[PATCH 6/9] select: Extract common code into do_sys_ppoll()

Dmitry Safonov
2019-09-09T10:24:06Z

Reduce the amount of code and shrink a .text section a bit:
[linux]$ ./scripts/bloat-o-meter -t /tmp/vmlinux.o.{old,new}
add/remove: 1/0 grow/shrink: 0/4 up/down: 284/-691 (-407)
Function old new delta
do_sys_ppoll - 284 +284
__x64_sys_ppoll 214 42 -172
__ia32_sys_ppoll 213 40 -173
__ia32_compat_sys_ppoll_time64 213 40 -173
__ia32_compat_sys_ppoll_time32 213 40 -173
Total: Before=13357557, After=13357150, chg -0.00%

The downside is that "tsp" and "sigmask" parameters gets (void *),
but it seems worth losing static type checking if there is only one
line in syscall definition.
Other way could be to add compat parameters in do_sys_ppoll(), but
that trashes 2 more registers..

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
fs/select.c | 94 ++++++++++++++++++-----------------------------------
1 file changed, 32 insertions(+), 62 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 458f2a944318..262300e58370 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1056,54 +1056,58 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
return ret;
}

-SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
- struct __kernel_timespec __user *, tsp, const sigset_t __user *, sigmask,
- size_t, sigsetsize)
+static int do_sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
+ void __user *tsp, const void __user *sigmask,
+ size_t sigsetsize, enum poll_time_type pt_type)
{
struct timespec64 ts, end_time, *to = NULL;
int ret;

if (tsp) {
- if (get_timespec64(&ts, tsp))
- return -EFAULT;
+ switch (pt_type) {
+ case PT_TIMESPEC:
+ if (get_timespec64(&ts, tsp))
+ return -EFAULT;
+ break;
+ case PT_OLD_TIMESPEC:
+ if (get_old_timespec32(&ts, tsp))
+ return -EFAULT;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -ENOSYS;
+ }

to = &end_time;
if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
return -EINVAL;
}

- ret = set_user_sigmask(sigmask, sigsetsize);
+ if (!in_compat_syscall())
+ ret = set_user_sigmask(sigmask, sigsetsize);
+ else
+ ret = set_compat_user_sigmask(sigmask, sigsetsize);
+
if (ret)
return ret;

ret = do_sys_poll(ufds, nfds, to);
- return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);
+ return poll_select_finish(&end_time, tsp, pt_type, ret);
}

-#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
+SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
+ struct __kernel_timespec __user *, tsp, const sigset_t __user *, sigmask,
+ size_t, sigsetsize)
+{
+ return do_sys_ppoll(ufds, nfds, tsp, sigmask, sigsetsize, PT_TIMESPEC);
+}

+#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, unsigned int, nfds,
struct old_timespec32 __user *, tsp, const sigset_t __user *, sigmask,
size_t, sigsetsize)
{
- struct timespec64 ts, end_time, *to = NULL;
- int ret;
-
- if (tsp) {
- if (get_old_timespec32(&ts, tsp))
- return -EFAULT;
-
- to = &end_time;
- if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
- return -EINVAL;
- }
-
- ret = set_user_sigmask(sigmask, sigsetsize);
- if (ret)
- return ret;
-
- ret = do_sys_poll(ufds, nfds, to);
- return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);
+ return do_sys_ppoll(ufds, nfds, tsp, sigmask, sigsetsize, PT_OLD_TIMESPEC);
}
#endif

@@ -1352,24 +1356,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds,
unsigned int, nfds, struct old_timespec32 __user *, tsp,
const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)
{
- struct timespec64 ts, end_time, *to = NULL;
- int ret;
-
- if (tsp) {
- if (get_old_timespec32(&ts, tsp))
- return -EFAULT;
-
- to = &end_time;
- if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
- return -EINVAL;
- }
-
- ret = set_compat_user_sigmask(sigmask, sigsetsize);
- if (ret)
- return ret;
-
- ret = do_sys_poll(ufds, nfds, to);
- return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);
+ return do_sys_ppoll(ufds, nfds, tsp, sigmask, sigsetsize, PT_OLD_TIMESPEC);
}
#endif

@@ -1378,24 +1365,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds,
unsigned int, nfds, struct __kernel_timespec __user *, tsp,
const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)
{
- struct timespec64 ts, end_time, *to = NULL;
- int ret;
-
- if (tsp) {
- if (get_timespec64(&ts, tsp))
- return -EFAULT;
-
- to = &end_time;
- if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
- return -EINVAL;
- }
-
- ret = set_compat_user_sigmask(sigmask, sigsetsize);
- if (ret)
- return ret;
-
- ret = do_sys_poll(ufds, nfds, to);
- return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);
+ return do_sys_ppoll(ufds, nfds, tsp, sigmask, sigsetsize, PT_TIMESPEC);
}

#endif
--
2.23.0