[PATCH v2 2/3] Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time

[Lukasz Majewski]

This is the helper function, which uses struct __timespec64
to provide 64 bit absolute time to futex syscalls.

The aim of this function is to move convoluted pre-processor
macro code from sysdeps/nptl/lowlevellock-futex.h to C
function in futex-internal.c

The futex_abstimed_wait64 function has been put into a separate
file on the purpose - to avoid issues apparent on the m68k
architecture related to small number of available registers (there
is not enough registers to put all necessary arguments in them if
the above function would be added to futex-internal.h with
__always_inline attribute).

Additional precautions for m68k port have been taken - the
futex-internal.c file will be compiled with -fno-inline flag.

---
Changes for v2:
- Handle the case when *abstime pointer is NULL
---
 sysdeps/nptl/futex-internal.c         | 70 +++++++++++++++++++++++++++
 sysdeps/nptl/futex-internal.h         |  6 +++
 sysdeps/unix/sysv/linux/m68k/Makefile |  2 +
 3 files changed, 78 insertions(+)

diff --git a/sysdeps/nptl/futex-internal.c b/sysdeps/nptl/futex-internal.c
index 3366aac162..3211b4c94f 100644
--- a/sysdeps/nptl/futex-internal.c
+++ b/sysdeps/nptl/futex-internal.c
@@ -45,6 +45,29 @@ __futex_abstimed_wait_cancelable32 (unsigned int* futex_word,
                                   abstime != NULL ? &ts32 : NULL,
                                   NULL /* Unused.  */, FUTEX_BITSET_MATCH_ANY);
 }
+
+static int
+__futex_abstimed_wait32 (unsigned int* futex_word,
+                         unsigned int expected, clockid_t clockid,
+                         const struct __timespec64* abstime,
+                         int private)
+{
+  struct timespec ts32;
+
+  if (abstime != NULL && ! in_time_t_range (abstime->tv_sec))
+    return -EOVERFLOW;
+
+  unsigned int clockbit = (clockid == CLOCK_REALTIME) ?
+    FUTEX_CLOCK_REALTIME : 0;
+  int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
+
+  if (abstime != NULL)
+    ts32 = valid_timespec64_to_timespec (*abstime);
+
+  return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
+                                abstime != NULL ? &ts32 : NULL,
+                                NULL /* Unused.  */, FUTEX_BITSET_MATCH_ANY);
+}
 #endif
 
 int
@@ -97,3 +120,50 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
       futex_fatal_error ();
     }
 }
+
+int
+__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
+                         clockid_t clockid,
+                         const struct __timespec64* abstime, int private)
+{
+  unsigned int clockbit;
+  int err;
+
+  /* Work around the fact that the kernel rejects negative timeout values
+     despite them being valid.  */
+  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
+    return ETIMEDOUT;
+
+  if (! lll_futex_supported_clockid(clockid))
+    return EINVAL;
+
+  clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
+  int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
+
+  err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
+                               abstime, NULL /* Unused.  */,
+                               FUTEX_BITSET_MATCH_ANY);
+#ifndef __ASSUME_TIME64_SYSCALLS
+  if (err == -ENOSYS)
+    err = __futex_abstimed_wait32 (futex_word, expected,
+                                   clockid, abstime, private);
+#endif
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment, unsupported
+		     clockid or due to the timeout not being
+		     normalized. Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 7f3910ad98..1ba0d61938 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -529,4 +529,10 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
                                     const struct __timespec64* abstime,
                                     int private) attribute_hidden;
 
+int
+__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
+                         clockid_t clockid,
+                         const struct __timespec64* abstime,
+                         int private) attribute_hidden;
+
 #endif  /* futex-internal.h */
diff --git a/sysdeps/unix/sysv/linux/m68k/Makefile b/sysdeps/unix/sysv/linux/m68k/Makefile
index be40fae68a..65164c5752 100644
--- a/sysdeps/unix/sysv/linux/m68k/Makefile
+++ b/sysdeps/unix/sysv/linux/m68k/Makefile
@@ -21,3 +21,5 @@ sysdep-dl-routines += dl-static
 sysdep-others += lddlibc4
 install-bin += lddlibc4
 endif
+
+CFLAGS-futex-internal.c += -fno-inline
-- 
2.20.1