Hi Stephen,
+asmlinkage long compat_sys_epoll_wait(int epfd,
+ struct compat_epoll_event __user *events,
+ int maxevents, int timeout)
+{
+ long i, ret, err = 0;
+ struct epoll_event __user *kbuf;
+ struct epoll_event ev;
+
+ if ((maxevents <= 0) ||
+ (maxevents > (INT_MAX / sizeof(struct
epoll_event))))
+ return -EINVAL;
+ kbuf = compat_alloc_user_space(sizeof(struct epoll_event) *
maxevents);
+ ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout);
+ for (i = 0; i < ret; i++) {
+ err |= __get_user(ev.events, &kbuf[i].events);
+ err |= __get_user(ev.data, &kbuf[i].data);
+ err |= put_user(ev.events, &events->events);
+ err |= put_user(ev.data, &events->data);
+ events++;
+ }
+
+ return err ? -EFAULT: ret;
+}
I don't think we can safely assume that we can access a potentially
4-bytes aligned u64 on 64 bit architectures that require compat:
put_user(ev.data, &events->data);
I thought again about the definition of "struct compat_epoll_event" and
the only cases that we can have, are:
1) 8-bytes "data" member alignment on 32 bit and 64 bit (ie, SPARC)
-> No need for compat
2) 4-bytes "data" member alignment on 32 bit and 64 bit (ie, X86-64 -
forced by "struct epoll_event" definition in eventpoll.h)
-> No need for compat
3) 4-bytes "data" member alignment on 32 bit and 8-bytes on 64 bit
(ie, IA-64)
-> Need compat
So, the only case where we need compat, can be covered by the generic
"struct compat_epoll_event" definition inside linux/compat.h. If we'd
instead go for an asm/compat.h definition of "struct compat_epoll_event",
then we'd probably need to define even special copy functions from/to
"struct epoll_event" <-> "struct compat_epoll_event".
But that's not necessary IMO since the only case we can have is #3.
How does the patch below look to you (moved stuff to fs/compat.c and using
CONFIG_HAS_COMPAT_EPOLL_EVENT)?
- Davide
diff -Nru linux-2.6.20/fs/compat.c linux-2.6.20.mod/fs/compat.c
--- linux-2.6.20/fs/compat.c 2007-02-21 11:47:00.000000000 -0800
+++ linux-2.6.20.mod/fs/compat.c 2007-02-21 12:04:26.000000000 -0800
@@ -48,6 +48,7 @@
#include <linux/highmem.h>
#include <linux/poll.h>
#include <linux/mm.h>
+#include <linux/eventpoll.h>
#include <net/sock.h> /* siocdevprivate_ioctl */
@@ -2235,3 +2236,119 @@
return sys_ni_syscall();
}
#endif
+
+
+#ifdef CONFIG_EPOLL
+
+/*
+ * epoll (fs/eventpoll.c) compat functions follow ...
