linux-kernel - [PATCH v2 3/9] ARM: oabi-compat: add epoll

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Message-Id: <20200918124624.1469673-4-arnd@arndb.de>
Date:   Fri, 18 Sep 2020 14:46:18 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Christoph Hellwig <hch@...radead.org>,
        Russell King <linux@...linux.org.uk>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        Arnd Bergmann <arnd@...db.de>, stable@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v2 3/9] ARM: oabi-compat: add epoll_pwait handler

The epoll_wait() syscall has a special version for OABI compat
mode to convert the arguments to the EABI structure layout
of the kernel. However, the later epoll_pwait() syscall was
added in arch/arm in linux-2.6.32 without this conversion.

Use the same kind of handler for both.

Fixes: 369842658a36 ("ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait")
Cc: stable@...r.kernel.org
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/kernel/sys_oabi-compat.c | 37 ++++++++++++++++++++++++++++---
 arch/arm/tools/syscall.tbl        |  2 +-
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
index 0203e545bbc8..a2b1ae01e5bf 100644
--- a/arch/arm/kernel/sys_oabi-compat.c
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -264,9 +264,8 @@ asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
 	return do_epoll_ctl(epfd, op, fd, &kernel, false);
 }
 
-asmlinkage long sys_oabi_epoll_wait(int epfd,
-				    struct oabi_epoll_event __user *events,
-				    int maxevents, int timeout)
+static long do_oabi_epoll_wait(int epfd, struct oabi_epoll_event __user *events,
+			       int maxevents, int timeout)
 {
 	struct epoll_event *kbuf;
 	struct oabi_epoll_event e;
@@ -299,6 +298,38 @@ asmlinkage long sys_oabi_epoll_wait(int epfd,
 	return err ? -EFAULT : ret;
 }
 
+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;
+
+	error = do_oabi_epoll_wait(epfd, events, maxevents, timeout);
+	restore_saved_sigmask_unless(error == -EINTR);
+
+	return error;
+}
+
 struct oabi_sembuf {
 	unsigned short	sem_num;
 	short		sem_op;
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 171077cbf419..39a24bee7df8 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -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
+346	common	epoll_pwait		sys_epoll_pwait		sys_oabi_epoll_pwait
 347	common	kexec_load		sys_kexec_load
 348	common	utimensat		sys_utimensat_time32
 349	common	signalfd		sys_signalfd
-- 
2.27.0