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Further documentation for overlay relocation (#1498)

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* Further documentation for overlay relocation

* Suggested changes

* Format

* REL_ -> RELOC_
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Tharo 2023-02-27 08:14:02 +00:00 committed by GitHub
parent 35887e25ee
commit 12f67e108a
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5 changed files with 128 additions and 64 deletions
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6
include/functions.h
View file

@ -1741,11 +1741,11 @@ Gfx* GfxPrint_Close(GfxPrint* this);
s32 GfxPrint_Printf(GfxPrint* this, const char* fmt, ...); s32 GfxPrint_Printf(GfxPrint* this, const char* fmt, ...);
void RcpUtils_PrintRegisterStatus(void); void RcpUtils_PrintRegisterStatus(void);
void RcpUtils_Reset(void); void RcpUtils_Reset(void);
void* Overlay_AllocateAndLoad(uintptr_t vRomStart, uintptr_t vRomEnd, void* vRamStart, void* vRamEnd); void* Overlay_AllocateAndLoad(uintptr_t vromStart, uintptr_t vromEnd, void* vramStart, void* vramEnd);
void MtxConv_F2L(Mtx* m1, MtxF* m2); void MtxConv_F2L(Mtx* m1, MtxF* m2);
void MtxConv_L2F(MtxF* m1, Mtx* m2); void MtxConv_L2F(MtxF* m1, Mtx* m2);
void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* overlayInfo, void* vRamStart); void Overlay_Relocate(void* allocatedRamAddress, OverlayRelocationSection* ovlRelocs, void* vramStart);
s32 Overlay_Load(uintptr_t vRomStart, uintptr_t vRomEnd, void* vRamStart, void* vRamEnd, void* allocatedVRamAddr); s32 Overlay_Load(uintptr_t vromStart, uintptr_t vromEnd, void* vramStart, void* vramEnd, void* allocatedRamAddr);
// ? func_800FC800(?); // ? func_800FC800(?);
// ? func_800FC83C(?); // ? func_800FC83C(?);
// ? func_800FCAB4(?); // ? func_800FCAB4(?);

22
include/z64.h
View file

@ -1165,24 +1165,34 @@ typedef struct ArenaNode {
/* 0x28 */ u8 unk_28[0x30-0x28]; // probably padding /* 0x28 */ u8 unk_28[0x30-0x28]; // probably padding
} ArenaNode; // size = 0x30 } ArenaNode; // size = 0x30
#define RELOC_SECTION(reloc) ((reloc) >> 30) /* Relocation entry field getters */
#define RELOC_OFFSET(reloc) ((reloc) & 0xFFFFFF) #define RELOC_SECTION(reloc) ((reloc) >> 30)
#define RELOC_OFFSET(reloc) ((reloc) & 0xFFFFFF)
#define RELOC_TYPE_MASK(reloc) ((reloc) & 0x3F000000) #define RELOC_TYPE_MASK(reloc) ((reloc) & 0x3F000000)
#define RELOC_TYPE_SHIFT 24 #define RELOC_TYPE_SHIFT 24
/* MIPS Relocation Types */ /* MIPS Relocation Types, matches the MIPS ELF spec */
#define R_MIPS_32 2 #define R_MIPS_32 2
#define R_MIPS_26 4 #define R_MIPS_26 4
#define R_MIPS_HI16 5 #define R_MIPS_HI16 5
#define R_MIPS_LO16 6 #define R_MIPS_LO16 6
/* Reloc section id, must fit in 2 bits otherwise the relocation format must be modified */
typedef enum {
/* 0 */ RELOC_SECTION_NULL,
/* 1 */ RELOC_SECTION_TEXT,
/* 2 */ RELOC_SECTION_DATA,
/* 3 */ RELOC_SECTION_RODATA,
/* 4 */ RELOC_SECTION_MAX
} RelocSectionId;
typedef struct OverlayRelocationSection { typedef struct OverlayRelocationSection {
/* 0x00 */ u32 textSize; /* 0x00 */ u32 textSize;
/* 0x04 */ u32 dataSize; /* 0x04 */ u32 dataSize;
/* 0x08 */ u32 rodataSize; /* 0x08 */ u32 rodataSize;
/* 0x0C */ u32 bssSize; /* 0x0C */ u32 bssSize;
/* 0x10 */ u32 nRelocations; /* 0x10 */ u32 nRelocations;
/* 0x14 */ u32 relocations[1]; /* 0x14 */ u32 relocations[1]; // size is nRelocations
} OverlayRelocationSection; // size >= 0x18 } OverlayRelocationSection; // size >= 0x18
typedef struct { typedef struct {

