target/cortex_m: faster reading of all CPU registers

Without the change cortex_m_debug_entry() reads all registers
calling cortex_m_load_core_reg_u32() for each register with
a poor usage of JTAG/SWD queue.
It is time consuming, especially on an USB FS based adapter.
Moreover if target_request debugmsgs are enabled, DCB_DCRDR
is saved and restored on each register read.

This change introduces cortex_m_fast_read_all_regs()
which queues all register reads and a single dap_run() transaction
does all work.

cortex_m_fast_read_all_regs() reads all registers unconditionally
regardless register cache is valid or not. This is a difference
from the original cortex_m_debug_entry() code.

cortex_m_debug_entry times from -d3 log, Cortex-M4F and CMSIS-DAP
(Kinetis K28F-FRDM kit)

target_request |                time [ms]
debugmsgs      | without the change | with the change
---------------+--------------------+-----------------
disable        |        186         |       27
enable         |        232         |       29

Added checking of DHCSR.S_REGRDY flag. If "not ready" is seen,
cortex_m->slow_register_read is set and fallback to the old
register read method cortex_m_slow_read_all_regs() is used
instead of cortex_m_fast_read_all_regs().

Change-Id: I0665d94b97ede217394640871dc451ec93410254
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/5321
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
This commit is contained in:
Tomas Vanek 2019-02-05 09:39:11 +01:00
parent 65d7629183
commit 88f429ead0
4 changed files with 179 additions and 11 deletions

View File

@ -251,7 +251,7 @@ static int armv7m_set_core_reg(struct reg *reg, uint8_t *buf)
return ERROR_OK;
}
static uint32_t armv7m_map_id_to_regsel(unsigned int arm_reg_id)
uint32_t armv7m_map_id_to_regsel(unsigned int arm_reg_id)
{
switch (arm_reg_id) {
case ARMV7M_R0 ... ARMV7M_R14:
@ -289,7 +289,7 @@ static uint32_t armv7m_map_id_to_regsel(unsigned int arm_reg_id)
}
}
static bool armv7m_map_reg_packing(unsigned int arm_reg_id,
bool armv7m_map_reg_packing(unsigned int arm_reg_id,
unsigned int *reg32_id, uint32_t *offset)
{

View File

@ -309,6 +309,11 @@ int armv7m_invalidate_core_regs(struct target *target);
int armv7m_restore_context(struct target *target);
uint32_t armv7m_map_id_to_regsel(unsigned int arm_reg_id);
bool armv7m_map_reg_packing(unsigned int arm_reg_id,
unsigned int *reg32_id, uint32_t *offset);
int armv7m_checksum_memory(struct target *target,
target_addr_t address, uint32_t count, uint32_t *checksum);
int armv7m_blank_check_memory(struct target *target,

