[BOLT][Instrumentation][NFC] define and use mmap flags

Reviewed By: rafauler, Amir
Differential Revision: https://reviews.llvm.org/D154056

Author: treapster

bolt/runtime/common.h

@@ -82,6 +82,30 @@ typedef int int32_t;
   "pop %%rbx\n"                                                                \
   "pop %%rax\n"
 
+#define PROT_READ 0x1  /* Page can be read.  */
+#define PROT_WRITE 0x2 /* Page can be written.  */
+#define PROT_EXEC 0x4  /* Page can be executed.  */
+#define PROT_NONE 0x0  /* Page can not be accessed.  */
+#define PROT_GROWSDOWN                                                         \
+  0x01000000 /* Extend change to start of                                      \
+                growsdown vma (mprotect only).  */
+#define PROT_GROWSUP                                                           \
+  0x02000000 /* Extend change to start of                                      \
+                growsup vma (mprotect only).  */
+
+/* Sharing types (must choose one and only one of these).  */
+#define MAP_SHARED 0x01  /* Share changes.  */
+#define MAP_PRIVATE 0x02 /* Changes are private.  */
+#define MAP_FIXED 0x10   /* Interpret addr exactly.  */
+
+#if defined(__APPLE__)
+#define MAP_ANONYMOUS 0x1000
+#else
+#define MAP_ANONYMOUS 0x20
+#endif
+
+#define MAP_FAILED ((void *)-1)
+
 // Functions that are required by freestanding environment. Compiler may
 // generate calls to these implicitly.
 extern "C" {

bolt/runtime/instr.cpp

@@ -134,16 +134,9 @@ class BumpPtrAllocator {
     Lock L(M);
 
     if (StackBase == nullptr) {
-#if defined(__APPLE__)
-    int MAP_PRIVATE_MAP_ANONYMOUS = 0x1002;
-#else
-    int MAP_PRIVATE_MAP_ANONYMOUS = 0x22;
-#endif
       StackBase = reinterpret_cast<uint8_t *>(
-          __mmap(0, MaxSize, 0x3 /* PROT_READ | PROT_WRITE*/,
-                 Shared ? 0x21 /*MAP_SHARED | MAP_ANONYMOUS*/
-                        : MAP_PRIVATE_MAP_ANONYMOUS /* MAP_PRIVATE | MAP_ANONYMOUS*/,
-                 -1, 0));
+          __mmap(0, MaxSize, PROT_READ | PROT_WRITE,
+                 (Shared ? MAP_SHARED : MAP_PRIVATE) | MAP_ANONYMOUS, -1, 0));
       StackSize = 0;
     }
 
@@ -669,7 +662,7 @@ ProfileWriterContext readDescriptions() {
   // mmap our binary to memory
   uint64_t Size = __lseek(FD, 0, 2 /*SEEK_END*/);
   uint8_t *BinContents = reinterpret_cast<uint8_t *>(
-      __mmap(0, Size, 0x1 /* PROT_READ*/, 0x2 /* MAP_PRIVATE*/, FD, 0));
+      __mmap(0, Size, PROT_READ, MAP_PRIVATE, FD, 0));
   Result.MMapPtr = BinContents;
   Result.MMapSize = Size;
   Elf64_Ehdr *Hdr = reinterpret_cast<Elf64_Ehdr *>(BinContents);
@@ -1555,10 +1548,9 @@ extern "C" void __attribute((force_align_arg_pointer)) __bolt_instr_setup() {
   assert (CountersEnd > CountersStart, "no counters");
   // Maps our counters to be shared instead of private, so we keep counting for
   // forked processes
-  __mmap(CountersStart, CountersEnd - CountersStart,
-         0x3 /*PROT_READ|PROT_WRITE*/,
-         0x31 /*MAP_ANONYMOUS | MAP_SHARED | MAP_FIXED*/, -1, 0);
-
+  void *Ret =
+      __mmap(CountersStart, CountersEnd - CountersStart, PROT_READ | PROT_WRITE,
+             MAP_ANONYMOUS | MAP_SHARED | MAP_FIXED, -1, 0);
   __bolt_ind_call_counter_func_pointer = __bolt_instr_indirect_call;
   __bolt_ind_tailcall_counter_func_pointer = __bolt_instr_indirect_tailcall;
   // Conservatively reserve 100MiB shared pages