/**
* Read basic registers of the the current context: R0 to R15, and CPSR;
* sets the core mode (such as USR or IRQ) and state (such as ARM or Thumb).
* In normal operation this is called on entry to halting debug state,
* possibly after some other operations supporting restore of debug state
* or making sure the CPU is fully idle (drain write buffer, etc).
*/
int arm_dpm_read_current_registers(struct arm_dpm *dpm)
{
struct arm *arm = dpm->arm;
uint32_t cpsr;
int retval;
struct reg *r;
retval = dpm->prepare(dpm);
if (retval != ERROR_OK)
return retval;
/* read R0 first (it's used for scratch), then CPSR */
r = arm->core_cache->reg_list + 0;
if (!r->valid) {
retval = dpm_read_reg(dpm, r, 0);
if (retval != ERROR_OK)
goto fail;
}
r->dirty = true;
retval = dpm->instr_read_data_r0(dpm, ARMV4_5_MRS(0, 0), &cpsr);
if (retval != ERROR_OK)
goto fail;
/* update core mode and state, plus shadow mapping for R8..R14 */
arm_set_cpsr(arm, cpsr);
/* REVISIT we can probably avoid reading R1..R14, saving time... */
for (unsigned i = 1; i < 16; i++) {
r = arm_reg_current(arm, i);
if (r->valid)
continue;
retval = dpm_read_reg(dpm, r, i);
if (retval != ERROR_OK)
goto fail;
}
/* NOTE: SPSR ignored (if it's even relevant). */
/* REVISIT the debugger can trigger various exceptions. See the
* ARMv7A architecture spec, section C5.7, for more info about
* what defenses are needed; v6 debug has the most issues.
*/
fail:
/* (void) */ dpm->finish(dpm);
return retval;
}
static int post_result(struct target *target)
{
struct arm *arm = target_to_arm(target);
/* REVISIT this looks wrong ... ARM11 and Cortex-A8
* should work this way at least sometimes.
*/
if (is_arm7_9(target_to_arm7_9(target)) ||
is_armv7a(target_to_armv7a(target))) {
uint32_t spsr;
/* return value in R0 */
buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, arm->semihosting_result);
arm->core_cache->reg_list[0].dirty = 1;
/* LR --> PC */
buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
buf_get_u32(arm_reg_current(arm, 14)->value, 0, 32));
arm->core_cache->reg_list[15].dirty = 1;
/* saved PSR --> current PSR */
spsr = buf_get_u32(arm->spsr->value, 0, 32);
/* REVISIT should this be arm_set_cpsr(arm, spsr)
* instead of a partially unrolled version?
*/
buf_set_u32(arm->cpsr->value, 0, 32, spsr);
arm->cpsr->dirty = 1;
arm->core_mode = spsr & 0x1f;
if (spsr & 0x20)
arm->core_state = ARM_STATE_THUMB;
} else {
/* resume execution, this will be pc+2 to skip over the
* bkpt instruction */
/* return result in R0 */
buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, arm->semihosting_result);
arm->core_cache->reg_list[0].dirty = 1;
}
return ERROR_OK;
}
int arm_get_gdb_reg_list(struct target *target,
struct reg **reg_list[], int *reg_list_size,
enum target_register_class reg_class)
{
struct arm *arm = target_to_arm(target);
unsigned int i;
if (!is_arm_mode(arm->core_mode)) {
LOG_ERROR("not a valid arm core mode - communication failure?");
return ERROR_FAIL;
}
switch (reg_class) {
case REG_CLASS_GENERAL:
*reg_list_size = 26;
*reg_list = malloc(sizeof(struct reg *) * (*reg_list_size));
for (i = 0; i < 16; i++)
(*reg_list)[i] = arm_reg_current(arm, i);
/* For GDB compatibility, take FPA registers size into account and zero-fill it*/
