x86: Remove vsyscall usage
Commit Message
This patch removes the vsyscall usage for x86_64 port. As indicated
by kernel code comments [1], vsyscalls are a legacy ABI and its concept
is problematic:
- It interferes with ASLR.
- It's awkward to write code that lives in kernel addresses but is
callable by userspace at fixed addresses.
- The whole concept is impossible for 32-bit compat userspace.
- UML cannot easily virtualize a vsyscall.
The VDSO is a better approach for such functionality. Tested on i686,
x86_64, and x32.
[1] arch/x86/kernel/vsyscall_64.c
--
* sysdeps/unix/sysv/linux/i386/gettimeofday.c
(__gettimeofday_syscall): Remove.
* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
Add function.
(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
if vDSO is not present.
* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
present.
* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
---
Comments
Ping.
On 23-04-2015 18:27, Adhemerval Zanella wrote:
> This patch removes the vsyscall usage for x86_64 port. As indicated
> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
> is problematic:
>
> - It interferes with ASLR.
> - It's awkward to write code that lives in kernel addresses but is
> callable by userspace at fixed addresses.
> - The whole concept is impossible for 32-bit compat userspace.
> - UML cannot easily virtualize a vsyscall.
>
> The VDSO is a better approach for such functionality. Tested on i686,
> x86_64, and x32.
>
> [1] arch/x86/kernel/vsyscall_64.c
>
> --
>
> * sysdeps/unix/sysv/linux/i386/gettimeofday.c
> (__gettimeofday_syscall): Remove.
> * sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
> * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
> Add function.
> (gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
> if vDSO is not present.
> * sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
> (time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
> present.
> * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
> * sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>
> ---
>
> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> index 3e00eb4..fdb0fab 100644
> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> @@ -20,16 +20,6 @@
>
> #ifdef SHARED
>
> -# include <dl-vdso.h>
> -# include <errno.h>
> -
> -/* If the vDSO is not available we fall back on the syscall. */
> -static int
> -__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
> -{
> - return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
> -}
> -# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
> # undef libc_ifunc_hidden_def
> # define libc_ifunc_hidden_def(name) \
> libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
> index e8a4e59..66b9a6c 100644
> --- a/sysdeps/unix/sysv/linux/i386/time.c
> +++ b/sysdeps/unix/sysv/linux/i386/time.c
> @@ -18,17 +18,6 @@
>
> #ifdef SHARED
>
> -# include <dl-vdso.h>
> -# include <errno.h>
> -
> -/* If the vDSO is not available we fall back on the old vsyscall. */
> -static time_t
> -__time_syscall (time_t *t)
> -{
> - INTERNAL_SYSCALL_DECL (err);
> - return INTERNAL_SYSCALL (time, err, 1, t);
> -}
> -# define TIME_FALLBACK (void*) &__time_syscall
> # undef libc_ifunc_hidden_def
> # define libc_ifunc_hidden_def(name) \
> libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> index c820fd7..c9cb6ea 100644
> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> @@ -21,6 +21,14 @@
> #ifdef SHARED
>
> # include <dl-vdso.h>
> +# include <errno.h>
> +
> +/* If the vDSO is not available we fall back on the syscall. */
> +static int
> +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
> +{
> + return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
> +}
>
> void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>
> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>
> /* If the vDSO is not available we fall back on the old vsyscall. */
> return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
> - ?: GETTIMEOFAY_FALLBACK);
> + ?: (void*) (&__gettimeofday_syscall));
> }
> asm (".type __gettimeofday, %gnu_indirect_function");
>
> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
> index 1ab9248..3459e17 100644
> --- a/sysdeps/unix/sysv/linux/x86/time.c
> +++ b/sysdeps/unix/sysv/linux/x86/time.c
> @@ -21,6 +21,15 @@
> #ifdef SHARED
>
> #include <dl-vdso.h>
> +#include <errno.h>
> +
> +/* If the vDSO is not available we fall back on the old vsyscall. */
> +static time_t
> +__time_syscall (time_t *t)
> +{
> + INTERNAL_SYSCALL_DECL (err);
> + return INTERNAL_SYSCALL (time, err, 1, t);
> +}
>
> void *time_ifunc (void) __asm__ ("time");
>
> @@ -29,7 +38,8 @@ time_ifunc (void)
> {
> PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>
> - return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
> + return _dl_vdso_vsym ("__vdso_time", &linux26)
> + ?: (void*) &__time_syscall;
> }
> asm (".type time, %gnu_indirect_function");
>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
> deleted file mode 100644
> index daa14de..0000000
> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
> +++ /dev/null
> @@ -1,26 +0,0 @@
> -/* Copyright (C) 2002-2015 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/>. */
> -
> -#include <sys/time.h>
> -
> -#ifdef SHARED
> -/* If the vDSO is not available we fall back on the old vsyscall. */
> -# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul
> -# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday
> -#endif
> -
> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
> deleted file mode 100644
> index 6ceb819..0000000
> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
> +++ /dev/null
> @@ -1,24 +0,0 @@
> -/* Copyright (C) 2001-2015 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
> -/* If the vDSO is not available we fall back on the old vsyscall. */
> -#define VSYSCALL_ADDR_vtime 0xffffffffff600400
> -#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime
> -#endif
> -
> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>
Ping.
