Haskell side.
*/
+#include "PosixSource.h"
#include "Rts.h"
#include "RtsUtils.h"
#include "RtsFlags.h"
/* Heavily arch-specific, I'm afraid.. */
+#if defined(i386_TARGET_ARCH) || defined(sparc_TARGET_ARCH) || defined(alpha_TARGET_ARCH) || defined(powerpc_TARGET_ARCH)
+
#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.
+*/
+static unsigned char __obscure_ccall_ret_code [] =
+ { 0x83, 0xc4, 0x04 /* addl $0x4, %esp */
+ , 0xc3 /* ret */
+ };
+#endif
+
+#if defined(alpha_TARGET_ARCH)
+/* To get the definition of PAL_imb: */
+#include <machine/pal.h>
+#endif
+
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 */
+ void *adjustor = NULL;
+ switch (cconv)
+ {
+ case 0: /* _stdcall */
+#if defined(i386_TARGET_ARCH)
/* Magic constant computed by inspecting the code length of
the following assembly language snippet
(offset and machine code prefixed):
<c>: ff e0 jmp %eax # and jump to it.
# the callee cleans up the stack
*/
- sizeof_adjustor = 14*sizeof(char);
-
- if ((adjustor = stgMallocBytes(sizeof_adjustor,"createAdjustor")) == NULL) {
- return NULL;
- }
-
- adj_code = (unsigned char*)adjustor;
- adj_code[0x00] = (unsigned char)0x58; /* popl %eax */
-
- adj_code[0x01] = (unsigned char)0x68; /* pushl hptr (which is a dword immediate ) */
- *((StgStablePtr*)(adj_code + 0x02)) = (StgStablePtr)hptr;
-
- adj_code[0x06] = (unsigned char)0x50; /* pushl %eax */
+ if ((adjustor = stgMallocBytes(14, "createAdjustor")) != NULL) {
+ unsigned char *const adj_code = (unsigned char *)adjustor;
+ adj_code[0x00] = (unsigned char)0x58; /* popl %eax */
- adj_code[0x07] = (unsigned char)0xb8; /* movl $wptr, %eax */
- *((StgFunPtr*)(adj_code + 0x08)) = (StgFunPtr)wptr;
+ adj_code[0x01] = (unsigned char)0x68; /* pushl hptr (which is a dword immediate ) */
+ *((StgStablePtr*)(adj_code + 0x02)) = (StgStablePtr)hptr;
- adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */
- adj_code[0x0d] = (unsigned char)0xe0;
+ adj_code[0x06] = (unsigned char)0x50; /* pushl %eax */
+ adj_code[0x07] = (unsigned char)0xb8; /* movl $wptr, %eax */
+ *((StgFunPtr*)(adj_code + 0x08)) = (StgFunPtr)wptr;
- } else { /* the adjustor will be _ccall'ed */
+ adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */
+ adj_code[0x0d] = (unsigned char)0xe0;
+ }
+#endif
+ break;
+ case 1: /* _ccall */
+#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 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);
+ if ((adjustor = stgMallocBytes(17, "createAdjustor")) != NULL) {
+ unsigned char *const adj_code = (unsigned char *)adjustor;
- if ((adjustor = stgMallocBytes(sizeof_adjustor,"createAdjustor")) == NULL) {
- return NULL;
- }
+ adj_code[0x00] = (unsigned char)0x68; /* pushl hptr (which is a dword immediate ) */
+ *((StgStablePtr*)(adj_code+0x01)) = (StgStablePtr)hptr;
+
+ adj_code[0x05] = (unsigned char)0xb8; /* movl $wptr, %eax */
+ *((StgFunPtr*)(adj_code + 0x06)) = (StgFunPtr)wptr;
- adj_code = (unsigned char*)adjustor;
+ adj_code[0x0a] = (unsigned char)0x68; /* pushl __obscure_ccall_ret_code */
+ *((StgFunPtr*)(adj_code + 0x0b)) = (StgFunPtr)__obscure_ccall_ret_code;
- adj_code[0x00] = (unsigned char)0x68; /* pushl hptr (which is a dword immediate ) */
- *((StgStablePtr*)(adj_code+0x01)) = (StgStablePtr)hptr;
+ 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>: BA 10 00 1B mov %i3, %i5
+ <04>: B8 10 00 1A mov %i2, %i4
+ <08>: B6 10 00 19 mov %i1, %i3
+ <0c>: B4 10 00 18 mov %i0, %i2
+ <10>: 13 00 3f fb sethi %hi(0x00ffeffa), %o1 # load up wptr (1 of 2)
+ <14>: 11 37 ab 6f sethi %hi(0xdeadbeef), %o0 # load up hptr (1 of 2)
+ <18>: 81 c2 63 fa jmp %o1+%lo(0x00ffeffa) # jump to wptr (load 2 of 2)
+ <1c>: 90 12 22 ef or %o0, %lo(0xdeadbeef), %o0 # load up hptr (2 of 2)
+ # [in delay slot]
+ <20>: de ad be ef # Place the value of the StgStablePtr somewhere readable
+
+ 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.
