Message ID | 1459350611-6100-1-git-send-email-Zubair.Kakakhel@imgtec.com |
---|---|
State | New |
Headers | show |
On 30 Mar 2016 16:10, Zubair Lutfullah Kakakhel wrote:
> The kernel patches for vdso support are already upstream.
can you make sure the vdso(7) man page is updated then ?
-mike
Hi, On 30/03/16 21:02, Mike Frysinger wrote: > On 30 Mar 2016 16:10, Zubair Lutfullah Kakakhel wrote: >> The kernel patches for vdso support are already upstream. > > can you make sure the vdso(7) man page is updated then ? > -mike > Thanks. I've sent a patch for man-pages. http://thread.gmane.org/gmane.linux.man/10349 Regards, ZubairLK
+ Joseph. Apologies. I forgot to cc you initially. Regards, ZubairLK On 30/03/16 16:10, Zubair Lutfullah Kakakhel wrote: > From: Alex Smith <alex.smith@imgtec.com> > > This patch adds support for using the implementations of gettimeofday() > and clock_gettime() provided by the kernel in the VDSO. The VDSO will > always provide clock_gettime() as CLOCK_{REALTIME,MONOTONIC}_COARSE can > be implemented regardless of platform. CLOCK_{REALTIME,MONOTONIC}, along > with gettimeofday(), are only implemented on platforms which make use of > either the CP0 count or GIC as their clocksource. On other platforms, > the VDSO does not provide the __vdso_gettimeofday symbol, as it is > never useful. > > The VDSO functions return ENOSYS when they encounter an unsupported > request, in which case glibc should fall back to the standard syscall. > > * sysdeps/unix/sysv/linux/mips/Makefile (sysdep_routines): > Include dl-vdso. > * sysdeps/unix/sysv/linux/mips/Versions: Add > __vdso_clock_gettime. > * sysdeps/unix/sysv/linux/mips/init-first.c: New file. > * sysdeps/unix/sysv/linux/mips/libc-vdso.h: New file. > * sysdeps/unix/sysv/linux/mips/mips32/sysdep.h: > (INTERNAL_VSYSCALL_CALL): Define to be compatible with MIPS > definitions of INTERNAL_SYSCALL_{ERROR_P,ERRNO}. > (HAVE_CLOCK_GETTIME_VSYSCALL): Define. > (HAVE_GETTIMEOFDAY_VSYSCALL): Define. > * sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h: Likewise. > * sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h: Likewise. > > --- > Hi, > > The kernel patches for vdso support are already upstream. > > I'm picking up this patch to upstream vdso support for MIPS in glibc. > > Rebased this patch on glibc-2.23 > > Tested with upstream kernel 4.5 and QEMU emulating Malta. > > ./vdsotest gettimeofday bench > gettimeofday: syscall: 1021 nsec/call > gettimeofday: libc: 262 nsec/call > gettimeofday: vdso: 174 nsec/call > > Regards, > ZubairLK > > --- > sysdeps/unix/sysv/linux/mips/Makefile | 2 ++ > sysdeps/unix/sysv/linux/mips/Versions | 4 +++ > sysdeps/unix/sysv/linux/mips/init-first.c | 44 ++++++++++++++++++++++++ > sysdeps/unix/sysv/linux/mips/libc-vdso.h | 33 ++++++++++++++++++ > sysdeps/unix/sysv/linux/mips/mips32/sysdep.h | 16 +++++++++ > sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h | 17 +++++++++ > sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h | 17 +++++++++ > 7 files changed, 133 insertions(+) > create mode 100644 sysdeps/unix/sysv/linux/mips/init-first.c > create mode 100644 sysdeps/unix/sysv/linux/mips/libc-vdso.h > > diff --git a/sysdeps/unix/sysv/linux/mips/Makefile b/sysdeps/unix/sysv/linux/mips/Makefile > index 8127025..c6729c1 100644 > --- a/sysdeps/unix/sysv/linux/mips/Makefile > +++ b/sysdeps/unix/sysv/linux/mips/Makefile > @@ -96,6 +96,8 @@ ifeq ($(subdir),elf) > ifeq ($(build-shared),yes) > # This is needed for DSO loading from static binaries. > sysdep-dl-routines += dl-static > + > +sysdep_routines += dl-vdso > endif > endif > > diff --git a/sysdeps/unix/sysv/linux/mips/Versions b/sysdeps/unix/sysv/linux/mips/Versions > index a56322a..453f276 100644 > --- a/sysdeps/unix/sysv/linux/mips/Versions > +++ b/sysdeps/unix/sysv/linux/mips/Versions > @@ -37,4 +37,8 @@ libc { > GLIBC_2.11 { > fallocate64; > } > + GLIBC_PRIVATE { > + # nptl/pthread_cond_timedwait.c uses INTERNAL_VSYSCALL(clock_gettime). > + __vdso_clock_gettime; > + } > } > diff --git a/sysdeps/unix/sysv/linux/mips/init-first.c b/sysdeps/unix/sysv/linux/mips/init-first.c > new file mode 100644 > index 0000000..46dba69 > --- /dev/null > +++ b/sysdeps/unix/sysv/linux/mips/init-first.c > @@ -0,0 +1,44 @@ > +/* Initialization code run first thing by the ELF startup code. > + Copyright (C) 2015 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/>. */ > + > +#ifdef SHARED > +# include <dl-vdso.h> > +# include <libc-vdso.h> > + > +int (*VDSO_SYMBOL(gettimeofday)) (struct timeval *, void *) attribute_hidden; > +int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *); > + > +static inline