Fold LIBC_RAND into LIBC_STDIO/TINYMATH/INTRIN

libc/stdio/rdrand_init.c

@@ -0,0 +1,43 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/nexgen32e/kcpuids.h"
+#include "libc/nexgen32e/vendor.internal.h"
+#include "libc/nexgen32e/x86feature.h"
+#include "libc/nexgen32e/x86info.h"
+#include "libc/stdio/rand.h"
+
+textstartup void rdrand_init(int argc, char **argv, char **envp,
+                             intptr_t *auxv) {
+  extern unsigned kMutableCpuids[KCPUIDS_LEN][4] asm("kCpuids");
+  /*
+   * Clear RDRAND on AMD models before Zen and then some
+   * since it's not only slow but can freeze after sleep
+   * https://bugzilla.redhat.com/show_bug.cgi?id=1150286
+   */
+  if ((X86_HAVE(RDRND) || X86_HAVE(RDSEED)) &&
+      (IsAuthenticAMD() &&
+       (kX86CpuFamily < 0x17 ||
+        (kX86CpuFamily == 0x17 &&
+         (0x70 <= kX86CpuModel && kX86CpuModel <= 0x7F))))) {
+    kMutableCpuids[KCPUIDS_1H][KCPUIDS_ECX] &= ~(1u << 30);
+    kMutableCpuids[KCPUIDS_7H][KCPUIDS_EBX] &= ~(1u << 18);
+  }
+}
+
+const void *const g_rdrand_init[] initarray = {rdrand_init};