ref: 37e45de9c105f32033e7562055581ec586ef1681
dir: /src/link/patch.c/
/*
* This file is part of RGBDS.
*
* Copyright (c) 2019, Eldred Habert and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*/
#include <inttypes.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "link/patch.h"
#include "link/section.h"
#include "link/symbol.h"
#include "linkdefs.h"
#include "extern/err.h"
static int32_t asl(int32_t value, int32_t shiftamt); // Forward decl for below
static int32_t asr(int32_t value, int32_t shiftamt)
{
uint32_t uvalue = value;
// Get the easy cases out of the way
if (shiftamt == 0)
return value;
if (value == 0 || shiftamt <= -32)
return 0;
if (shiftamt > 31)
return (value < 0) ? -1 : 0;
if (shiftamt < 0)
return asl(value, -shiftamt);
if (value > 0)
return uvalue >> shiftamt;
{
// Calculate an OR mask for sign extension
// 1->0x80000000, 2->0xC0000000, ..., 31->0xFFFFFFFE
uint32_t shiftamt_high_bits = -((uint32_t)1 << (32 - shiftamt));
return (uvalue >> shiftamt) | shiftamt_high_bits;
}
}
static int32_t asl(int32_t value, int32_t shiftamt)
{
// Repeat the easy cases here to avoid INT_MIN funny business
if (shiftamt == 0)
return value;
if (value == 0 || shiftamt >= 32)
return 0;
if (shiftamt < -31)
return (value < 0) ? -1 : 0;
if (shiftamt < 0)
return asr(value, -shiftamt);
return (uint32_t)value << shiftamt;
}
/* This is an "empty"-type stack */
struct RPNStack {
int32_t *buf;
size_t size;
size_t capacity;
} stack;
static inline void initRPNStack(void)
{
stack.capacity = 64;
stack.buf = malloc(sizeof(*stack.buf) * stack.capacity);
if (!stack.buf)
err(1, "Failed to init RPN stack");
}
static inline void clearRPNStack(void)
{
stack.size = 0;
}
static void pushRPN(int32_t value)
{
if (stack.size >= stack.capacity) {
static const size_t increase_factor = 2;
if (stack.capacity > SIZE_MAX / increase_factor)
errx(1, "Overflow in RPN stack resize");
stack.capacity *= increase_factor;
stack.buf =
realloc(stack.buf, sizeof(*stack.buf) * stack.capacity);
/*
* Static analysis tools complain that the capacity might become
* zero due to overflow, but fail to realize that it's caught by
* the overflow check above. Hence the stringent check below.
*/
if (!stack.buf || !stack.capacity)
err(1, "Failed to resize RPN stack");
}
stack.buf[stack.size] = value;
stack.size++;
}
static int32_t popRPN(char const *fileName)
{
if (stack.size == 0)
errx(1, "%s: Internal error, RPN stack empty", fileName);
stack.size--;
return stack.buf[stack.size];
}
static inline void freeRPNStack(void)
{
free(stack.buf);
}
/* RPN operators */
static uint32_t getRPNByte(uint8_t const **expression, int32_t *size,
char const *fileName)
{
if (!(*size)--)
errx(1, "%s: RPN expression overread", fileName);
return *(*expression)++;
}
static struct Symbol const *getSymbol(struct Symbol const * const *symbolList,
uint32_t index)
{
struct Symbol const *symbol = symbolList[index];
/* If the symbol is defined elsewhere... */
if (symbol->type == SYMTYPE_IMPORT)
return sym_GetSymbol(symbol->name);
return symbol;
}
/**
* Compute a patch's value from its RPN string.
* @param patch The patch to compute the value of
* @param section The section the patch is contained in
* @return The patch's value
*/
static int32_t computeRPNExpr(struct Patch const *patch,
struct Symbol const * const *fileSymbols)
{
/* Small shortcut to avoid a lot of repetition */
#define popRPN() popRPN(patch->fileName)
uint8_t const *expression = patch->rpnExpression;
int32_t size = patch->rpnSize;
clearRPNStack();
while (size > 0) {
enum RPNCommand command = getRPNByte(&expression, &size,
patch->fileName);
int32_t value;
/*
* Friendly reminder:
* Be VERY careful with two `popRPN` in the same expression.