+
+ JRS, 21 Aug 01: the above para is a fiction. The caller passes
+ args in %i0 .. %i5 and then the rest at [%sp+92]. We want to
+ tailjump to wptr, passing hptr as the new first arg, and a dummy
+ second arg, which would be where the return address is on x86.
+ That means we have to shuffle the original caller's args along by
+ two.
+
+ We do a half-correct solution which works only if the original
+ caller passed 4 or fewer arg words. Move %i0 .. %i3 into %i3
+ .. %i6, so we can park hptr in %i0 and a bogus arg in %i1. The
+ fully correct solution would be to subtract 8 from %sp and then
+ place %i4 and %i5 at [%sp+92] and [%sp+96] respectively. This
+ machinery should then work in all cases. (Or would it? Perhaps
+ it would trash parts of the caller's frame. Dunno).
+
+ SUP, 25 Apr 02: We are quite lucky to push a multiple of 8 bytes in
+ front of the existing arguments, because %sp must stay double-word
+ aligned at all times, see: http://www.sparc.org/standards/psABI3rd.pdf
+ Although we extend the *caller's* stack frame, this shouldn't cause
+ any problems for a C-like caller: alloca is implemented similarly, and
+ local variables should be accessed via %fp, not %sp. In a nutshell:
+ This should work. (Famous last words! :-)
+ */
+ if ((adjustor = stgMallocBytes(4*(8+1), "createAdjustor")) != NULL) {
+ unsigned long *const adj_code = (unsigned long *)adjustor;
+
+ /* mov %o3, %o5 */
+ adj_code[0] = (unsigned long)0x9A10000B;
+ /* mov %o2, %o4 */
+ adj_code[1] = (unsigned long)0x9810000A;
+ /* mov %o1, %o3 */
+ adj_code[2] = (unsigned long)0x96100009;
+ /* mov %o0, %o2 */
+ adj_code[3] = (unsigned long)0x94100008;
+
+ /* sethi %hi(wptr), %o1 */
+ adj_code[4] = (unsigned long)0x13000000;
+ adj_code[4] |= ((unsigned long)wptr) >> 10;
+
+ /* sethi %hi(hptr), %o0 */
+ adj_code[5] = (unsigned long)0x11000000;
+ adj_code[5] |= ((unsigned long)hptr) >> 10;
+
+ /* jmp %o1+%lo(wptr) */
+ adj_code[6] = (unsigned long)0x81c26000;
+ adj_code[6] |= ((unsigned long)wptr) & 0x000003ff;
+
+ /* or %o0, %lo(hptr), %o0 */
+ adj_code[7] = (unsigned long)0x90122000;
+ adj_code[7] |= ((unsigned long)hptr) & 0x000003ff;
+
+ adj_code[8] = (StgStablePtr)hptr;
+
+ /* flush cache */
+ asm("flush %0" : : "r" (adj_code ));
+ asm("flush %0" : : "r" (adj_code + 2));
+ asm("flush %0" : : "r" (adj_code + 4));
+ asm("flush %0" : : "r" (adj_code + 6));
+
+ /* max. 5 instructions latency, and we need at >= 1 for returning */
+ asm("nop");
+ asm("nop");
+ asm("nop");
+ asm("nop");
+ }
+#elif defined(alpha_TARGET_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
+ shown is longwords stored in little-endian order):
+
+ <00>: 46520414 mov a2, a4
+ <04>: 46100412 mov a0, a2
+ <08>: a61b0020 ldq a0, 0x20(pv) # load up hptr
+ <0c>: 46730415 mov a3, a5
+ <10>: a77b0028 ldq pv, 0x28(pv) # load up wptr
+ <14>: 46310413 mov a1, a3
+ <18>: 6bfb---- jmp (pv), <hint> # jump to wptr (with hint)
+ <1c>: 00000000 # padding for alignment
+ <20>: [8 bytes for hptr quadword]
+ <28>: [8 bytes for wptr quadword]
+
+ The "computed" jump at <08> above is really a jump to a fixed
+ location. Accordingly, we place an always-correct hint in the
+ jump instruction, namely the address offset from <0c> to wptr,
+ 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.
+ 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.
+
+ On the Alpha the calling convention is so complex and dependent
+ on the callee's signature -- for example, the stack pointer has
+ to be a multiple of 16 -- that it seems impossible to me [ccshan]
+ to handle the general case correctly without changing how the
+ adjustor is called from C. For now, our solution of shuffling
+ registers only and ignoring the stack only works if the original
+ caller passed 4 or fewer argument words.
