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/* ===-- enable_execute_stack.c - Implement __enable_execute_stack ---------=== |
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* |
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* The LLVM Compiler Infrastructure |
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* |
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* This file is dual licensed under the MIT and the University of Illinois Open |
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* Source Licenses. See LICENSE.TXT for details. |
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* |
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* ===----------------------------------------------------------------------=== |
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*/ |
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#include "int_lib.h" |
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#ifndef _WIN32 |
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#include <sys/mman.h> |
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#endif |
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/* #include "config.h" |
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* FIXME: CMake - include when cmake system is ready. |
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* Remove #define HAVE_SYSCONF 1 line. |
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*/ |
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#define HAVE_SYSCONF 1 |
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#ifdef _WIN32 |
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#define WIN32_LEAN_AND_MEAN |
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#include <Windows.h> |
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#else |
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#ifndef __APPLE__ |
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#include <unistd.h> |
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#endif /* __APPLE__ */ |
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#endif /* _WIN32 */ |
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#if __LP64__ |
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#define TRAMPOLINE_SIZE 48 |
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#else |
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#define TRAMPOLINE_SIZE 40 |
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#endif |
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/* |
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* The compiler generates calls to __enable_execute_stack() when creating |
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* trampoline functions on the stack for use with nested functions. |
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* It is expected to mark the page(s) containing the address |
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* and the next 48 bytes as executable. Since the stack is normally rw- |
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* that means changing the protection on those page(s) to rwx. |
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*/ |
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COMPILER_RT_ABI void |
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__enable_execute_stack(void* addr) |
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{ |
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#if _WIN32 |
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MEMORY_BASIC_INFORMATION mbi; |
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if (!VirtualQuery (addr, &mbi, sizeof(mbi))) |
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return; /* We should probably assert here because there is no return value */ |
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VirtualProtect (mbi.BaseAddress, mbi.RegionSize, PAGE_EXECUTE_READWRITE, &mbi.Protect); |
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#else |
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#if __APPLE__ |
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/* On Darwin, pagesize is always 4096 bytes */ |
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const uintptr_t pageSize = 4096; |
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#elif !defined(HAVE_SYSCONF) |
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#error "HAVE_SYSCONF not defined! See enable_execute_stack.c" |
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#else |
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const uintptr_t pageSize = sysconf(_SC_PAGESIZE); |
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#endif /* __APPLE__ */ |
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const uintptr_t pageAlignMask = ~(pageSize-1); |
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uintptr_t p = (uintptr_t)addr; |
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unsigned char* startPage = (unsigned char*)(p & pageAlignMask); |
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unsigned char* endPage = (unsigned char*)((p+TRAMPOLINE_SIZE+pageSize) & pageAlignMask); |
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size_t length = endPage - startPage; |
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(void) mprotect((void *)startPage, length, PROT_READ | PROT_WRITE | PROT_EXEC); |
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#endif |
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} |