nptl: Add <thread_pointer.h> for hppa

Message ID 20241101192339.123141-2-mjeanson@efficios.com
State New
Headers
Series nptl: Add <thread_pointer.h> for hppa |

Checks

Context Check Description
redhat-pt-bot/TryBot-apply_patch success Patch applied to master at the time it was sent
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Commit Message

Michael Jeanson Nov. 1, 2024, 7:23 p.m. UTC
  This will be required by the rseq extensible ABI implementation on all
Linux architectures exposing the '__rseq_size' and '__rseq_offset'
symbols to set the initial value of the 'cpu_id' field which can be used
by applications to test if rseq is available and registered. As long as
the symbols are exposed it is valid for an application to perform this
test even if rseq is not yet implemented in libc for this architecture.

Compile tested with build-many-glibcs.py but I don't have access to any
hardware to run the tests.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
Cc: Florian Weimer <fweimer@redhat.com>
Cc: John David Anglin <danglin@gcc.gnu.org>
Cc: Carlos O'Donell <carlos@redhat.com>
---
 sysdeps/hppa/nptl/thread_pointer.h | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 sysdeps/hppa/nptl/thread_pointer.h
  

Comments

John David Anglin Nov. 2, 2024, 1:46 p.m. UTC | #1
Okay.  Tests pass on hppa.

The __thread_pointer function is essentially the same as the __get_cr27 function
in sysdeps/hppa/nptl/tls.h.  I guess __get_cr27 could be eliminated with some cast
adjustments if sysdeps/hppa/nptl/tls.h included this header.

Dave

On 2024-11-01 3:23 p.m., Michael Jeanson wrote:
> This will be required by the rseq extensible ABI implementation on all
> Linux architectures exposing the '__rseq_size' and '__rseq_offset'
> symbols to set the initial value of the 'cpu_id' field which can be used
> by applications to test if rseq is available and registered. As long as
> the symbols are exposed it is valid for an application to perform this
> test even if rseq is not yet implemented in libc for this architecture.
>
> Compile tested with build-many-glibcs.py but I don't have access to any
> hardware to run the tests.
>
> Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
> ---
> Cc: Florian Weimer <fweimer@redhat.com>
> Cc: John David Anglin <danglin@gcc.gnu.org>
> Cc: Carlos O'Donell <carlos@redhat.com>
> ---
>   sysdeps/hppa/nptl/thread_pointer.h | 30 ++++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
>   create mode 100644 sysdeps/hppa/nptl/thread_pointer.h
>
> diff --git a/sysdeps/hppa/nptl/thread_pointer.h b/sysdeps/hppa/nptl/thread_pointer.h
> new file mode 100644
> index 0000000000..96f5e9b4c0
> --- /dev/null
> +++ b/sysdeps/hppa/nptl/thread_pointer.h
> @@ -0,0 +1,30 @@
> +/* __thread_pointer definition.  hppa version.
> +   Copyright (C) 2021-2024 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _SYS_THREAD_POINTER_H
> +#define _SYS_THREAD_POINTER_H
> +
> +static inline void *
> +__thread_pointer (void)
> +{
> +  void *__thread_register;
> +  __asm__ ("mfctl %%cr27, %0" : "=r" (__thread_register));
> +  return __thread_register;
> +}
> +
> +#endif /* _SYS_THREAD_POINTER_H */
  
Michael Jeanson Nov. 4, 2024, 4:17 p.m. UTC | #2
On 2024-11-02 09:46, John David Anglin wrote:
> Okay.  Tests pass on hppa.
> 
> The __thread_pointer function is essentially the same as the __get_cr27 function
> in sysdeps/hppa/nptl/tls.h.  I guess __get_cr27 could be eliminated with some cast
> adjustments if sysdeps/hppa/nptl/tls.h included this header.
> 
> Dave

I'd be happy to send a follow up patch implementing this if it's something you are
interested in.

Thanks,

Michael
  
John David Anglin Nov. 5, 2024, 12:12 a.m. UTC | #3
On 2024-11-04 11:17 a.m., Michael Jeanson wrote:
> On 2024-11-02 09:46, John David Anglin wrote:
>> Okay.  Tests pass on hppa.
>>
>> The __thread_pointer function is essentially the same as the __get_cr27 function
>> in sysdeps/hppa/nptl/tls.h.  I guess __get_cr27 could be eliminated with some cast
>> adjustments if sysdeps/hppa/nptl/tls.h included this header.
>>
>> Dave
> I'd be happy to send a follow up patch implementing this if it's something you are
> interested in.
Yes, I think it should be done.  I willing to test follow up.

Thanks,
Dave
  

Patch

diff --git a/sysdeps/hppa/nptl/thread_pointer.h b/sysdeps/hppa/nptl/thread_pointer.h
new file mode 100644
index 0000000000..96f5e9b4c0
--- /dev/null
+++ b/sysdeps/hppa/nptl/thread_pointer.h
@@ -0,0 +1,30 @@ 
+/* __thread_pointer definition.  hppa version.
+   Copyright (C) 2021-2024 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _SYS_THREAD_POINTER_H
+#define _SYS_THREAD_POINTER_H
+
+static inline void *
+__thread_pointer (void)
+{
+  void *__thread_register;
+  __asm__ ("mfctl %%cr27, %0" : "=r" (__thread_register));
+  return __thread_register;
+}
+
+#endif /* _SYS_THREAD_POINTER_H */