[project @ 2005-07-09 00:13:14 by igloo]
[ghc-hetmet.git] / ghc / rts / Adjustor.c
index 387d792..0c45f8c 100644 (file)
@@ -46,16 +46,21 @@ Haskell side.
 #include <windows.h>
 #endif
 
-#if defined(openbsd_TARGET_OS)
+#if defined(openbsd_HOST_OS) || defined(linux_HOST_OS)
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/mman.h>
 
 /* no C99 header stdint.h on OpenBSD? */
+#if defined(openbsd_HOST_OS)
 typedef unsigned long my_uintptr_t;
+#else
+#include <stdint.h>
+typedef uintptr_t my_uintptr_t;
+#endif
 #endif
 
-#if defined(powerpc_TARGET_ARCH) && defined(linux_TARGET_OS)
+#if defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS)
 #include <string.h>
 #endif
 
@@ -72,7 +77,7 @@ static void*
 mallocBytesRWX(int len)
 {
   void *addr = stgMallocBytes(len, "mallocBytesRWX");
-#if defined(i386_TARGET_ARCH) && defined(_WIN32)
+#if defined(i386_HOST_ARCH) && defined(_WIN32)
   /* This could be necessary for processors which distinguish between READ and
      EXECUTE memory accesses, e.g. Itaniums. */
   DWORD dwOldProtect = 0;
@@ -80,7 +85,7 @@ mallocBytesRWX(int len)
     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)
+#elif defined(openbsd_HOST_OS) || defined(linux_HOST_OS)
   /* malloced memory isn't executable by default on OpenBSD */
   my_uintptr_t pageSize         = sysconf(_SC_PAGESIZE);
   my_uintptr_t mask             = ~(pageSize - 1);
@@ -94,20 +99,69 @@ mallocBytesRWX(int len)
   return addr;
 }
 
-#if defined(i386_TARGET_ARCH)
-static unsigned char *obscure_ccall_ret_code;
+#ifdef LEADING_UNDERSCORE
+#define UNDERSCORE "_"
+#else 
+#define UNDERSCORE ""
+#endif
+#if defined(i386_HOST_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.
+*/
+static void  GNUC3_ATTRIBUTE(used) obscure_ccall_wrapper(void)
+{
+  __asm__ (
+     ".globl " UNDERSCORE "obscure_ccall_ret_code\n"
+     UNDERSCORE "obscure_ccall_ret_code:\n\t"
+     "addl $0x4, %esp\n\t"
+     "ret"
+   );
+}
+extern void obscure_ccall_ret_code(void);
+
+#if defined(openbsd_HOST_OS)
+static unsigned char *obscure_ccall_ret_code_dyn;
+#endif
+
+#endif
+
+#if defined(x86_64_HOST_ARCH)
+static void GNUC3_ATTRIBUTE(used) obscure_ccall_wrapper(void)
+{
+  __asm__ (
+   ".globl " UNDERSCORE "obscure_ccall_ret_code\n"
+   UNDERSCORE "obscure_ccall_ret_code:\n\t"
+   "addq $0x8, %rsp\n\t"
+   "ret"
+  );
+}
+extern void obscure_ccall_ret_code(void);
 #endif
 
-#if defined(alpha_TARGET_ARCH)
+#if defined(alpha_HOST_ARCH)
 /* To get the definition of PAL_imb: */
-# if defined(linux_TARGET_OS)
+# if defined(linux_HOST_OS)
 #  include <asm/pal.h>
 # else
 #  include <machine/pal.h>
 # endif
 #endif
 
-#if defined(ia64_TARGET_ARCH)
+#if defined(ia64_HOST_ARCH)
 #include "Storage.h"
 
 /* Layout of a function descriptor */
@@ -134,11 +188,11 @@ stgAllocStable(size_t size_in_bytes, StgStablePtr *stable)
   *stable = getStablePtr((StgPtr)arr);
 
   /* and return a ptr to the goods inside the array */
-  return(BYTE_ARR_CTS(arr));
+  return(&(arr->payload));
 }
 #endif
 
-#if defined(powerpc_TARGET_ARCH) && defined(linux_TARGET_OS)
+#if defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS)
 __asm__("obscure_ccall_ret_code:\n\t"
         "lwz 1,0(1)\n\t"
         "lwz 0,4(1)\n\t"
@@ -147,8 +201,8 @@ __asm__("obscure_ccall_ret_code:\n\t"
 extern void obscure_ccall_ret_code(void);
 #endif
 
