diff mbox series

y2038: linux: Provide __ppoll64 implementation

Message ID 20191104160911.31763-1-lukma@denx.de
State New
Headers show
Series y2038: linux: Provide __ppoll64 implementation | expand

Commit Message

Lukasz Majewski Nov. 4, 2019, 4:09 p.m. UTC 
This patch provides new __ppoll64 explicit 64 bit function for handling polling
events (with struct timespec specified timeout) for a set of file descriptors.
Moreover, a 32 bit version - __ppoll has been refactored to internally use
__ppoll64.

The __ppoll is now supposed to be used on systems still supporting 32 bit time
(__TIMESIZE != 64) - hence the necessary conversion to 64 bit struct
__timespec64.

The new ppoll_time64 syscall available from Linux 5.1+ has been used, when
applicable.

The Linux kernel checks if passed tv_nsec value overflows, so there is no need
to repeat it in the glibc.

When ppoll syscall on systems supporting 32 bit time ABI is used, the check is
performed if passed data (which may have 64 bit tv_sec) fits into 32 bit range.

Build tests:
- The code has been tested on x86_64/x86 (native compilation):
make PARALLELMFLAGS="-j8" && make check PARALLELMFLAGS="-j8" && \\
make xcheck PARALLELMFLAGS="-j8"

- The glibc has been build tested (make PARALLELMFLAGS="-j8") for
x86 (i386), x86_64-x32, and armv7

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master

- Use of cross-test-ssh.sh for ARM (armv7):
  make PARALLELMFLAGS="-j8" test-wrapper='./cross-test-ssh.sh root@192.168.7.2' xcheck

Linux kernel, headers and minimal kernel version for glibc build test
matrix:
- Linux v5.1 (with ppoll_time64) and glibc build with v5.1 as
  minimal kernel version (--enable-kernel="5.1.0")
  The __ASSUME_TIME64_SYSCALLS flag defined.

- Linux v5.1 and default minimal kernel version
  The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports ppoll_time64
  syscall.

- Linux v4.19 (no ppoll_time64 support) with default minimal kernel version for
  contemporary glibc
  This kernel doesn't support ppoll_time64 syscall, so the fallback to ppoll is
  tested.

Above tests were performed with Y2038 redirection applied as well as without
(so the __TIMESIZE != 64 execution path is checked as well).

No regressions were observed.
---
 include/sys/poll.h              | 13 ++++++++-
 sysdeps/unix/sysv/linux/ppoll.c | 49 ++++++++++++++++++++++++++++++---
 2 files changed, 57 insertions(+), 5 deletions(-)

Comments

Joseph Myers Nov. 7, 2019, 12:09 a.m. UTC | #1 
On Mon, 4 Nov 2019, Lukasz Majewski wrote:

> +# ifdef __NR_ppoll_time64
> +  int ret = SYSCALL_CANCEL (ppoll_time64, fds, nfds, timeout, sigmask,
> +                            _NSIG / 8);
> +  if (ret == 0 || errno != ENOSYS)
> +    return ret;

A positive return from ppoll also indicates success and should result in 
the function returning without retrying with the 32-bit syscall.
diff mbox series

Patch

diff --git a/include/sys/poll.h b/include/sys/poll.h
index a42bc93873..f904e21f89 100644
--- a/include/sys/poll.h
+++ b/include/sys/poll.h
@@ -6,6 +6,17 @@  extern int __poll (struct pollfd *__fds, unsigned long int __nfds,
 		   int __timeout);
 libc_hidden_proto (__poll)
 libc_hidden_proto (ppoll)
-#endif
 
+# if __TIMESIZE == 64
+#  define __ppoll64 __ppoll
+# else
+# include <time.h>
+# include <signal.h>
+
+extern int __ppoll64 (struct pollfd *fds, nfds_t nfds,
+                      const struct __timespec64 *timeout,
+                      const sigset_t *sigmask);
+libc_hidden_proto (__ppoll64)
+# endif
+#endif
 #endif
diff --git a/sysdeps/unix/sysv/linux/ppoll.c b/sysdeps/unix/sysv/linux/ppoll.c
index 8a6ccd1dcc..dddc30f13e 100644
--- a/sysdeps/unix/sysv/linux/ppoll.c
+++ b/sysdeps/unix/sysv/linux/ppoll.c
@@ -21,21 +21,62 @@ 
 #include <time.h>
 #include <sys/poll.h>
 #include <sysdep-cancel.h>
+#include <kernel-features.h>
 
 
 int
-ppoll (struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
-       const sigset_t *sigmask)
+__ppoll64 (struct pollfd *fds, nfds_t nfds, const struct __timespec64 *timeout,
+           const sigset_t *sigmask)
 {
   /* The Linux kernel can in some situations update the timeout value.
      We do not want that so use a local variable.  */
-  struct timespec tval;
+  struct __timespec64 tval;
   if (timeout != NULL)
     {
       tval = *timeout;
       timeout = &tval;
     }
 
-  return SYSCALL_CANCEL (ppoll, fds, nfds, timeout, sigmask, _NSIG / 8);
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_ppoll_time64
+#  define __NR_ppoll_time64 __NR_ppoll
+# endif
+  return SYSCALL_CANCEL (ppoll_time64, fds, nfds, timeout, sigmask, _NSIG / 8);
+#else
+# ifdef __NR_ppoll_time64
+  int ret = SYSCALL_CANCEL (ppoll_time64, fds, nfds, timeout, sigmask,
+                            _NSIG / 8);
+  if (ret == 0 || errno != ENOSYS)
+    return ret;
+# endif
+  struct timespec ts32;
+  if (timeout)
+    {
+      if (! in_time_t_range (timeout->tv_sec))
+        {
+          __set_errno (EOVERFLOW);
+          return -1;
+        }
+
+      ts32 = valid_timespec64_to_timespec (*timeout);
+    }
+
+  return SYSCALL_CANCEL (ppoll, fds, nfds, timeout ? &ts32 : NULL, sigmask,
+                         _NSIG / 8);
+#endif
+}
+
+#if __TIMESIZE != 64
+int
+__ppoll (struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
+         const sigset_t *sigmask)
+{
+  struct __timespec64 ts64;
+  if (timeout)
+    ts64 = valid_timespec_to_timespec64 (*timeout);
+
+  return __ppoll64 (fds, nfds, timeout ? &ts64 : NULL, sigmask);
 }
+#endif
+strong_alias (__ppoll, ppoll)
 libc_hidden_def (ppoll)