PowerPC: Influence cpu/arch hwcap features via GLIBC_TUNABLES

This patch enables the option to influence hwcaps used by PowerPC.
The environment variable, GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,-zzz....,
can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature xxx
and zzz, where the feature name is case-sensitive and has to match the ones
mentioned in the file{sysdeps/powerpc/dl-procinfo.c}.

Note that the hwcap tunables only used in the IFUNC selection.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

8 files changed, 20 insertions, 70 deletions

diff --git a/sysdeps/powerpc/cpu-features.c b/sysdeps/powerpc/cpu-features.c
deleted file mode 100644
index 0ef3cf8..0000000
--- a/sysdeps/powerpc/cpu-features.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Initialize cpu feature data.  PowerPC version.
-   Copyright (C) 2017-2023 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/>.  */
-
-#include <stdint.h>
-#include <cpu-features.h>
-#include <elf/dl-tunables.h>
-
-static inline void
-init_cpu_features (struct cpu_features *cpu_features)
-{
-  /* Default is to use aligned memory access on optimized function unless
-     tunables is enable, since for this case user can explicit disable
-     unaligned optimizations.  */
-  int32_t cached_memfunc = TUNABLE_GET (glibc, cpu, cached_memopt, int32_t,
-					NULL);
-  cpu_features->use_cached_memopt = (cached_memfunc > 0);
-}
diff --git a/sysdeps/powerpc/cpu-features.h b/sysdeps/powerpc/cpu-features.h
deleted file mode 100644
index d316dc3..0000000
--- a/sysdeps/powerpc/cpu-features.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Initialize cpu feature data.  PowerPC version.
-   Copyright (C) 2017-2023 Free Software Foundation, Inc.
-
-   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 __CPU_FEATURES_POWERPC_H
-# define __CPU_FEATURES_POWERPC_H
-
-#include <stdbool.h>
-
-struct cpu_features
-{
-  bool use_cached_memopt;
-};
-
-#endif /* __CPU_FEATURES_H  */
diff --git a/sysdeps/powerpc/dl-tunables.list b/sysdeps/powerpc/dl-tunables.list
index 87d6235..807b7f8 100644
--- a/sysdeps/powerpc/dl-tunables.list
+++ b/sysdeps/powerpc/dl-tunables.list
@@ -24,5 +24,8 @@ glibc {
       maxval: 1
       default: 0
     }
+    hwcaps {
+      type: STRING
+    }
   }
 }
diff --git a/sysdeps/powerpc/hwcapinfo.c b/sysdeps/powerpc/hwcapinfo.c
index e26e64d..f2c473c 100644
--- a/sysdeps/powerpc/hwcapinfo.c
+++ b/sysdeps/powerpc/hwcapinfo.c
@@ -19,6 +19,7 @@
 #include <unistd.h>
 #include <shlib-compat.h>
 #include <dl-procinfo.h>
+#include <cpu-features.c>
 
 tcbhead_t __tcb __attribute__ ((visibility ("hidden")));
 
@@ -63,6 +64,9 @@ __tcb_parse_hwcap_and_convert_at_platform (void)
   else if (h1 & PPC_FEATURE_POWER5)
     h1 |= PPC_FEATURE_POWER4;
 
+  uint64_t array_hwcaps[] = { h1, h2 };
+  init_cpu_features (&GLRO(dl_powerpc_cpu_features), array_hwcaps);
+
   /* Consolidate both HWCAP and HWCAP2 into a single doubleword so that
      we can read both in a single load later.  */
   __tcb.hwcap = (h1 << 32) | (h2 & 0xffffffff);
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
index b4f8053..986c37d 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
@@ -21,6 +21,7 @@
 #include <wchar.h>
 #include <ldsodefs.h>
 #include <ifunc-impl-list.h>
+#include <cpu-features.h>
 
 size_t
 __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
@@ -28,7 +29,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 {
   size_t i = max;
 
-  unsigned long int hwcap = GLRO(dl_hwcap);
+  const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features);
+  unsigned long int hwcap = features->hwcap;
   /* hwcap contains only the latest supported ISA, the code checks which is
      and fills the previous supported ones.  */
   if (hwcap & PPC_FEATURE_ARCH_2_06)
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h b/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
index 3dd00e0..4f075d3 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
@@ -16,6 +16,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <ldsodefs.h>
+#include <cpu-features.h>
 
 /* The code checks if _rtld_global_ro was realocated before trying to access
    the dl_hwcap field. The assembly is to make the compiler not optimize the
@@ -32,11 +33,12 @@
 # define __GLRO(value)  GLRO(value)
 #endif
 
-/* dl_hwcap contains only the latest supported ISA, the macro checks which is
-   and fills the previous ones.  */
+/* Get the hardware information post the tunables set, the macro checks
+   it and fills the previous ones.  */
 #define INIT_ARCH() \
-  unsigned long int hwcap = __GLRO(dl_hwcap); 			\
-  unsigned long int __attribute__((unused)) hwcap2 = __GLRO(dl_hwcap2); \
+  const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features);	\
+  unsigned long int hwcap = features->hwcap;				\
+  unsigned long int __attribute__((unused)) hwcap2 = features->hwcap2; \
   bool __attribute__((unused)) use_cached_memopt =		\
     __GLRO(dl_powerpc_cpu_features.use_cached_memopt);		\
   if (hwcap & PPC_FEATURE_ARCH_2_06)				\
diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
index 9b8943b..449208e 100644
--- a/sysdeps/powerpc/powerpc64/dl-machine.h
+++ b/sysdeps/powerpc/powerpc64/dl-machine.h
@@ -27,7 +27,6 @@
 #include <dl-tls.h>
 #include <sysdep.h>
 #include <hwcapinfo.h>
-#include <cpu-features.c>
 #include <dl-static-tls.h>
 #include <dl-funcdesc.h>
 #include <dl-machine-rel.h>
@@ -297,7 +296,6 @@ static inline void __attribute__ ((unused))
 dl_platform_init (void)
 {
   __tcb_parse_hwcap_and_convert_at_platform ();
-  init_cpu_features (&GLRO(dl_powerpc_cpu_features));
 }
 #endif
 
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index ebe9434..fc26dd0 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -17,6 +17,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <assert.h>
+#include <cpu-features.h>
 #include <string.h>
 #include <wchar.h>
 #include <ldsodefs.h>
@@ -27,9 +28,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			size_t max)
 {
   size_t i = max;
-
-  unsigned long int hwcap = GLRO(dl_hwcap);
-  unsigned long int hwcap2 = GLRO(dl_hwcap2);
+  const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features);
+  unsigned long int hwcap = features->hwcap;
+  unsigned long int hwcap2 = features->hwcap2;
 #ifdef SHARED
   int cacheline_size = GLRO(dl_cache_line_size);
 #endif