-#if defined(powerpc_TARGET_ARCH) || defined(powerpc64_TARGET_ARCH)
-#if !(defined(powerpc_TARGET_ARCH) && defined(linux_TARGET_OS))
+#if defined(powerpc_HOST_ARCH) || defined(powerpc64_HOST_ARCH)
+#if !(defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS))
 
 /* !!! !!! WARNING: !!! !!!
  * This structure is accessed from AdjustorAsm.s
@@ -156,14 +210,14 @@ extern void obscure_ccall_ret_code(void);
  */
 
 typedef struct AdjustorStub {
-#if defined(powerpc_TARGET_ARCH) && defined(darwin_TARGET_OS)
+#if defined(powerpc_HOST_ARCH) && defined(darwin_HOST_OS)
     unsigned        lis;
     unsigned        ori;
     unsigned        lwz;
     unsigned        mtctr;
     unsigned        bctr;
     StgFunPtr       code;
-#elif defined(powerpc64_TARGET_ARCH) && defined(darwin_TARGET_OS)
+#elif defined(powerpc64_HOST_ARCH) && defined(darwin_HOST_OS)
         /* powerpc64-darwin: just guessing that it won't use fundescs. */
     unsigned        lis;
     unsigned        ori;
@@ -192,14 +246,20 @@ typedef struct AdjustorStub {
 #endif
 
 void*
-createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr, char *typeString)
+createAdjustor(int cconv, StgStablePtr hptr,
+              StgFunPtr wptr,
+              char *typeString
+#if !defined(powerpc_HOST_ARCH) && !defined(powerpc64_HOST_ARCH) && !defined(x86_64_HOST_ARCH)
+                 STG_UNUSED
+#endif
+              )
 {
   void *adjustor = NULL;
 
   switch (cconv)
   {
   case 0: /* _stdcall */
-#if defined(i386_TARGET_ARCH)
+#if defined(i386_HOST_ARCH)
     /* Magic constant computed by inspecting the code length of
        the following assembly language snippet
        (offset and machine code prefixed):
@@ -232,7 +292,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr, char *typeString)
     break;
 
   case 1: /* _ccall */
-#if defined(i386_TARGET_ARCH)
+#if defined(i386_HOST_ARCH)
   /* Magic constant computed by inspecting the code length of
      the following assembly language snippet
      (offset and machine code prefixed):
@@ -268,12 +328,122 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr, char *typeString)
        *((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;
+       *((StgFunPtr*)(adj_code + 0x0b)) = 
+#if !defined(openbsd_HOST_OS)
+                       (StgFunPtr)obscure_ccall_ret_code;
+#else
+                       (StgFunPtr)obscure_ccall_ret_code_dyn;
+#endif
 