for (i = 16; i < 24; i++)
(*reg_list)[i] = &arm_gdb_dummy_fp_reg;
(*reg_list)[24] = &arm_gdb_dummy_fps_reg;
(*reg_list)[25] = arm->cpsr;
return ERROR_OK;
break;
case REG_CLASS_ALL:
*reg_list_size = (arm->core_type != ARM_MODE_MON ? 48 : 51);
*reg_list = malloc(sizeof(struct reg *) * (*reg_list_size));
for (i = 0; i < 16; i++)
(*reg_list)[i] = arm_reg_current(arm, i);
for (i = 13; i < ARRAY_SIZE(arm_core_regs); i++) {
int reg_index = arm->core_cache->reg_list[i].number;
if (!(arm_core_regs[i].mode == ARM_MODE_MON
&& arm->core_type != ARM_MODE_MON))
(*reg_list)[reg_index] = &(arm->core_cache->reg_list[i]);
}
/* When we supply the target description, there is no need for fake FPA */
for (i = 16; i < 24; i++) {
(*reg_list)[i] = &arm_gdb_dummy_fp_reg;
(*reg_list)[i]->size = 0;
}
(*reg_list)[24] = &arm_gdb_dummy_fps_reg;
(*reg_list)[24]->size = 0;
return ERROR_OK;
break;
default:
LOG_ERROR("not a valid register class type in query.");
return ERROR_FAIL;
break;
}
}
static int do_semihosting(struct target *target)
{
struct arm *arm = target_to_arm(target);
uint32_t r0 = buf_get_u32(arm->core_cache->reg_list[0].value, 0, 32);
uint32_t r1 = buf_get_u32(arm->core_cache->reg_list[1].value, 0, 32);
uint8_t params[16];
int retval, result;
/*
* TODO: lots of security issues are not considered yet, such as:
* - no validation on target provided file descriptors
* - no safety checks on opened/deleted/renamed file paths
* Beware the target app you use this support with.
*
* TODO: explore mapping requests to GDB's "File-I/O Remote
* Protocol Extension" ... when GDB is active.
*/
switch (r0) {
case 0x01: /* SYS_OPEN */
retval = target_read_memory(target, r1, 4, 3, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t a = target_buffer_get_u32(target, params+0);
uint32_t m = target_buffer_get_u32(target, params+4);
uint32_t l = target_buffer_get_u32(target, params+8);
if (l <= 255 && m <= 11) {
uint8_t fn[256];
retval = target_read_memory(target, a, 1, l, fn);
if (retval != ERROR_OK)
return retval;
fn[l] = 0;
if (strcmp((char *)fn, ":tt") == 0) {
if (m < 4)
result = dup(STDIN_FILENO);
else
result = dup(STDOUT_FILENO);
} else {
/* cygwin requires the permission setting
* otherwise it will fail to reopen a previously
* written file */
result = open((char *)fn, open_modeflags[m], 0644);
}
arm->semihosting_errno = errno;
} else {
result = -1;
arm->semihosting_errno = EINVAL;
}
}
break;
case 0x02: /* SYS_CLOSE */
retval = target_read_memory(target, r1, 4, 1, params);
if (retval != ERROR_OK)
return retval;
else {
int fd = target_buffer_get_u32(target, params+0);
result = close(fd);
arm->semihosting_errno = errno;
}
break;
case 0x03: /* SYS_WRITEC */
{
unsigned char c;
retval = target_read_memory(target, r1, 1, 1, &c);
if (retval != ERROR_OK)
return retval;
putchar(c);
result = 0;
}
break;
case 0x04: /* SYS_WRITE0 */
do {
unsigned char c;
retval = target_read_memory(target, r1++, 1, 1, &c);
if (retval != ERROR_OK)
return retval;
if (!c)
break;
putchar(c);
} while (1);
result = 0;
break;
case 0x05: /* SYS_WRITE */
retval = target_read_memory(target, r1, 4, 3, params);
if (retval != ERROR_OK)
return retval;
else {
int fd = target_buffer_get_u32(target, params+0);
