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