LoongArch: Add glibc.cpu.hwcap support.

Key Points:
1. On lasx & lsx platforms, We must use _dl_runtime_{profile, resolve}_{lsx, lasx}
   to save vector registers.
2. Via "tunables", users can choose str/mem_{lasx,lsx,unaligned} functions with
   `export GLIBC_TUNABLES=glibc.cpu.hwcaps=LASX,...`.
   Note: glibc.cpu.hwcaps doesn't affect _dl_runtime_{profile, resolve}_{lsx, lasx}
   selection.

Usage Notes:
1. Only valid inputs: LASX, LSX, UAL. Case-sensitive, comma-separated, no spaces.
2. Example: `export GLIBC_TUNABLES=glibc.cpu.hwcaps=LASX,UAL` turns on LASX & UAL.
   Unmentioned features turn off. With default ifunc: lasx > lsx > unaligned >
   aligned > generic, effect is: lasx > unaligned > aligned > generic; lsx off.
3. Incorrect GLIBC_TUNABLES settings will show error messages.
   For example: On lsx platforms, you cannot enable lasx features. If you do
   that, you will get error messages.
4. Valid input examples:
   - GLIBC_TUNABLES=glibc.cpu.hwcaps=LASX: lasx > aligned > generic.
   - GLIBC_TUNABLES=glibc.cpu.hwcaps=LSX,UAL: lsx > unaligned > aligned > generic.
   - GLIBC_TUNABLES=glibc.cpu.hwcaps=LASX,UAL,LASX,UAL,LSX,LASX,UAL: Repetitions
     allowed but not recommended. Results in: lasx > lsx > unaligned > aligned >
     generic.

5 files changed, 158 insertions, 4 deletions

diff --git a/sysdeps/unix/sysv/linux/loongarch/cpu-features.c b/sysdeps/unix/sysv/linux/loongarch/cpu-features.c
new file mode 100644
index 0000000000..1290c4ce9f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/cpu-features.c
@@ -0,0 +1,29 @@
+/* Initialize CPU feature data.  LoongArch64 version.
+   This file is part of the GNU C Library.
+   Copyright (C) 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <cpu-features.h>
+#include <elf/dl-hwcaps.h>
+#include <elf/dl-tunables.h>
+extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *) attribute_hidden;
+
+static inline void
+init_cpu_features (struct cpu_features *cpu_features)
+{
+    GLRO (dl_larch_cpu_features).hwcap = GLRO (dl_hwcap);
+    TUNABLE_GET (glibc, cpu, hwcaps, tunable_val_t *, TUNABLE_CALLBACK (set_hwcaps));
+}
diff --git a/sysdeps/unix/sysv/linux/loongarch/cpu-features.h b/sysdeps/unix/sysv/linux/loongarch/cpu-features.h
index d1a280a5ee..450963cebc 100644
--- a/sysdeps/unix/sysv/linux/loongarch/cpu-features.h
+++ b/sysdeps/unix/sysv/linux/loongarch/cpu-features.h
@@ -19,13 +19,23 @@
 #ifndef _CPU_FEATURES_LOONGARCH64_H
 #define _CPU_FEATURES_LOONGARCH64_H
 
+#include <stdint.h>
 #include <sys/auxv.h>
 
-#define SUPPORT_UAL (GLRO (dl_hwcap) & HWCAP_LOONGARCH_UAL)
-#define SUPPORT_LSX (GLRO (dl_hwcap) & HWCAP_LOONGARCH_LSX)
-#define SUPPORT_LASX (GLRO (dl_hwcap) & HWCAP_LOONGARCH_LASX)
+struct cpu_features
+ {
+    uint64_t hwcap;
+ };
 
+/* Get a pointer to the CPU features structure.  */
+extern const struct cpu_features *_dl_larch_get_cpu_features (void)
+     __attribute__ ((pure));
+
+#define SUPPORT_UAL (GLRO (dl_larch_cpu_features).hwcap & HWCAP_LOONGARCH_UAL)
+#define SUPPORT_LSX (GLRO (dl_larch_cpu_features).hwcap & HWCAP_LOONGARCH_LSX)
+#define SUPPORT_LASX (GLRO (dl_larch_cpu_features).hwcap & HWCAP_LOONGARCH_LASX)
+#define RTLD_SUPPORT_LSX (GLRO (dl_hwcap) & HWCAP_LOONGARCH_LSX)
+#define RTLD_SUPPORT_LASX (GLRO (dl_hwcap) & HWCAP_LOONGARCH_LASX)
 #define INIT_ARCH()
 
 #endif /* _CPU_FEATURES_LOONGARCH64_H  */
-
diff --git a/sysdeps/unix/sysv/linux/loongarch/dl-procinfo.c b/sysdeps/unix/sysv/linux/loongarch/dl-procinfo.c
new file mode 100644
index 0000000000..6217fda983
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/dl-procinfo.c
@@ -0,0 +1,60 @@
+/* Data for LoongArch64 version of processor capability information.
+   Linux version.
+   Copyright (C) 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* If anything should be added here check whether the size of each string
+   is still ok with the given array size.
+
+   All the #ifdefs in the definitions are quite irritating but
+   necessary if we want to avoid duplicating the information.  There
+   are three different modes:
+
+   - PROCINFO_DECL is defined.  This means we are only interested in
+     declarations.
+
+   - PROCINFO_DECL is not defined:
+
+     + if SHARED is defined the file is included in an array
+       initializer.  The .element = { ... } syntax is needed.
+
+     + if SHARED is not defined a normal array initialization is
+       needed.
+  */
+
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS
+#endif
+
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_larch_cpu_features
+# else
+PROCINFO_CLASS struct cpu_features _dl_larch_cpu_features
+# endif
+# ifndef PROCINFO_DECL
+= { }
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
+
+#undef PROCINFO_DECL
+#undef PROCINFO_CLASS
diff --git a/sysdeps/unix/sysv/linux/loongarch/dl-sysdep.c b/sysdeps/unix/sysv/linux/loongarch/dl-sysdep.c
new file mode 100644
index 0000000000..455fd71abc
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/dl-sysdep.c
@@ -0,0 +1,21 @@
+/* Operating system support for run-time dynamic linker.  LoongArch version.
+   Copyright (C) 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <sysdeps/loongarch/cpu-tunables.c>
+#include <sysdeps/unix/sysv/linux/dl-sysdep.c>
diff --git a/sysdeps/unix/sysv/linux/loongarch/libc-start.c b/sysdeps/unix/sysv/linux/loongarch/libc-start.c
new file mode 100644
index 0000000000..f1346ece0a
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/libc-start.c
@@ -0,0 +1,34 @@
+/* Override csu/libc-start.c on LoongArch64.
+   Copyright (C) 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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SHARED
+
+/* Mark symbols hidden in static PIE for early self relocation to work.  */
+# if BUILD_PIE_DEFAULT
+#  pragma GCC visibility push(hidden)
+# endif
+
+# include <ldsodefs.h>
+# include <cpu-features.c>
+
+extern struct cpu_features _dl_larch_cpu_features;
+
+# define ARCH_INIT_CPU_FEATURES() init_cpu_features (&_dl_larch_cpu_features)
+
+#endif
+#include <csu/libc-start.c>