uint32_t a = target_buffer_get_u32(target, params+4);
size_t l = target_buffer_get_u32(target, params+8);
uint8_t *buf = malloc(l);
if (!buf) {
result = -1;
arm->semihosting_errno = ENOMEM;
} else {
retval = target_read_buffer(target, a, l, buf);
if (retval != ERROR_OK) {
free(buf);
return retval;
}
result = write(fd, buf, l);
arm->semihosting_errno = errno;
if (result >= 0)
result = l - result;
free(buf);
}
}
break;
case 0x06: /* SYS_READ */
retval = target_read_memory(target, r1, 4, 3, params);
if (retval != ERROR_OK)
return retval;
else {
int fd = target_buffer_get_u32(target, params+0);
uint32_t a = target_buffer_get_u32(target, params+4);
ssize_t l = target_buffer_get_u32(target, params+8);
uint8_t *buf = malloc(l);
if (!buf) {
result = -1;
arm->semihosting_errno = ENOMEM;
} else {
result = read(fd, buf, l);
arm->semihosting_errno = errno;
if (result >= 0) {
retval = target_write_buffer(target, a, result, buf);
if (retval != ERROR_OK) {
free(buf);
return retval;
}
result = l - result;
}
free(buf);
}
}
break;
case 0x07: /* SYS_READC */
result = getchar();
break;
case 0x08: /* SYS_ISERROR */
retval = target_read_memory(target, r1, 4, 1, params);
if (retval != ERROR_OK)
return retval;
result = (target_buffer_get_u32(target, params+0) != 0);
break;
case 0x09: /* SYS_ISTTY */
retval = target_read_memory(target, r1, 4, 1, params);
if (retval != ERROR_OK)
return retval;
result = isatty(target_buffer_get_u32(target, params+0));
break;
case 0x0a: /* SYS_SEEK */
retval = target_read_memory(target, r1, 4, 2, params);
if (retval != ERROR_OK)
return retval;
else {
int fd = target_buffer_get_u32(target, params+0);
off_t pos = target_buffer_get_u32(target, params+4);
result = lseek(fd, pos, SEEK_SET);
arm->semihosting_errno = errno;
if (result == pos)
result = 0;
}
break;
case 0x0c: /* SYS_FLEN */
retval = target_read_memory(target, r1, 4, 1, params);
if (retval != ERROR_OK)
return retval;
else {
int fd = target_buffer_get_u32(target, params+0);
struct stat buf;
result = fstat(fd, &buf);
if (result == -1) {
arm->semihosting_errno = errno;
result = -1;
break;
}
result = buf.st_size;
}
break;
case 0x0e: /* SYS_REMOVE */
retval = target_read_memory(target, r1, 4, 2, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t a = target_buffer_get_u32(target, params+0);
uint32_t l = target_buffer_get_u32(target, params+4);
if (l <= 255) {
uint8_t fn[256];
retval = target_read_memory(target, a, 1, l, fn);
if (retval != ERROR_OK)
return retval;
fn[l] = 0;
result = remove((char *)fn);
arm->semihosting_errno = errno;
} else {
result = -1;
arm->semihosting_errno = EINVAL;
}
}
break;
case 0x0f: /* SYS_RENAME */
retval = target_read_memory(target, r1, 4, 4, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t a1 = target_buffer_get_u32(target, params+0);
uint32_t l1 = target_buffer_get_u32(target, params+4);
uint32_t a2 = target_buffer_get_u32(target, params+8);
uint32_t l2 = target_buffer_get_u32(target, params+12);
if (l1 <= 255 && l2 <= 255) {
uint8_t fn1[256], fn2[256];
retval = target_read_memory(target, a1, 1, l1, fn1);
if (retval != ERROR_OK)
return retval;
retval = target_read_memory(target, a2, 1, l2, fn2);
if (retval != ERROR_OK)
return retval;
fn1[l1] = 0;
fn2[l2] = 0;
result = rename((char *)fn1, (char *)fn2);
