44 lines
1.8 KiB
C
44 lines
1.8 KiB
C
//===----- trampoline_setup.c - Implement __trampoline_setup -------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "int_lib.h"
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extern void __clear_cache(void *start, void *end);
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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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#if __ppc__ && !defined(__powerpc64__)
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COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack,
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int trampSizeAllocated,
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const void *realFunc, void *localsPtr) {
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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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compilerrt_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__ && !defined(__powerpc64__)
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