1/* ===----- trampoline_setup.c - Implement __trampoline_setup -------------===
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
13extern void __clear_cache(void* start, void* end);
14
15/*
16 * The ppc compiler generates calls to __trampoline_setup() when creating
17 * trampoline functions on the stack for use with nested functions.
18 * This function creates a custom 40-byte trampoline function on the stack
19 * which loads r11 with a pointer to the outer function's locals
20 * and then jumps to the target nested function.
21 */
22
23#if __ppc__ && !defined(__powerpc64__)
24void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
25 const void* realFunc, void* localsPtr)
26{
27 /* should never happen, but if compiler did not allocate */
28 /* enough space on stack for the trampoline, abort */
29 if ( trampSizeAllocated < 40 )
30 compilerrt_abort();
31
32 /* create trampoline */
33 trampOnStack[0] = 0x7c0802a6; /* mflr r0 */
34 trampOnStack[1] = 0x4800000d; /* bl Lbase */
35 trampOnStack[2] = (uint32_t)realFunc;
36 trampOnStack[3] = (uint32_t)localsPtr;
37 trampOnStack[4] = 0x7d6802a6; /* Lbase: mflr r11 */
38 trampOnStack[5] = 0x818b0000; /* lwz r12,0(r11) */
39 trampOnStack[6] = 0x7c0803a6; /* mtlr r0 */
40 trampOnStack[7] = 0x7d8903a6; /* mtctr r12 */
41 trampOnStack[8] = 0x816b0004; /* lwz r11,4(r11) */
42 trampOnStack[9] = 0x4e800420; /* bctr */
43
44 /* clear instruction cache */
45 __clear_cache(trampOnStack, &trampOnStack[10]);
46}
47#endif /* __ppc__ && !defined(__powerpc64__) */