GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/enable_execute_stack.c Lines: 0 7 0.0 %
Date: 2017-11-13 Branches: 0 0 0.0 %

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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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}