Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 1 | /* ===-- enable_execute_stack.c - Implement __enable_execute_stack ---------=== |
| 2 | * |
| 3 | * The LLVM Compiler Infrastructure |
| 4 | * |
| 5 | * This file is dual licensed under the MIT and the University of Illinois Open |
| 6 | * Source Licenses. See LICENSE.TXT for details. |
| 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | */ |
| 10 | |
| 11 | #include "int_lib.h" |
| 12 | |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 13 | #ifndef _WIN32 |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 14 | #include <sys/mman.h> |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 15 | #endif |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 16 | |
| 17 | /* #include "config.h" |
| 18 | * FIXME: CMake - include when cmake system is ready. |
| 19 | * Remove #define HAVE_SYSCONF 1 line. |
| 20 | */ |
| 21 | #define HAVE_SYSCONF 1 |
| 22 | |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 23 | #ifdef _WIN32 |
| 24 | #define WIN32_LEAN_AND_MEAN |
| 25 | #include <Windows.h> |
| 26 | #else |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 27 | #ifndef __APPLE__ |
| 28 | #include <unistd.h> |
| 29 | #endif /* __APPLE__ */ |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 30 | #endif /* _WIN32 */ |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 31 | |
| 32 | #if __LP64__ |
| 33 | #define TRAMPOLINE_SIZE 48 |
| 34 | #else |
| 35 | #define TRAMPOLINE_SIZE 40 |
| 36 | #endif |
| 37 | |
| 38 | /* |
| 39 | * The compiler generates calls to __enable_execute_stack() when creating |
| 40 | * trampoline functions on the stack for use with nested functions. |
| 41 | * It is expected to mark the page(s) containing the address |
| 42 | * and the next 48 bytes as executable. Since the stack is normally rw- |
| 43 | * that means changing the protection on those page(s) to rwx. |
| 44 | */ |
| 45 | |
| 46 | COMPILER_RT_ABI void |
| 47 | __enable_execute_stack(void* addr) |
| 48 | { |
| 49 | |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 50 | #if _WIN32 |
| 51 | MEMORY_BASIC_INFORMATION mbi; |
| 52 | if (!VirtualQuery (addr, &mbi, sizeof(mbi))) |
| 53 | return; /* We should probably assert here because there is no return value */ |
| 54 | VirtualProtect (mbi.BaseAddress, mbi.RegionSize, PAGE_EXECUTE_READWRITE, &mbi.Protect); |
| 55 | #else |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 56 | #if __APPLE__ |
| 57 | /* On Darwin, pagesize is always 4096 bytes */ |
| 58 | const uintptr_t pageSize = 4096; |
| 59 | #elif !defined(HAVE_SYSCONF) |
| 60 | #error "HAVE_SYSCONF not defined! See enable_execute_stack.c" |
| 61 | #else |
| 62 | const uintptr_t pageSize = sysconf(_SC_PAGESIZE); |
| 63 | #endif /* __APPLE__ */ |
| 64 | |
| 65 | const uintptr_t pageAlignMask = ~(pageSize-1); |
| 66 | uintptr_t p = (uintptr_t)addr; |
| 67 | unsigned char* startPage = (unsigned char*)(p & pageAlignMask); |
| 68 | unsigned char* endPage = (unsigned char*)((p+TRAMPOLINE_SIZE+pageSize) & pageAlignMask); |
| 69 | size_t length = endPage - startPage; |
| 70 | (void) mprotect((void *)startPage, length, PROT_READ | PROT_WRITE | PROT_EXEC); |
Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 71 | #endif |
Stephen Hines | 2d1fdb2 | 2014-05-28 23:58:16 -0700 | [diff] [blame] | 72 | } |