+
+TODO: Depending on how much allocation overhead stgMallocBytes uses for
+ header information (more precisely, if the overhead is no more than
+ 4 bytes), we should move the first three instructions above down by
+ 4 bytes (getting rid of the nop), hence saving memory. [ccshan]
+ */
+ ASSERT(((StgWord64)wptr & 3) == 0);
+ if ((adjustor = stgMallocBytes(48, "createAdjustor")) != NULL) {
+ StgWord64 *const code = (StgWord64 *)adjustor;
- 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;
+ code[0] = 0x4610041246520414L;
+ code[1] = 0x46730415a61b0020L;
+ code[2] = 0x46310413a77b0028L;
+ code[3] = 0x000000006bfb0000L
+ | (((StgWord32*)(wptr) - (StgWord32*)(code) - 3) & 0x3fff);
- adj_code[0x0f] = (unsigned char)0xc3; /* ret */
+ code[4] = (StgWord64)hptr;
+ code[5] = (StgWord64)wptr;
+ /* Ensure that instruction cache is consistent with our new code */
+ __asm__ volatile("call_pal %0" : : "i" (PAL_imb));
+ }
+#elif defined(powerpc_TARGET_ARCH)
+/*
+ For PowerPC, the following code is used:
+
+ mr r10,r8
+ mr r9,r7
+ mr r8,r6
+ mr r7,r5
+ mr r6,r4
+ mr r5,r3
+ lis r0,0xDEAD ;hi(wptr)
+ lis r3,0xDEAF ;hi(hptr)
+ ori r0,r0,0xBEEF ; lo(wptr)
+ ori r3,r3,0xFACE ; lo(hptr)
+ mtctr r0
+ bctr
+
+ The arguments (passed in registers r3 - r10) are shuffled along by two to
+ make room for hptr and a dummy argument. As r9 and r10 are overwritten by
+ 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).
+*/
+ if ((adjustor = stgMallocBytes(4*13, "createAdjustor")) != NULL) {
+ unsigned long *const adj_code = (unsigned long *)adjustor;
+
+ // make room for extra arguments
+ adj_code[0] = 0x7d0a4378; //mr r10,r8
+ adj_code[1] = 0x7ce93b78; //mr r9,r7
+ adj_code[2] = 0x7cc83378; //mr r8,r6
+ adj_code[3] = 0x7ca72b78; //mr r7,r5
+ adj_code[4] = 0x7c862378; //mr r6,r4
+ adj_code[5] = 0x7c651b78; //mr r5,r3
+
+ adj_code[6] = 0x3c000000; //lis r0,hi(wptr)
+ adj_code[6] |= ((unsigned long)wptr) >> 16;
+
+ adj_code[7] = 0x3c600000; //lis r3,hi(hptr)
+ adj_code[6] |= ((unsigned long)hptr) >> 16;
+
+ adj_code[8] = 0x60000000; //ori r0,r0,lo(wptr)
+ adj_code[8] |= ((unsigned long)wptr) & 0xFFFF;
+
+ adj_code[9] = 0x60630000; //ori r3,r3,lo(hptr)
+ adj_code[9] |= ((unsigned long)hptr) & 0xFFFF;
+
+ adj_code[10] = 0x7c0903a6; //mtctr r0
+ adj_code[11] = 0x4e800420; //bctr
+ adj_code[12] = (unsigned long)hptr;
+
+ // Flush the Instruction cache:
+ // MakeDataExecutable(adjustor,4*13);
+ /* This would require us to link with CoreServices.framework */
+ { /* this should do the same: */
+ int n = 13;
+ unsigned long *p = adj_code;
+ while(n--)
+ {
+ __asm__ volatile ("dcbf 0,%0\n\tsync\n\ticbi 0,%0"
+ : : "g" (p));
+ p++;
+ }
+ __asm__ volatile ("sync\n\tisync");
+ }
+ }
+#else
+#error Adjustor creation is not supported on this platform.
+#endif
+ break;
+
+ default:
+ ASSERT(0);
+ break;
}
/* Have fun! */
- return ((void*)adjustor);
+ return adjustor;
}
+#endif
+
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);
} else {
freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 0x02)));
}
+#elif defined(sparc_TARGET_ARCH)
+ if ( *(unsigned long*)ptr != 0x9A10000B ) {
+ fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ return;
+ }
+
+ /* Free the stable pointer first..*/
+ freeStablePtr(*((StgStablePtr*)((unsigned long*)ptr + 8)));
+#elif defined(alpha_TARGET_ARCH)
+ if ( *(StgWord64*)ptr != 0xa77b0018a61b0010L ) {
+ fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr);
+ return;
+ }
+
+ /* Free the stable pointer first..*/
+ 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);
+ return;
+ }
+ freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 4*12)));
+#else
+ ASSERT(0);
+#endif
*((unsigned char*)ptr) = '\0';
free(ptr);
}
-#endif /* i386_TARGET_ARCH */
-
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