forked from OSchip/llvm-project
49 lines
1.7 KiB
C
49 lines
1.7 KiB
C
/* ===----- trampoline_setup.c - Implement __trampoline_setup -------------===
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*
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* The LLVM Compiler Infrastructure
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*
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* This file is distributed under the University of Illinois Open Source
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* License. See LICENSE.TXT for details.
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*
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* ===----------------------------------------------------------------------===
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*/
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#include <stdint.h>
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#include <stdlib.h>
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extern void __clear_cache(void* start, void* end);
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/*
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* The ppc compiler generates calls to __trampoline_setup() when creating
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* trampoline functions on the stack for use with nested functions.
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* This function creates a custom 40-byte trampoline function on the stack
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* which loads r11 with a pointer to the outer function's locals
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* and then jumps to the target nested function.
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*/
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#if __ppc__
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void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
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const void* realFunc, void* localsPtr)
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{
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/* should never happen, but if compiler did not allocate */
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/* enough space on stack for the trampoline, abort */
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if ( trampSizeAllocated < 40 )
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abort();
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/* create trampoline */
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trampOnStack[0] = 0x7c0802a6; /* mflr r0 */
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trampOnStack[1] = 0x4800000d; /* bl Lbase */
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trampOnStack[2] = (uint32_t)realFunc;
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trampOnStack[3] = (uint32_t)localsPtr;
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trampOnStack[4] = 0x7d6802a6; /* Lbase: mflr r11 */
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trampOnStack[5] = 0x818b0000; /* lwz r12,0(r11) */
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trampOnStack[6] = 0x7c0803a6; /* mtlr r0 */
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trampOnStack[7] = 0x7d8903a6; /* mtctr r12 */
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trampOnStack[8] = 0x816b0004; /* lwz r11,4(r11) */
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trampOnStack[9] = 0x4e800420; /* bctr */
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/* clear instruction cache */
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__clear_cache(trampOnStack, &trampOnStack[10]);
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}
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#endif /* __ppc__ */
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