WiiUPluginLoaderBackend/source/utils/ElfUtils.cpp

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#include <coreinit/cache.h>
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#include <cstring>
#include "ElfUtils.h"
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#include "utils/logger.h"
// See https://github.com/decaf-emu/decaf-emu/blob/43366a34e7b55ab9d19b2444aeb0ccd46ac77dea/src/libdecaf/src/cafe/loader/cafe_loader_reloc.cpp#L144
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bool ElfUtils::elfLinkOne(char type, size_t offset, int32_t addend, uint32_t destination, uint32_t symbol_addr, relocation_trampoline_entry_t *trampoline_data, uint32_t trampoline_data_length,
RelocationType reloc_type, uint8_t trampolineId) {
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if (type == R_PPC_NONE) {
return true;
}
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auto target = destination + offset;
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auto value = symbol_addr + addend;
auto relValue = value - static_cast<uint32_t>(target);
switch (type) {
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case R_PPC_NONE:
break;
case R_PPC_ADDR32:
*((uint32_t *) (target)) = value;
break;
case R_PPC_ADDR16_LO:
*((uint16_t *) (target)) = static_cast<uint16_t>(value & 0xFFFF);
break;
case R_PPC_ADDR16_HI:
*((uint16_t *) (target)) = static_cast<uint16_t>(value >> 16);
break;
case R_PPC_ADDR16_HA:
*((uint16_t *) (target)) = static_cast<uint16_t>((value + 0x8000) >> 16);
break;
case R_PPC_DTPMOD32:
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DEBUG_FUNCTION_LINE("################IMPLEMENT ME");
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//*((int32_t *)(target)) = tlsModuleIndex;
break;
case R_PPC_DTPREL32:
*((uint32_t *) (target)) = value;
break;
case R_PPC_GHS_REL16_HA:
*((uint16_t *) (target)) = static_cast<uint16_t>((relValue + 0x8000) >> 16);
break;
case R_PPC_GHS_REL16_HI:
*((uint16_t *) (target)) = static_cast<uint16_t>(relValue >> 16);
break;
case R_PPC_GHS_REL16_LO:
*((uint16_t *) (target)) = static_cast<uint16_t>(relValue & 0xFFFF);
break;
case R_PPC_REL14: {
auto distance = static_cast<int32_t>(value) - static_cast<int32_t>(target);
if (distance > 0x7FFC || distance < -0x7FFC) {
DEBUG_FUNCTION_LINE("***14-bit relative branch cannot hit target.");
return false;
}
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if (distance & 3) {
DEBUG_FUNCTION_LINE("***RELOC ERROR %d: lower 2 bits must be zero before shifting.", -470040);
return false;
}
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if ((distance >= 0 && (distance & 0xFFFF8000)) ||
(distance < 0 && ((distance & 0xFFFF8000) != 0xFFFF8000))) {
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DEBUG_FUNCTION_LINE("***RELOC ERROR %d: upper 17 bits before shift must all be the same.", -470040);
return false;
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}
*(int32_t *) target = (*(int32_t *) target & 0xFFBF0003) | (distance & 0x0000fffc);
break;
}
case R_PPC_REL24: {
// if (isWeakSymbol && !symbolValue) {
// symbolValue = static_cast<uint32_t>(target);
// value = symbolValue + addend;
// }
auto distance = static_cast<int32_t>(value) - static_cast<int32_t>(target);
if (distance > 0x1FFFFFC || distance < -0x1FFFFFC) {
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if (trampoline_data == nullptr) {
DEBUG_FUNCTION_LINE("***24-bit relative branch cannot hit target. Trampoline isn't provided");
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DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X", value, target, distance);
return false;
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} else {
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relocation_trampoline_entry_t *freeSlot = nullptr;
for (uint32_t i = 0; i < trampoline_data_length; i++) {
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// We want to override "old" relocations of imports
// Pending relocations have the status RELOC_TRAMP_IMPORT_IN_PROGRESS.
// When all relocations are done successfully, they will be turned into RELOC_TRAMP_IMPORT_DONE
// so they can be overridden/updated/reused on the next application launch.
//
// Relocations that won't change will have the status RELOC_TRAMP_FIXED and are set to free when the module is unloaded.
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if (trampoline_data[i].status == RELOC_TRAMP_FREE ||
trampoline_data[i].status == RELOC_TRAMP_IMPORT_DONE) {
freeSlot = &(trampoline_data[i]);
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break;
}
}
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if (freeSlot == nullptr) {
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DEBUG_FUNCTION_LINE("***24-bit relative branch cannot hit target. Trampoline data list is full");
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DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X", value, target, target - (uint32_t) & (freeSlot->trampoline[0]));
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return false;
}
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if (target - (uint32_t) & (freeSlot->trampoline[0]) > 0x1FFFFFC) {
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DEBUG_FUNCTION_LINE("**Cannot link 24-bit jump (too far to tramp buffer).");
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DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X", value, target, (target - (uint32_t) & (freeSlot->trampoline[0])));
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return false;
}
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freeSlot->trampoline[0] = 0x3D600000 | ((((uint32_t) value) >> 16) & 0x0000FFFF); // lis r11, real_addr@h
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freeSlot->trampoline[1] = 0x616B0000 | (((uint32_t) value) & 0x0000ffff); // ori r11, r11, real_addr@l
freeSlot->trampoline[2] = 0x7D6903A6; // mtctr r11
freeSlot->trampoline[3] = 0x4E800420; // bctr
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DCFlushRange((void *) freeSlot->trampoline, sizeof(freeSlot->trampoline));
ICInvalidateRange((unsigned char *) freeSlot->trampoline, sizeof(freeSlot->trampoline));
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freeSlot->id = trampolineId;
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DCFlushRange((void *) &freeSlot->id, sizeof(freeSlot->id));
ICInvalidateRange((unsigned char *) &freeSlot->id, sizeof(freeSlot->id));
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if (reloc_type == RELOC_TYPE_FIXED) {
freeSlot->status = RELOC_TRAMP_FIXED;
} else {
// Relocations for the imports may be overridden
freeSlot->status = RELOC_TRAMP_IMPORT_DONE;
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}
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auto symbolValue = (uint32_t) & (freeSlot->trampoline[0]);
value = symbolValue + addend;
distance = static_cast<int32_t>(value) - static_cast<int32_t>(target);
}
}
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if (distance & 3) {
DEBUG_FUNCTION_LINE("***RELOC ERROR %d: lower 2 bits must be zero before shifting.", -470022);
return false;
}
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if (distance < 0 && (distance & 0xFE000000) != 0xFE000000) {
DEBUG_FUNCTION_LINE("***RELOC ERROR %d: upper 7 bits before shift must all be the same (1).", -470040);
return false;
}
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if (distance >= 0 && (distance & 0xFE000000)) {
DEBUG_FUNCTION_LINE("***RELOC ERROR %d: upper 7 bits before shift must all be the same (0).", -470040);
return false;
}
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*(int32_t *) target = (*(int32_t *) target & 0xfc000003) | (distance & 0x03fffffc);
break;
}
default:
DEBUG_FUNCTION_LINE("***ERROR: Unsupported Relocation_Add Type (%08X):", type);
return false;
}
return true;
}