forked from OSchip/llvm-project
68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
//===-- enable_execute_stack.c - Implement __enable_execute_stack ---------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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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#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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// 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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COMPILER_RT_ABI void __enable_execute_stack(void *addr) {
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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,
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&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 =
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(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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}
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