arm->semihosting_errno = errno;
} else {
result = -1;
arm->semihosting_errno = EINVAL;
}
}
break;
case 0x11: /* SYS_TIME */
result = time(NULL);
break;
case 0x13: /* SYS_ERRNO */
result = arm->semihosting_errno;
break;
case 0x15: /* SYS_GET_CMDLINE */
retval = target_read_memory(target, r1, 4, 2, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t a = target_buffer_get_u32(target, params+0);
uint32_t l = target_buffer_get_u32(target, params+4);
char *arg = "foobar";
uint32_t s = strlen(arg) + 1;
if (l < s)
result = -1;
else {
retval = target_write_buffer(target, a, s, (uint8_t *)arg);
if (retval != ERROR_OK)
return retval;
result = 0;
}
}
break;
case 0x16: /* SYS_HEAPINFO */
retval = target_read_memory(target, r1, 4, 1, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t a = target_buffer_get_u32(target, params+0);
/* tell the remote we have no idea */
memset(params, 0, 4*4);
retval = target_write_memory(target, a, 4, 4, params);
if (retval != ERROR_OK)
return retval;
result = 0;
}
break;
case 0x18: /* angel_SWIreason_ReportException */
switch (r1) {
case 0x20026: /* ADP_Stopped_ApplicationExit */
fprintf(stderr, "semihosting: *** application exited ***\n");
break;
case 0x20000: /* ADP_Stopped_BranchThroughZero */
case 0x20001: /* ADP_Stopped_UndefinedInstr */
case 0x20002: /* ADP_Stopped_SoftwareInterrupt */
case 0x20003: /* ADP_Stopped_PrefetchAbort */
case 0x20004: /* ADP_Stopped_DataAbort */
case 0x20005: /* ADP_Stopped_AddressException */
case 0x20006: /* ADP_Stopped_IRQ */
case 0x20007: /* ADP_Stopped_FIQ */
case 0x20020: /* ADP_Stopped_BreakPoint */
case 0x20021: /* ADP_Stopped_WatchPoint */
case 0x20022: /* ADP_Stopped_StepComplete */
case 0x20023: /* ADP_Stopped_RunTimeErrorUnknown */
case 0x20024: /* ADP_Stopped_InternalError */
case 0x20025: /* ADP_Stopped_UserInterruption */
case 0x20027: /* ADP_Stopped_StackOverflow */
case 0x20028: /* ADP_Stopped_DivisionByZero */
case 0x20029: /* ADP_Stopped_OSSpecific */
default:
fprintf(stderr, "semihosting: exception %#x\n",
(unsigned) r1);
}
return target_call_event_callbacks(target, TARGET_EVENT_HALTED);
case 0x12: /* SYS_SYSTEM */
/* Provide SYS_SYSTEM functionality. Uses the
* libc system command, there may be a reason *NOT*
* to use this, but as I can't think of one, I
* implemented it this way.
*/
retval = target_read_memory(target, r1, 4, 2, params);
if (retval != ERROR_OK)
return retval;
else {
uint32_t len = target_buffer_get_u32(target, params+4);
uint32_t c_ptr = target_buffer_get_u32(target, params);
uint8_t cmd[256];
if (len > 255) {
result = -1;
arm->semihosting_errno = EINVAL;
} else {
memset(cmd, 0x0, 256);
retval = target_read_memory(target, c_ptr, 1, len, cmd);
if (retval != ERROR_OK)
return retval;
else
result = system((const char *)cmd);
}
}
break;
case 0x0d: /* SYS_TMPNAM */
case 0x10: /* SYS_CLOCK */
case 0x17: /* angel_SWIreason_EnterSVC */
case 0x30: /* SYS_ELAPSED */
case 0x31: /* SYS_TICKFREQ */
default:
fprintf(stderr, "semihosting: unsupported call %#x\n",
(unsigned) r0);
result = -1;
arm->semihosting_errno = ENOTSUP;
}
/* resume execution to the original mode */
/* REVISIT this looks wrong ... ARM11 and Cortex-A8
* should work this way at least sometimes.