* C does not guarantee order of evaluation of operands!!
* So, if there are two `popRPN` in the same expression, make
* sure the operation is commutative.
*/
switch (command) {
struct Symbol const *symbol;
char const *name;
struct Section const *sect;
case RPN_ADD:
value = popRPN() + popRPN();
break;
case RPN_SUB:
value = popRPN();
value = popRPN() - value;
break;
case RPN_MUL:
value = popRPN() * popRPN();
break;
case RPN_DIV:
value = popRPN();
if (value == 0) {
error("%s: Division by 0", patch->fileName);
popRPN();
value = INT32_MAX;
} else {
value = popRPN() / value;
}
break;
case RPN_MOD:
value = popRPN();
if (value == 0) {
error("%s: Modulo by 0", patch->fileName);
popRPN();
value = 0;
} else {
value = popRPN() % value;
}
break;
case RPN_UNSUB:
value = -popRPN();
break;
case RPN_OR:
value = popRPN() | popRPN();
break;
case RPN_AND:
value = popRPN() & popRPN();
break;
case RPN_XOR:
value = popRPN() ^ popRPN();
break;
case RPN_UNNOT:
value = ~popRPN();
break;
case RPN_LOGAND:
value = popRPN();
value = popRPN() && value;
break;
case RPN_LOGOR:
value = popRPN();
value = popRPN() || value;
break;
case RPN_LOGUNNOT:
value = !popRPN();
break;
case RPN_LOGEQ:
value = popRPN() == popRPN();
break;
case RPN_LOGNE:
value = popRPN() != popRPN();
break;
case RPN_LOGGT:
value = popRPN();
value = popRPN() > value;
break;
case RPN_LOGLT:
value = popRPN();
value = popRPN() < value;
break;
case RPN_LOGGE:
value = popRPN();
value = popRPN() >= value;
break;
case RPN_LOGLE:
value = popRPN();
value = popRPN() <= value;
break;
case RPN_SHL:
value = popRPN();
value = asl(popRPN(), value);
break;
case RPN_SHR:
value = popRPN();
value = asr(popRPN(), value);
break;
case RPN_BANK_SYM:
value = 0;
for (uint8_t shift = 0; shift < 32; shift += 8)
value |= getRPNByte(&expression, &size,
patch->fileName) << shift;
symbol = getSymbol(fileSymbols, value);
if (!symbol) {
error("%s: Requested BANK() of symbol \"%s\", which was not found",
patch->fileName,
fileSymbols[value]->name);
value = 1;
} else if (!symbol->section) {
error("%s: Requested BANK() of non-label symbol \"%s\"",
patch->fileName,
fileSymbols[value]->name);
value = 1;
} else {
value = symbol->section->bank;
}
break;
case RPN_BANK_SECT:
name = (char const *)expression;
while (getRPNByte(&expression, &size, patch->fileName))
;
sect = sect_GetSection(name);
if (!sect) {
error("%s: Requested BANK() of section \"%s\", which was not found",
patch->fileName, name);
value = 1;
} else {
value = sect->bank;
}
break;
case RPN_BANK_SELF:
if (!patch->pcSection) {
error("%s: PC has no bank outside a section");
value = 1;
} else {
value = patch->pcSection->bank;
}
break;
case RPN_HRAM:
value = popRPN();
if (value < 0
|| (value > 0xFF && value < 0xFF00)
|| value > 0xFFFF)
error("%s: Value %" PRId32 " is not in HRAM range",
patch->fileName, value);
value &= 0xFF;
break;
case RPN_RST:
value = popRPN();
/* Acceptable values are 0x00, 0x08, 0x10, ..., 0x38
* They can be easily checked with a bitmask
*/
if (value & ~0x38)
error("%s: Value %" PRId32 " is not a RST vector",
patch->fileName, value);
value |= 0xC7;
break;
case RPN_CONST:
value = 0;
for (uint8_t shift = 0; shift < 32; shift += 8)
value |= getRPNByte(&expression, &size,
patch->fileName) << shift;
break;
case RPN_SYM:
value = 0;
for (uint8_t shift = 0; shift < 32; shift += 8)
value |= getRPNByte(&expression, &size,
patch->fileName) << shift;
symbol = getSymbol(fileSymbols, value);
