| Message ID | 1525908319.28825.220.camel@cavium.com |
|---|---|
| State | New |
| Headers | show |
| Series | gettimeofday / vdso / aarch64 question | expand |
On Mai 09 2018, Steve Ellcey <sellcey@cavium.com> wrote: > +libc_ifunc_hidden (__redirect___gettimeofday, __gettimeofday, > + vdso_gettimeofday ?: (void *) __gettimeofday_syscall) > +# undef libc_hidden_def > +# define libc_hidden_def(name) \ > + __hidden_ver1 (__gettimeofday_syscall, __GI___gettimeofday, \ > + __gettimeofday_syscall); > +weak_alias (__gettimeofday, gettimeofday) > +libc_hidden_weak (gettimeofday) You are (re)defining libc_hidden_def, but don't use it. Andreas.
On Thu, 2018-05-10 at 09:42 +0200, Andreas Schwab wrote: > On Mai 09 2018, Steve Ellcey <sellcey@cavium.com> wrote: > > > > > +libc_ifunc_hidden (__redirect___gettimeofday, __gettimeofday, > > + vdso_gettimeofday ?: (void *) > > __gettimeofday_syscall) > > +# undef libc_hidden_def > > +# define libc_hidden_def(name) \ > > + __hidden_ver1 (__gettimeofday_syscall, __GI___gettimeofday, \ > > + __gettimeofday_syscall); > > +weak_alias (__gettimeofday, gettimeofday) > > +libc_hidden_weak (gettimeofday) > You are (re)defining libc_hidden_def, but don't use it. > > Andreas. Argh. Staring at it too long to see it. I have it building now, I will submit a patch once the testsuite finishes. Steve Ellcey
On 10/05/2018 13:22, Steve Ellcey wrote: > On Thu, 2018-05-10 at 09:42 +0200, Andreas Schwab wrote: >> On Mai 09 2018, Steve Ellcey <sellcey@cavium.com> wrote: >> >>> >>> +libc_ifunc_hidden (__redirect___gettimeofday, __gettimeofday, >>> + vdso_gettimeofday ?: (void *) >>> __gettimeofday_syscall) >>> +# undef libc_hidden_def >>> +# define libc_hidden_def(name) \ >>> + __hidden_ver1 (__gettimeofday_syscall, __GI___gettimeofday, \ >>> + __gettimeofday_syscall); >>> +weak_alias (__gettimeofday, gettimeofday) >>> +libc_hidden_weak (gettimeofday) >> You are (re)defining libc_hidden_def, but don't use it. >> >> Andreas. > > Argh. Staring at it too long to see it. I have it building now, > I will submit a patch once the testsuite finishes. > > Steve Ellcey > Keep in mind that different that x86 and powerpc implementations, where the vDSO symbol does not fail; the arm64 vDSO implements a syscall fallback in case of underlying hardware requires an out-of-line counter access (arch_timer_enable_workaround). Using a ifunc accessors to call vDSO directly will result in a slight different semantic since generic implementation (kernel/time/time.c) might return EFAULT in some cases (which won't be handled by ifunc implementation). This should not be an issue since POSIX [1] defines no error code should reserved for the symbol, but it might trigger some test in LTP. I recommend you document it on commit log with the rationale to use ifunc instead of usual INLINE_VSYSCALL. [1] http://pubs.opengroup.org/onlinepubs/9699919799/
diff --git a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c index e69de29..7631322 100644 --- a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c +++ b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c @@ -0,0 +1,66 @@ +/* Copyright (C) 2018 Free Software Foundation, Inc. + + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* Get the current time of day and timezone information, + putting it into *tv and *tz. If tz is null, *tz is not filled. + Returns 0 on success, -1 on errors. */ + +#ifdef SHARED + +# define __gettimeofday __redirect___gettimeofday +# include <sys/time.h> +# undef __gettimeofday +# include <dl-vdso.h> +static int +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz) +{ + /* Should this be INLINE_SYSCALL or INLINE_VSYSCALL? */ + return INLINE_SYSCALL (gettimeofday, 2, tv, tz); +} +/* PREPARE_VERSION will need an __LP64__ ifdef when ILP32 support + goes in. See _libc_vdso_platform_setup in + sysdeps/unix/sysv/linux/aarch64/init-first.c. */ + +# undef INIT_ARCH +# define INIT_ARCH() \ + PREPARE_VERSION (linux_version, "LINUX_2.6.39", 123718537); \ + void *vdso_gettimeofday = \ + _dl_vdso_vsym ("__kernel_gettimeofday", &linux_version); + +libc_ifunc_hidden (__redirect___gettimeofday, __gettimeofday, + vdso_gettimeofday ?: (void *) __gettimeofday_syscall) +# undef libc_hidden_def +# define libc_hidden_def(name) \ + __hidden_ver1 (__gettimeofday_syscall, __GI___gettimeofday, \ + __gettimeofday_syscall); +weak_alias (__gettimeofday, gettimeofday) +libc_hidden_weak (gettimeofday) + +#else + +# include <sys/time.h> +# include <sysdep.h> +int +__gettimeofday (struct timeval *tv, struct timezone *tz) +{ + return INLINE_SYSCALL (gettimeofday, 2, tv, tz); +} +libc_hidden_def (__gettimeofday) +weak_alias (__gettimeofday, gettimeofday) +libc_hidden_weak (gettimeofday) +#endif