Mercurial > jdk8-mips64-public > hotspot / changeset

     1.1 --- a/src/os/linux/vm/os_linux.cpp	Thu Dec 15 20:00:01 2016 -0500
     1.2 +++ b/src/os/linux/vm/os_linux.cpp	Tue Dec 20 16:06:10 2016 -0500
     1.3 @@ -1075,29 +1075,30 @@
     1.4  
     1.5  // Locate initial thread stack. This special handling of initial thread stack
     1.6  // is needed because pthread_getattr_np() on most (all?) Linux distros returns
     1.7 -// bogus value for initial thread.
     1.8 +// bogus value for the primordial process thread. While the launcher has created
     1.9 +// the VM in a new thread since JDK 6, we still have to allow for the use of the
    1.10 +// JNI invocation API from a primordial thread.
    1.11  void os::Linux::capture_initial_stack(size_t max_size) {
    1.12 -  // stack size is the easy part, get it from RLIMIT_STACK
    1.13 -  size_t stack_size;
    1.14 +
    1.15 +  // max_size is either 0 (which means accept OS default for thread stacks) or
    1.16 +  // a user-specified value known to be at least the minimum needed. If we
    1.17 +  // are actually on the primordial thread we can make it appear that we have a
    1.18 +  // smaller max_size stack by inserting the guard pages at that location. But we
    1.19 +  // cannot do anything to emulate a larger stack than what has been provided by
    1.20 +  // the OS or threading library. In fact if we try to use a stack greater than
    1.21 +  // what is set by rlimit then we will crash the hosting process.
    1.22 +
    1.23 +  // Maximum stack size is the easy part, get it from RLIMIT_STACK.
    1.24 +  // If this is "unlimited" then it will be a huge value.
    1.25    struct rlimit rlim;
    1.26    getrlimit(RLIMIT_STACK, &rlim);
    1.27 -  stack_size = rlim.rlim_cur;
    1.28 +  size_t stack_size = rlim.rlim_cur;
    1.29  
    1.30    // 6308388: a bug in ld.so will relocate its own .data section to the
    1.31    //   lower end of primordial stack; reduce ulimit -s value a little bit
    1.32    //   so we won't install guard page on ld.so's data section.
    1.33    stack_size -= 2 * page_size();
    1.34  
    1.35 -  // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
    1.36 -  //   7.1, in both cases we will get 2G in return value.
    1.37 -  // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
    1.38 -  //   SuSE 7.2, Debian) can not handle alternate signal stack correctly
    1.39 -  //   for initial thread if its stack size exceeds 6M. Cap it at 2M,
    1.40 -  //   in case other parts in glibc still assumes 2M max stack size.
    1.41 -  // FIXME: alt signal stack is gone, maybe we can relax this constraint?
    1.42 -  // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
    1.43 -  if (stack_size > 2 * K * K IA64_ONLY(*2))
    1.44 -      stack_size = 2 * K * K IA64_ONLY(*2);
    1.45    // Try to figure out where the stack base (top) is. This is harder.
    1.46    //
    1.47    // When an application is started, glibc saves the initial stack pointer in
    1.48 @@ -1257,14 +1258,18 @@
    1.49    // stack_top could be partially down the page so align it
    1.50    stack_top = align_size_up(stack_top, page_size());
    1.51  
    1.52 -  if (max_size && stack_size > max_size) {
    1.53 -     _initial_thread_stack_size = max_size;
    1.54 +  // Allowed stack value is minimum of max_size and what we derived from rlimit
    1.55 +  if (max_size > 0) {
    1.56 +    _initial_thread_stack_size = MIN2(max_size, stack_size);
    1.57    } else {
    1.58 -     _initial_thread_stack_size = stack_size;
    1.59 +    // Accept the rlimit max, but if stack is unlimited then it will be huge, so
    1.60 +    // clamp it at 8MB as we do on Solaris
    1.61 +    _initial_thread_stack_size = MIN2(stack_size, 8*M);
    1.62    }
    1.63  
    1.64    _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
    1.65    _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
    1.66 +  assert(_initial_thread_stack_bottom < (address)stack_top, "overflow!");
    1.67  }
    1.68  
    1.69  ////////////////////////////////////////////////////////////////////////////////