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* dll_init.cc (reserve_at, release_at): New functions. 

(load_after_fork): If the DLL was loaded higher than the required address,
assume that it loaded at it's base address and also reserve memory there to
force it to be relocated.
This commit is contained in:
Christopher Faylor 2011-04-06 13:58:00 +00:00
parent 641965646a
commit 8d777a13fc
2 changed files with 68 additions and 11 deletions
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7
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,10 @@
2011-04-06 Jon TURNEY <jon.turney@dronecode.org.uk>
* dll_init.cc (reserve_at, release_at): New functions.
(load_after_fork): If the DLL was loaded higher than the required
address, assume that it loaded at it's base address and also reserve
memory there to force it to be relocated.
2011-04-04 Yaakov Selkowitz <yselkowitz@users.sourceforge.net>
* include/cygwin/types.h: Move #include <sys/sysmacros.h> to

72
winsup/cygwin/dll_init.cc
View File

@ -78,7 +78,7 @@ dll::init ()
/* This should be a no-op. Why didn't we just import this variable? */
if (!p.envptr)
p.envptr = &__cygwin_environ;
else
else if (*(p.envptr) != __cygwin_environ)
*(p.envptr) = __cygwin_environ;
/* Don't run constructors or the "main" if we've forked. */
@ -257,12 +257,44 @@ release_upto (const PWCHAR name, DWORD here)
}
}
/* Mark one page at "here" as reserved. This may force
Windows NT to load a DLL elsewhere. */
static DWORD
reserve_at (const PWCHAR name, DWORD here)
{
DWORD size;
MEMORY_BASIC_INFORMATION mb;
if (!VirtualQuery ((void *) here, &mb, sizeof (mb)))
size = 64 * 1024;
if (mb.State != MEM_FREE)
return 0;
size = mb.RegionSize;
if (!VirtualAlloc ((void *) here, size, MEM_RESERVE, PAGE_NOACCESS))
api_fatal ("couldn't allocate memory %p(%d) for '%W' alignment, %E\n",
here, size, name);
return here;
}
/* Release the memory previously allocated by "reserve_at" above. */
static void
release_at (const PWCHAR name, DWORD here)
{
if (!VirtualFree ((void *) here, 0, MEM_RELEASE))
api_fatal ("couldn't release memory %p for '%W' alignment, %E\n",
here, name);
}
/* Reload DLLs after a fork. Iterates over the list of dynamically loaded
DLLs and attempts to load them in the same place as they were loaded in the
parent. */
void
dll_list::load_after_fork (HANDLE parent)
{
DWORD preferred_block = 0;
for (dll *d = &dlls.start; (d = d->next) != NULL; )
if (d->type == DLL_LOAD)
for (int i = 0; i < 2; i++)
@ -284,10 +316,18 @@ dll_list::load_after_fork (HANDLE parent)
if (h == d->handle)
h = LoadLibraryW (d->name);
}
/* If we reached here on the second iteration of the for loop
then there is a lot of memory to release. */
if (i > 0)
release_upto (d->name, (DWORD) d->handle);
{
release_upto (d->name, (DWORD) d->handle);
if (preferred_block)
release_at (d->name, preferred_block);
preferred_block = 0;
}
if (h == d->handle)
break; /* Success */
@ -297,11 +337,20 @@ dll_list::load_after_fork (HANDLE parent)
d->name, d->handle, h);
/* Dll loaded in the wrong place. Dunno why this happens but it
always seems to happen when there are multiple DLLs attempting to
load into the same address space. In the "forked" process, the
second DLL always loads into a different location. So, block all
of the memory up to the new load address and try again. */
always seems to happen when there are multiple DLLs with the
same base address. In the "forked" process, the relocated DLL
may load at a different address. So, block all of the memory up
to the relocated load address and try again. */
reserve_upto (d->name, (DWORD) d->handle);
/* Also, if the DLL loaded at a higher address than wanted (probably
it's base address), reserve the memory at that address. This can
happen if it couldn't load at the preferred base in the parent, but
can in the child, due to differences in the load ordering.
Block memory at it's preferred address and try again. */
if ((DWORD) h > (DWORD) d->handle)
preferred_block = reserve_at (d->name, (DWORD) h);
}
in_forkee = false;
}
@ -311,7 +360,7 @@ struct dllcrt0_info
HMODULE h;
per_process *p;
int res;
dllcrt0_info (HMODULE h0, per_process *p0): h(h0), p(p0) {}
dllcrt0_info (HMODULE h0, per_process *p0): h (h0), p (p0) {}
};
extern "C" int
@ -329,9 +378,9 @@ dll_dllcrt0 (HMODULE h, per_process *p)
void
dll_dllcrt0_1 (VOID *x)
{
HMODULE& h = ((dllcrt0_info *)x)->h;
per_process*& p = ((dllcrt0_info *)x)->p;
int& res = ((dllcrt0_info *)x)->res;
HMODULE& h = ((dllcrt0_info *) x)->h;
per_process*& p = ((dllcrt0_info *) x)->p;
int& res = ((dllcrt0_info *) x)->res;
if (p == NULL)
p = &__cygwin_user_data;
@ -431,6 +480,7 @@ void __stdcall
update_envptrs ()
{
for (dll *d = dlls.istart (DLL_ANY); d; d = dlls.inext ())
*(d->p.envptr) = __cygwin_environ;
if (*(d->p.envptr) != __cygwin_environ)
*(d->p.envptr) = __cygwin_environ;
*main_environ = __cygwin_environ;
}