1 //===----- trampoline_setup.c - Implement __trampoline_setup -------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "int_lib.h" 10 11 extern void __clear_cache(void *start, void *end); 12 13 // The ppc compiler generates calls to __trampoline_setup() when creating 14 // trampoline functions on the stack for use with nested functions. 15 // This function creates a custom 40-byte trampoline function on the stack 16 // which loads r11 with a pointer to the outer function's locals 17 // and then jumps to the target nested function. 18 19 #if __powerpc__ && !defined(__powerpc64__) 20 COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack, 21 int trampSizeAllocated, 22 const void *realFunc, void *localsPtr) { 23 // should never happen, but if compiler did not allocate 24 // enough space on stack for the trampoline, abort 25 if (trampSizeAllocated < 40) 26 compilerrt_abort(); 27 28 // create trampoline 29 trampOnStack[0] = 0x7c0802a6; // mflr r0 30 trampOnStack[1] = 0x4800000d; // bl Lbase 31 trampOnStack[2] = (uint32_t)realFunc; 32 trampOnStack[3] = (uint32_t)localsPtr; 33 trampOnStack[4] = 0x7d6802a6; // Lbase: mflr r11 34 trampOnStack[5] = 0x818b0000; // lwz r12,0(r11) 35 trampOnStack[6] = 0x7c0803a6; // mtlr r0 36 trampOnStack[7] = 0x7d8903a6; // mtctr r12 37 trampOnStack[8] = 0x816b0004; // lwz r11,4(r11) 38 trampOnStack[9] = 0x4e800420; // bctr 39 40 // clear instruction cache 41 __clear_cache(trampOnStack, &trampOnStack[10]); 42 } 43 #endif // __powerpc__ && !defined(__powerpc64__) 44 45 // The AArch64 compiler generates calls to __trampoline_setup() when creating 46 // trampoline functions on the stack for use with nested functions. 47 // This function creates a custom 36-byte trampoline function on the stack 48 // which loads x18 with a pointer to the outer function's locals 49 // and then jumps to the target nested function. 50 // Note: x18 is a reserved platform register on Windows and macOS. 51 52 #if defined(__aarch64__) && defined(__ELF__) 53 COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack, 54 int trampSizeAllocated, 55 const void *realFunc, void *localsPtr) { 56 // This should never happen, but if compiler did not allocate 57 // enough space on stack for the trampoline, abort. 58 if (trampSizeAllocated < 36) 59 compilerrt_abort(); 60 61 // create trampoline 62 // Load realFunc into x17. mov/movk 16 bits at a time. 63 trampOnStack[0] = 64 0xd2800000u | ((((uint64_t)realFunc >> 0) & 0xffffu) << 5) | 0x11; 65 trampOnStack[1] = 66 0xf2a00000u | ((((uint64_t)realFunc >> 16) & 0xffffu) << 5) | 0x11; 67 trampOnStack[2] = 68 0xf2c00000u | ((((uint64_t)realFunc >> 32) & 0xffffu) << 5) | 0x11; 69 trampOnStack[3] = 70 0xf2e00000u | ((((uint64_t)realFunc >> 48) & 0xffffu) << 5) | 0x11; 71 // Load localsPtr into x18 72 trampOnStack[4] = 73 0xd2800000u | ((((uint64_t)localsPtr >> 0) & 0xffffu) << 5) | 0x12; 74 trampOnStack[5] = 75 0xf2a00000u | ((((uint64_t)localsPtr >> 16) & 0xffffu) << 5) | 0x12; 76 trampOnStack[6] = 77 0xf2c00000u | ((((uint64_t)localsPtr >> 32) & 0xffffu) << 5) | 0x12; 78 trampOnStack[7] = 79 0xf2e00000u | ((((uint64_t)localsPtr >> 48) & 0xffffu) << 5) | 0x12; 80 trampOnStack[8] = 0xd61f0220; // br x17 81 82 // Clear instruction cache. 83 __clear_cache(trampOnStack, &trampOnStack[9]); 84 } 85 #endif // defined(__aarch64__) && !defined(__APPLE__) && !defined(_WIN64) 86