50
src/code/load.c
View file

@ -1,14 +1,14 @@
#include "global.h" #include "global.h"
s32 Overlay_Load(uintptr_t vRomStart, uintptr_t vRomEnd, void* vRamStart, void* vRamEnd, void* allocatedVRamAddr) { s32 Overlay_Load(uintptr_t vromStart, uintptr_t vromEnd, void* vramStart, void* vramEnd, void* allocatedRamAddr) {
s32 pad[3]; s32 pad[3];
uintptr_t end; uintptr_t end;
OverlayRelocationSection* ovl; OverlayRelocationSection* ovlRelocs;
u32 ovlOffset; u32 relocSectionOffset;
size_t size; size_t size;
size = vRomEnd - vRomStart; size = vromEnd - vromStart;
end = (uintptr_t)allocatedVRamAddr + size; end = (uintptr_t)allocatedRamAddr + size;
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
// "Start loading dynamic link function" // "Start loading dynamic link function"
@ -17,44 +17,52 @@ s32 Overlay_Load(uintptr_t vRomStart, uintptr_t vRomEnd, void* vRamStart, void*
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
// "DMA transfer of TEXT, DATA, RODATA + rel (%08x-%08x)" // "DMA transfer of TEXT, DATA, RODATA + rel (%08x-%08x)"
osSyncPrintf("TEXT,DATA,RODATA+relをＤＭＡ転送します(%08x-%08x)\n", allocatedVRamAddr, end); osSyncPrintf("TEXT,DATA,RODATA+relをＤＭＡ転送します(%08x-%08x)\n", allocatedRamAddr, end);
} }
DmaMgr_RequestSync(allocatedVRamAddr, vRomStart, size); // DMA the overlay, wait until transfer completes
DmaMgr_RequestSync(allocatedRamAddr, vromStart, size);
ovlOffset = ((s32*)end)[-1]; // The overlay file is expected to contain a 32-bit offset from the end of the file to the start of the
// relocation section.
relocSectionOffset = ((s32*)end)[-1];
ovlRelocs = (OverlayRelocationSection*)(end - relocSectionOffset);
ovl = (OverlayRelocationSection*)(end - ovlOffset);
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
osSyncPrintf("TEXT(%08x), DATA(%08x), RODATA(%08x), BSS(%08x)\n", ovl->textSize, ovl->dataSize, ovl->rodataSize, osSyncPrintf("TEXT(%08x), DATA(%08x), RODATA(%08x), BSS(%08x)\n", ovlRelocs->textSize, ovlRelocs->dataSize,
ovl->bssSize); ovlRelocs->rodataSize, ovlRelocs->bssSize);
} }
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
osSyncPrintf("リロケーションします\n"); // "Relocate" osSyncPrintf("リロケーションします\n"); // "Relocate"
} }
Overlay_Relocate(allocatedVRamAddr, ovl, vRamStart); // Relocate pointers in overlay code and data
Overlay_Relocate(allocatedRamAddr, ovlRelocs, vramStart);
if (ovl->bssSize != 0) { // Clear bss if present, bss is located immediately following the relocations
if (ovlRelocs->bssSize != 0) {
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
// "Clear BSS area (% 08x-% 08x)" // "Clear BSS area (% 08x-% 08x)"
osSyncPrintf("BSS領域をクリアします(%08x-%08x)\n", end, end + ovl->bssSize); osSyncPrintf("BSS領域をクリアします(%08x-%08x)\n", end, end + ovlRelocs->bssSize);
} }
bzero((void*)end, ovl->bssSize); bzero((void*)end, ovlRelocs->bssSize);
} }
size = (uintptr_t)&ovl->relocations[ovl->nRelocations] - (uintptr_t)ovl; size = (uintptr_t)&ovlRelocs->relocations[ovlRelocs->nRelocations] - (uintptr_t)ovlRelocs;
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
// "Clear REL area (%08x-%08x)" // "Clear REL area (%08x-%08x)"
osSyncPrintf("REL領域をクリアします(%08x-%08x)\n", ovl, (uintptr_t)ovl + size); osSyncPrintf("REL領域をクリアします(%08x-%08x)\n", ovlRelocs, (uintptr_t)ovlRelocs + size);
} }
bzero(ovl, size); // Clear relocations, this space remains allocated and goes unused
bzero(ovlRelocs, size);
size = (uintptr_t)vRamEnd - (uintptr_t)vRamStart; // Manually flush caches
osWritebackDCache(allocatedVRamAddr, size); size = (uintptr_t)vramEnd - (uintptr_t)vramStart;
osInvalICache(allocatedVRamAddr, size); osWritebackDCache(allocatedRamAddr, size);
osInvalICache(allocatedRamAddr, size);
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
// "Finish loading dynamic link function" // "Finish loading dynamic link function"