On 11-05-2015 16:12, Adhemerval Zanella wrote:
> Ping.
>
> On 23-04-2015 18:27, Adhemerval Zanella wrote:
>> This patch removes the vsyscall usage for x86_64 port. As indicated
>> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
>> is problematic:
>>
>> - It interferes with ASLR.
>> - It's awkward to write code that lives in kernel addresses but is
>> callable by userspace at fixed addresses.
>> - The whole concept is impossible for 32-bit compat userspace.
>> - UML cannot easily virtualize a vsyscall.
>>
>> The VDSO is a better approach for such functionality. Tested on i686,
>> x86_64, and x32.
>>
>> [1] arch/x86/kernel/vsyscall_64.c
>>
>> --
>>
>> * sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> (__gettimeofday_syscall): Remove.
>> * sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
>> * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
>> Add function.
>> (gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
>> if vDSO is not present.
>> * sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
>> (time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
>> present.
>> * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
>> * sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>>
>> ---
>>
>> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> index 3e00eb4..fdb0fab 100644
>> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> @@ -20,16 +20,6 @@
>>
>> #ifdef SHARED
>>
>> -# include <dl-vdso.h>
>> -# include <errno.h>
>> -
>> -/* If the vDSO is not available we fall back on the syscall. */
>> -static int
>> -__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
>> -{
>> - return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
>> -}
>> -# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
>> # undef libc_ifunc_hidden_def
>> # define libc_ifunc_hidden_def(name) \
>> libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
>> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
>> index e8a4e59..66b9a6c 100644
>> --- a/sysdeps/unix/sysv/linux/i386/time.c
>> +++ b/sysdeps/unix/sysv/linux/i386/time.c
>> @@ -18,17 +18,6 @@
>>
>> #ifdef SHARED
>>
>> -# include <dl-vdso.h>
>> -# include <errno.h>
>> -
>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>> -static time_t
>> -__time_syscall (time_t *t)
>> -{
>> - INTERNAL_SYSCALL_DECL (err);
>> - return INTERNAL_SYSCALL (time, err, 1, t);
>> -}
>> -# define TIME_FALLBACK (void*) &__time_syscall
>> # undef libc_ifunc_hidden_def
>> # define libc_ifunc_hidden_def(name) \
>> libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
>> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> index c820fd7..c9cb6ea 100644
>> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> @@ -21,6 +21,14 @@
>> #ifdef SHARED
>>
>> # include <dl-vdso.h>
>> +# include <errno.h>
>> +
>> +/* If the vDSO is not available we fall back on the syscall. */
>> +static int
>> +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
>> +{
>> + return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
>> +}
>>
>> void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>>
>> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>>
>> /* If the vDSO is not available we fall back on the old vsyscall. */
>> return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
>> - ?: GETTIMEOFAY_FALLBACK);
>> + ?: (void*) (&__gettimeofday_syscall));
>> }
>> asm (".type __gettimeofday, %gnu_indirect_function");
>>
>> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
>> index 1ab9248..3459e17 100644
>> --- a/sysdeps/unix/sysv/linux/x86/time.c
>> +++ b/sysdeps/unix/sysv/linux/x86/time.c
>> @@ -21,6 +21,15 @@
>> #ifdef SHARED
>>
>> #include <dl-vdso.h>
>> +#include <errno.h>
>> +
>> +/* If the vDSO is not available we fall back on the old vsyscall. */
>> +static time_t
>> +__time_syscall (time_t *t)
>> +{
>> + INTERNAL_SYSCALL_DECL (err);
>> + return INTERNAL_SYSCALL (time, err, 1, t);
>> +}
>>
>> void *time_ifunc (void) __asm__ ("time");
>>
>> @@ -29,7 +38,8 @@ time_ifunc (void)
>> {
>> PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>>
>> - return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
>> + return _dl_vdso_vsym ("__vdso_time", &linux26)
>> + ?: (void*) &__time_syscall;
>> }
>> asm (".type time, %gnu_indirect_function");
>>
>> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>> deleted file mode 100644
>> index daa14de..0000000
>> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>> +++ /dev/null
>> @@ -1,26 +0,0 @@
>> -/* Copyright (C) 2002-2015 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/>. */
>> -
>> -#include <sys/time.h>
>> -
>> -#ifdef SHARED
>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>> -# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul
>> -# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday
>> -#endif
>> -
>> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
>> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
>> deleted file mode 100644
>> index 6ceb819..0000000
>> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
>> +++ /dev/null
>> @@ -1,24 +0,0 @@
>> -/* Copyright (C) 2001-2015 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
>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>> -#define VSYSCALL_ADDR_vtime 0xffffffffff600400
>> -#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime
>> -#endif
>> -
>> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>>
I will commit it soon if noone opposes it.
