[PATCH v2 2/2] powerpc: Add HWCAP3/HWCAP4 data to TCB for Power Architecture.

Peter Bergner bergner@linux.ibm.com
Tue Mar 19 23:50:31 GMT 2024


On 12/13/23 5:47 PM, Peter Bergner wrote:
> On 12/5/23 6:38 AM, Manjunath Matti wrote:
>> This patch adds a new feature for powerpc.  In order to get faster
>> access to the HWCAP3/HWCAP4 masks, similar to HWCAP/HWCAP2 (i.e. for
>> implementing __builtin_cpu_supports() in GCC) without the overhead of
>> reading them from the auxiliary vector, we now reserve space for them
>> in the TCB.
>>
>> This is an ABI change for GLIBC 2.39.
>>
>> Suggested-by: Peter Bergner <bergner@linux.ibm.com>
>> ---
>>  elf/dl-diagnostics.c                          |  2 +
>>  elf/dl-support.c                              |  2 +
>>  elf/elf.h                                     |  4 ++
>>  sysdeps/generic/ldsodefs.h                    |  2 +
>>  sysdeps/powerpc/dl-procinfo.c                 |  6 ++-
>>  sysdeps/powerpc/dl-procinfo.h                 | 52 +++++++++++++------
>>  sysdeps/powerpc/hwcapinfo.c                   | 11 ++--
>>  sysdeps/unix/sysv/linux/dl-parse_auxv.h       |  2 +
>>  sysdeps/unix/sysv/linux/dl-sysdep.c           |  2 +
>>  .../unix/sysv/linux/powerpc/cpu-features.c    |  2 +
>>  .../unix/sysv/linux/powerpc/cpu-features.h    |  2 +
>>  sysdeps/unix/sysv/linux/powerpc/libc-start.c  |  6 +++
>>  12 files changed, 74 insertions(+), 19 deletions(-)
> 
> LGTM.  The only catch is that this patch is dependent on the associated
> kernel patch that adds the AT_HWCAP3 and AT_HWCAP4 getting upstream so
> glibc can rely on their values.  I'm still working on upstreaming that.

The kernel patch this is dependent on has finally reached Linus's tree,
so I have pushed this patch.

Peter



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