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/***************************************************************************
* ARM Stack Unwinder, Michael.McTernan.2001@cs.bris.ac.uk
* Updated, adapted and several bug fixes on 2018 by Eduardo José Tagle
*
* This program is PUBLIC DOMAIN.
* This means that there is no copyright and anyone is able to take a copy
* for free and use it as they wish, with or without modifications, and in
* any context, commercially or otherwise. The only limitation is that I
* don't guarantee that the software is fit for any purpose or accept any
* liability for its use or misuse - this software is without warranty.
***************************************************************************
* File Description: Utility functions and glue for ARM unwinding sub-modules.
**************************************************************************/
#if defined(__arm__) || defined(__thumb__)
#define MODULE_NAME "UNWARM"
#include <stdint.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include "unwarm.h"
#include "unwarmmem.h"
#ifdef UNW_DEBUG
/**
* Printf wrapper.
* This is used such that alternative outputs for any output can be selected
* by modification of this wrapper function.
*/
void UnwPrintf(const char *format, ...) {
va_list args;
va_start( args, format );
vprintf(format, args );
}
#endif
/**
* Invalidate all general purpose registers.
*/
void UnwInvalidateRegisterFile(RegData *regFile) {
uint8_t t = 0;
do {
regFile[t].o = REG_VAL_INVALID;
t++;
} while (t < 13);
}
/**
* Initialize the data used for unwinding.
*/
void UnwInitState(UnwState * const state, /**< Pointer to structure to fill. */
const UnwindCallbacks *cb, /**< Callbacks. */
void *rptData, /**< Data to pass to report function. */
uint32_t pcValue, /**< PC at which to start unwinding. */
uint32_t spValue) { /**< SP at which to start unwinding. */
UnwInvalidateRegisterFile(state->regData);
/* Store the pointer to the callbacks */
state->cb = cb;
state->reportData = rptData;
/* Setup the SP and PC */
state->regData[13].v = spValue;
state->regData[13].o = REG_VAL_FROM_CONST;
state->regData[15].v = pcValue;
state->regData[15].o = REG_VAL_FROM_CONST;
UnwPrintd3("\nInitial: PC=0x%08x SP=0x%08x\n", pcValue, spValue);
/* Invalidate all memory addresses */
memset(state->memData.used, 0, sizeof(state->memData.used));
}
// Detect if function names are available
static int __attribute__ ((noinline)) has_function_names() {
uint32_t flag_word = ((uint32_t*)(((uint32_t)(&has_function_names)) & (-4))) [-1];
return ((flag_word & 0xFF000000) == 0xFF000000) ? 1 : 0;
}
/**
* Call the report function to indicate some return address.
* This returns the value of the report function, which if true
* indicates that unwinding may continue.
*/
bool UnwReportRetAddr(UnwState * const state, uint32_t addr) {
UnwReport entry;
// We found two acceptable values.
entry.name = nullptr;
entry.address = addr & 0xFFFFFFFE; // Remove Thumb bit
entry.function = 0;
// If there are function names, try to solve name
if (has_function_names()) {
// Lets find the function name, if possible
// Align address to 4 bytes
uint32_t pf = addr & (-4);
// Scan backwards until we find the function name
uint32_t v;
while (state->cb->readW(pf-4,&v)) {
// Check if name descriptor is valid
if ((v & 0xFFFFFF00) == 0xFF000000 && (v & 0xFF) > 1) {
// Assume the name was found!
entry.name = ((const char*)pf) - 4 - (v & 0xFF);
entry.function = pf;
break;
}
// Go backwards to the previous word
pf -= 4;
}
}
/* Cast away const from reportData.
* The const is only to prevent the unw module modifying the data.
*/
return state->cb->report((void *)state->reportData, &entry);
}
/**
* Write some register to memory.
* This will store some register and meta data onto the virtual stack.
* The address for the write
* \param state [in/out] The unwinding state.
* \param wAddr [in] The address at which to write the data.
* \param reg [in] The register to store.
* \return true if the write was successful, false otherwise.
*/
bool UnwMemWriteRegister(UnwState * const state, const uint32_t addr, const RegData * const reg) {
return UnwMemHashWrite(&state->memData, addr, reg->v, M_IsOriginValid(reg->o));
}
/**
* Read a register from memory.
* This will read a register from memory, and setup the meta data.
* If the register has been previously written to memory using
* UnwMemWriteRegister, the local hash will be used to return the
* value while respecting whether the data was valid or not. If the
* register was previously written and was invalid at that point,
* REG_VAL_INVALID will be returned in *reg.
* \param state [in] The unwinding state.
* \param addr [in] The address to read.
* \param reg [out] The result, containing the data value and the origin
* which will be REG_VAL_FROM_MEMORY, or REG_VAL_INVALID.
* \return true if the address could be read and *reg has been filled in.
* false is the data could not be read.
*/
bool UnwMemReadRegister(UnwState * const state, const uint32_t addr, RegData * const reg) {
bool tracked;
// Check if the value can be found in the hash
if (UnwMemHashRead(&state->memData, addr, ®->v, &tracked)) {
reg->o = tracked ? REG_VAL_FROM_MEMORY : REG_VAL_INVALID;
return true;
}
else if (state->cb->readW(addr, ®->v)) { // Not in the hash, so read from real memory
reg->o = REG_VAL_FROM_MEMORY;
return true;
}
else return false; // Not in the hash, and failed to read from memory
}
#endif // __arm__ || __thumb__
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