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__) */
48