View File

@ -202,6 +202,163 @@ static int cortex_m_load_core_reg_u32(struct target *target,
return retval;
}
static int cortex_m_slow_read_all_regs(struct target *target)
{
struct armv7m_common *armv7m = target_to_armv7m(target);
const unsigned int num_regs = armv7m->arm.core_cache->num_regs;
for (unsigned int reg_id = 0; reg_id < num_regs; reg_id++) {
struct reg *r = &armv7m->arm.core_cache->reg_list[reg_id];
if (r->exist) {
int retval = armv7m->arm.read_core_reg(target, r, reg_id, ARM_MODE_ANY);
if (retval != ERROR_OK)
return retval;
}
}
return ERROR_OK;
}
static int cortex_m_queue_reg_read(struct target *target, uint32_t regsel,
uint32_t *reg_value, uint32_t *dhcsr)
{
struct armv7m_common *armv7m = target_to_armv7m(target);
int retval;
retval = mem_ap_write_u32(armv7m->debug_ap, DCB_DCRSR, regsel);
if (retval != ERROR_OK)
return retval;
retval = mem_ap_read_u32(armv7m->debug_ap, DCB_DHCSR, dhcsr);
if (retval != ERROR_OK)
return retval;
return mem_ap_read_u32(armv7m->debug_ap, DCB_DCRDR, reg_value);
}
static int cortex_m_fast_read_all_regs(struct target *target)
{
struct cortex_m_common *cortex_m = target_to_cm(target);
struct armv7m_common *armv7m = target_to_armv7m(target);
int retval;
uint32_t dcrdr;
/* because the DCB_DCRDR is used for the emulated dcc channel
* we have to save/restore the DCB_DCRDR when used */
if (target->dbg_msg_enabled) {
retval = mem_ap_read_u32(armv7m->debug_ap, DCB_DCRDR, &dcrdr);
if (retval != ERROR_OK)
return retval;
}
const unsigned int num_regs = armv7m->arm.core_cache->num_regs;
const unsigned int n_r32 = ARMV7M_LAST_REG - ARMV7M_CORE_FIRST_REG + 1
+ ARMV7M_FPU_LAST_REG - ARMV7M_FPU_FIRST_REG + 1;
/* we need one 32-bit word for each register except FP D0..D15, which
* need two words */
uint32_t r_vals[n_r32];
uint32_t dhcsr[n_r32];
unsigned int wi = 0; /* write index to r_vals and dhcsr arrays */
unsigned int reg_id; /* register index in the reg_list, ARMV7M_R0... */
for (reg_id = 0; reg_id < num_regs; reg_id++) {
struct reg *r = &armv7m->arm.core_cache->reg_list[reg_id];
if (!r->exist)
continue; /* skip non existent registers */
if (r->size <= 8) {
/* Any 8-bit or shorter register is unpacked from a 32-bit
* container register. Skip it now. */
continue;
}
uint32_t regsel = armv7m_map_id_to_regsel(reg_id);
retval = cortex_m_queue_reg_read(target, regsel, &r_vals[wi],
&dhcsr[wi]);
if (retval != ERROR_OK)
return retval;
wi++;
assert(r->size == 32 || r->size == 64);
if (r->size == 32)
continue; /* done with 32-bit register */
assert(reg_id >= ARMV7M_FPU_FIRST_REG && reg_id <= ARMV7M_FPU_LAST_REG);
/* the odd part of FP register (S1, S3...) */
retval = cortex_m_queue_reg_read(target, regsel + 1, &r_vals[wi],
&dhcsr[wi]);
if (retval != ERROR_OK)
return retval;
wi++;
}
assert(wi <= n_r32);
retval = dap_run(armv7m->debug_ap->dap);
if (retval != ERROR_OK)
return retval;
if (target->dbg_msg_enabled) {
/* restore DCB_DCRDR - this needs to be in a separate
* transaction otherwise the emulated DCC channel breaks */
retval = mem_ap_write_atomic_u32(armv7m->debug_ap, DCB_DCRDR, dcrdr);
if (retval != ERROR_OK)
return retval;
}
bool not_ready = false;
for (unsigned int i = 0; i < wi; i++) {
if ((dhcsr[i] & S_REGRDY) == 0) {
not_ready = true;
LOG_DEBUG("Register %u was not ready during fast read", i);
}
cortex_m_cumulate_dhcsr_sticky(cortex_m, dhcsr[i]);
}
if (not_ready) {
/* Any register was not ready,
* fall back to slow read with S_REGRDY polling */
return ERROR_TIMEOUT_REACHED;
}
LOG_DEBUG("read %u 32-bit registers", wi);
unsigned int ri = 0; /* read index from r_vals array */
for (reg_id = 0; reg_id < num_regs; reg_id++) {
struct reg *r = &armv7m->arm.core_cache->reg_list[reg_id];
if (!r->exist)
continue; /* skip non existent registers */
r->dirty = false;
unsigned int reg32_id;
uint32_t offset;
if (armv7m_map_reg_packing(reg_id, &reg32_id, &offset)) {
/* Unpack a partial register from 32-bit container register */
struct reg *r32 = &armv7m->arm.core_cache->reg_list[reg32_id];
/* The container register ought to precede all regs unpacked
* from it in the reg_list. So the value should be ready
* to unpack */
assert(r32->valid);
buf_cpy(r32->value + offset, r->value, r->size);
} else {
assert(r->size == 32 || r->size == 64);
buf_set_u32(r->value, 0, 32, r_vals[ri++]);
if (r->size == 64) {
assert(reg_id >= ARMV7M_FPU_FIRST_REG && reg_id <= ARMV7M_FPU_LAST_REG);
/* the odd part of FP register (S1, S3...) */
buf_set_u32(r->value + 4, 0, 32, r_vals[ri++]);
}
}
r->valid = true;
}
assert(ri == wi);
return retval;
}
static int cortex_m_store_core_reg_u32(struct target *target,
uint32_t regsel, uint32_t value)
{
@ -610,7 +767,6 @@ static int cortex_m_examine_exception_reason(struct target *target)
static int cortex_m_debug_entry(struct target *target)
{
int i;
uint32_t xPSR;
int retval;
struct cortex_m_common *cortex_m = target_to_cm(target);
@ -646,15 +802,20 @@ static int cortex_m_debug_entry(struct target *target)
secure_state = (dscsr & DSCSR_CDS) == DSCSR_CDS;
}
/* Examine target state and mode
* First load register accessible through core debug port */
int num_regs = arm->core_cache->num_regs;
for (i = 0; i < num_regs; i++) {
r = &armv7m->arm.core_cache->reg_list[i];
if (r->exist && !r->valid)
arm->read_core_reg(target, r, i, ARM_MODE_ANY);
/* Load all registers to arm.core_cache */
if (!cortex_m->slow_register_read) {
retval = cortex_m_fast_read_all_regs(target);
if (retval == ERROR_TIMEOUT_REACHED) {
cortex_m->slow_register_read = true;
LOG_DEBUG("Switched to slow register read");
}
}
if (cortex_m->slow_register_read)
retval = cortex_m_slow_read_all_regs(target);
if (retval != ERROR_OK)
return retval;
r = arm->cpsr;
xPSR = buf_get_u32(r->value, 0, 32);

View File

@ -238,6 +238,8 @@ struct cortex_m_common {
const struct cortex_m_part_info *core_info;
struct armv7m_common armv7m;
bool slow_register_read; /* A register has not been ready, poll S_REGRDY */
int apsel;
/* Whether this target has the erratum that makes C_MASKINTS not apply to