powerpc: Add HWCAP3/HWCAP4 data to TCB for Power Architecture.

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>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>

3 files changed, 10 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/powerpc/cpu-features.c b/sysdeps/unix/sysv/linux/powerpc/cpu-features.c
index 8e8a5ec2ea..a947d62db6 100644
--- a/sysdeps/unix/sysv/linux/powerpc/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/powerpc/cpu-features.c
@@ -94,6 +94,8 @@ init_cpu_features (struct cpu_features *cpu_features, uint64_t hwcaps[])
      which are set by __tcb_parse_hwcap_and_convert_at_platform.  */
   cpu_features->hwcap = hwcaps[0];
   cpu_features->hwcap2 = hwcaps[1];
+  cpu_features->hwcap3 = hwcaps[2];
+  cpu_features->hwcap4 = hwcaps[3];
   /* Default is to use aligned memory access on optimized function unless
      tunables is enable, since for this case user can explicit disable
      unaligned optimizations.  */
diff --git a/sysdeps/unix/sysv/linux/powerpc/cpu-features.h b/sysdeps/unix/sysv/linux/powerpc/cpu-features.h
index 1294f0b601..e9eb6a13c8 100644
--- a/sysdeps/unix/sysv/linux/powerpc/cpu-features.h
+++ b/sysdeps/unix/sysv/linux/powerpc/cpu-features.h
@@ -26,6 +26,8 @@ struct cpu_features
   bool use_cached_memopt;
   unsigned long int hwcap;
   unsigned long int hwcap2;
+  unsigned long int hwcap3;
+  unsigned long int hwcap4;
 };
 
 static const char hwcap_names[] = {
diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
index a4705daf1c..6a00cd88cd 100644
--- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c
+++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
@@ -87,6 +87,12 @@ __libc_start_main_impl (int argc, char **argv,
       case AT_HWCAP2:
 	_dl_hwcap2 = (unsigned long int) av->a_un.a_val;
 	break;
+      case AT_HWCAP3:
+	_dl_hwcap3 = (unsigned long int) av->a_un.a_val;
+	break;
+      case AT_HWCAP4:
+	_dl_hwcap4 = (unsigned long int) av->a_un.a_val;
+	break;
       case AT_PLATFORM:
 	_dl_platform = (void *) av->a_un.a_val;
 	break;