1 /* ===----- trampoline_setup.c - Implement __trampoline_setup -------------===
2 *
3 * The LLVM Compiler Infrastructure
4 *
5 * This file is distributed under the University of Illinois Open Source
6 * License. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 */
10
11 #include <stdint.h>
12 #include <stdlib.h>
13
14 extern void __clear_cache(void* start, void* end);
15
16 /*
17 * The ppc compiler generates calls to __trampoline_setup() when creating
18 * trampoline functions on the stack for use with nested functions.
19 * This function creates a custom 40-byte trampoline function on the stack
20 * which loads r11 with a pointer to the outer function's locals
21 * and then jumps to the target nested function.
22 */
23
24 #if __ppc__
__trampoline_setup(uint32_t * trampOnStack,int trampSizeAllocated,const void * realFunc,void * localsPtr)25 void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
26 const void* realFunc, void* localsPtr)
27 {
28 /* should never happen, but if compiler did not allocate */
29 /* enough space on stack for the trampoline, abort */
30 if ( trampSizeAllocated < 40 )
31 abort();
32
33 /* create trampoline */
34 trampOnStack[0] = 0x7c0802a6; /* mflr r0 */
35 trampOnStack[1] = 0x4800000d; /* bl Lbase */
36 trampOnStack[2] = (uint32_t)realFunc;
37 trampOnStack[3] = (uint32_t)localsPtr;
38 trampOnStack[4] = 0x7d6802a6; /* Lbase: mflr r11 */
39 trampOnStack[5] = 0x818b0000; /* lwz r12,0(r11) */
40 trampOnStack[6] = 0x7c0803a6; /* mtlr r0 */
41 trampOnStack[7] = 0x7d8903a6; /* mtctr r12 */
42 trampOnStack[8] = 0x816b0004; /* lwz r11,4(r11) */
43 trampOnStack[9] = 0x4e800420; /* bctr */
44
45 /* clear instruction cache */
46 __clear_cache(trampOnStack, &trampOnStack[10]);
47 }
48 #endif /* __ppc__ */
49