        adj_code[0x0f] = (unsigned char)0xff; /* jmp *%eax */
        adj_code[0x10] = (unsigned char)0xe0; 
     }
-#elif defined(sparc_TARGET_ARCH)
+#elif defined(x86_64_HOST_ARCH)
+    /*
+      stack at call:
+               argn
+              ...
+              arg7
+               return address
+              %rdi,%rsi,%rdx,%rcx,%r8,%r9 = arg0..arg6
+
+      if there are <6 integer args, then we can just push the
+      StablePtr into %edi and shuffle the other args up.
+
+      If there are >=6 integer args, then we have to flush one arg
+      to the stack, and arrange to adjust the stack ptr on return.
+      The stack will be rearranged to this:
+
+             argn
+            ...
+            arg7
+            return address  *** <-- dummy arg in stub fn.
+            arg6
+            obscure_ccall_ret_code
+
+      This unfortunately means that the type of the stub function
+      must have a dummy argument for the original return address
+      pointer inserted just after the 6th integer argument.
+
+      Code for the simple case:
+
+   0:   4d 89 c1                mov    %r8,%r9
+   3:   49 89 c8                mov    %rcx,%r8
+   6:   48 89 d1                mov    %rdx,%rcx
+   9:   48 89 f2                mov    %rsi,%rdx
+   c:   48 89 fe                mov    %rdi,%rsi
+   f:   48 8b 3d 0a 00 00 00    mov    10(%rip),%rdi
+  16:   e9 00 00 00 00          jmpq   stub_function
+  ... 
+  20: .quad 0  # aligned on 8-byte boundary
+
+
+  And the version for >=6 integer arguments:
+
+   0:   41 51                   push   %r9
+   2:   68 00 00 00 00          pushq  $obscure_ccall_ret_code
+   7:   4d 89 c1                mov    %r8,%r9
+   a:   49 89 c8                mov    %rcx,%r8
+   d:   48 89 d1                mov    %rdx,%rcx
+  10:   48 89 f2                mov    %rsi,%rdx
+  13:   48 89 fe                mov    %rdi,%rsi
+  16:   48 8b 3d 0b 00 00 00    mov    11(%rip),%rdi
+  1d:   e9 00 00 00 00          jmpq   stub_function
+  ...
+  28: .quad 0  # aligned on 8-byte boundary
+    */
+
+    /* we assume the small code model (gcc -mcmmodel=small) where
+     * all symbols are <2^32, so hence wptr should fit into 32 bits.
+     */
+    ASSERT(((long)wptr >> 32) == 0);
+
+    {  
+       int i = 0;
+       char *c;
+
+       // determine whether we have 6 or more integer arguments,
+       // and therefore need to flush one to the stack.
+       for (c = typeString; *c != '\0'; c++) {
+           if (*c == 'i' || *c == 'l') i++;
+           if (i == 6) break;
+       }
+
+       if (i < 6) {
+           adjustor = mallocBytesRWX(40);
+
+           *(StgInt32 *)adjustor      = 0x49c1894d;
+           *(StgInt32 *)(adjustor+4)  = 0x8948c889;
+           *(StgInt32 *)(adjustor+8)  = 0xf28948d1;
+           *(StgInt32 *)(adjustor+12) = 0x48fe8948;
+           *(StgInt32 *)(adjustor+16) = 0x000a3d8b;
+           *(StgInt32 *)(adjustor+20) = 0x00e90000;
+           
+           *(StgInt32 *)(adjustor+23) = 
+               (StgInt32)((StgInt64)wptr - (StgInt64)adjustor - 27);
+           *(StgInt64 *)(adjustor+32) = (StgInt64)hptr;
+       }
+       else
+       {
+           adjustor = mallocBytesRWX(48);
+
+           *(StgInt32 *)adjustor      = 0x00685141;
+           *(StgInt32 *)(adjustor+4)  = 0x4d000000;
+           *(StgInt32 *)(adjustor+8)  = 0x8949c189;
+           *(StgInt32 *)(adjustor+12) = 0xd18948c8;
+           *(StgInt32 *)(adjustor+16) = 0x48f28948;
+           *(StgInt32 *)(adjustor+20) = 0x8b48fe89;
+           *(StgInt32 *)(adjustor+24) = 0x00000b3d;
+           *(StgInt32 *)(adjustor+28) = 0x0000e900;
+           
+           *(StgInt32 *)(adjustor+3) = 
+               (StgInt32)(StgInt64)obscure_ccall_ret_code;
+           *(StgInt32 *)(adjustor+30) = 
+               (StgInt32)((StgInt64)wptr - (StgInt64)adjustor - 34);
+           *(StgInt64 *)(adjustor+40) = (StgInt64)hptr;
+       }
+    }
+#elif defined(sparc_HOST_ARCH)
   /* Magic constant computed by inspecting the code length of the following
      assembly language snippet (offset and machine code prefixed):
 
@@ -338,7 +508,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr, char *typeString)
         asm("nop");
         asm("nop");
     }
-#elif defined(alpha_TARGET_ARCH)
+#elif defined(alpha_HOST_ARCH)
   /* Magic constant computed by inspecting the code length of
      the following assembly language snippet
      (offset and machine code prefixed; note that the machine code
@@ -361,7 +531,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr, char *typeString)
      divided by 4, taking the lowest 14 bits.
 
