X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FAdjustor.c;h=ea91d9045d60bd813db17a1d5875c0619f13786f;hb=45bb77c6deeb9fc61e31e5b6975fe694d6642aba;hp=b488d43c836e694a16e73f7b9d92ca827f106299;hpb=e2c936e2c47429d43b8d39ad9b9c3a05ffb8e722;p=ghc-hetmet.git diff --git a/ghc/rts/Adjustor.c b/ghc/rts/Adjustor.c index b488d43..ea91d90 100644 --- a/ghc/rts/Adjustor.c +++ b/ghc/rts/Adjustor.c @@ -38,8 +38,8 @@ Haskell side. */ #include "PosixSource.h" #include "Rts.h" +#include "RtsExternal.h" #include "RtsUtils.h" -#include "RtsFlags.h" #include #if defined(_WIN32) @@ -48,16 +48,21 @@ Haskell side. /* 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; @@ -68,49 +73,23 @@ execPage (void* addr, int writable) 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) @@ -189,7 +168,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */ adj_code[0x0d] = (unsigned char)0xe0; - execPage(adjustor,rtsTrue); + execPage(adjustor, pageExecuteReadWrite); } #endif break; @@ -203,7 +182,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) <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 @@ -211,7 +190,7 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) 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. @@ -229,13 +208,13 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) 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 @@ -522,7 +501,7 @@ 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); + prog_belch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } @@ -534,7 +513,7 @@ freeHaskellFunctionPtr(void* ptr) } #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; } @@ -542,7 +521,7 @@ freeHaskellFunctionPtr(void* ptr) 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; } @@ -550,7 +529,7 @@ freeHaskellFunctionPtr(void* ptr) 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))); @@ -559,7 +538,7 @@ freeHaskellFunctionPtr(void* ptr) 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]); @@ -578,11 +557,37 @@ freeHaskellFunctionPtr(void* ptr) * 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; }