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249dbe74d3
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. Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* include/linux/eventpoll.h ( Efficient event polling implementation )
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* Copyright (C) 2001,...,2006 Davide Libenzi
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*/
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#ifndef _LINUX_EVENTPOLL_H
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#define _LINUX_EVENTPOLL_H
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#include <uapi/linux/eventpoll.h>
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#include <uapi/linux/kcmp.h>
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/* Forward declarations to avoid compiler errors */
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struct file;
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#ifdef CONFIG_EPOLL
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#ifdef CONFIG_KCMP
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struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff);
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#endif
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/* Used to release the epoll bits inside the "struct file" */
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void eventpoll_release_file(struct file *file);
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/*
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* This is called from inside fs/file_table.c:__fput() to unlink files
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* from the eventpoll interface. We need to have this facility to cleanup
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* correctly files that are closed without being removed from the eventpoll
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* interface.
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*/
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static inline void eventpoll_release(struct file *file)
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{
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/*
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* Fast check to avoid the get/release of the semaphore. Since
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* we're doing this outside the semaphore lock, it might return
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* false negatives, but we don't care. It'll help in 99.99% of cases
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* to avoid the semaphore lock. False positives simply cannot happen
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* because the file in on the way to be removed and nobody ( but
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* eventpoll ) has still a reference to this file.
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*/
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if (likely(!file->f_ep))
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return;
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/*
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* The file is being closed while it is still linked to an epoll
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* descriptor. We need to handle this by correctly unlinking it
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* from its containers.
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*/
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eventpoll_release_file(file);
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}
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int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
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bool nonblock);
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/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
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static inline int ep_op_has_event(int op)
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{
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return op != EPOLL_CTL_DEL;
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}
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#else
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static inline void eventpoll_release(struct file *file) {}
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#endif
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#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
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/* ARM OABI has an incompatible struct layout and needs a special handler */
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extern struct epoll_event __user *
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epoll_put_uevent(__poll_t revents, __u64 data,
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struct epoll_event __user *uevent);
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#else
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static inline struct epoll_event __user *
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epoll_put_uevent(__poll_t revents, __u64 data,
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struct epoll_event __user *uevent)
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{
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if (__put_user(revents, &uevent->events) ||
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__put_user(data, &uevent->data))
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return NULL;
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return uevent+1;
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}
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#endif
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#endif /* #ifndef _LINUX_EVENTPOLL_H */
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