--- a/src/hotspot/os/linux/os_linux.cpp Mon Nov 20 09:46:55 2017 +0000
+++ b/src/hotspot/os/linux/os_linux.cpp Mon Nov 20 15:56:32 2017 -0500
@@ -853,8 +853,8 @@
}
}
- if (os::Linux::is_initial_thread()) {
- // If current thread is initial thread, its stack is mapped on demand,
+ if (os::is_primordial_thread()) {
+ // If current thread is primordial thread, its stack is mapped on demand,
// see notes about MAP_GROWSDOWN. Here we try to force kernel to map
// the entire stack region to avoid SEGV in stack banging.
// It is also useful to get around the heap-stack-gap problem on SuSE
@@ -915,19 +915,20 @@
}
//////////////////////////////////////////////////////////////////////////////
-// initial thread
-
-// Check if current thread is the initial thread, similar to Solaris thr_main.
-bool os::Linux::is_initial_thread(void) {
+// primordial thread
+
+// Check if current thread is the primordial thread, similar to Solaris thr_main.
+bool os::is_primordial_thread(void) {
char dummy;
// If called before init complete, thread stack bottom will be null.
// Can be called if fatal error occurs before initialization.
- if (initial_thread_stack_bottom() == NULL) return false;
- assert(initial_thread_stack_bottom() != NULL &&
- initial_thread_stack_size() != 0,
- "os::init did not locate initial thread's stack region");
- if ((address)&dummy >= initial_thread_stack_bottom() &&
- (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) {
+ if (os::Linux::initial_thread_stack_bottom() == NULL) return false;
+ assert(os::Linux::initial_thread_stack_bottom() != NULL &&
+ os::Linux::initial_thread_stack_size() != 0,
+ "os::init did not locate primordial thread's stack region");
+ if ((address)&dummy >= os::Linux::initial_thread_stack_bottom() &&
+ (address)&dummy < os::Linux::initial_thread_stack_bottom() +
+ os::Linux::initial_thread_stack_size()) {
return true;
} else {
return false;
@@ -958,7 +959,7 @@
return false;
}
-// Locate initial thread stack. This special handling of initial thread stack
+// Locate primordial thread stack. This special handling of primordial thread stack
// is needed because pthread_getattr_np() on most (all?) Linux distros returns
// bogus value for the primordial process thread. While the launcher has created
// the VM in a new thread since JDK 6, we still have to allow for the use of the
@@ -982,7 +983,10 @@
// 6308388: a bug in ld.so will relocate its own .data section to the
// lower end of primordial stack; reduce ulimit -s value a little bit
// so we won't install guard page on ld.so's data section.
- stack_size -= 2 * page_size();
+ // But ensure we don't underflow the stack size - allow 1 page spare
+ if (stack_size >= (size_t)(3 * page_size())) {
+ stack_size -= 2 * page_size();
+ }
// Try to figure out where the stack base (top) is. This is harder.
//
@@ -1103,16 +1107,16 @@
if (i != 28 - 2) {
assert(false, "Bad conversion from /proc/self/stat");
- // product mode - assume we are the initial thread, good luck in the
+ // product mode - assume we are the primordial thread, good luck in the
// embedded case.
- warning("Can't detect initial thread stack location - bad conversion");
+ warning("Can't detect primordial thread stack location - bad conversion");
stack_start = (uintptr_t) &rlim;
}
} else {
// For some reason we can't open /proc/self/stat (for example, running on
// FreeBSD with a Linux emulator, or inside chroot), this should work for
// most cases, so don't abort:
- warning("Can't detect initial thread stack location - no /proc/self/stat");
+ warning("Can't detect primordial thread stack location - no /proc/self/stat");
stack_start = (uintptr_t) &rlim;
}
}
@@ -1132,7 +1136,7 @@
stack_top = (uintptr_t)high;
} else {
// failed, likely because /proc/self/maps does not exist
- warning("Can't detect initial thread stack location - find_vma failed");
+ warning("Can't detect primordial thread stack location - find_vma failed");
// best effort: stack_start is normally within a few pages below the real
// stack top, use it as stack top, and reduce stack size so we won't put
// guard page outside stack.
@@ -3136,10 +3140,10 @@
// where we're going to put our guard pages, truncate the mapping at
// that point by munmap()ping it. This ensures that when we later
// munmap() the guard pages we don't leave a hole in the stack
-// mapping. This only affects the main/initial thread
+// mapping. This only affects the main/primordial thread
bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
- if (os::Linux::is_initial_thread()) {
+ if (os::is_primordial_thread()) {
// As we manually grow stack up to bottom inside create_attached_thread(),
// it's likely that os::Linux::initial_thread_stack_bottom is mapped and
// we don't need to do anything special.
@@ -3164,14 +3168,14 @@
// If this is a growable mapping, remove the guard pages entirely by
// munmap()ping them. If not, just call uncommit_memory(). This only
-// affects the main/initial thread, but guard against future OS changes
-// It's safe to always unmap guard pages for initial thread because we
-// always place it right after end of the mapped region
+// affects the main/primordial thread, but guard against future OS changes.
+// It's safe to always unmap guard pages for primordial thread because we
+// always place it right after end of the mapped region.
bool os::remove_stack_guard_pages(char* addr, size_t size) {
uintptr_t stack_extent, stack_base;
- if (os::Linux::is_initial_thread()) {
+ if (os::is_primordial_thread()) {
return ::munmap(addr, size) == 0;
}
@@ -4860,10 +4864,9 @@
extern void report_error(char* file_name, int line_no, char* title,
char* format, ...);
-// this is called _before_ the most of global arguments have been parsed
+// this is called _before_ most of the global arguments have been parsed
void os::init(void) {
char dummy; // used to get a guess on initial stack address
-// first_hrtime = gethrtime();
clock_tics_per_sec = sysconf(_SC_CLK_TCK);
@@ -4880,7 +4883,7 @@
Linux::initialize_os_info();
- // main_thread points to the aboriginal thread
+ // _main_thread points to the thread that created/loaded the JVM.
Linux::_main_thread = pthread_self();
Linux::clock_init();
@@ -5851,8 +5854,8 @@
//
#ifndef ZERO
static void current_stack_region(address * bottom, size_t * size) {
- if (os::Linux::is_initial_thread()) {
- // initial thread needs special handling because pthread_getattr_np()
+ if (os::is_primordial_thread()) {
+ // primordial thread needs special handling because pthread_getattr_np()
// may return bogus value.
*bottom = os::Linux::initial_thread_stack_bottom();
*size = os::Linux::initial_thread_stack_size();