On 05-06-2015 15:59, Adhemerval Zanella wrote:
> Ping.
>
> On 11-05-2015 16:12, Adhemerval Zanella wrote:
>> Ping.
>>
>> On 23-04-2015 18:27, Adhemerval Zanella wrote:
>>> This patch removes the vsyscall usage for x86_64 port. As indicated
>>> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
>>> is problematic:
>>>
>>> - It interferes with ASLR.
>>> - It's awkward to write code that lives in kernel addresses but is
>>> callable by userspace at fixed addresses.
>>> - The whole concept is impossible for 32-bit compat userspace.
>>> - UML cannot easily virtualize a vsyscall.
>>>
>>> The VDSO is a better approach for such functionality. Tested on i686,
>>> x86_64, and x32.
>>>
>>> [1] arch/x86/kernel/vsyscall_64.c
>>>
>>> --
>>>
>>> * sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> (__gettimeofday_syscall): Remove.
>>> * sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
>>> * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
>>> Add function.
>>> (gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
>>> if vDSO is not present.
>>> * sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
>>> (time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
>>> present.
>>> * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
>>> * sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>>>
>>> ---
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> index 3e00eb4..fdb0fab 100644
>>> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> @@ -20,16 +20,6 @@
>>>
>>> #ifdef SHARED
>>>
>>> -# include <dl-vdso.h>
>>> -# include <errno.h>
>>> -
>>> -/* If the vDSO is not available we fall back on the syscall. */
>>> -static int
>>> -__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
>>> -{
>>> - return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
>>> -}
>>> -# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
>>> # undef libc_ifunc_hidden_def
>>> # define libc_ifunc_hidden_def(name) \
>>> libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
>>> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
>>> index e8a4e59..66b9a6c 100644
>>> --- a/sysdeps/unix/sysv/linux/i386/time.c
>>> +++ b/sysdeps/unix/sysv/linux/i386/time.c
>>> @@ -18,17 +18,6 @@
>>>
>>> #ifdef SHARED
>>>
>>> -# include <dl-vdso.h>
>>> -# include <errno.h>
>>> -
>>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>>> -static time_t
>>> -__time_syscall (time_t *t)
>>> -{
>>> - INTERNAL_SYSCALL_DECL (err);
>>> - return INTERNAL_SYSCALL (time, err, 1, t);
>>> -}
>>> -# define TIME_FALLBACK (void*) &__time_syscall
>>> # undef libc_ifunc_hidden_def
>>> # define libc_ifunc_hidden_def(name) \
>>> libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
>>> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> index c820fd7..c9cb6ea 100644
>>> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> @@ -21,6 +21,14 @@
>>> #ifdef SHARED
>>>
>>> # include <dl-vdso.h>
>>> +# include <errno.h>
>>> +
>>> +/* If the vDSO is not available we fall back on the syscall. */
>>> +static int
>>> +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
>>> +{
>>> + return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
>>> +}
>>>
>>> void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>>>
>>> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>>>
>>> /* If the vDSO is not available we fall back on the old vsyscall. */
>>> return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
>>> - ?: GETTIMEOFAY_FALLBACK);
>>> + ?: (void*) (&__gettimeofday_syscall));
>>> }
>>> asm (".type __gettimeofday, %gnu_indirect_function");
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
>>> index 1ab9248..3459e17 100644
>>> --- a/sysdeps/unix/sysv/linux/x86/time.c
>>> +++ b/sysdeps/unix/sysv/linux/x86/time.c
>>> @@ -21,6 +21,15 @@
>>> #ifdef SHARED
>>>
>>> #include <dl-vdso.h>
>>> +#include <errno.h>
>>> +
>>> +/* If the vDSO is not available we fall back on the old vsyscall. */
>>> +static time_t
>>> +__time_syscall (time_t *t)
>>> +{
>>> + INTERNAL_SYSCALL_DECL (err);
>>> + return INTERNAL_SYSCALL (time, err, 1, t);
>>> +}
>>>
>>> void *time_ifunc (void) __asm__ ("time");
>>>
>>> @@ -29,7 +38,8 @@ time_ifunc (void)
>>> {
>>> PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>>>
>>> - return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
>>> + return _dl_vdso_vsym ("__vdso_time", &linux26)
>>> + ?: (void*) &__time_syscall;
>>> }
>>> asm (".type time, %gnu_indirect_function");
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>>> deleted file mode 100644
>>> index daa14de..0000000
>>> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>>> +++ /dev/null
>>> @@ -1,26 +0,0 @@
>>> -/* Copyright (C) 2002-2015 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/>. */
>>> -
>>> -#include <sys/time.h>
>>> -
>>> -#ifdef SHARED
>>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>>> -# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul
>>> -# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday
>>> -#endif
>>> -
>>> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
>>> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
>>> deleted file mode 100644
>>> index 6ceb819..0000000
>>> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
>>> +++ /dev/null
>>> @@ -1,24 +0,0 @@
>>> -/* Copyright (C) 2001-2015 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
>>> -/* If the vDSO is not available we fall back on the old vsyscall. */
>>> -#define VSYSCALL_ADDR_vtime 0xffffffffff600400
>>> -#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime
>>> -#endif
>>> -
>>> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>>>
On Thu, Apr 23, 2015 at 06:27:29PM -0300, Adhemerval Zanella wrote:
> This patch removes the vsyscall usage for x86_64 port. As indicated
> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
> is problematic:
>
> - It interferes with ASLR.
