#include "RtsFlags.h"
/* Heavily arch-specific, I'm afraid.. */
-#if defined(i386_TARGET_ARCH)
+#if defined(i386_TARGET_ARCH) || defined(sparc_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.
+*/
+static unsigned char __obscure_ccall_ret_code [] =
+ { 0x83, 0xc4, 0x04 /* addl $0x4, %esp */
+ , 0xc3 /* ret */
+ };
+
+
void*
createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr)
{
void *adjustor;
unsigned char* adj_code;
size_t sizeof_adjustor;
-
+
if (cconv == 0) { /* the adjustor will be _stdcall'ed */
+#if defined(sparc_TARGET_ARCH)
+ /* SPARC doesn't have a calling convention other than _ccall */
+ if (cconv == 0) {
+ return NULL;
+ }
+#endif
+
/* Magic constant computed by inspecting the code length of
the following assembly language snippet
(offset and machine code prefixed):
} else { /* the adjustor will be _ccall'ed */
+#if defined(i386_TARGET_ARCH)
/* Magic constant computed by inspecting the code length of
the following assembly language snippet
(offset and machine code prefixed):
- <00>: 68 ef be ad de pushl $0xdeadbeef # constant is large enough to
+ <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>: ff d0 call %eax # and call it.
- <0c>: 83 c4 04 addl $0x4,%esp # remove stable pointer.
- <0f>: c3 ret # return to where you came from.
+ <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
+ <0f>: ff e0 jmp *%eax # jump to wptr
The ccall'ing version is a tad different, passing in the return
address of the caller to the auto-generated C stub (which enters
- via the stable pointer.) (The auto-generated C stub is on this
+ via the stable pointer.) (The auto-generated C stub is in on this
game, don't worry :-)
- The adjustor makes the assumption that any return value
+ 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.
+
+ Note: The adjustor makes the assumption that any return value
coming back from the C stub is not stored on the stack.
That's (thankfully) the case here with the restricted set of
return types that we support.
+
+
*/
- sizeof_adjustor = 16*sizeof(char);
+ sizeof_adjustor = 17*sizeof(char);
if ((adjustor = stgMallocBytes(sizeof_adjustor,"createAdjustor")) == NULL) {
return NULL;
adj_code[0x05] = (unsigned char)0xb8; /* movl $wptr, %eax */
*((StgFunPtr*)(adj_code + 0x06)) = (StgFunPtr)wptr;
- adj_code[0x0a] = (unsigned char)0xff; /* call %eax */
- adj_code[0x0b] = (unsigned char)0xd0;
-
- adj_code[0x0c] = (unsigned char)0x83; /* addl $0x4, %esp */
- adj_code[0x0d] = (unsigned char)0xc4;
- adj_code[0x0e] = (unsigned char)0x04;
+ 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;
+
+#elif defined(sparc_TARGET_ARCH)
+ /* Magic constant computed by inspecting the code length of
+ the following assembly language snippet
+ (offset and machine code prefixed):
+
+ <00>: 13 00 3f fb sethi %hi(0x00ffeffa), %o1 # load up wptr (1 of 2)
+ <04>: 11 37 ab 6f sethi %hi(0xdeadbeef), %o0 # load up hptr (1 of 2)
+ <08>: 81 c2 63 fa jmp %o1+%lo(0x00ffeffa) # jump to wptr (load 2 of 2)
+ <0c>: 90 12 22 ef or %o0, %lo(0xdeadbeef), %o0 # load up hptr (2 of 2)
+ # [in delay slot]
+ <10>: de ad be ef # Place the value of the StgStablePtr somewhere readable
- adj_code[0x0f] = (unsigned char)0xc3; /* ret */
+ ccall'ing on a SPARC leaves little to be performed by the caller.
+ The callee shifts the window on entry and restores it on exit.
+ Input paramters and results are passed via registers. (%o0 in the
+ code above contains the input paramter to wptr.) The return address
+ is stored in %o7/%i7. Since we don't shift the window in this code,
+ the return address is preserved and wptr will return to our caller.
+ */
+ sizeof_adjustor = 28*sizeof(char);
+
+ if ((adjustor = stgMallocBytes(sizeof_adjustor,"createAdjustor")) == NULL) {
+ return NULL;
+ }
+
+ adj_code = (unsigned char*)adjustor;
+
+ /* sethi %hi(wptr), %o1 */
+ *((unsigned long*)(adj_code+0x00)) = (unsigned long)0x13000000;
+ *((unsigned long*)(adj_code+0x00)) |= ((unsigned long)wptr) >> 10;
+
+ /* sethi %hi(hptr), %o0 */
+ *((unsigned long*)(adj_code+0x04)) = (unsigned long)0x11000000;
+ *((unsigned long*)(adj_code+0x04)) |= ((unsigned long)hptr) >> 10;
+
+ /* jmp %o1+%lo(wptr) */
+ *((unsigned long*)(adj_code+0x08)) = (unsigned long)0x81c26000;
+ *((unsigned long*)(adj_code+0x08)) |= ((unsigned long)wptr) & 0x000003ff;
+
+ /* or %o0, %lo(hptr), %o0 */
+ *((unsigned long*)(adj_code+0x0c)) = (unsigned long)0x90122000;
+ *((unsigned long*)(adj_code+0x0c)) |= ((unsigned long)hptr) & 0x000003ff;
+
+ *((StgStablePtr*)(adj_code+0x10)) = (StgStablePtr)hptr;
+#endif
+
}
/* Have fun! */
void
freeHaskellFunctionPtr(void* ptr)
{
+#if defined(i386_TARGET_ARCH)
if ( *(unsigned char*)ptr != 0x68 &&
*(unsigned char*)ptr != 0x58 ) {
fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
/* Free the stable pointer first..*/
if (*(unsigned char*)ptr == 0x68) { /* Aha, a ccall adjustor! */
- freeStablePointer(*((StgStablePtr*)((unsigned char*)ptr + 0x01)));
+ freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x01)));
} else {
- freeStablePointer(*((StgStablePtr*)((unsigned char*)ptr + 0x02)));
+ freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x02)));
}
+#elif defined(sparc_TARGET_ARCH)
+ if ( *(unsigned char*)ptr != 0x13 ) {
+ fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ return;
+ }
+
+ /* Free the stable pointer first..*/
+ freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x10)));
+#endif
*((unsigned char*)ptr) = '\0';
free(ptr);
}
-#endif /* i386_TARGET_ARCH */
+#endif /* i386_TARGET_ARCH || sparc_TARGET_ARCH */
projects / ghc-hetmet.git / blobdiff