riscv: Get cache information through sysconf

Add support to query cache information on RISC-V through sysconf()
function. The cache information had been added in AUX vector of RISC-V
architecture in Linux kernel v.5.10-rc1.
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/riscv/sysconf.c b/sysdeps/unix/sysv/linux/riscv/sysconf.c
new file mode 100644
index 0000000..02b469c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/sysconf.c
@@ -0,0 +1,100 @@
+/* Copyright (C) 2020 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 <errno.h>
+#include <unistd.h>
+#include <sys/auxv.h>
+
+static long int linux_sysconf (int name);
+
+static inline bool
+getauxval2_einval (unsigned long int type, unsigned long int *result)
+{
+  if (__getauxval2 (type, result))
+    return true;
+
+  __set_errno (EINVAL);
+
+  return false;
+}
+
+static inline long int
+sysconf_get_cache_associativity (unsigned long type)
+{
+  unsigned long int result;
+
+  if (getauxval2_einval (type, &result))
+    return (result & 0xffff0000) >> 16;
+
+  return -1;
+}
+
+static inline long int
+sysconf_get_cache_linesize (unsigned long type)
+{
+  unsigned long int result;
+
+  if (getauxval2_einval (type, &result))
+    return result & 0xffff;
+
+  return -1;
+}
+
+static inline long int
+sysconf_get_cache_size (unsigned long type)
+{
+  unsigned long int result;
+
+  if (getauxval2_einval (type, &result))
+    return result;
+
+  return -1;
+}
+
+/* Get the value of the system variable NAME.  */
+long int
+__sysconf (int name)
+{
+  switch (name)
+    {
+      case _SC_LEVEL1_ICACHE_SIZE:
+	return sysconf_get_cache_size (AT_L1I_CACHESIZE);
+      case _SC_LEVEL1_ICACHE_ASSOC:
+	return sysconf_get_cache_associativity (AT_L1I_CACHEGEOMETRY);
+      case _SC_LEVEL1_ICACHE_LINESIZE:
+	return sysconf_get_cache_linesize (AT_L1I_CACHEGEOMETRY);
+      case _SC_LEVEL1_DCACHE_SIZE:
+	return sysconf_get_cache_size (AT_L1D_CACHESIZE);
+      case _SC_LEVEL1_DCACHE_ASSOC:
+	return sysconf_get_cache_associativity (AT_L1D_CACHEGEOMETRY);
+      case _SC_LEVEL1_DCACHE_LINESIZE:
+	return sysconf_get_cache_linesize (AT_L1D_CACHEGEOMETRY);
+      case _SC_LEVEL2_CACHE_SIZE:
+	return sysconf_get_cache_size (AT_L2_CACHESIZE);
+      case _SC_LEVEL2_CACHE_ASSOC:
+	return sysconf_get_cache_associativity (AT_L2_CACHEGEOMETRY);
+      case _SC_LEVEL2_CACHE_LINESIZE:
+	return sysconf_get_cache_linesize (AT_L2_CACHEGEOMETRY);
+      default:
+	return linux_sysconf (name);
+    }
+}
+
+/* Now the generic Linux version.  */
+#undef __sysconf
+#define __sysconf static linux_sysconf
+#include <sysdeps/unix/sysv/linux/sysconf.c>