if (!symbol) {
error("%s: Unknown symbol \"%s\"",
patch->fileName,
fileSymbols[value]->name);
} else if (strcmp(symbol->name, "@")) {
value = symbol->value;
/* Symbols attached to sections have offsets */
if (symbol->section)
value += symbol->section->org;
} else if (!patch->pcSection) {
error("%s: PC has no value outside a section",
patch->fileName);
value = 0;
} else {
value = patch->pcOffset + patch->pcSection->org;
}
break;
}
pushRPN(value);
}
if (stack.size > 1)
error("%s: RPN stack has %zu entries on exit, not 1",
patch->fileName, stack.size);
return popRPN();
#undef popRPN
}
void patch_CheckAssertions(struct Assertion *assert)
{
verbosePrint("Checking assertions...");
initRPNStack();
while (assert) {
if (!computeRPNExpr(&assert->patch,
(struct Symbol const * const *)
assert->fileSymbols)) {
switch ((enum AssertionType)assert->patch.type) {
case ASSERT_FATAL:
fatal("%s: %s", assert->patch.fileName,
assert->message[0] ? assert->message
: "assert failure");
/* Not reached */
break; /* Here so checkpatch doesn't complain */
case ASSERT_ERROR:
error("%s: %s", assert->patch.fileName,
assert->message[0] ? assert->message
: "assert failure");
break;
case ASSERT_WARN:
warnx("%s: %s", assert->patch.fileName,
assert->message[0] ? assert->message
: "assert failure");
break;
}
}
struct Assertion *next = assert->next;
free(assert);
assert = next;
}
freeRPNStack();
}
/**
* Applies all of a section's patches
* @param section The section to patch
* @param arg Ignored callback arg
*/
static void applyFilePatches(struct Section *section, struct Section *dataSection)
{
if (!sect_HasData(section->type))
return;
verbosePrint("Patching section \"%s\"...\n", section->name);
for (uint32_t patchID = 0; patchID < section->nbPatches; patchID++) {
struct Patch *patch = §ion->patches[patchID];
int32_t value = computeRPNExpr(patch,
(struct Symbol const * const *)
section->fileSymbols);
uint16_t offset = patch->offset + section->offset;
/* `jr` is quite unlike the others... */
if (patch->type == PATCHTYPE_JR) {
/* Target is relative to the byte *after* the operand */
uint16_t address = patch->pcSection->org
+ patch->pcOffset + 1;
int16_t jumpOffset = value - address;
if (jumpOffset < -128 || jumpOffset > 127)
error("%s: jr target out of reach (expected -129 < %" PRId16 " < 128)",
patch->fileName, jumpOffset);
dataSection->data[offset] = jumpOffset & 0xFF;
} else {
/* Patch a certain number of bytes */
struct {
uint8_t size;
int32_t min;
int32_t max;
} const types[] = {
[PATCHTYPE_BYTE] = {1, -128, 255},
[PATCHTYPE_WORD] = {2, -32768, 65536},
[PATCHTYPE_LONG] = {4, INT32_MIN, INT32_MAX}
};
if (value < types[patch->type].min
|| value > types[patch->type].max)
error("%s: Value %#" PRIx32 "%s is not %u-bit",
patch->fileName, value,
value < 0 ? " (maybe negative?)" : "",
types[patch->type].size * 8U);
for (uint8_t i = 0; i < types[patch->type].size; i++) {
dataSection->data[offset + i] = value & 0xFF;
value >>= 8;
}
}
}
}
/**
* Applies all of a section's patches, iterating over "components" of
* unionized sections
* @param section The section to patch
* @param arg Ignored callback arg
*/
static void applyPatches(struct Section *section, void *arg)
{
(void)arg;
struct Section *dataSection = section;
do {
applyFilePatches(section, dataSection);
section = section->nextu;
} while (section);
}
void patch_ApplyPatches(void)
{
initRPNStack();
sect_ForEach(applyPatches, NULL);
freeRPNStack();
}