X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FAdjustor.c;h=bf1002d927bac3271436d9783a2016aa6c79ba19;hb=10a9b180ee41f88056b50327fb898dca93a1dbb1;hp=e9fc769e722cbc8aeb738b9ab0ef52800acda0c4;hpb=6a9485d7f7d2c2d9f762215450c89e878ada13a4;p=ghc-hetmet.git diff --git a/ghc/rts/Adjustor.c b/ghc/rts/Adjustor.c index e9fc769..bf1002d 100644 --- a/ghc/rts/Adjustor.c +++ b/ghc/rts/Adjustor.c @@ -38,37 +38,67 @@ Haskell side. */ #include "PosixSource.h" #include "Rts.h" +#include "RtsExternal.h" #include "RtsUtils.h" -#include "RtsFlags.h" - #include +#if defined(_WIN32) +#include +#endif + +#if defined(openbsd_TARGET_OS) +#include +#include +#endif + /* Heavily arch-specific, I'm afraid.. */ +typedef enum { + pageExecuteRead, + pageExecuteReadWrite +} pageMode; + +/* + * Function: execPage() + * + * 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 void +execPage (void* addr, pageMode mode) +{ +#if defined(i386_TARGET_ARCH) && defined(_WIN32) && 0 + SYSTEM_INFO sInfo; + DWORD dwOldProtect = 0; + + /* doesn't return a result, so presumably it can't fail... */ + GetSystemInfo(&sInfo); + + if ( VirtualProtect ( (void*)((unsigned long)addr & (sInfo.dwPageSize - 1)), + sInfo.dwPageSize, + ( mode == pageExecuteReadWrite ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ), + &dwOldProtect) == 0 ) { + DWORD rc = GetLastError(); + barf("execPage: failed to protect 0x%p; error=%lu; old protection: %lu\n", addr, rc, dwOldProtect); + } +#else + +#if defined(openbsd_TARGET_OS) + /* malloc memory isn't executable by default on OpenBSD */ + unsigned long pagesize = sysconf(_SC_PAGESIZE); + unsigned long round = (unsigned long)addr & (pagesize - 1); + if (mprotect(addr - round, pagesize, PROT_EXEC|PROT_READ|PROT_WRITE) == -1) + barf("execPage: failed to protect 0x%p\n", addr); +#endif + + (void)addr; (void)mode; /* keep gcc -Wall happy */ +#endif +} + #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 */ - }; +static unsigned char *obscure_ccall_ret_code; #endif #if defined(alpha_TARGET_ARCH) @@ -132,7 +162,8 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) : ff e0 jmp %eax # and jump to it. # the callee cleans up the stack */ - if ((adjustor = stgMallocBytes(14, "createAdjustor")) != NULL) { + adjustor = stgMallocBytes(14, "createAdjustor"); + { unsigned char *const adj_code = (unsigned char *)adjustor; adj_code[0x00] = (unsigned char)0x58; /* popl %eax */ @@ -146,6 +177,8 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) adj_code[0x0c] = (unsigned char)0xff; /* jmp %eax */ adj_code[0x0d] = (unsigned char)0xe0; + + execPage(adjustor, pageExecuteReadWrite); } #endif break; @@ -159,7 +192,7 @@ 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 @@ -167,7 +200,7 @@ 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. @@ -176,7 +209,8 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) That's (thankfully) the case here with the restricted set of return types that we support. */ - if ((adjustor = stgMallocBytes(17, "createAdjustor")) != NULL) { + adjustor = stgMallocBytes(17, "createAdjustor"); + { unsigned char *const adj_code = (unsigned char *)adjustor; adj_code[0x00] = (unsigned char)0x68; /* pushl hptr (which is a dword immediate ) */ @@ -185,11 +219,13 @@ 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, pageExecuteReadWrite); } #elif defined(sparc_TARGET_ARCH) /* Magic constant computed by inspecting the code length of the following @@ -221,7 +257,8 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr) similarly, and local variables should be accessed via %fp, not %sp. In a nutshell: This should work! (Famous last words! :-) */ - if ((adjustor = stgMallocBytes(4*(11+1), "createAdjustor")) != NULL) { + adjustor = stgMallocBytes(4*(11+1), "createAdjustor"); + { unsigned long *const adj_code = (unsigned long *)adjustor; adj_code[ 0] = 0x9C23A008UL; /* sub %sp, 8, %sp */ @@ -297,7 +334,8 @@ TODO: Depending on how much allocation overhead stgMallocBytes uses for 4 bytes (getting rid of the nop), hence saving memory. [ccshan] */ ASSERT(((StgWord64)wptr & 3) == 0); - if ((adjustor = stgMallocBytes(48, "createAdjustor")) != NULL) { + adjustor = stgMallocBytes(48, "createAdjustor"); + { StgWord64 *const code = (StgWord64 *)adjustor; code[0] = 0x4610041246520414L; @@ -334,7 +372,8 @@ TODO: Depending on how much allocation overhead stgMallocBytes uses for 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) { + adjustor = stgMallocBytes(4*13, "createAdjustor"); + { unsigned long *const adj_code = (unsigned long *)adjustor; // make room for extra arguments @@ -476,7 +515,7 @@ 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); + errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } @@ -488,7 +527,7 @@ freeHaskellFunctionPtr(void* ptr) } #elif defined(sparc_TARGET_ARCH) if ( *(unsigned long*)ptr != 0x9C23A008UL ) { - fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); + errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } @@ -496,7 +535,7 @@ 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); + errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } @@ -504,7 +543,7 @@ 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); + errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } freeStablePtr(*((StgStablePtr*)((unsigned char*)ptr + 4*12))); @@ -513,7 +552,7 @@ freeHaskellFunctionPtr(void* ptr) StgWord64 *code = (StgWord64 *)(fdesc+1); if (fdesc->ip != (StgWord64)code) { - fprintf(stderr, "freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); + errorBelch("freeHaskellFunctionPtr: not for me, guv! %p\n", ptr); return; } freeStablePtr((StgStablePtr)code[16]); @@ -527,3 +566,41 @@ freeHaskellFunctionPtr(void* ptr) stgFree(ptr); } + +/* + * Function: initAdjustor() + * + * Perform initialisation of adjustor thunk layer (if needed.) + */ +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 = 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 +}