linux: Fix vDSO macros build with time64 interfaces

As indicated on libc-help [1] the ec138c67cb commit broke 32-bit
builds when configured with --enable-kernel=5.1 or higher.  The
scenario 10 from [2] might also occur in this configuration and
INLINE_VSYSCALL will try to use the vDSO symbol and
HAVE_CLOCK_GETTIME64_VSYSCALL does not set HAVE_VSYSCALL prior its
usage.

Also, there is no easy way to just enable the code to use one
vDSO symbol since the macro INLINE_VSYSCALL is redefined if
HAVE_VSYSCALL is set.

Instead of adding more pre-processor handling and making the code
even more convoluted, this patch removes the requirement of defining
HAVE_VSYSCALL before including sysdep-vdso.h to enable vDSO usage.

The INLINE_VSYSCALL is now expected to be issued inside a
HAVE_*_VSYSCALL check, since it will try to use the internal vDSO
pointers.

Both clock_getres and clock_gettime vDSO code for time64_t were
removed since there is no vDSO setup code for the symbol (an
architecture can not set HAVE_CLOCK_GETTIME64_VSYSCALL).

Checked on i686-linux-gnu (default and with --enable-kernel=5.1),
x86_64-linux-gnu, aarch64-linux-gnu, and powerpc64le-linux-gnu.
I also checked against a build to mips64-linux-gnu and
sparc64-linux-gnu.

[1] https://sourceware.org/ml/libc-help/2019-12/msg00014.html
[2] https://sourceware.org/ml/libc-alpha/2019-12/msg00142.html

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 5 insertions, 10 deletions

diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c
index 2eb99ec4b5..c019cfb3cf 100644
--- a/sysdeps/unix/sysv/linux/sched_getcpu.c
+++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
@@ -18,22 +18,17 @@
 #include <errno.h>
 #include <sched.h>
 #include <sysdep.h>
-
-#ifdef HAVE_GETCPU_VSYSCALL
-# define HAVE_VSYSCALL
-#endif
 #include <sysdep-vdso.h>
 
 int
 sched_getcpu (void)
 {
-#ifdef __NR_getcpu
   unsigned int cpu;
-  int r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
-
-  return r == -1 ? r : cpu;
+  int r = -1;
+#ifdef HAVE_GETCPU_VSYSCALL
+  r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
 #else
-  __set_errno (ENOSYS);
-  return -1;
+  r = INLINE_SYSCALL_CALL (getcpu, &cpu, NULL, NULL);
 #endif
+  return r == -1 ? r : cpu;
 }