[PATCHv2] powerpc: Fix syscalls during early process initialization [BZ #22685]
Commit Message
Changes since v1:
- Re-implemented the patch to re-define a powerpc-specific
__access_noerrno.
--- 8< ---
The tunables framework needs to execute syscall early in process
initialization, before the TCB is available for consumption. This
behavior conflicts with powerpc{|64|64le}'s lock elision code, that
checks the TCB before trying to abort transactions immediately before
executing a syscall.
This patch adds a powerpc-specific implementation of __access_noerrno
that does not abort transactions before the executing syscall.
Tested on powerpc{|64|64le}.
2018-01-12 Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
[BZ #22685]
* sysdeps/unix/sysv/linux/powerpc/not-errno.h: New file. Reuse
Linux code, but remove the code that aborts transactions.
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
---
sysdeps/unix/sysv/linux/powerpc/not-errno.h | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/powerpc/not-errno.h
Comments
On 01/12/2018 05:07 PM, Tulio Magno Quites Machado Filho wrote:
> +/* __access_noerrno is used during process initialization in elf/dl-tunables.c
> + before the TCB is initialized, prohibiting the usage of
> + ABORT_TRANSACTION. */
> +#undef ABORT_TRANSACTION
> +#define ABORT_TRANSACTION
> +
> +#include "sysdeps/unix/sysv/linux/not-errno.h"
This #define isn't properly scoped, so I really don't like this approach
for a header file.
Thanks,
Florian
Florian Weimer <fweimer@redhat.com> writes:
> On 01/12/2018 05:07 PM, Tulio Magno Quites Machado Filho wrote:
>> +/* __access_noerrno is used during process initialization in elf/dl-tunables.c
>> + before the TCB is initialized, prohibiting the usage of
>> + ABORT_TRANSACTION. */
>> +#undef ABORT_TRANSACTION
>> +#define ABORT_TRANSACTION
>> +
>> +#include "sysdeps/unix/sysv/linux/not-errno.h"
>
> This #define isn't properly scoped, so I really don't like this approach
> for a header file.
Do you think that checking for TUNABLES_INTERNAL would be enough?
On 01/12/2018 05:40 PM, Tulio Magno Quites Machado Filho wrote:
> Florian Weimer <fweimer@redhat.com> writes:
>
>> On 01/12/2018 05:07 PM, Tulio Magno Quites Machado Filho wrote:
>>> +/* __access_noerrno is used during process initialization in elf/dl-tunables.c
>>> + before the TCB is initialized, prohibiting the usage of
>>> + ABORT_TRANSACTION. */
>>> +#undef ABORT_TRANSACTION
>>> +#define ABORT_TRANSACTION
>>> +
>>> +#include "sysdeps/unix/sysv/linux/not-errno.h"
>>
>> This #define isn't properly scoped, so I really don't like this approach
>> for a header file.
>
> Do you think that checking for TUNABLES_INTERNAL would be enough?
I'm not sure what you mean.
If you move the current definition of ABORT_TRANSACTION to
ABORT_TRANSACTION_IMPL, you could perhaps do
#undef ABORT_TRANSACTION
#define ABORT_TRANSACTION
#include "sysdeps/unix/sysv/linux/not-errno.h"
#undef ABORT_TRANSACTION
#define ABORT_TRANSACTION ABORT_TRANSACTION_IMPL
(with comments, obviously).
Thanks,
Florian
new file mode 100644
@@ -0,0 +1,25 @@
+/* Syscall wrapper that do not set errno. Linux powerpc version.
+ 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/>. */
+
+/* __access_noerrno is used during process initialization in elf/dl-tunables.c
+ before the TCB is initialized, prohibiting the usage of
+ ABORT_TRANSACTION. */
+#undef ABORT_TRANSACTION
+#define ABORT_TRANSACTION
+
+#include "sysdeps/unix/sysv/linux/not-errno.h"