      We only support passing 4 or fewer argument words, for the same
-     reason described under sparc_TARGET_ARCH above by JRS, 21 Aug 01.
+     reason described under sparc_HOST_ARCH above by JRS, 21 Aug 01.
      On the Alpha the first 6 integer arguments are in a0 through a5,
      and the rest on the stack.  Hence we want to shuffle the original
      caller's arguments by two.
@@ -396,7 +566,7 @@ TODO: Depending on how much allocation overhead stgMallocBytes uses for
        /* Ensure that instruction cache is consistent with our new code */
        __asm__ volatile("call_pal %0" : : "i" (PAL_imb));
     }
-#elif defined(powerpc_TARGET_ARCH) && defined(linux_TARGET_OS)
+#elif defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS)
 
 #define OP_LO(op,lo)  ((((unsigned)(op)) << 16) | (((unsigned)(lo)) & 0xFFFF))
 #define OP_HI(op,hi)  ((((unsigned)(op)) << 16) | (((unsigned)(hi)) >> 16))
@@ -605,103 +775,135 @@ TODO: Depending on how much allocation overhead stgMallocBytes uses for
         }
     }
 
-#elif defined(powerpc_TARGET_ARCH) || defined(powerpc64_TARGET_ARCH)
+#elif defined(powerpc_HOST_ARCH) || defined(powerpc64_HOST_ARCH)
         
 #define OP_LO(op,lo)  ((((unsigned)(op)) << 16) | (((unsigned)(lo)) & 0xFFFF))
 #define OP_HI(op,hi)  ((((unsigned)(op)) << 16) | (((unsigned)(hi)) >> 16))
-        {
-            AdjustorStub *adjustorStub;
-            int sz = 0, extra_sz, total_sz;
-
-                  // from AdjustorAsm.s
-                  // not declared as a function so that AIX-style
-                  // fundescs can never get in the way.
-            extern void *adjustorCode;
-            
+    {
+        /* The following code applies to all PowerPC and PowerPC64 platforms
+           whose stack layout is based on the AIX ABI.
+
+           Besides (obviously) AIX, this includes
+            Mac OS 9 and BeOS/PPC (may they rest in peace),
+                which use the 32-bit AIX ABI
+            powerpc64-linux,
+                which uses the 64-bit AIX ABI
+            and Darwin (Mac OS X),
+                which uses the same stack layout as AIX,
+                but no function descriptors.
+
+           The actual stack-frame shuffling is implemented out-of-line
+           in the function adjustorCode, in AdjustorAsm.S.
+           Here, we set up an AdjustorStub structure, which
+           is a function descriptor (on platforms that have function
+           descriptors) or a short piece of stub code (on Darwin) to call
+           adjustorCode with a pointer to the AdjustorStub struct loaded
+           into register r2.
+
+           One nice thing about this is that there is _no_ code generated at
+           runtime on the platforms that have function descriptors.
+        */
+        AdjustorStub *adjustorStub;
+        int sz = 0, extra_sz, total_sz;
+
+            // from AdjustorAsm.s
+            // not declared as a function so that AIX-style
+            // fundescs can never get in the way.
+        extern void *adjustorCode;
+        
 #ifdef FUNDESCS
-            adjustorStub = stgMallocBytes(sizeof(AdjustorStub), "createAdjustor");
+        adjustorStub = stgMallocBytes(sizeof(AdjustorStub), "createAdjustor");
 #else
-            adjustorStub = mallocBytesRWX(sizeof(AdjustorStub));
+        adjustorStub = mallocBytesRWX(sizeof(AdjustorStub));
 #endif
-            adjustor = adjustorStub;
-               
-           adjustorStub->code = (void*) &adjustorCode;
+        adjustor = adjustorStub;
+            
+        adjustorStub->code = (void*) &adjustorCode;
 
 #ifdef FUNDESCS
-                // function descriptors are a cool idea.
-                // We don't need to generate any code at runtime.
-            adjustorStub->toc = adjustorStub;
+            // function descriptors are a cool idea.
+            // We don't need to generate any code at runtime.
+        adjustorStub->toc = adjustorStub;
 #else
 
