| 1 | //===----- trampoline_setup.c - Implement __trampoline_setup -------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "int_lib.h" |
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| 10 | |
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| 11 | extern void __clear_cache(void *start, void *end); |
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| 12 | |
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| 13 | // The ppc compiler generates calls to __trampoline_setup() when creating |
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| 14 | // trampoline functions on the stack for use with nested functions. |
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| 15 | // This function creates a custom 40-byte trampoline function on the stack |
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| 16 | // which loads r11 with a pointer to the outer function's locals |
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| 17 | // and then jumps to the target nested function. |
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| 18 | |
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| 19 | #if __powerpc__ && !defined(__powerpc64__) |
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| 20 | COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack, |
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| 21 | int trampSizeAllocated, |
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| 22 | const void *realFunc, void *localsPtr) { |
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| 23 | // should never happen, but if compiler did not allocate |
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| 24 | // enough space on stack for the trampoline, abort |
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| 25 | if (trampSizeAllocated < 40) |
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| 26 | compilerrt_abort(); |
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| 27 | |
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| 28 | // create trampoline |
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| 29 | trampOnStack[0] = 0x7c0802a6; // mflr r0 |
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| 30 | trampOnStack[1] = 0x4800000d; // bl Lbase |
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| 31 | trampOnStack[2] = (uint32_t)realFunc; |
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| 32 | trampOnStack[3] = (uint32_t)localsPtr; |
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| 33 | trampOnStack[4] = 0x7d6802a6; // Lbase: mflr r11 |
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| 34 | trampOnStack[5] = 0x818b0000; // lwz r12,0(r11) |
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| 35 | trampOnStack[6] = 0x7c0803a6; // mtlr r0 |
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| 36 | trampOnStack[7] = 0x7d8903a6; // mtctr r12 |
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| 37 | trampOnStack[8] = 0x816b0004; // lwz r11,4(r11) |
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| 38 | trampOnStack[9] = 0x4e800420; // bctr |
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| 39 | |
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| 40 | // clear instruction cache |
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| 41 | __clear_cache(trampOnStack, &trampOnStack[10]); |
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| 42 | } |
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| 43 | #endif // __powerpc__ && !defined(__powerpc64__) |
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| 44 | |
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