void > +_libc_vdso_platform_setup (void) > +{ > + PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); > + > + void *p = _dl_vdso_vsym ("__vdso_gettimeofday", &linux26); > + PTR_MANGLE (p); > + VDSO_SYMBOL (gettimeofday) = p; > + > + p = _dl_vdso_vsym ("__vdso_clock_gettime", &linux26); > + PTR_MANGLE (p); > + VDSO_SYMBOL (clock_gettime) = p; > +} > + > +# define VDSO_SETUP _libc_vdso_platform_setup > +#endif > + > +#include <csu/init-first.c> > diff --git a/sysdeps/unix/sysv/linux/mips/libc-vdso.h b/sysdeps/unix/sysv/linux/mips/libc-vdso.h > new file mode 100644 > index 0000000..1580de8 > --- /dev/null > +++ b/sysdeps/unix/sysv/linux/mips/libc-vdso.h > @@ -0,0 +1,33 @@ > +/* VDSO function pointer declarations. > + Copyright (C) 2015 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/>. */ > + > +#ifndef _LIBC_VDSO_H > +#define _LIBC_VDSO_H > + > +#ifdef SHARED > + > +# include <sysdep-vdso.h> > + > +extern int (*VDSO_SYMBOL(gettimeofday)) (struct timeval *, void *) > + attribute_hidden; > +extern int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *); > + > +#endif > + > +#endif /* _LIBC_VDSO_H */ > diff --git a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h > index 2160df7..2335409 100644 > --- a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h > +++ b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h > @@ -371,6 +371,22 @@ > #define __SYSCALL_CLOBBERS "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \ > "$14", "$15", "$24", "$25", "hi", "lo", "memory" > > +/* Standard MIPS syscalls have an error flag, and return a positive errno > + when the error flag is set. Emulate this behaviour for vsyscalls so that > + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ > +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ > + ({ \ > + long _ret = funcptr (args); \ > + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ > + if (err) \ > + _ret = -_ret; \ > + _ret; \ > + }) > + > +/* List of system calls which are supported as vsyscalls. */ > +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 > +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 > + > #endif /* __ASSEMBLER__ */ > > /* Pointer mangling is not yet supported for MIPS. */ > diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h > index 466dcde..661b3dc 100644 > --- a/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h > +++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h > @@ -295,6 +295,23 @@ > > #define __SYSCALL_CLOBBERS "$1", "$3", "$10", "$11", "$12", "$13", \ > "$14", "$15", "$24", "$25", "hi", "lo", "memory" > + > +/* Standard MIPS syscalls have an error flag, and return a positive errno > + when the error flag is set. Emulate this behaviour for vsyscalls so that > + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ > +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ > + ({ \ > + long _ret = funcptr (args); \ > + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ > + if (err) \ > + _ret = -_ret; \ > + _ret; \ > + }) > + > +/* List of system calls which are supported as vsyscalls. */ > +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 > +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 > + > #endif /* __ASSEMBLER__ */ > > /* Pointer mangling is not yet supported for MIPS. */ > diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h > index db8b237..476eca3 100644 > --- a/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h > +++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h > @@ -291,6 +291,23 @@ > > #define __SYSCALL_CLOBBERS "$1", "$3", "$10", "$11", "$12", "$13", \ > "$14", "$15", "$24", "$25", "hi", "lo", "memory" > + > +/* Standard MIPS syscalls have an error flag, and return a positive errno > + when the error flag is set. Emulate this behaviour for vsyscalls so that > + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ > +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ > + ({ \ > + long _ret = funcptr (args); \ > + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ > + if (err) \ > + _ret = -_ret; \ > + _ret; \ > + }) > + > +/* List of system calls which are supported as vsyscalls. */ > +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 > +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 > + > #endif /* __ASSEMBLER__ */ > > /* Pointer mangling is not yet supported for MIPS. */ >
On Wed, 30 Mar 2016, Zubair Lutfullah Kakakhel wrote: > +/* Initialization code run first thing by the ELF startup code. > + Copyright (C) 2015 Free Software Foundation, Inc. Copyright notices for all new files should include 2016. OK with that fixed for all affected files in this patch.
