1 files changed, 96 insertions, 0 deletions
diff --git a/lib/builtins/clear_cache.c b/lib/builtins/clear_cache.c
new file mode 100644
index 000000000000..86e68afad3b7
--- /dev/null
+++ b/lib/builtins/clear_cache.c
@@ -0,0 +1,96 @@
+/* ===-- clear_cache.c - Implement __clear_cache ---------------------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+#if __APPLE__
+  #include <libkern/OSCacheControl.h>
+#endif
+#if defined(__NetBSD__) && defined(__arm__)
+  #include <machine/sysarch.h>
+#endif
+
+#if defined(__ANDROID__) && defined(__mips__)
+  #include <sys/cachectl.h>
+#endif
+
+#if defined(__ANDROID__) && defined(__arm__)
+  #include <asm/unistd.h>
+#endif
+
+/*
+ * The compiler generates calls to __clear_cache() when creating 
+ * trampoline functions on the stack for use with nested functions.
+ * It is expected to invalidate the instruction cache for the 
+ * specified range.
+ */
+
+void __clear_cache(void *start, void *end) {
+#if __i386__ || __x86_64__
+/*
+ * Intel processors have a unified instruction and data cache
+ * so there is nothing to do
+ */
+#elif defined(__arm__) && !defined(__APPLE__)
+    #if defined(__NetBSD__)
+        struct arm_sync_icache_args arg;
+
+        arg.addr = (uintptr_t)start;
+        arg.len = (uintptr_t)end - (uintptr_t)start;
+
+        sysarch(ARM_SYNC_ICACHE, &arg);
+    #elif defined(__ANDROID__)
+         const register int start_reg __asm("r0") = (int) (intptr_t) start;
+         const register int end_reg __asm("r1") = (int) (intptr_t) end;
+         const register int flags __asm("r2") = 0;
+         const register int syscall_nr __asm("r7") = __ARM_NR_cacheflush;
+        __asm __volatile("svc 0x0" : "=r"(start_reg)
+            : "r"(syscall_nr), "r"(start_reg), "r"(end_reg), "r"(flags) : "r0");
+         if (start_reg != 0) {
+             compilerrt_abort();
+         }
+    #else
+        compilerrt_abort();
+    #endif
+#elif defined(__ANDROID__) && defined(__mips__)
+  const uintptr_t start_int = (uintptr_t) start;
+  const uintptr_t end_int = (uintptr_t) end;
+  _flush_cache(start, (end_int - start_int), BCACHE);
+#elif defined(__aarch64__) && !defined(__APPLE__)
+  uint64_t xstart = (uint64_t)(uintptr_t) start;
+  uint64_t xend = (uint64_t)(uintptr_t) end;
+
+  // Get Cache Type Info
+  uint64_t ctr_el0;
+  __asm __volatile("mrs %0, ctr_el0" : "=r"(ctr_el0));
+
+  /*
+   * dc & ic instructions must use 64bit registers so we don't use
+   * uintptr_t in case this runs in an IPL32 environment.
+   */
+  const size_t dcache_line_size = 4 << ((ctr_el0 >> 16) & 15);
+  for (uint64_t addr = xstart; addr < xend; addr += dcache_line_size)
+    __asm __volatile("dc cvau, %0" :: "r"(addr));
+  __asm __volatile("dsb ish");
+
+  const size_t icache_line_size = 4 << ((ctr_el0 >> 0) & 15);
+  for (uint64_t addr = xstart; addr < xend; addr += icache_line_size)
+    __asm __volatile("ic ivau, %0" :: "r"(addr));
+  __asm __volatile("isb sy");
+#else
+    #if __APPLE__
+        /* On Darwin, sys_icache_invalidate() provides this functionality */
+        sys_icache_invalidate(start, end-start);
+    #else
+        compilerrt_abort();
+    #endif
+#endif
+}
+