[glibc] Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time

[glibc] Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time

[Lukasz Majewski]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b2cdadde4d5c2b49b0f486a141ae0443ab8be375

commit b2cdadde4d5c2b49b0f486a141ae0443ab8be375
Author: Lukasz Majewski <lukma@denx.de>
Date:   Tue Sep 8 10:54:35 2020 +0200

    Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time
    
    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).
    
    Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Diff:
---
 sysdeps/nptl/futex-internal.c | 70 +++++++++++++++++++++++++++++++++++++++++++
 sysdeps/nptl/futex-internal.h |  6 ++++
 2 files changed, 76 insertions(+)

diff --git a/sysdeps/nptl/futex-internal.c b/sysdeps/nptl/futex-internal.c
index a2e355bf86..f418ed2dbb 100644
--- a/sysdeps/nptl/futex-internal.c
+++ b/sysdeps/nptl/futex-internal.c
@@ -47,6 +47,29 @@ __futex_abstimed_wait_cancelable32 (unsigned int* futex_word,
                                   pts32, 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
@@ -99,3 +122,50 @@ __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 */