Blame SOURCES/8197429-pr3456-rh1536622.patch

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diff -r eecfc14e66ee src/os/linux/vm/os_linux.cpp
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--- openjdk/hotspot/src/os/linux/vm/os_linux.cpp	Mon Jan 22 16:25:24 2018 +0000
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+++ openjdk/hotspot/src/os/linux/vm/os_linux.cpp	Wed Feb 21 13:52:31 2018 +0000
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@@ -1,5 +1,5 @@
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 /*
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- * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  *
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  * This code is free software; you can redistribute it and/or modify it
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@@ -674,6 +674,10 @@
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   }
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 }
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+void os::Linux::expand_stack_to(address bottom) {
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+  _expand_stack_to(bottom);
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+}
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+
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 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
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   assert(t!=NULL, "just checking");
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   assert(t->osthread()->expanding_stack(), "expand should be set");
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diff -r eecfc14e66ee src/os/linux/vm/os_linux.hpp
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--- openjdk/hotspot/src/os/linux/vm/os_linux.hpp	Mon Jan 22 16:25:24 2018 +0000
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+++ openjdk/hotspot/src/os/linux/vm/os_linux.hpp	Wed Feb 21 13:52:31 2018 +0000
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@@ -1,5 +1,5 @@
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 /*
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- * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  *
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  * This code is free software; you can redistribute it and/or modify it
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@@ -245,6 +245,8 @@
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   static int safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime);
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 private:
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+  static void expand_stack_to(address bottom);
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+
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   typedef int (*sched_getcpu_func_t)(void);
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   typedef int (*numa_node_to_cpus_func_t)(int node, unsigned long *buffer, int bufferlen);
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   typedef int (*numa_max_node_func_t)(void);
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diff -r eecfc14e66ee src/os_cpu/linux_x86/vm/os_linux_x86.cpp
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--- openjdk/hotspot/src/os_cpu/linux_x86/vm/os_linux_x86.cpp	Mon Jan 22 16:25:24 2018 +0000
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+++ openjdk/hotspot/src/os_cpu/linux_x86/vm/os_linux_x86.cpp	Wed Feb 21 13:52:31 2018 +0000
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@@ -1,5 +1,5 @@
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 /*
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- * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  *
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  * This code is free software; you can redistribute it and/or modify it
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@@ -892,6 +892,25 @@
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 void os::workaround_expand_exec_shield_cs_limit() {
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 #if defined(IA32)
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   size_t page_size = os::vm_page_size();
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+
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+  /*
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+   * JDK-8197429
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+   *
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+   * Expand the stack mapping to the end of the initial stack before
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+   * attempting to install the codebuf.  This is needed because newer
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+   * Linux kernels impose a distance of a megabyte between stack
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+   * memory and other memory regions.  If we try to install the
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+   * codebuf before expanding the stack the installation will appear
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+   * to succeed but we'll get a segfault later if we expand the stack
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+   * in Java code.
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+   *
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+   */
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+  if (os::Linux::is_initial_thread()) {
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+    address limit = Linux::initial_thread_stack_bottom();
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+    limit += (StackYellowPages + StackRedPages) * page_size;
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+    os::Linux::expand_stack_to(limit);
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+  }
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+
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   /*
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    * Take the highest VA the OS will give us and exec
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    *
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@@ -910,6 +929,16 @@
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   char* hint = (char*) (Linux::initial_thread_stack_bottom() -
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                         ((StackYellowPages + StackRedPages + 1) * page_size));
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   char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
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+
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+  if (codebuf == NULL) {
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+    // JDK-8197429: There may be a stack gap of one megabyte between
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+    // the limit of the stack and the nearest memory region: this is a
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+    // Linux kernel workaround for CVE-2017-1000364.  If we failed to
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+    // map our codebuf, try again at an address one megabyte lower.
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+    hint -= 1 * M;
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+    codebuf = os::attempt_reserve_memory_at(page_size, hint);
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+  }
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+
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   if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
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     return; // No matter, we tried, best effort.
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   }