*/
if (is_arm7_9(target_to_arm7_9(target))) {
uint32_t spsr;
/* return value in R0 */
buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
arm->core_cache->reg_list[0].dirty = 1;
/* LR --> PC */
buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
buf_get_u32(arm_reg_current(arm, 14)->value, 0, 32));
arm->core_cache->reg_list[15].dirty = 1;
/* saved PSR --> current PSR */
spsr = buf_get_u32(arm->spsr->value, 0, 32);
/* REVISIT should this be arm_set_cpsr(arm, spsr)
* instead of a partially unrolled version?
*/
buf_set_u32(arm->cpsr->value, 0, 32, spsr);
arm->cpsr->dirty = 1;
arm->core_mode = spsr & 0x1f;
if (spsr & 0x20)
arm->core_state = ARM_STATE_THUMB;
} else {
/* resume execution, this will be pc+2 to skip over the
* bkpt instruction */
/* return result in R0 */
buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
arm->core_cache->reg_list[0].dirty = 1;
}
return target_resume(target, 1, 0, 0, 0);
}
/**
* Checks for and processes an ARM semihosting request. This is meant
* to be called when the target is stopped due to a debug mode entry.
* If the value 0 is returned then there was nothing to process. A non-zero
* return value signifies that a request was processed and the target resumed,
* or an error was encountered, in which case the caller must return
* immediately.
*
* @param target Pointer to the ARM target to process. This target must
* not represent an ARMv6-M or ARMv7-M processor.
* @param retval Pointer to a location where the return code will be stored
* @return non-zero value if a request was processed or an error encountered
*/
int arm_semihosting(struct target *target, int *retval)
{
struct arm *arm = target_to_arm(target);
uint32_t pc, lr, spsr;
struct reg *r;
if (!arm->is_semihosting)
return 0;
if (is_arm7_9(target_to_arm7_9(target))) {
if (arm->core_mode != ARM_MODE_SVC)
return 0;
/* Check for PC == 0x00000008 or 0xffff0008: Supervisor Call vector. */
r = arm->pc;
pc = buf_get_u32(r->value, 0, 32);
if (pc != 0x00000008 && pc != 0xffff0008)
return 0;
r = arm_reg_current(arm, 14);
lr = buf_get_u32(r->value, 0, 32);
/* Core-specific code should make sure SPSR is retrieved
* when the above checks pass...
*/
if (!arm->spsr->valid) {
LOG_ERROR("SPSR not valid!");
*retval = ERROR_FAIL;
return 1;
}
spsr = buf_get_u32(arm->spsr->value, 0, 32);
/* check instruction that triggered this trap */
if (spsr & (1 << 5)) {
/* was in Thumb (or ThumbEE) mode */
uint8_t insn_buf[2];
uint16_t insn;
*retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u16(target, insn_buf);
/* SVC 0xab */
if (insn != 0xDFAB)
return 0;
} else if (spsr & (1 << 24)) {
/* was in Jazelle mode */
return 0;
} else {
/* was in ARM mode */
uint8_t insn_buf[4];
uint32_t insn;
*retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u32(target, insn_buf);
/* SVC 0x123456 */
if (insn != 0xEF123456)
return 0;
}
} else if (is_armv7m(target_to_armv7m(target))) {
uint16_t insn;
if (target->debug_reason != DBG_REASON_BREAKPOINT)
return 0;
r = arm->pc;
pc = buf_get_u32(r->value, 0, 32);
pc &= ~1;
*retval = target_read_u16(target, pc, &insn);
if (*retval != ERROR_OK)
return 1;
/* bkpt 0xAB */
if (insn != 0xBEAB)
return 0;
} else {
LOG_ERROR("Unsupported semi-hosting Target");
return 0;
}
*retval = do_semihosting(target);
return 1;
}
/**
* Checks for and processes an ARM semihosting request. This is meant
* to be called when the target is stopped due to a debug mode entry.
