*/
#include "PosixSource.h"
#include "Rts.h"
+#include "RtsExternal.h"
#include "RtsUtils.h"
-#include "RtsFlags.h"
#include <stdlib.h>
#if defined(_WIN32)
/* Heavily arch-specific, I'm afraid.. */
+typedef enum {
+ pageExecuteRead,
+ pageExecuteReadWrite
+} pageMode;
+
/*
* Function: execPage()
*
- * Set the executable bit on page containing addr. CURRENTLY DISABLED.
+ * Set the executable bit on page containing addr.
*
* TODO: Can the code span more than one page? If yes, we need to make two
* pages executable!
*/
static rtsBool
-execPage (void* addr, int writable)
+execPage (void* addr, pageMode mode)
{
#if defined(i386_TARGET_ARCH) && defined(_WIN32) && 0
SYSTEM_INFO sInfo;
if ( VirtualProtect ( (void*)((unsigned long)addr & (sInfo.dwPageSize - 1)),
sInfo.dwPageSize,
- ( writable ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ),
+ ( mode == pageExecuteReadWrite ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ),
&dwOldProtect) == 0 ) {
# if 1
DWORD rc = GetLastError();
- fprintf(stderr, "execPage: failed to protect 0x%p; error=%lu; old protection: %lu\n", addr, rc, dwOldProtect);
+ prog_belch("execPage: failed to protect 0x%p; error=%lu; old protection: %lu\n", addr, rc, dwOldProtect);
# endif
return rtsFalse;
}
return rtsTrue;
#else
- (void)addr; (void)writable; /* keep gcc -Wall happy */
+ (void)addr; (void)mode; /* keep gcc -Wall happy */
return rtsTrue;
#endif
}
-
-static unsigned char __obscure_ccall_ret_code [] =
#if defined(i386_TARGET_ARCH)
-/* Now here's something obscure for you:
-
- When generating an adjustor thunk that uses the C calling
- convention, we have to make sure that the thunk kicks off
- the process of jumping into Haskell with a tail jump. Why?
- Because as a result of jumping in into Haskell we may end
- up freeing the very adjustor thunk we came from using
- freeHaskellFunctionPtr(). Hence, we better not return to
- the adjustor code on our way out, since it could by then
- point to junk.
-
- The fix is readily at hand, just include the opcodes
- for the C stack fixup code that we need to perform when
- returning in some static piece of memory and arrange
- to return to it before tail jumping from the adjustor thunk.
-
- For this to work we make the assumption that bytes in .data
- are considered executable.
-*/
- { 0x83, 0xc4, 0x04 /* addl $0x4, %esp */
- , 0xc3 /* ret */
- };
-#else
-/* No such mind-twisters on non-Intel platforms */
- { };
+static unsigned char *obscure_ccall_ret_code;
#endif
#if defined(alpha_TARGET_ARCH)
adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */
adj_code[0x0d] = (unsigned char)0xe0;
- execPage(adjustor,rtsTrue);
+ execPage(adjustor, pageExecuteReadWrite);
}
#endif
break;
<00>: 68 ef be ad de pushl $0xdeadbeef # constant is large enough to
# hold a StgStablePtr
<05>: b8 fa ef ff 00 movl $0x00ffeffa, %eax # load up wptr
- <0a>: 68 ef be ad de pushl $__obscure_ccall_ret_code # push the return address
+ <0a>: 68 ef be ad de pushl $obscure_ccall_ret_code # push the return address
<0f>: ff e0 jmp *%eax # jump to wptr
The ccall'ing version is a tad different, passing in the return
via the stable pointer.) (The auto-generated C stub is in on this
game, don't worry :-)
- See the comment next to __obscure_ccall_ret_code why we need to
+ See the comment next to obscure_ccall_ret_code why we need to
perform a tail jump instead of a call, followed by some C stack
fixup.
adj_code[0x05] = (unsigned char)0xb8; /* movl $wptr, %eax */
*((StgFunPtr*)(adj_code + 0x06)) = (StgFunPtr)wptr;
- adj_code[0x0a] = (unsigned char)0x68; /* pushl __obscure_ccall_ret_code */
- *((StgFunPtr*)(adj_code + 0x0b)) = (StgFunPtr)__obscure_ccall_ret_code;
+ adj_code[0x0a] = (unsigned char)0x68; /* pushl obscure_ccall_ret_code */
+ *((StgFunPtr*)(adj_code + 0x0b)) = (StgFunPtr)obscure_ccall_ret_code;
adj_code[0x0f] = (unsigned char)0xff; /* jmp *%eax */
adj_code[0x10] = (unsigned char)0xe0;
- execPage(adjustor,rtsTrue);
+ execPage(adjustor, pageExecuteReadWrite);
}
#elif defined(sparc_TARGET_ARCH)
/* Magic constant computed by inspecting the code length of the following
#if defined(i386_TARGET_ARCH)
if ( *(unsigned char*)ptr != 0x68 &&
*(unsigned char*)ptr != 0x58 ) {
- fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
return;
}
}
#elif defined(sparc_TARGET_ARCH)
if ( *(unsigned long*)ptr != 0x9C23A008UL ) {
- fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
return;
}
freeStablePtr(*((StgStablePtr*)((unsigned long*)ptr + 11)));
#elif defined(alpha_TARGET_ARCH)
if ( *(StgWord64*)ptr != 0xa77b0018a61b0010L ) {
- fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
return;
}
freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x10)));
#elif defined(powerpc_TARGET_ARCH)
if ( *(StgWord*)ptr != 0x7d0a4378 ) {
- fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
return;
}
freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 4*12)));
StgWord64 *code = (StgWord64 *)(fdesc+1);
if (fdesc->ip != (StgWord64)code) {
- fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
return;
}
freeStablePtr((StgStablePtr)code[16]);
* Function: initAdjustor()
*
* Perform initialisation of adjustor thunk layer (if needed.)
- *
- * TODO: Call this at RTS initialisation time.
*/
rtsBool
initAdjustor(void)
{
- return execPage(__obscure_ccall_ret_code, rtsFalse);
+#if defined(i386_TARGET_ARCH)
+ /* Now here's something obscure for you:
+
+ When generating an adjustor thunk that uses the C calling
+ convention, we have to make sure that the thunk kicks off
+ the process of jumping into Haskell with a tail jump. Why?
+ Because as a result of jumping in into Haskell we may end
+ up freeing the very adjustor thunk we came from using
+ freeHaskellFunctionPtr(). Hence, we better not return to
+ the adjustor code on our way out, since it could by then
+ point to junk.
+
+ The fix is readily at hand, just include the opcodes
+ for the C stack fixup code that we need to perform when
+ returning in some static piece of memory and arrange
+ to return to it before tail jumping from the adjustor thunk.
+ */
+
+ obscure_ccall_ret_code = stgMallocBytes(4, "initAdjustor");
+
+ 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
+ return rtsTrue;
}
projects / ghc-hetmet.git / blobdiff