8263884: Clean up os::is_allocatable() across Posix platforms

Reviewed-by: stefank

src/hotspot/os/posix/os_posix.cpp

@@ -546,6 +546,26 @@ bool os::get_host_name(char* buf, size_t buflen) {
   return true;
 }
 
+#ifndef _LP64
+// Helper, on 32bit, for os::has_allocatable_memory_limit
+static bool is_allocatable(size_t s) {
+  if (s < 2 * G) {
+    return true;
+  }
+  // Use raw anonymous mmap here; no need to go through any
+  // of our reservation layers. We will unmap right away.
+  void* p = ::mmap(NULL, s, PROT_NONE,
+                   MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS, -1, 0);
+  if (p == MAP_FAILED) {
+    return false;
+  } else {
+    ::munmap(p, s);
+    return true;
+  }
+}
+#endif // !_LP64
+
+
 bool os::has_allocatable_memory_limit(size_t* limit) {
   struct rlimit rlim;
   int getrlimit_res = getrlimit(RLIMIT_AS, &rlim);

src/hotspot/os_cpu/bsd_x86/os_bsd_x86.cpp

@@ -641,26 +641,6 @@ bool os::supports_sse() {
   return true;
 }
 
-bool os::is_allocatable(size_t bytes) {
-#ifdef AMD64
-  // unused on amd64?
-  return true;
-#else
-
-  if (bytes < 2 * G) {
-    return true;
-  }
-
-  char* addr = reserve_memory(bytes);
-
-  if (addr != NULL) {
-    release_memory(addr, bytes);
-  }
-
-  return addr != NULL;
-#endif // AMD64
-}
-
 juint os::cpu_microcode_revision() {
   juint result = 0;
   char data[8];

src/hotspot/os_cpu/bsd_x86/os_bsd_x86.hpp

@@ -37,8 +37,6 @@
 
   static jlong rdtsc();
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }

src/hotspot/os_cpu/bsd_zero/os_bsd_zero.cpp

@@ -158,24 +158,6 @@ void os::Bsd::init_thread_fpu_state(void) {
   // Nothing to do
 }
 
-bool os::is_allocatable(size_t bytes) {
-#ifdef _LP64
-  return true;
-#else
-  if (bytes < 2 * G) {
-    return true;
-  }
-
-  char* addr = reserve_memory(bytes);
-
-  if (addr != NULL) {
-    release_memory(addr, bytes);
-  }
-
-  return addr != NULL;
-#endif // _LP64
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 // thread stack
 

src/hotspot/os_cpu/bsd_zero/os_bsd_zero.hpp

@@ -28,8 +28,6 @@
 
   static void setup_fpu() {}
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }

src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp

@@ -304,10 +304,6 @@ int os::Linux::get_fpu_control_word(void) {
 void os::Linux::set_fpu_control_word(int fpu_control) {
 }
 
-bool os::is_allocatable(size_t bytes) {
-  return true;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // thread stack
 

src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.hpp

@@ -32,8 +32,6 @@
 
   static void setup_fpu();
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }

src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp

@@ -413,10 +413,6 @@ void os::setup_fpu() {
 #endif
 }
 
-bool os::is_allocatable(size_t bytes) {
-  return true;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // thread stack
 

src/hotspot/os_cpu/linux_arm/os_linux_arm.hpp

@@ -34,8 +34,6 @@
 
   static void setup_fpu();
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }

src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp

@@ -478,26 +478,6 @@ juint os::cpu_microcode_revision() {
   return result;
 }
 
-bool os::is_allocatable(size_t bytes) {
-#ifdef AMD64
-  // unused on amd64?
-  return true;
-#else
-
-  if (bytes < 2 * G) {
-    return true;
-  }
-
-  char* addr = reserve_memory(bytes);
-
-  if (addr != NULL) {
-    release_memory(addr, bytes);
-  }
-
-  return addr != NULL;
-#endif // AMD64
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // thread stack
 

src/hotspot/os_cpu/linux_x86/os_linux_x86.hpp

@@ -31,8 +31,6 @@
 
   static jlong rdtsc();
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }

src/hotspot/os_cpu/linux_zero/os_linux_zero.cpp

@@ -182,24 +182,6 @@ void os::Linux::set_fpu_control_word(int fpu) {
   ShouldNotCallThis();
 }
 
-bool os::is_allocatable(size_t bytes) {
-#ifdef _LP64
-  return true;
-#else
-  if (bytes < 2 * G) {
-    return true;
-  }
-
-  char* addr = reserve_memory(bytes);
-
-  if (addr != NULL) {
-    release_memory(addr, bytes);
-  }
-
-  return addr != NULL;
-#endif // _LP64
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 // thread stack
 

src/hotspot/os_cpu/linux_zero/os_linux_zero.hpp

@@ -28,8 +28,6 @@
 
   static void setup_fpu() {}
 
-  static bool is_allocatable(size_t bytes);
-
   // Used to register dynamic code cache area with the OS
   // Note: Currently only used in 64 bit Windows implementations
   static bool register_code_area(char *low, char *high) { return true; }