File openjdk-6-src-b17-stack-protector.patch of Package java-1_6_0-openjdk
Index: icedtea6-1.7/openjdk/hotspot/src/os/linux/vm/os_linux.cpp
===================================================================
--- icedtea6-1.7.orig/openjdk/hotspot/src/os/linux/vm/os_linux.cpp
+++ icedtea6-1.7/openjdk/hotspot/src/os/linux/vm/os_linux.cpp
@@ -22,6 +22,8 @@
*
*/
+# define __STDC_FORMAT_MACROS
+
// do not include precompiled header file
# include "incls/_os_linux.cpp.incl"
@@ -53,6 +55,8 @@
# include <sys/ipc.h>
# include <sys/shm.h>
# include <link.h>
+# include <stdint.h>
+# include <inttypes.h>
#define MAX_PATH (2 * K)
@@ -2519,6 +2523,91 @@ bool os::uncommit_memory(char* addr, siz
!= MAP_FAILED;
}
+// Linux uses a growable mapping for the stack, and if the mapping for
+// the stack guard pages is not removed when we detach a thread the
+// stack cannot grow beyond the pages where the stack guard was
+// mapped. If at some point later in the process the stack expands to
+// that point, the Linux kernel cannot expand the stack any further
+// because the guard pages are in the way, and a segfault occurs.
+//
+// However, it's essential not to split the stack region by unmapping
+// a region (leaving a hole) that's already part of the stack mapping,
+// so if the stack mapping has already grown beyond the guard pages at
+// the time we create them, we have to truncate the stack mapping.
+// So, we need to know the extent of the stack mapping when
+// create_stack_guard_pages() is called.
+
+// Find the bounds of the stack mapping. Return true for success.
+//
+// We only need this for stacks that are growable: at the time of
+// writing thread stacks don't use growable mappings (i.e. those
+// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
+// only applies to the main thread.
+static bool
+get_stack_bounds(uintptr_t *bottom, uintptr_t *top)
+{
+ FILE *f = fopen("/proc/self/maps", "r");
+ if (f == NULL)
+ return false;
+
+ while (!feof(f)) {
+ size_t dummy;
+ char *str = NULL;
+ ssize_t len = getline(&str, &dummy, f);
+ if (len == -1) {
+ return false;
+ }
+
+ if (len > 0 && str[len-1] == '\n') {
+ str[len-1] = 0;
+ len--;
+ }
+
+ static const char *stack_str = "[stack]";
+ if (len > (ssize_t)strlen(stack_str)
+ && (strcmp(str + len - strlen(stack_str), stack_str)
+ == 0)) {
+ if (sscanf(str, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
+ uintptr_t sp = (uintptr_t)__builtin_frame_address(0);
+ if (sp >= *bottom && sp <= *top) {
+ free(str);
+ return true;
+ }
+ }
+ }
+
+ free(str);
+ }
+
+ return false;
+}
+
+// If the (growable) stack mapping already extends beyond the point
+// 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.
+bool os::create_stack_guard_pages(char* addr, size_t size) {
+ uintptr_t stack_extent, stack_base;
+ if (get_stack_bounds(&stack_extent, &stack_base)) {
+ if (stack_extent < (uintptr_t)addr)
+ ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent);
+ }
+
+ return os::commit_memory(addr, size);
+}
+
+// If this is a growable mapping, remove the guard pages entirely by
+// munmap()ping them. If not, just call uncommit_memory().
+bool os::remove_stack_guard_pages(char* addr, size_t size) {
+ uintptr_t stack_extent, stack_base;
+ if (get_stack_bounds(&stack_extent, &stack_base)) {
+ return ::munmap(addr, size) == 0;
+ }
+
+ return os::uncommit_memory(addr, size);
+}
+
static address _highest_vm_reserved_address = NULL;
// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
Index: icedtea6-1.7/openjdk/hotspot/src/os/solaris/vm/os_solaris.cpp
===================================================================
--- icedtea6-1.7.orig/openjdk/hotspot/src/os/solaris/vm/os_solaris.cpp
+++ icedtea6-1.7/openjdk/hotspot/src/os/solaris/vm/os_solaris.cpp
@@ -2696,6 +2696,14 @@ void os::free_memory(char* addr, size_t
}
}
+bool os::create_stack_guard_pages(char* addr, size_t size) {
+ return os::commit_memory(addr, size);
+}
+
+bool os::remove_stack_guard_pages(char* addr, size_t size) {
+ return os::uncommit_memory(addr, size);
+}
+
// Change the page size in a given range.
void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
assert((intptr_t)addr % alignment_hint == 0, "Address should be aligned.");
Index: icedtea6-1.7/openjdk/hotspot/src/os/windows/vm/os_windows.cpp
===================================================================
--- icedtea6-1.7.orig/openjdk/hotspot/src/os/windows/vm/os_windows.cpp
+++ icedtea6-1.7/openjdk/hotspot/src/os/windows/vm/os_windows.cpp
@@ -2778,6 +2778,14 @@ bool os::release_memory(char* addr, size
return VirtualFree(addr, 0, MEM_RELEASE) != 0;
}
+bool os::create_stack_guard_pages(char* addr, size_t size) {
+ return os::commit_memory(addr, size);
+}
+
+bool os::remove_stack_guard_pages(char* addr, size_t size) {
+ return os::uncommit_memory(addr, size);
+}
+
// Set protections specified
bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
bool is_committed) {
Index: icedtea6-1.7/openjdk/hotspot/src/share/vm/runtime/os.hpp
===================================================================
--- icedtea6-1.7.orig/openjdk/hotspot/src/share/vm/runtime/os.hpp
+++ icedtea6-1.7/openjdk/hotspot/src/share/vm/runtime/os.hpp
@@ -213,6 +213,9 @@ class os: AllStatic {
static bool guard_memory(char* addr, size_t bytes);
static bool unguard_memory(char* addr, size_t bytes);
+ static bool create_stack_guard_pages(char* addr, size_t bytes);
+ static bool remove_stack_guard_pages(char* addr, size_t bytes);
+
static char* map_memory(int fd, const char* file_name, size_t file_offset,
char *addr, size_t bytes, bool read_only = false,
bool allow_exec = false);
Index: icedtea6-1.7/openjdk/hotspot/src/share/vm/runtime/thread.cpp
===================================================================
--- icedtea6-1.7.orig/openjdk/hotspot/src/share/vm/runtime/thread.cpp
+++ icedtea6-1.7/openjdk/hotspot/src/share/vm/runtime/thread.cpp
@@ -2114,7 +2114,7 @@ void JavaThread::create_stack_guard_page
int allocate = os::allocate_stack_guard_pages();
// warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
- if (allocate && !os::commit_memory((char *) low_addr, len)) {
+ if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
warning("Attempt to allocate stack guard pages failed.");
return;
}
@@ -2135,7 +2135,7 @@ void JavaThread::remove_stack_guard_page
size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
if (os::allocate_stack_guard_pages()) {
- if (os::uncommit_memory((char *) low_addr, len)) {
+ if (os::remove_stack_guard_pages((char *) low_addr, len)) {
_stack_guard_state = stack_guard_unused;
} else {
warning("Attempt to deallocate stack guard pages failed.");