diff --git a/sysdeps/unix/sysv/linux/mips/Makefile b/sysdeps/unix/sysv/linux/mips/Makefile index 8127025..c6729c1 100644 --- a/sysdeps/unix/sysv/linux/mips/Makefile +++ b/sysdeps/unix/sysv/linux/mips/Makefile @@ -96,6 +96,8 @@ ifeq ($(subdir),elf) ifeq ($(build-shared),yes) # This is needed for DSO loading from static binaries. sysdep-dl-routines += dl-static + +sysdep_routines += dl-vdso endif endif diff --git a/sysdeps/unix/sysv/linux/mips/Versions b/sysdeps/unix/sysv/linux/mips/Versions index a56322a..453f276 100644 --- a/sysdeps/unix/sysv/linux/mips/Versions +++ b/sysdeps/unix/sysv/linux/mips/Versions @@ -37,4 +37,8 @@ libc { GLIBC_2.11 { fallocate64; } + GLIBC_PRIVATE { + # nptl/pthread_cond_timedwait.c uses INTERNAL_VSYSCALL(clock_gettime). + __vdso_clock_gettime; + } } diff --git a/sysdeps/unix/sysv/linux/mips/init-first.c b/sysdeps/unix/sysv/linux/mips/init-first.c new file mode 100644 index 0000000..46dba69 --- /dev/null +++ b/sysdeps/unix/sysv/linux/mips/init-first.c @@ -0,0 +1,44 @@ +/* Initialization code run first thing by the ELF startup code. + Copyright (C) 2015 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/>. */ + +#ifdef SHARED +# include <dl-vdso.h> +# include <libc-vdso.h> + +int (*VDSO_SYMBOL(gettimeofday)) (struct timeval *, void *) attribute_hidden; +int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *); + +static inline void +_libc_vdso_platform_setup (void) +{ + PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); + + void *p = _dl_vdso_vsym ("__vdso_gettimeofday", &linux26); + PTR_MANGLE (p); + VDSO_SYMBOL (gettimeofday) = p; + + p = _dl_vdso_vsym ("__vdso_clock_gettime", &linux26); + PTR_MANGLE (p); + VDSO_SYMBOL (clock_gettime) = p; +} + +# define VDSO_SETUP _libc_vdso_platform_setup +#endif + +#include <csu/init-first.c> diff --git a/sysdeps/unix/sysv/linux/mips/libc-vdso.h b/sysdeps/unix/sysv/linux/mips/libc-vdso.h new file mode 100644 index 0000000..1580de8 --- /dev/null +++ b/sysdeps/unix/sysv/linux/mips/libc-vdso.h @@ -0,0 +1,33 @@ +/* VDSO function pointer declarations. + Copyright (C) 2015 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/>. */ + +#ifndef _LIBC_VDSO_H +#define _LIBC_VDSO_H + +#ifdef SHARED + +# include <sysdep-vdso.h> + +extern int (*VDSO_SYMBOL(gettimeofday)) (struct timeval *, void *) + attribute_hidden; +extern int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *); + +#endif + +#endif /* _LIBC_VDSO_H */ diff --git a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h index 2160df7..2335409 100644 --- a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h +++ b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h @@ -371,6 +371,22 @@ #define __SYSCALL_CLOBBERS "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \ "$14", "$15", "$24", "$25", "hi", "lo", "memory" +/* Standard MIPS syscalls have an error flag, and return a positive errno + when the error flag is set. Emulate this behaviour for vsyscalls so that + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ + ({ \ + long _ret = funcptr (args); \ + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ + if (err) \ + _ret = -_ret; \ + _ret; \ + }) + +/* List of system calls which are supported as vsyscalls. */ +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 + #endif /* __ASSEMBLER__ */ /* Pointer mangling is not yet supported for MIPS. */ diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h index 466dcde..661b3dc 100644 --- a/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h +++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h @@ -295,6 +295,23 @@ #define __SYSCALL_CLOBBERS "$1", "$3", "$10", "$11", "$12", "$13", \ "$14", "$15", "$24", "$25", "hi", "lo", "memory" + +/* Standard MIPS syscalls