WUMSLoader/relocator/src/ElfUtils.cpp

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#include <stdio.h>
#include <string.h>
#include <coreinit/cache.h>
#include "utils/logger.h"
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#include "ElfUtils.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_trampolin_entry_t *trampolin_data, uint32_t trampolin_data_length, RelocationType reloc_type) {
if (type == R_PPC_NONE) {
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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:
DEBUG_FUNCTION_LINE("################IMPLEMENT ME\n");
//*((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)) ||
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(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);
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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) {
if (trampolin_data == NULL) {
DEBUG_FUNCTION_LINE("***24-bit relative branch cannot hit target. Trampolin isn't provided\n");
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DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X\n", value, target, distance);
return false;
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} else {
relocation_trampolin_entry_t *freeSlot = NULL;
for (uint32_t i = 0; i < trampolin_data_length; i++) {
// 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.
if (trampolin_data[i].status == RELOC_TRAMP_FREE ||
trampolin_data[i].status == RELOC_TRAMP_IMPORT_DONE) {
freeSlot = &(trampolin_data[i]);
break;
}
}
if (freeSlot != NULL) {
DEBUG_FUNCTION_LINE("***24-bit relative branch cannot hit target. Trampolin data list is full\n");
DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X\n", value, target, distance);
return false;
}
if (target - (uint32_t) &(freeSlot->trampolin[0]) > 0x1FFFFFC) {
DEBUG_FUNCTION_LINE("**Cannot link 24-bit jump (too far to tramp buffer).");
DEBUG_FUNCTION_LINE("***value %08X - target %08X = distance %08X\n", value, target, distance);
return false;
}
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freeSlot->trampolin[0] = 0x3D600000 | ((((uint32_t) value) >> 16) & 0x0000FFFF); // lis r11, real_addr@h
freeSlot->trampolin[1] = 0x616B0000 | (((uint32_t) value) & 0x0000ffff); // ori r11, r11, real_addr@l
freeSlot->trampolin[2] = 0x7D6903A6; // mtctr r11
freeSlot->trampolin[3] = 0x4E800420; // bctr
DCFlushRange((void *) freeSlot->trampolin, sizeof(freeSlot->trampolin));
ICInvalidateRange((unsigned char *) freeSlot->trampolin, sizeof(freeSlot->trampolin));
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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_IN_PROGRESS;
}
uint32_t symbolValue = (uint32_t) &(freeSlot->trampolin[0]);
value = symbolValue + addend;
distance = static_cast<int32_t>(value) - static_cast<int32_t>(target);
DEBUG_FUNCTION_LINE("Created tramp\n");
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}
}
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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;
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}
return true;
}