the code is through with it, it has to be freed in order to release Haskell
and C resources. Failure to do so result in memory leaks on both the C and
Haskell side.
-
*/
+
#include "PosixSource.h"
#include "Rts.h"
#include "RtsExternal.h"
#if defined(openbsd_TARGET_OS)
#include <unistd.h>
+#include <sys/types.h>
#include <sys/mman.h>
+
+/* no C99 header stdint.h on OpenBSD? */
+typedef unsigned long my_uintptr_t;
#endif
/* Heavily arch-specific, I'm afraid.. */
-typedef enum {
- pageExecuteRead,
- pageExecuteReadWrite
-} pageMode;
-
/*
- * Function: execPage()
- *
- * Set the executable bit on page containing addr.
+ * Allocate len bytes which are readable, writable, and executable.
*
- * TODO: Can the code span more than one page? If yes, we need to make two
- * pages executable!
+ * ToDo: If this turns out to be a performance bottleneck, one could
+ * e.g. cache the last VirtualProtect/mprotect-ed region and do
+ * nothing in case of a cache hit.
*/
-static void
-execPage (void* addr, pageMode mode)
+static void*
+mallocBytesRWX(int len)
{
-#if defined(i386_TARGET_ARCH) && defined(_WIN32) && 0
- SYSTEM_INFO sInfo;
- DWORD dwOldProtect = 0;
-
- /* doesn't return a result, so presumably it can't fail... */
- GetSystemInfo(&sInfo);
-
- if ( VirtualProtect ( (void*)((unsigned long)addr & (sInfo.dwPageSize - 1)),
- sInfo.dwPageSize,
- ( mode == pageExecuteReadWrite ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ),
- &dwOldProtect) == 0 ) {
- DWORD rc = GetLastError();
- barf("execPage: failed to protect 0x%p; error=%lu; old protection: %lu\n", addr, rc, dwOldProtect);
- }
-#else
-
-#if defined(openbsd_TARGET_OS)
- /* malloc memory isn't executable by default on OpenBSD */
- unsigned long pagesize = sysconf(_SC_PAGESIZE);
- unsigned long round = (unsigned long)addr & (pagesize - 1);
- if (mprotect(addr - round, pagesize, PROT_EXEC|PROT_READ|PROT_WRITE) == -1)
- barf("execPage: failed to protect 0x%p\n", addr);
-#endif
-
- (void)addr; (void)mode; /* keep gcc -Wall happy */
+ void *addr = stgMallocBytes(len, "mallocBytesRWX");
+#if defined(i386_TARGET_ARCH) && defined(_WIN32)
+ /* This could be necessary for processors which distinguish between READ and
+ EXECUTE memory accesses, e.g. Itaniums. */
+ DWORD dwOldProtect = 0;
+ if (VirtualProtect (addr, len, PAGE_EXECUTE_READWRITE, &dwOldProtect) == 0) {
+ barf("mallocBytesRWX: failed to protect 0x%p; error=%lu; old protection: %lu\n",
+ addr, (unsigned long)GetLastError(), (unsigned long)dwOldProtect);
+ }
+#elif defined(openbsd_TARGET_OS)
+ /* malloced memory isn't executable by default on OpenBSD */
+ my_uintptr_t pageSize = sysconf(_SC_PAGESIZE);
+ my_uintptr_t mask = ~(pageSize - 1);
+ my_uintptr_t startOfFirstPage = ((my_uintptr_t)addr ) & mask;
+ my_uintptr_t startOfLastPage = ((my_uintptr_t)addr + len - 1) & mask;
+ my_uintptr_t size = startOfLastPage - startOfFirstPage + pageSize;
+ if (mprotect((void*)startOfFirstPage, (size_t)size, PROT_EXEC | PROT_READ | PROT_WRITE) != 0) {
+ barf("mallocBytesRWX: failed to protect 0x%p\n", addr);
+ }
#endif
+ return addr;
}
#if defined(i386_TARGET_ARCH)
<c>: ff e0 jmp %eax # and jump to it.
# the callee cleans up the stack
*/
- adjustor = stgMallocBytes(14, "createAdjustor");
+ adjustor = mallocBytesRWX(14);
{
unsigned char *const adj_code = (unsigned char *)adjustor;
adj_code[0x00] = (unsigned char)0x58; /* popl %eax */
adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */
adj_code[0x0d] = (unsigned char)0xe0;
-
- execPage(adjustor, pageExecuteReadWrite);
}
#endif
break;
That's (thankfully) the case here with the restricted set of
return types that we support.
*/
- adjustor = stgMallocBytes(17, "createAdjustor");
+ adjustor = mallocBytesRWX(17);
{
unsigned char *const adj_code = (unsigned char *)adjustor;
adj_code[0x0f] = (unsigned char)0xff; /* jmp *%eax */
adj_code[0x10] = (unsigned char)0xe0;
-
- execPage(adjustor, pageExecuteReadWrite);
}
#elif defined(sparc_TARGET_ARCH)
/* Magic constant computed by inspecting the code length of the following
similarly, and local variables should be accessed via %fp, not %sp. In a
nutshell: This should work! (Famous last words! :-)
*/
- adjustor = stgMallocBytes(4*(11+1), "createAdjustor");
+ adjustor = mallocBytesRWX(4*(11+1));
{
unsigned long *const adj_code = (unsigned long *)adjustor;
4 bytes (getting rid of the nop), hence saving memory. [ccshan]
*/
ASSERT(((StgWord64)wptr & 3) == 0);
- adjustor = stgMallocBytes(48, "createAdjustor");
+ adjustor = mallocBytesRWX(48);
{
StgWord64 *const code = (StgWord64 *)adjustor;
this code, it only works for up to 6 arguments (when floating point arguments
are involved, this may be more or less, depending on the exact situation).
*/
- adjustor = stgMallocBytes(4*13, "createAdjustor");
+ adjustor = mallocBytesRWX(4*13);
{
unsigned long *const adj_code = (unsigned long *)adjustor;
to return to it before tail jumping from the adjustor thunk.
*/
- obscure_ccall_ret_code = stgMallocBytes(4, "initAdjustor");
+ obscure_ccall_ret_code = mallocBytesRWX(4);
obscure_ccall_ret_code[0x00] = (unsigned char)0x83; /* addl $0x4, %esp */
obscure_ccall_ret_code[0x01] = (unsigned char)0xc4;
obscure_ccall_ret_code[0x02] = (unsigned char)0x04;
obscure_ccall_ret_code[0x03] = (unsigned char)0xc3; /* ret */
-
- execPage(obscure_ccall_ret_code, pageExecuteRead);
#endif
}
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