+ */
+
+#ifdef CONFIG_HAS_COMPAT_EPOLL_EVENT
+
+asmlinkage long compat_sys_epoll_ctl(int epfd, int op, int fd,
+ struct compat_epoll_event __user *event)
+{
+ long err = 0;
+ struct compat_epoll_event user;
+ struct epoll_event __user *kernel = NULL;
+ union {
+ u64 q;
+ u32 d[2];
+ } mux;
+
+ if (event) {
+ if (copy_from_user(&user, event, sizeof(user)))
+ return -EFAULT;
+ kernel = compat_alloc_user_space(sizeof(struct epoll_event));
+ err |= __put_user(user.events, &kernel->events);
+ mux.d[0] = user.data[0];
+ mux.d[1] = user.data[1];
+ err |= __put_user(mux.q, &kernel->data);
+ }
+
+ return err ? err: sys_epoll_ctl(epfd, op, fd, kernel);
+}
+
+asmlinkage long compat_sys_epoll_wait(int epfd, struct compat_epoll_event
__user *events,
+ int maxevents, int timeout)
+{
+ long i, ret, err = 0;
+ struct epoll_event __user *kbuf;
+ struct epoll_event ev;
+ union {
+ u64 q;
+ u32 d[2];
+ } mux;
+
+ if (maxevents <= 0 || maxevents > (INT_MAX / sizeof(struct
epoll_event)))
+ return -EINVAL;
+ kbuf = compat_alloc_user_space(sizeof(struct epoll_event) * maxevents);
+ ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout);
+ for (i = 0; i < ret; i++) {
+ err |= __get_user(ev.events, &kbuf[i].events);
+ err |= __get_user(ev.data, &kbuf[i].data);
+ err |= put_user(ev.events, &events->events);
+ mux.q = ev.data;
+ err |= put_user(mux.d[0], &events->data[0]);
+ err |= put_user(mux.d[1], &events->data[1]);
+ events++;
+ }
+
+ return err ? -EFAULT: ret;
+}
+
+#endif /* CONFIG_HAS_COMPAT_EPOLL_EVENT */
+
+#ifdef TIF_RESTORE_SIGMASK
+
+asmlinkage long compat_sys_epoll_pwait(int epfd, struct compat_epoll_event
__user *events,
+ int maxevents, int timeout, const compat_sigset_t __user
*sigmask,
+ compat_size_t sigsetsize)
+{
+ long err;
+ compat_sigset_t ss32;
+ sigset_t ksigmask, sigsaved;
+
+ /*
+ * If the caller wants a certain signal mask to be set during the wait,
+ * we apply it here.
+ */
+ if (sigmask) {
+ if (sigsetsize != sizeof(compat_sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
+ return -EFAULT;
+ sigset_from_compat(&ksigmask, &ss32);
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+#ifdef CONFIG_HAS_COMPAT_EPOLL_EVENT
+ err = compat_sys_epoll_wait(epfd, events, maxevents, timeout);
+#else
+ err = sys_epoll_wait(epfd, events, maxevents, timeout);
+#endif
+
+ /*
+ * If we changed the signal mask, we need to restore the original one.
+ * In case we've got a signal while waiting, we do not restore the
+ * signal mask yet, and we allow do_signal() to deliver the signal on
the way
+ * back to userspace, before the signal mask is restored.
+ */
+ if (sigmask) {
+ if (err == -EINTR) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ } else
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ }
+
+ return err;
+}
+
+#endif /* TIF_RESTORE_SIGMASK */
+
+#endif /* CONFIG_EPOLL */
+
diff -Nru linux-2.6.20/include/linux/compat.h
linux-2.6.20.mod/include/linux/compat.h
--- linux-2.6.20/include/linux/compat.h 2007-02-09 16:14:20.000000000 -0800
+++ linux-2.6.20.mod/include/linux/compat.h 2007-02-21 12:06:04.000000000
-0800
@@ -234,5 +234,32 @@
compat_ulong_t maxnode, const compat_ulong_t __user *old_nodes,
const compat_ulong_t __user *new_nodes);
+/*
+ * epoll (fs/eventpoll.c) compat bits follow ...
+ */
+struct epoll_event;
+
+#ifdef CONFIG_HAS_COMPAT_EPOLL_EVENT
+
+struct compat_epoll_event {
+ u32 events;
+ u32 data[2];
+};
+
+asmlinkage long compat_sys_epoll_ctl(int epfd, int op, int fd,
+ struct compat_epoll_event __user *event);
+asmlinkage long compat_sys_epoll_wait(int epfd, struct compat_epoll_event
__user *events,
+ int maxevents, int timeout);
+
+#else /* CONFIG_HAS_COMPAT_EPOLL_EVENT */
+
+#define compat_epoll_event epoll_event
+
+#endif /* CONFIG_HAS_COMPAT_EPOLL_EVENT */
+
+asmlinkage long compat_sys_epoll_pwait(int epfd, struct compat_epoll_event
__user *events,
+ int maxevents, int timeout, const compat_sigset_t __user
*sigmask,
+ compat_size_t sigsetsize);
+
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */
-
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