> - It's awkward to write code that lives in kernel addresses but is
> callable by userspace at fixed addresses.
> - The whole concept is impossible for 32-bit compat userspace.
> - UML cannot easily virtualize a vsyscall.
>
> The VDSO is a better approach for such functionality. Tested on i686,
> x86_64, and x32.
>
> [1] arch/x86/kernel/vsyscall_64.c
>
> --
>
> * sysdeps/unix/sysv/linux/i386/gettimeofday.c
> (__gettimeofday_syscall): Remove.
> * sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
> * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
> Add function.
> (gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
> if vDSO is not present.
> * sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
> (time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
> present.
> * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
> * sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>
Looks good to me.
Siddhesh
@@ -20,16 +20,6 @@
#ifdef SHARED
-# include <dl-vdso.h>
-# include <errno.h>
-
-/* If the vDSO is not available we fall back on the syscall. */
-static int
-__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
-{
- return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
-}
-# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
# undef libc_ifunc_hidden_def
# define libc_ifunc_hidden_def(name) \
libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
@@ -18,17 +18,6 @@
#ifdef SHARED
-# include <dl-vdso.h>
-# include <errno.h>
-
-/* If the vDSO is not available we fall back on the old vsyscall. */
-static time_t
-__time_syscall (time_t *t)
-{
- INTERNAL_SYSCALL_DECL (err);
- return INTERNAL_SYSCALL (time, err, 1, t);
-}
-# define TIME_FALLBACK (void*) &__time_syscall
# undef libc_ifunc_hidden_def
# define libc_ifunc_hidden_def(name) \
libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
@@ -21,6 +21,14 @@
#ifdef SHARED
# include <dl-vdso.h>
+# include <errno.h>
+
+/* If the vDSO is not available we fall back on the syscall. */
+static int
+__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
+{
+ return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
+}
void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
@@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
/* If the vDSO is not available we fall back on the old vsyscall. */
return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
- ?: GETTIMEOFAY_FALLBACK);
+ ?: (void*) (&__gettimeofday_syscall));
}
asm (".type __gettimeofday, %gnu_indirect_function");
@@ -21,6 +21,15 @@
#ifdef SHARED
#include <dl-vdso.h>
+#include <errno.h>
+
+/* If the vDSO is not available we fall back on the old vsyscall. */
+static time_t
+__time_syscall (time_t *t)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ return INTERNAL_SYSCALL (time, err, 1, t);
+}
void *time_ifunc (void) __asm__ ("time");
@@ -29,7 +38,8 @@ time_ifunc (void)
{
PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
- return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
+ return _dl_vdso_vsym ("__vdso_time", &linux26)
+ ?: (void*) &__time_syscall;
}
asm (".type time, %gnu_indirect_function");
deleted file mode 100644
@@ -1,26 +0,0 @@
-/* Copyright (C) 2002-2015 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/>. */
-
-#include <sys/time.h>
-
-#ifdef SHARED
-/* If the vDSO is not available we fall back on the old vsyscall. */
-# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul
-# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday
-#endif
-
-#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
deleted file mode 100644
@@ -1,24 +0,0 @@
-/* Copyright (C) 2001-2015 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
-/* If the vDSO is not available we fall back on the old vsyscall. */
-#define VSYSCALL_ADDR_vtime 0xffffffffff600400
-#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime
-#endif
-
-#include <sysdeps/unix/sysv/linux/x86/time.c>