graal-compiler: src/share/vm/runtime/virtualspace.cpp comparison

comparison src/share/vm/runtime/virtualspace.cpp @ 237:1fdb98a17101

6716785: implicit null checks not triggering with CompressedOops Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check Reviewed-by: kvn, jmasa, phh, jcoomes

author	coleenp
date	Sat, 19 Jul 2008 17:38:22 -0400
parents	a61af66fc99e
children	93befa083681 1ee8caae33af

comparison

equal deleted inserted replaced

-:9c2ecc2ffb12
+:1fdb98a17101
 #include "incls/_virtualspace.cpp.incl"
 // ReservedSpace
 ReservedSpace::ReservedSpace(size_t size) {
-initialize(size, 0, false, NULL);
+initialize(size, 0, false, NULL, 0);
 }
 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
-bool large, char* requested_address) {
+bool large,
-initialize(size, alignment, large, requested_address);
+char* requested_address,
+const size_t noaccess_prefix) {
+initialize(size+noaccess_prefix, alignment, large, requested_address,
+noaccess_prefix);
 }
 char *
 ReservedSpace::align_reserved_region(char* addr, const size_t len,
 const size_t prefix_size,
 }
 ReservedSpace::ReservedSpace(const size_t prefix_size,
 const size_t prefix_align,
 const size_t suffix_size,
-const size_t suffix_align)
+const size_t suffix_align,
+const size_t noaccess_prefix)
 {
 assert(prefix_size != 0, "sanity");
 assert(prefix_align != 0, "sanity");
 assert(suffix_size != 0, "sanity");
 assert(suffix_align != 0, "sanity");
 assert((suffix_size & suffix_align - 1) == 0,
 "suffix_size not divisible by suffix_align");
 assert((suffix_align & prefix_align - 1) == 0,
 "suffix_align not divisible by prefix_align");
+// Add in noaccess_prefix to prefix_size;
+const size_t adjusted_prefix_size = prefix_size + noaccess_prefix;
+const size_t size = adjusted_prefix_size + suffix_size;
 // On systems where the entire region has to be reserved and committed up
 // front, the compound alignment normally done by this method is unnecessary.
 const bool try_reserve_special = UseLargePages &&
 prefix_align == os::large_page_size();
 if (!os::can_commit_large_page_memory() && try_reserve_special) {
-initialize(prefix_size + suffix_size, prefix_align, true);
+initialize(size, prefix_align, true, NULL, noaccess_prefix);
 return;
 }
 _base = NULL;
 _size = 0;
 _alignment = 0;
 _special = false;
+_noaccess_prefix = 0;
+// Assert that if noaccess_prefix is used, it is the same as prefix_align.
+assert(noaccess_prefix == 0 ||
+noaccess_prefix == prefix_align, "noaccess prefix wrong");
 // Optimistically try to reserve the exact size needed.
-const size_t size = prefix_size + suffix_size;
 char* addr = os::reserve_memory(size, NULL, prefix_align);
 if (addr == NULL) return;
 // Check whether the result has the needed alignment (unlikely unless
 // prefix_align == suffix_align).
-const size_t ofs = size_t(addr) + prefix_size & suffix_align - 1;
+const size_t ofs = size_t(addr) + adjusted_prefix_size & suffix_align - 1;
 if (ofs != 0) {
 // Wrong alignment.  Release, allocate more space and do manual alignment.
 //
 // On most operating systems, another allocation with a somewhat larger size
 // will return an address "close to" that of the previous allocation.  The
 if (!os::release_memory(addr, size)) {
 fatal("os::release_memory failed");
 }
 const size_t extra = MAX2(ofs, suffix_align - ofs);
-addr = reserve_and_align(size + extra, prefix_size, prefix_align,
+addr = reserve_and_align(size + extra, adjusted_prefix_size, prefix_align,
 suffix_size, suffix_align);
 if (addr == NULL) {
 // Try an even larger region.  If this fails, address space is exhausted.
-addr = reserve_and_align(size + suffix_align, prefix_size,
+addr = reserve_and_align(size + suffix_align, adjusted_prefix_size,
 prefix_align, suffix_size, suffix_align);
 }
 }
 _base = addr;
 _size = size;
 _alignment = prefix_align;
+_noaccess_prefix = noaccess_prefix;
 }
 void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
-char* requested_address) {
+char* requested_address,
+const size_t noaccess_prefix) {
 const size_t granularity = os::vm_allocation_granularity();
 assert((size & granularity - 1) == 0,
 "size not aligned to os::vm_allocation_granularity()");