-                // no function descriptors :-(
-                // We need to do things "by hand".
-#if defined(powerpc_TARGET_ARCH)
-                // lis  r2, hi(adjustorStub)
-            adjustorStub->lis = OP_HI(0x3c40, adjustorStub);
-                // ori  r2, r2, lo(adjustorStub)
-            adjustorStub->ori = OP_LO(0x6042, adjustorStub);
-                // lwz r0, code(r2)
-            adjustorStub->lwz = OP_LO(0x8002, (char*)(&adjustorStub->code)
-                                            - (char*)adjustorStub);
-                // mtctr r0
-            adjustorStub->mtctr = 0x7c0903a6;
-                // bctr
-            adjustorStub->bctr = 0x4e800420;
+            // no function descriptors :-(
+            // We need to do things "by hand".
+#if defined(powerpc_HOST_ARCH)
+            // lis  r2, hi(adjustorStub)
+        adjustorStub->lis = OP_HI(0x3c40, adjustorStub);
+            // ori  r2, r2, lo(adjustorStub)
+        adjustorStub->ori = OP_LO(0x6042, adjustorStub);
+            // lwz r0, code(r2)
+        adjustorStub->lwz = OP_LO(0x8002, (char*)(&adjustorStub->code)
+                                        - (char*)adjustorStub);
+            // mtctr r0
+        adjustorStub->mtctr = 0x7c0903a6;
+            // bctr
+        adjustorStub->bctr = 0x4e800420;
 #else
-            barf("adjustor creation not supported on this platform");
+        barf("adjustor creation not supported on this platform");
 #endif
 
-            // Flush the Instruction cache:
+        // Flush the Instruction cache:
+        {
+            int n = sizeof(AdjustorStub)/sizeof(unsigned);
+            unsigned *p = (unsigned*)adjustor;
+            while(n--)
             {
-                int n = sizeof(AdjustorStub)/sizeof(unsigned);
-                unsigned *p = (unsigned*)adjustor;
-                while(n--)
-                {
-                    __asm__ volatile ("dcbf 0,%0\n\tsync\n\ticbi 0,%0"
-                                        : : "r" (p));
-                    p++;
-                }
-                __asm__ volatile ("sync\n\tisync");
+                __asm__ volatile ("dcbf 0,%0\n\tsync\n\ticbi 0,%0"
+                                    : : "r" (p));
+                p++;
             }
+            __asm__ volatile ("sync\n\tisync");
+        }
 #endif
 
-            printf("createAdjustor: %s\n", typeString);
-            while(*typeString)
-            {
-                char t = *typeString++;
+            // Calculate the size of the stack frame, in words.
+        while(*typeString)
+        {
+            char t = *typeString++;
 
-                switch(t)
-                {
-#if defined(powerpc64_TARGET_ARCH)
-                    case 'd': sz += 1; break;
-                    case 'l': sz += 1; break;
-#else
-                    case 'd': sz += 2; break;
-                    case 'l': sz += 2; break;
+            switch(t)
+            {
+#if defined(powerpc_HOST_ARCH)
+                    // on 32-bit platforms, Double and Int64 occupy two words.
+                case 'd':
+                case 'l':
+                    sz += 2;
+                    break;
 #endif
-                    case 'f': sz += 1; break;
-                    case 'i': sz += 1; break;
-                }
+                    // everything else is one word.
+                default:
+                    sz += 1;
             }
-            extra_sz = sz - 8;
-            if(extra_sz < 0)
-                extra_sz = 0;
-            total_sz = (6 /* linkage area */
-                      + 8 /* minimum parameter area */
-                      + 2 /* two extra arguments */
-                      + extra_sz)*sizeof(StgWord);
-           
-                // align to 16 bytes.
-                // AIX only requires 8 bytes, but who cares?
-            total_sz = (total_sz+15) & ~0xF;
-           
-            adjustorStub->hptr = hptr;
-            adjustorStub->wptr = wptr;
-            adjustorStub->negative_framesize = -total_sz;
-            adjustorStub->extrawords_plus_one = extra_sz + 1;
         }
+            // The first eight words of the parameter area
+            // are just "backing store" for the parameters passed in
+            // the GPRs. extra_sz is the number of words beyond those first
+            // 8 words.
+        extra_sz = sz - 8;
+        if(extra_sz < 0)
+            extra_sz = 0;
+
+            // Calculate the total size of the stack frame.
+        total_sz = (6 /* linkage area */
+                  + 8 /* minimum parameter area */
+                  + 2 /* two extra arguments */
+                  + extra_sz)*sizeof(StgWord);
+       
+            // align to 16 bytes.
+            // AIX only requires 8 bytes, but who cares?
+        total_sz = (total_sz+15) & ~0xF;
+       
+            // Fill in the information that adjustorCode in AdjustorAsm.S
+            // will use to create a new stack frame with the additional args.
+        adjustorStub->hptr = hptr;
+        adjustorStub->wptr = wptr;
+        adjustorStub->negative_framesize = -total_sz;
+        adjustorStub->extrawords_plus_one = extra_sz + 1;
+    }
 
