notls patch

commit 60dc9adee66e6f83ccb406a965e61c49e2541d28
Author: tstuefe <thomas.stuefe@gmail.com>
Date:   Wed Jul 19 14:29:12 2023 +0200

    remove TLS stuff

diff --git a/src/hotspot/os/linux/os_linux.cpp b/src/hotspot/os/linux/os_linux.cpp
index 9f357d8e6b0..3dd44c1e0d2 100644
--- a/src/hotspot/os/linux/os_linux.cpp
+++ b/src/hotspot/os/linux/os_linux.cpp
@@ -835,67 +835,10 @@ static void *thread_native_entry(Thread *thread) {
   return 0;
 }
 
-// On Linux, glibc places static TLS blocks (for __thread variables) on
-// the thread stack. This decreases the stack size actually available
-// to threads.
-//
-// For large static TLS sizes, this may cause threads to malfunction due
-// to insufficient stack space. This is a well-known issue in glibc:
-// http://sourceware.org/bugzilla/show_bug.cgi?id=11787.
-//
-// As a workaround, we call a private but assumed-stable glibc function,
-// __pthread_get_minstack() to obtain the minstack size and derive the
-// static TLS size from it. We then increase the user requested stack
-// size by this TLS size. The same function is used to determine whether
-// adjustStackSizeForGuardPages() needs to be true.
-//
-// Due to compatibility concerns, this size adjustment is opt-in and
-// controlled via AdjustStackSizeForTLS.
 typedef size_t (*GetMinStack)(const pthread_attr_t *attr);
 
 GetMinStack _get_minstack_func = NULL;  // Initialized via os::init_2()
 
-// Returns the size of the static TLS area glibc puts on thread stacks.
-// The value is cached on first use, which occurs when the first thread
-// is created during VM initialization.
-static size_t get_static_tls_area_size(const pthread_attr_t *attr) {
-  size_t tls_size = 0;
-  if (_get_minstack_func != NULL) {
-    // Obtain the pthread minstack size by calling __pthread_get_minstack.
-    size_t minstack_size = _get_minstack_func(attr);
-
-    // Remove non-TLS area size included in minstack size returned
-    // by __pthread_get_minstack() to get the static TLS size.
-    // If adjustStackSizeForGuardPages() is true, minstack size includes
-    // guard_size. Otherwise guard_size is automatically added
-    // to the stack size by pthread_create and is no longer included
-    // in minstack size. In both cases, the guard_size is taken into
-    // account, so there is no need to adjust the result for that.
-    //
-    // Although __pthread_get_minstack() is a private glibc function,
-    // it is expected to have a stable behavior across future glibc
-    // versions while glibc still allocates the static TLS blocks off
-    // the stack. Following is glibc 2.28 __pthread_get_minstack():
-    //
-    // size_t
-    // __pthread_get_minstack (const pthread_attr_t *attr)
-    // {
-    //   return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
-    // }
-    //
-    //
-    // The following 'minstack_size > os::vm_page_size() + PTHREAD_STACK_MIN'
-    // if check is done for precaution.
-    if (minstack_size > (size_t)os::vm_page_size() + PTHREAD_STACK_MIN) {
-      tls_size = minstack_size - (size_t)os::vm_page_size() - PTHREAD_STACK_MIN;
-    }
-  }
-
-  log_info(os, thread)("Stack size adjustment for TLS is " SIZE_FORMAT,
-                       tls_size);
-  return tls_size;
-}
-
 // In glibc versions prior to 2.27 the guard size mechanism
 // was not implemented properly. The POSIX standard requires adding
 // the size of the guard pages to the stack size, instead glibc
@@ -909,7 +852,6 @@ bool os::Linux::adjustStackSizeForGuardPages() {
 }
 
 #if defined(__GLIBC__) // TLS not in jdk11
-static bool AdjustStackSizeForTLS = false; // Dumy decl as substitute for cmdline parameter
 static void init_adjust_stacksize_for_guard_pages() {
   assert(_get_minstack_func == NULL, "initialization error");
   _get_minstack_func =(GetMinStack)dlsym(RTLD_DEFAULT, "__pthread_get_minstack");
@@ -966,10 +908,7 @@ bool os::create_thread(Thread* thread, ThreadType thr_type,
   // Apply stack size adjustments if needed. However, be careful not to end up
   // with a size of zero due to overflow. Don't add the adjustment in that case.
   size_t stack_adjust_size = 0;
-  if (AdjustStackSizeForTLS) {
-    // Adjust the stack_size for on-stack TLS - see get_static_tls_area_size().
-    stack_adjust_size += get_static_tls_area_size(&attr);
-  } else if (os::Linux::adjustStackSizeForGuardPages()) {
+  if (os::Linux::adjustStackSizeForGuardPages()) {
     stack_adjust_size += guard_size;
   }