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linux: Fix vDSO macros build with time64 interfaces

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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>
This commit is contained in:
Adhemerval Zanella
2019-12-13 17:30:15 -03:00
parent b03688bfbb
commit d0def09ff6
10 changed files with 58 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
sysdeps/unix/sysv/linux/clock_gettime.c
View File

@ -21,10 +21,6 @@
#include <errno.h>
#include <time.h>
#include "kernel-posix-cpu-timers.h"
#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
# define HAVE_VSYSCALL
#endif
#include <sysdep-vdso.h>
#include <shlib-compat.h>
@ -34,22 +30,34 @@ int
__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
{
#ifdef __ASSUME_TIME64_SYSCALLS
# ifndef __NR_clock_gettime64
# define __NR_clock_gettime64 __NR_clock_gettime
# define __vdso_clock_gettime64 __vdso_clock_gettime
/* 64 bit ABIs or Newer 32-bit ABIs that only support 64-bit time_t. */
# ifdef __NR_clock_gettime64
return INLINE_SYSCALL_CALL (clock_gettime64, clock_id, tp);
# else
# ifdef HAVE_CLOCK_GETTIME_VSYSCALL
return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
# else
return INLINE_SYSCALL_CALL (clock_gettime, clock_id, tp);
# endif
# endif
return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
#else
# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
if (ret64 == 0 || errno != ENOSYS)
return ret64;
int r;
/* Old 32-bit ABI with possible 64-bit time_t support. */
# ifdef __NR_clock_gettime64
r = INLINE_SYSCALL_CALL (clock_gettime64, clock_id, tp);
if (r == 0 || errno != ENOSYS)
return r;
# endif
/* Fallback code that uses 32-bit support. */
struct timespec tp32;
int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
if (ret == 0)
# ifdef HAVE_CLOCK_GETTIME_VSYSCALL
r = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
# else
r = INLINE_SYSCALL_CALL (clock_gettime, clock_id, &tp32);
# endif
if (r == 0)
*tp = valid_timespec_to_timespec64 (tp32);
return ret;
return r;
#endif
}