16
src/code/loadfragment2.c
View file

@ -1,17 +1,17 @@
#include "global.h" #include "global.h"
void* Overlay_AllocateAndLoad(uintptr_t vRomStart, uintptr_t vRomEnd, void* vRamStart, void* vRamEnd) { void* Overlay_AllocateAndLoad(uintptr_t vromStart, uintptr_t vromEnd, void* vramStart, void* vramEnd) {
void* allocatedVRamAddr = SystemArena_MallocRDebug((s32)vRamEnd - (s32)vRamStart, "../loadfragment2.c", 31); void* allocatedRamAddr = SystemArena_MallocRDebug((s32)vramEnd - (s32)vramStart, "../loadfragment2.c", 31);
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
osSyncPrintf("OVL:SPEC(%08x-%08x) REAL(%08x-%08x) OFFSET(%08x)\n", vRamStart, vRamEnd, allocatedVRamAddr, osSyncPrintf("OVL:SPEC(%08x-%08x) REAL(%08x-%08x) OFFSET(%08x)\n", vramStart, vramEnd, allocatedRamAddr,
((uintptr_t)vRamEnd - (uintptr_t)vRamStart) + (uintptr_t)allocatedVRamAddr, ((uintptr_t)vramEnd - (uintptr_t)vramStart) + (uintptr_t)allocatedRamAddr,
(uintptr_t)vRamStart - (uintptr_t)allocatedVRamAddr); (uintptr_t)vramStart - (uintptr_t)allocatedRamAddr);
} }
if (allocatedVRamAddr != NULL) { if (allocatedRamAddr != NULL) {
Overlay_Load(vRomStart, vRomEnd, vRamStart, vRamEnd, allocatedVRamAddr); Overlay_Load(vromStart, vromEnd, vramStart, vramEnd, allocatedRamAddr);
} }
return allocatedVRamAddr; return allocatedRamAddr;
} }