 assert((alignment & granularity - 1) == 0,
 "alignment not aligned to os::vm_allocation_granularity()");
 _base = NULL;
 _size = 0;
 _special = false;
 _alignment = 0;
+_noaccess_prefix = 0;
 if (size == 0) {
 return;
 }
 // If OS doesn't support demand paging for large page memory, we need
 // If the memory was requested at a particular address, use
 // os::attempt_reserve_memory_at() to avoid over mapping something
 // important.  If available space is not detected, return NULL.
 if (requested_address != 0) {
-base = os::attempt_reserve_memory_at(size, requested_address);
+base = os::attempt_reserve_memory_at(size,
+requested_address-noaccess_prefix);
 } else {
 base = os::reserve_memory(size, NULL, alignment);
 }
 if (base == NULL) return;
 }
 // Done
 _base = base;
 _size = size;
 _alignment = MAX2(alignment, (size_t) os::vm_page_size());
+_noaccess_prefix = noaccess_prefix;
+// Assert that if noaccess_prefix is used, it is the same as alignment.
+assert(noaccess_prefix == 0 ||
+noaccess_prefix == _alignment, "noaccess prefix wrong");
 assert(markOopDesc::encode_pointer_as_mark(_base)->decode_pointer() == _base,
 "area must be distinguisable from marks for mark-sweep");
 assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size],
 "area must be distinguisable from marks for mark-sweep");
 assert((size % os::vm_allocation_granularity()) == 0,
 "size not allocation aligned");
 _base = base;
 _size = size;
 _alignment = alignment;
+_noaccess_prefix = 0;
 _special = special;
 }
 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment,
 }
 void ReservedSpace::release() {
 if (is_reserved()) {
+char *real_base = _base - _noaccess_prefix;
+const size_t real_size = _size + _noaccess_prefix;
 if (special()) {
-os::release_memory_special(_base, _size);
+os::release_memory_special(real_base, real_size);
 } else{
-os::release_memory(_base, _size);
+os::release_memory(real_base, real_size);
 }
 _base = NULL;
 _size = 0;
+_noaccess_prefix = 0;
 _special = false;
 }
 }
+void ReservedSpace::protect_noaccess_prefix(const size_t size) {
+// If there is noaccess prefix, return.
+if (_noaccess_prefix == 0) return;
+assert(_noaccess_prefix >= (size_t)os::vm_page_size(),
+"must be at least page size big");
+// Protect memory at the base of the allocated region.
+// If special, the page was committed (only matters on windows)
+if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE,
+_special)) {
+fatal("cannot protect protection page");
+}
+_base += _noaccess_prefix;
+_size -= _noaccess_prefix;
+assert((size == _size) && ((uintptr_t)_base % _alignment == 0),
+"must be exactly of required size and alignment");
+}
+ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment,
+bool large, char* requested_address) :
+ReservedSpace(size, alignment, large,
+requested_address,
+UseCompressedOops ? lcm(os::vm_page_size(), alignment) : 0) {
+// Only reserved space for the java heap should have a noaccess_prefix
+// if using compressed oops.
+protect_noaccess_prefix(size);
+}
+ReservedHeapSpace::ReservedHeapSpace(const size_t prefix_size,
+const size_t prefix_align,
+const size_t suffix_size,
+const size_t suffix_align) :
+ReservedSpace(prefix_size, prefix_align, suffix_size, suffix_align,
+UseCompressedOops ? lcm(os::vm_page_size(), prefix_align) : 0) {
+protect_noaccess_prefix(prefix_size+suffix_size);
+}
 // VirtualSpace
 VirtualSpace::VirtualSpace() {
 _low_boundary           = NULL;
 _middle_high_boundary   = NULL;
 _upper_high_boundary    = NULL;
 _lower_alignment        = 0;
 _middle_alignment       = 0;
 _upper_alignment        = 0;
+_special                = false;
 }
 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
 if(!rs.is_reserved()) return false;  // allocation failed.
 release();
 }
 void VirtualSpace::release() {
-(void)os::release_memory(low_boundary(), reserved_size());
+// This does not release memory it never reserved.
+// Caller must release via rs.release();
 _low_boundary           = NULL;
 _high_boundary          = NULL;
 _low                    = NULL;
 _high                   = NULL;
 _lower_high             = NULL;

Mercurial > hg > graal-compiler

comparison src/share/vm/runtime/virtualspace.cpp @ 237:1fdb98a17101