Thread (21 messages) 21 messages, 3 authors, 2021-07-22

Re: [PATCH v2 5/9] ARM: oabi-compat: rework epoll_wait/epoll_pwait emulation

From: Christoph Hellwig <hch@infradead.org>
Date: 2020-09-19 05:32:39
Also in: linux-arch, linux-mm, lkml

quoted hunk ↗ jump to hunk
index 855aa7cc9b8e..156880943c16 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);
+}
+
Maybe split these infrastructure additions into a separate helper?
+#if !defined(CONFIG_ARM) || !defined(CONFIG_OABI_COMPAT)
+/* ARM OABI has an incompatible struct layout and needs a special handler */
+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;
+}
+#else
+struct epoll_event __user *
+epoll_put_uevent(__poll_t revents, __u64 data,
+		 struct epoll_event __user *uevent);
+#endif
So after you argued for this variant I still have minor nitpicks:

I alway find positive ifdefs better where possible, e.g.

#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
external declaration here
#else
the real thing
#endif

but I still find the fact that the native case goes into the arch
helper a little weird.

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