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Cygwin: Allow accessing 48 bit address space in Windows 8.1 or later 

64 bit Windows started out with a 44 bit address space due to a
restriction of the AMD64 CPUs at the time.  Starting with Windows
8.1, these CPUs are not supported anymore and Windows switched to
the full 48 bit address space supported by AMD64.

Cygwin didn't follow suit yet so mmaps are still restricted to
the lower 44 bit address space.  Fix that by using a system-specific
upper address for mmap allocations, 44 bit up to Windows 8, 48 bit
starting with Windows 8.1.

While at it, move the heap by another 8 Gigs to leave some space
for a potential extension of DLL address space, and restrict the
mmap lower address so the heap can grow to 32 Gigs before colliding
with mmaps.
This commit is contained in:
Corinna Vinschen 2019-06-04 16:58:53 +02:00
parent f03ea8e1c5
commit e1254add73
4 changed files with 20 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
winsup/cygwin/heap.cc
View File

@ -34,9 +34,9 @@ eval_start_address ()
executable starts at 0x1:00400000L, the Cygwin DLL starts at
0x1:80040000L, other rebased DLLs are located in the region from
0x2:00000000L up to 0x4:00000000L, -auto-image-based DLLs are located
in the region from 0x4:00000000L up to 0x6:00000000L.
So we let the heap start at 0x6:00000000L. */
uintptr_t start_address = 0x600000000L;
in the region from 0x4:00000000L up to 0x6:00000000L. Leave another
8 Gigs slack space, so lets start the heap at 0x8:00000000L. */
uintptr_t start_address = 0x800000000L;
#else
/* Windows performs heap ASLR. This spoils the entire region below
0x20000000 for us, because that region is used by Windows to randomize

6
winsup/cygwin/mmap.cc
View File

@ -801,8 +801,10 @@ mmap_worker (mmap_list *map_list, fhandler_base *fh, caddr_t base, size_t len,
#ifdef __x86_64__
/* The memory region used for memory maps */
#define MMAP_STORAGE_LOW 0x00800000000L /* Leave 8 Gigs for heap. */
#define MMAP_STORAGE_HIGH 0x70000000000L /* Leave enough room for OS. */
#define MMAP_STORAGE_LOW 0x001000000000L /* Leave 32 Gigs for heap. */
/* Up to Win 8 only supporting 44 bit address space, starting with Win 8.1
48 bit address space. */
#define MMAP_STORAGE_HIGH wincap.mmap_storage_high ()
/* FIXME? Unfortunately the OS doesn't support a top down allocation with
a ceiling value. The ZeroBits mechanism only works for

9
winsup/cygwin/wincap.cc
View File

@ -20,6 +20,7 @@ details. */
wincaps wincap_vista __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:1,
mmap_storage_high:0x070000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:true,
@ -46,6 +47,7 @@ wincaps wincap_vista __attribute__((section (".cygwin_dll_common"), shared)) = {
wincaps wincap_7 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:1,
mmap_storage_high:0x070000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -72,6 +74,7 @@ wincaps wincap_7 __attribute__((section (".cygwin_dll_common"), shared)) = {
wincaps wincap_8 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x070000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -98,6 +101,7 @@ wincaps wincap_8 __attribute__((section (".cygwin_dll_common"), shared)) = {
wincaps wincap_8_1 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -124,6 +128,7 @@ wincaps wincap_8_1 __attribute__((section (".cygwin_dll_common"), shared)) = {
wincaps wincap_10_1507 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -150,6 +155,7 @@ wincaps wincap_10_1507 __attribute__((section (".cygwin_dll_common"), shared))
wincaps wincap_10_1703 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -176,6 +182,7 @@ wincaps wincap_10_1703 __attribute__((section (".cygwin_dll_common"), shared)) =
wincaps wincap_10_1709 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -202,6 +209,7 @@ wincaps wincap_10_1709 __attribute__((section (".cygwin_dll_common"), shared)) =
wincaps wincap_10_1803 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,
@ -228,6 +236,7 @@ wincaps wincap_10_1803 __attribute__((section (".cygwin_dll_common"), shared)) =
wincaps wincap_10_1809 __attribute__((section (".cygwin_dll_common"), shared)) = {
def_guard_pages:2,
mmap_storage_high:0x700000000000LL,
{
is_server:false,
needs_count_in_si_lpres2:false,

4
winsup/cygwin/wincap.h
View File

@ -12,6 +12,7 @@ details. */
struct wincaps
{
DWORD def_guard_pages;
int64_t mmap_storage_high;
/* The bitfields must be 8 byte aligned on x86_64, otherwise the bitfield
ops generated by gcc are off by 4 bytes. */
struct __attribute__ ((aligned (8))) {
@ -71,6 +72,9 @@ public:
{
return ((wincaps *) this->caps)->def_guard_pages * page_size ();
}
#ifdef __x86_64__
intptr_t IMPLEMENT (mmap_storage_high)
#endif
bool IMPLEMENT (is_server)
bool IMPLEMENT (needs_count_in_si_lpres2)
bool IMPLEMENT (needs_query_information)