk2MLBpS6dKgk+Bdl3ce64tXMDWm Hwnv2472nk9CekGEslTcGf322mcSuHLrXX8gQI8H1dtCigaz/f5YFFNOB8S3+XW2dhKOK6N Rl0wHOU7kQNzOOiMgPY2g== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:ZDmt+JVyqPo=:wUWBan/XhTM7os4S00g0T1 sAA5nlHwb2VVfsFK9dU/a72r9wdjyeUBgIFSad74IASqgKIVGCoU+8vZ7BfHvdlMiqjHAQp9Z tgCOQ+zioezPU4zafO96vEDsV5BF9fVIZkeVKR9d/W/Bfj1aG0pVpwdcSc11+/eoFhv69GK8w w8QHdRPUVOPNHiYwh65IIuC8Ow9o80p5akdwFNDzx/v44Hv4qGjrgA7RVfxSNtBPQ/3moCKyW wSFfkeEc5qed66reLd4wMONAaR8dya2lOTQddbcrXhUfOkoU7Hgnytl431wF8Kw/7Fnty0p6v csZbFnhptYVWvuEB0e0pCeH9V2vAW9wUct0VI0gh/tZi1FNqlCPpJeUElc/pAnc0ZOfXRFeqk hx6oEqu32UlvEGgtKT79aP346fSXQEPKGg/NBf3PU9h5ZAf0LWxPUgiE2eGqKyaij+zjd1M3w Rua29DbwZhTMWZ/OlqwLboQ3VGaZiDA75hKH1iUV7H+J3vvCKGVTyyUHQ/W0hx9M/g75B+2cP ImMGY8kLdF0n5crMk+bRxpEFdmqh90hlyOHzvdBkTNSGyI0ARmeAmDuIEaj/4mC+DEBR2+pel av/0ToexShtb0AthHNwYs1xfxh55pIlVpyHtdcptQD6g2CtaRcUtJWUS8CrERRaFSumcX9q2t BC/Dnec1dYFdqDUDukAvVwYCUqaKaeIyRkWPernuN+z7P7K89nAW2flez9NT72UaMBubcb26Q gIkmca9Si1jS80rxKq1DDxkLiYZ5g8/VNHKrm0opo1X7zy9hV0nCqymt1Rkjyvrvw59QYUVm/ UUpavLZQBScTTuFf50HVhGD+9UL/yjmdAh2WCFRLV+NFjWwPrDfOXE4XUDlJFNNvevClVaL X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 39a24bee7df8..fe5cd48fed91 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 12eebcdea9c8..796d9e72dc96 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1745,8 +1745,8 @@ 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) @@ -1754,7 +1754,6 @@ 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 */