have an error flag, and return a positive errno + when the error flag is set. Emulate this behaviour for vsyscalls so that + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ + ({ \ + long _ret = funcptr (args); \ + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ + if (err) \ + _ret = -_ret; \ + _ret; \ + }) + +/* List of system calls which are supported as vsyscalls. */ +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 + #endif /* __ASSEMBLER__ */ /* Pointer mangling is not yet supported for MIPS. */ diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h index db8b237..476eca3 100644 --- a/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h +++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h @@ -291,6 +291,23 @@ #define __SYSCALL_CLOBBERS "$1", "$3", "$10", "$11", "$12", "$13", \ "$14", "$15", "$24", "$25", "hi", "lo", "memory" + +/* Standard MIPS syscalls have an error flag, and return a positive errno + when the error flag is set. Emulate this behaviour for vsyscalls so that + the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */ +#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \ + ({ \ + long _ret = funcptr (args); \ + err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \ + if (err) \ + _ret = -_ret; \ + _ret; \ + }) + +/* List of system calls which are supported as vsyscalls. */ +#define HAVE_CLOCK_GETTIME_VSYSCALL 1 +#define HAVE_GETTIMEOFDAY_VSYSCALL 1 + #endif /* __ASSEMBLER__ */ /* Pointer mangling is not yet supported for MIPS. */
From: Alex Smith <alex.smith@imgtec.com> This patch adds support for using the implementations of gettimeofday() and clock_gettime() provided by the kernel in the VDSO. The VDSO will always provide clock_gettime() as CLOCK_{REALTIME,MONOTONIC}_COARSE can be implemented regardless of platform. CLOCK_{REALTIME,MONOTONIC}, along with gettimeofday(), are only implemented on platforms which make use of either the CP0 count or GIC as their clocksource. On other platforms, the VDSO does not provide the __vdso_gettimeofday symbol, as it is never useful. The VDSO functions return ENOSYS when they encounter an unsupported request, in which case glibc should fall back to the standard syscall. * sysdeps/unix/sysv/linux/mips/Makefile (sysdep_routines): Include dl-vdso. * sysdeps/unix/sysv/linux/mips/Versions: Add __vdso_clock_gettime. * sysdeps/unix/sysv/linux/mips/init-first.c: New file. * sysdeps/unix/sysv/linux/mips/libc-vdso.h: New file. * sysdeps/unix/sysv/linux/mips/mips32/sysdep.h: (INTERNAL_VSYSCALL_CALL): Define to be compatible with MIPS definitions of INTERNAL_SYSCALL_{ERROR_P,ERRNO}. (HAVE_CLOCK_GETTIME_VSYSCALL): Define. (HAVE_GETTIMEOFDAY_VSYSCALL): Define. * sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h: Likewise. --- Hi, The kernel patches for vdso support are already upstream. I'm picking up this patch to upstream vdso support for MIPS in glibc. Rebased this patch on glibc-2.23 Tested with upstream kernel 4.5 and QEMU emulating Malta. ./vdsotest gettimeofday bench gettimeofday: syscall: 1021 nsec/call gettimeofday: libc: 262 nsec/call gettimeofday: vdso: 174 nsec/call Regards, ZubairLK --- sysdeps/unix/sysv/linux/mips/Makefile | 2 ++ sysdeps/unix/sysv/linux/mips/Versions | 4 +++ sysdeps/unix/sysv/linux/mips/init-first.c | 44 ++++++++++++++++++++++++ sysdeps/unix/sysv/linux/mips/libc-vdso.h | 33 ++++++++++++++++++ sysdeps/unix/sysv/linux/mips/mips32/sysdep.h | 16 +++++++++ sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h | 17 +++++++++ sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h | 17 +++++++++ 7 files changed, 133 insertions(+) create mode 100644 sysdeps/unix/sysv/linux/mips/init-first.c create mode 100644 sysdeps/unix/sysv/linux/mips/libc-vdso.h