[glibc] y2038: linux: Provide __timer_gettime64 implementation

[Lukasz Majewski <lukma at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=562cdc19c761b6749ae31845156366d4b319e200

commit 562cdc19c761b6749ae31845156366d4b319e200
Author: Lukasz Majewski <lukma@denx.de>
Date:   Tue Nov 5 17:04:24 2019 +0100

    y2038: linux: Provide __timer_gettime64 implementation
    
    This patch provides new __timer_gettime64 explicit 64 bit function for reading
    status of specified timer. To be more precise - the remaining time and interval
    set with timer_settime.
    Moreover, a 32 bit version - __timer_gettime has been refactored to internally
    use __timer_gettime64.
    
    The __timer_gettime is now supposed to be used on systems still supporting 32
    bit time (__TIMESIZE != 64) - hence the necessary conversion from 64 bit struct
    __timespec64 to struct timespec.
    
    The new __timer_gettime64 syscall available from Linux 5.1+ has been used, when
    applicable.
    
    The original INLINE_SYSCALL() macro has been replaced with
    INLINE_SYSCALL_CALL() to avoid explicit passing the number of arguments.
    
    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 timer_gettime64) 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 timer_gettime64
      syscall.
    
    - Linux v4.19 (no timer_gettime64 support) with default minimal kernel version
      for contemporary glibc (3.2.0)
      This kernel doesn't support timer_gettime64 syscall, so the fallback to
      timer_gettime 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.
    
    Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Diff:
---
 include/time.h                          |  7 ++++++
 sysdeps/unix/sysv/linux/timer_gettime.c | 44 ++++++++++++++++++++++++++++++---
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/include/time.h b/include/time.h
index 1eb3d82..51c0fce 100644
--- a/include/time.h
+++ b/include/time.h
@@ -179,6 +179,13 @@ extern int __futimens64 (int fd, const struct __timespec64 tsp[2]);
 libc_hidden_proto (__futimens64);
 #endif
 
+#if __TIMESIZE == 64
+# define __timer_gettime64 __timer_gettime
+#else
+extern int __timer_gettime64 (timer_t timerid, struct __itimerspec64 *value);
+libc_hidden_proto (__timer_gettime64);
+#endif
+
 /* Compute the `struct tm' representation of T,
    offset OFFSET seconds east of UTC,
    and store year, yday, mon, mday, wday, hour, min, sec into *TP.
diff --git a/sysdeps/unix/sysv/linux/timer_gettime.c b/sysdeps/unix/sysv/linux/timer_gettime.c
index 8d9bef9..20d34db 100644
--- a/sysdeps/unix/sysv/linux/timer_gettime.c
+++ b/sysdeps/unix/sysv/linux/timer_gettime.c
@@ -20,15 +20,51 @@
 #include <stdlib.h>
 #include <time.h>
 #include <sysdep.h>
+#include <kernel-features.h>
 #include "kernel-posix-timers.h"
 
 int
-timer_gettime (timer_t timerid, struct itimerspec *value)
+__timer_gettime64 (timer_t timerid, struct __itimerspec64 *value)
 {
   struct timer *kt = (struct timer *) timerid;
 
-  /* Delete the kernel timer object.  */
-  int res = INLINE_SYSCALL (timer_gettime, 2, kt->ktimerid, value);
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_timer_gettime64
+#  define __NR_timer_gettime64 __NR_timer_gettime
+# endif
+  return INLINE_SYSCALL_CALL (timer_gettime64, kt->ktimerid, value);
+#else
+# ifdef __NR_timer_gettime64
+  int ret = INLINE_SYSCALL_CALL (timer_gettime64, kt->ktimerid, value);
+  if (ret == 0 || errno != ENOSYS)
+    return ret;
+# endif
+  struct itimerspec its32;
+  int retval = INLINE_SYSCALL_CALL (timer_gettime, kt->ktimerid, &its32);
+  if (retval == 0)
+    {
+      value->it_interval = valid_timespec_to_timespec64 (its32.it_interval);
+      value->it_value = valid_timespec_to_timespec64 (its32.it_value);
+    }
 
-  return res;
+  return retval;
+#endif
 }
+
+#if __TIMESIZE != 64
+int
+__timer_gettime (timer_t timerid, struct itimerspec *value)
+{
+  struct __itimerspec64 its64;
+  int retval = __timer_gettime64 (timerid, &its64);
+  if (retval == 0)
+    {
+      value->it_interval = valid_timespec64_to_timespec (its64.it_interval);
+      value->it_value = valid_timespec64_to_timespec (its64.it_value);
+    }
+
+  return retval;
+}
+#endif
+weak_alias (__timer_gettime, timer_gettime)
+libc_hidden_def (timer_gettime)