98
src/code/relocation.c
View file

@ -1,7 +1,44 @@
/**
* @file relocation.c
*
* This file contains the routine responsible for runtime relocation of dynamically loadable code segments (overlays),
* see the description of Overlay_Relocate for details.
*
* @see Overlay_Relocate
*/
#include "global.h" #include "global.h"
void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* overlayInfo, void* vRamStart) { // Extract MIPS register rs from an instruction word
u32 sections[4]; #define MIPS_REG_RS(insn) (((insn) >> 0x15) & 0x1F)
// Extract MIPS register rt from an instruction word
#define MIPS_REG_RT(insn) (((insn) >> 0x10) & 0x1F)
// Extract MIPS jump target from an instruction word
#define MIPS_JUMP_TARGET(insn) (((insn)&0x03FFFFFF) << 2)
/**
* Performs runtime relocation of overlay files, loadable code segments.
*
* Overlays are expected to be loadable anywhere in direct-mapped cached (KSEG0) memory, with some appropriate
* alignment requirements; memory addresses in such code must be updated once loaded in order to execute properly.
* When compiled, overlays are given 'fake' KSEG0 RAM addresses larger than the total possible available main memory
* (>= 0x80800000), such addresses are referred to as Virtual RAM (VRAM) to distinguish them. When loading the overlay
* the relocation table produced at compile time is consulted to determine where and how to update these VRAM addresses
* to correct RAM addresses based on the location the overlay was loaded at, enabling the code to execute at this
* address as if it were compiled to run at this address.
*
* Each relocation is represented by a packed 32-bit value, formatted in the following way:
* - [31:30] 2-bit section id, taking values from the `RelocSectionId` enum.
* - [29:24] 6-bit relocation type describing which relocation operation should be performed. Same as ELF32 MIPS.
* - [23: 0] 24-bit section-relative offset indicating where in the section to apply this relocation.
*
* @param allocatedRamAddress Memory address the binary was loaded at.
* @param ovlRelocs Overlay relocation section containing overlay section layout and runtime relocations.
* @param vramStart Virtual RAM address that the overlay was compiled at.
*/
void Overlay_Relocate(void* allocatedRamAddress, OverlayRelocationSection* ovlRelocs, void* vramStart) {
uintptr_t sections[RELOC_SECTION_MAX];
u32 relocatedValue; u32 relocatedValue;
u32 dbg; u32 dbg;
u32 relocOffset; u32 relocOffset;
@ -9,12 +46,18 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
uintptr_t unrelocatedAddress; uintptr_t unrelocatedAddress;
u32 i; u32 i;
u32* relocDataP; u32* relocDataP;
//! MIPS ELF relocation does not generally require tracking register values, so at first glance it appears this
//! register tracking was an unnecessary complication. However there is a bug in the IDO compiler that can cause
//! relocations to be emitted in the wrong order under rare circumstances when the compiler attempts to reuse a
//! previous HI16 relocation for a different LO16 relocation as an optimization. This register tracking is likely
//! a workaround to prevent improper matching of unrelated HI16 and LO16 relocations that would otherwise arise
//! due to the incorrect ordering.
u32* luiRefs[32]; u32* luiRefs[32];
u32 luiVals[32]; u32 luiVals[32];
uintptr_t relocatedAddress; uintptr_t relocatedAddress;
u32 reloc; u32 reloc;
u32* luiInstRef; u32* luiInstRef;
uintptr_t allocu32 = (uintptr_t)allocatedVRamAddress; uintptr_t allocu32 = (uintptr_t)allocatedRamAddress;
u32* regValP; u32* regValP;
u32 isLoNeg; u32 isLoNeg;
s32 pad; s32 pad;
@ -25,18 +68,21 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
relocatedAddress = 0; relocatedAddress = 0;
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
osSyncPrintf("DoRelocation(%08x, %08x, %08x)\n", allocatedVRamAddress, overlayInfo, vRamStart); osSyncPrintf("DoRelocation(%08x, %08x, %08x)\n", allocatedRamAddress, ovlRelocs, vramStart);
osSyncPrintf("text=%08x, data=%08x, rodata=%08x, bss=%08x\n", overlayInfo->textSize, overlayInfo->dataSize, osSyncPrintf("text=%08x, data=%08x, rodata=%08x, bss=%08x\n", ovlRelocs->textSize, ovlRelocs->dataSize,
overlayInfo->rodataSize, overlayInfo->bssSize); ovlRelocs->rodataSize, ovlRelocs->bssSize);
} }
sections[0] = 0; sections[RELOC_SECTION_NULL] = 0;
sections[1] = allocu32; sections[RELOC_SECTION_TEXT] = allocu32;
sections[2] = allocu32 + overlayInfo->textSize; sections[RELOC_SECTION_DATA] = allocu32 + ovlRelocs->textSize;
sections[3] = sections[2] + overlayInfo->dataSize; sections[RELOC_SECTION_RODATA] = sections[RELOC_SECTION_DATA] + ovlRelocs->dataSize;
for (i = 0; i < overlayInfo->nRelocations; i++) { for (i = 0; i < ovlRelocs->nRelocations; i++) {
reloc = overlayInfo->relocations[i]; reloc = ovlRelocs->relocations[i];
// This will always resolve to a 32-bit aligned address as each section containing code or pointers must be
// aligned to at least 4 bytes and the MIPS ABI defines the offset of both 16-bit and 32-bit relocations to
