util: Add cpuinfo-aarch64.c

Move the code from tcg/.  The only use of these bits so far
is with respect to the atomicity of tcg operations.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

util/cpuinfo-aarch64.c

@@ -0,0 +1,67 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Host specific cpu indentification for AArch64.
+ */
+
+#include "qemu/osdep.h"
+#include "host/cpuinfo.h"
+
+#ifdef CONFIG_LINUX
+# ifdef CONFIG_GETAUXVAL
+#  include <sys/auxv.h>
+# else
+#  include <asm/hwcap.h>
+#  include "elf.h"
+# endif
+#endif
+#ifdef CONFIG_DARWIN
+# include <sys/sysctl.h>
+#endif
+
+unsigned cpuinfo;
+
+#ifdef CONFIG_DARWIN
+static bool sysctl_for_bool(const char *name)
+{
+    int val = 0;
+    size_t len = sizeof(val);
+
+    if (sysctlbyname(name, &val, &len, NULL, 0) == 0) {
+        return val != 0;
+    }
+
+    /*
+     * We might in the future ask for properties not present in older kernels,
+     * but we're only asking about static properties, all of which should be
+     * 'int'.  So we shouln't see ENOMEM (val too small), or any of the other
+     * more exotic errors.
+     */
+    assert(errno == ENOENT);
+    return false;
+}
+#endif
+
+/* Called both as constructor and (possibly) via other constructors. */
+unsigned __attribute__((constructor)) cpuinfo_init(void)
+{
+    unsigned info = cpuinfo;
+
+    if (info) {
+        return info;
+    }
+
+    info = CPUINFO_ALWAYS;
+
+#ifdef CONFIG_LINUX
+    unsigned long hwcap = qemu_getauxval(AT_HWCAP);
+    info |= (hwcap & HWCAP_ATOMICS ? CPUINFO_LSE : 0);
+    info |= (hwcap & HWCAP_USCAT ? CPUINFO_LSE2 : 0);
+#endif
+#ifdef CONFIG_DARWIN
+    info |= sysctl_for_bool("hw.optional.arm.FEAT_LSE") * CPUINFO_LSE;
+    info |= sysctl_for_bool("hw.optional.arm.FEAT_LSE2") * CPUINFO_LSE2;
+#endif
+
+    cpuinfo = info;
+    return info;
+}

util/meson.build

@@ -109,6 +109,8 @@ if have_block
   util_ss.add(when: 'CONFIG_LINUX', if_true: files('vfio-helpers.c'))
 endif
 
-if cpu in ['x86', 'x86_64']
+if cpu == 'aarch64'
+  util_ss.add(files('cpuinfo-aarch64.c'))
+elif cpu in ['x86', 'x86_64']
   util_ss.add(files('cpuinfo-i386.c'))
 endif