-#elif defined(ia64_TARGET_ARCH)
+#elif defined(ia64_HOST_ARCH)
 /*
     Up to 8 inputs are passed in registers.  We flush the last two inputs to
     the stack, initially into the 16-byte scratch region left by the caller.
@@ -798,7 +1000,7 @@ TODO: Depending on how much allocation overhead stgMallocBytes uses for
 void
 freeHaskellFunctionPtr(void* ptr)
 {
-#if defined(i386_TARGET_ARCH)
+#if defined(i386_HOST_ARCH)
  if ( *(unsigned char*)ptr != 0x68 &&
       *(unsigned char*)ptr != 0x58 ) {
    errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
@@ -810,8 +1012,17 @@ freeHaskellFunctionPtr(void* ptr)
     freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x01)));
  } else {
     freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x02)));
- }    
-#elif defined(sparc_TARGET_ARCH)
+ }
+#elif defined(x86_64_HOST_ARCH)
+ if ( *(StgWord16 *)ptr == 0x894d ) {
+     freeStablePtr(*(StgStablePtr*)(ptr+32));
+ } else if ( *(StgWord16 *)ptr == 0x5141 ) {
+     freeStablePtr(*(StgStablePtr*)(ptr+40));
+ } else {
+   errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+   return;
+ }
+#elif defined(sparc_HOST_ARCH)
  if ( *(unsigned long*)ptr != 0x9C23A008UL ) {
    errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
    return;
@@ -819,7 +1030,7 @@ freeHaskellFunctionPtr(void* ptr)
 
  /* Free the stable pointer first..*/
  freeStablePtr(*((StgStablePtr*)((unsigned long*)ptr + 11)));
-#elif defined(alpha_TARGET_ARCH)
+#elif defined(alpha_HOST_ARCH)
  if ( *(StgWord64*)ptr != 0xa77b0018a61b0010L ) {
    errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
    return;
@@ -827,20 +1038,20 @@ freeHaskellFunctionPtr(void* ptr)
 
  /* Free the stable pointer first..*/
  freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x10)));
-#elif defined(powerpc_TARGET_ARCH) && defined(linux_TARGET_OS)
+#elif defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS)
  if ( *(StgWord*)ptr != 0x48000008 ) {
    errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
    return;
  }
  freeStablePtr(((StgStablePtr*)ptr)[1]);
-#elif defined(powerpc_TARGET_ARCH) || defined(powerpc64_TARGET_ARCH)
+#elif defined(powerpc_HOST_ARCH) || defined(powerpc64_HOST_ARCH)
  extern void* adjustorCode;
  if ( ((AdjustorStub*)ptr)->code != (StgFunPtr) &adjustorCode ) {
    errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
    return;
  }
  freeStablePtr(((AdjustorStub*)ptr)->hptr);
-#elif defined(ia64_TARGET_ARCH)
+#elif defined(ia64_HOST_ARCH)
  IA64FunDesc *fdesc = (IA64FunDesc *)ptr;
  StgWord64 *code = (StgWord64 *)(fdesc+1);
 
@@ -868,30 +1079,11 @@ freeHaskellFunctionPtr(void* ptr)
 void
 initAdjustor(void)
 {
-#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 = 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 */
+#if defined(i386_HOST_ARCH) && defined(openbsd_HOST_OS)
+    obscure_ccall_ret_code_dyn = mallocBytesRWX(4);
+    obscure_ccall_ret_code_dyn[0] = ((unsigned char *)obscure_ccall_ret_code)[0];
+    obscure_ccall_ret_code_dyn[1] = ((unsigned char *)obscure_ccall_ret_code)[1];
+    obscure_ccall_ret_code_dyn[2] = ((unsigned char *)obscure_ccall_ret_code)[2];
+    obscure_ccall_ret_code_dyn[3] = ((unsigned char *)obscure_ccall_ret_code)[3];
 #endif
 }