// be the start of the 32-bit word containing the target.
relocDataP = (u32*)(sections[RELOC_SECTION(reloc)] + RELOC_OFFSET(reloc)); relocDataP = (u32*)(sections[RELOC_SECTION(reloc)] + RELOC_OFFSET(reloc));
relocData = *relocDataP; relocData = *relocDataP;
@ -47,7 +93,7 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
// Check address is valid for relocation // Check address is valid for relocation
if ((*relocDataP & 0x0F000000) == 0) { if ((*relocDataP & 0x0F000000) == 0) {
relocOffset = *relocDataP - (uintptr_t)vRamStart; relocOffset = *relocDataP - (uintptr_t)vramStart;
relocatedValue = relocOffset + allocu32; relocatedValue = relocOffset + allocu32;
relocatedAddress = relocatedValue; relocatedAddress = relocatedValue;
unrelocatedAddress = relocData; unrelocatedAddress = relocData;
@ -60,10 +106,10 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
// Extract the address from the target field of the J-type MIPS instruction. // Extract the address from the target field of the J-type MIPS instruction.
// Relocate the address and update the instruction. // Relocate the address and update the instruction.
unrelocatedAddress = PHYS_TO_K0((*relocDataP & 0x03FFFFFF) << 2); unrelocatedAddress = PHYS_TO_K0(MIPS_JUMP_TARGET(*relocDataP));
relocOffset = unrelocatedAddress - (uintptr_t)vRamStart; relocOffset = unrelocatedAddress - (uintptr_t)vramStart;
relocatedValue = (*relocDataP & 0xFC000000) | (((allocu32 + relocOffset) & 0x0FFFFFFF) >> 2); relocatedValue = (*relocDataP & 0xFC000000) | (((allocu32 + relocOffset) & 0x0FFFFFFF) >> 2);
relocatedAddress = PHYS_TO_K0((relocatedValue & 0x03FFFFFF) << 2); relocatedAddress = PHYS_TO_K0(MIPS_JUMP_TARGET(relocatedValue));
*relocDataP = relocatedValue; *relocDataP = relocatedValue;
break; break;
@ -72,8 +118,8 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
// Store the reference to the LUI instruction (hi) using the `rt` register of the instruction. // Store the reference to the LUI instruction (hi) using the `rt` register of the instruction.
// This will be updated later in the `R_MIPS_LO16` section. // This will be updated later in the `R_MIPS_LO16` section.
luiRefs[(*relocDataP >> 0x10) & 0x1F] = relocDataP; luiRefs[MIPS_REG_RT(*relocDataP)] = relocDataP;
luiVals[(*relocDataP >> 0x10) & 0x1F] = *relocDataP; luiVals[MIPS_REG_RT(*relocDataP)] = *relocDataP;
break; break;
case R_MIPS_LO16 << RELOC_TYPE_SHIFT: case R_MIPS_LO16 << RELOC_TYPE_SHIFT:
@ -83,13 +129,13 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
// If the lo part is negative, add 1 to the LUI value. // If the lo part is negative, add 1 to the LUI value.
// Note: The lo instruction is assumed to have a signed immediate. // Note: The lo instruction is assumed to have a signed immediate.
luiInstRef = luiRefs[(*relocDataP >> 0x15) & 0x1F]; luiInstRef = luiRefs[MIPS_REG_RS(*relocDataP)];
regValP = &luiVals[(*relocDataP >> 0x15) & 0x1F]; regValP = &luiVals[MIPS_REG_RS(*relocDataP)];
// Check address is valid for relocation // Check address is valid for relocation
if ((((*regValP << 0x10) + (s16)*relocDataP) & 0x0F000000) == 0) { if ((((*regValP << 0x10) + (s16)*relocDataP) & 0x0F000000) == 0) {
relocOffset = ((*regValP << 0x10) + (s16)*relocDataP) - (uintptr_t)vRamStart; relocOffset = ((*regValP << 0x10) + (s16)*relocDataP) - (uintptr_t)vramStart;
isLoNeg = (((relocOffset + allocu32) & 0x8000) ? 1 : 0); isLoNeg = ((relocOffset + allocu32) & 0x8000) ? 1 : 0; // adjust for signed immediate
unrelocatedAddress = (*luiInstRef << 0x10) + (s16)relocData; unrelocatedAddress = (*luiInstRef << 0x10) + (s16)relocData;
*luiInstRef = *luiInstRef =
(*luiInstRef & 0xFFFF0000) | ((((relocOffset + allocu32) >> 0x10) & 0xFFFF) + isLoNeg); (*luiInstRef & 0xFFFF0000) | ((((relocOffset + allocu32) >> 0x10) & 0xFFFF) + isLoNeg);
@ -101,18 +147,18 @@ void Overlay_Relocate(void* allocatedVRamAddress, OverlayRelocationSection* over
break; break;
} }
dbg = 0x10; dbg = 16;
switch (RELOC_TYPE_MASK(reloc)) { switch (RELOC_TYPE_MASK(reloc)) {
case R_MIPS_32 << RELOC_TYPE_SHIFT: case R_MIPS_32 << RELOC_TYPE_SHIFT:
dbg = 0x16; dbg += 6;
FALLTHROUGH; FALLTHROUGH;
case R_MIPS_26 << RELOC_TYPE_SHIFT: case R_MIPS_26 << RELOC_TYPE_SHIFT:
dbg += 0xA; dbg += 10;
FALLTHROUGH; FALLTHROUGH;
case R_MIPS_LO16 << RELOC_TYPE_SHIFT: case R_MIPS_LO16 << RELOC_TYPE_SHIFT:
if (gOverlayLogSeverity >= 3) { if (gOverlayLogSeverity >= 3) {
osSyncPrintf("%02d %08x %08x %08x ", dbg, relocDataP, relocatedValue, relocatedAddress); osSyncPrintf("%02d %08x %08x %08x ", dbg, relocDataP, relocatedValue, relocatedAddress);
osSyncPrintf(" %08x %08x %08x %08x\n", (uintptr_t)relocDataP + (uintptr_t)vRamStart - allocu32, osSyncPrintf(" %08x %08x %08x %08x\n", (uintptr_t)relocDataP + (uintptr_t)vramStart - allocu32,
relocData, unrelocatedAddress, relocOffset); relocData, unrelocatedAddress, relocOffset);
} }
// Adding a break prevents matching // Adding a break prevents matching