* If the value 0 is returned then there was nothing to process. A non-zero
* return value signifies that a request was processed and the target resumed,
* or an error was encountered, in which case the caller must return
* immediately.
*
* @param target Pointer to the ARM target to process. This target must
* not represent an ARMv6-M or ARMv7-M processor.
* @param retval Pointer to a location where the return code will be stored
* @return non-zero value if a request was processed or an error encountered
*/
int arm_semihosting(struct target *target, int *retval)
{
struct arm *arm = target_to_arm(target);
struct armv7a_common *armv7a = target_to_armv7a(target);
uint32_t pc, lr, spsr;
struct reg *r;
if (!arm->is_semihosting)
return 0;
if (is_arm7_9(target_to_arm7_9(target)) ||
is_armv7a(armv7a)) {
uint32_t vbar = 0x00000000;
if (arm->core_mode != ARM_MODE_SVC)
return 0;
if (is_armv7a(armv7a)) {
struct arm_dpm *dpm = armv7a->arm.dpm;
*retval = dpm->prepare(dpm);
if (*retval == ERROR_OK) {
*retval = dpm->instr_read_data_r0(dpm,
ARMV4_5_MRC(15, 0, 0, 12, 0, 0),
&vbar);
dpm->finish(dpm);
if (*retval != ERROR_OK)
return 1;
} else {
return 1;
}
}
/* Check for PC == 0x00000008 or 0xffff0008: Supervisor Call vector. */
r = arm->pc;
pc = buf_get_u32(r->value, 0, 32);
if (pc != (vbar + 0x00000008) && pc != 0xffff0008)
return 0;
r = arm_reg_current(arm, 14);
lr = buf_get_u32(r->value, 0, 32);
/* Core-specific code should make sure SPSR is retrieved
* when the above checks pass...
*/
if (!arm->spsr->valid) {
LOG_ERROR("SPSR not valid!");
*retval = ERROR_FAIL;
return 1;
}
spsr = buf_get_u32(arm->spsr->value, 0, 32);
/* check instruction that triggered this trap */
if (spsr & (1 << 5)) {
/* was in Thumb (or ThumbEE) mode */
uint8_t insn_buf[2];
uint16_t insn;
*retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u16(target, insn_buf);
/* SVC 0xab */
if (insn != 0xDFAB)
return 0;
} else if (spsr & (1 << 24)) {
/* was in Jazelle mode */
return 0;
} else {
/* was in ARM mode */
uint8_t insn_buf[4];
uint32_t insn;
*retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u32(target, insn_buf);
/* SVC 0x123456 */
if (insn != 0xEF123456)
return 0;
}
} else if (is_armv7m(target_to_armv7m(target))) {
uint16_t insn;
if (target->debug_reason != DBG_REASON_BREAKPOINT)
return 0;
r = arm->pc;
pc = buf_get_u32(r->value, 0, 32);
pc &= ~1;
*retval = target_read_u16(target, pc, &insn);
if (*retval != ERROR_OK)
return 1;
/* bkpt 0xAB */
if (insn != 0xBEAB)
return 0;
} else {
LOG_ERROR("Unsupported semi-hosting Target");
return 0;
}
/* Perform semihosting if we are not waiting on a fileio
* operation to complete.
*/
if (!arm->semihosting_hit_fileio) {
*retval = do_semihosting(target);
if (*retval != ERROR_OK) {
LOG_ERROR("Failed semihosting operation");
return 0;
}
}
/* Post result to target if we are not waiting on a fileio
* operation to complete:
*/
if (!arm->semihosting_hit_fileio) {
*retval = post_result(target);
if (*retval != ERROR_OK) {
LOG_ERROR("Failed to post semihosting result");
return 0;
}
*retval = target_resume(target, 1, 0, 0, 0);
if (*retval != ERROR_OK) {
LOG_ERROR("Failed to resume target");
return 0;
}
return 1;
}
return 0;
}
