eCos.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <helper/time_support.h>
#include <jtag/jtag.h>
#include "target/target.h"
#include "target/armv7m.h"
#include "rtos.h"
#include "helper/log.h"
#include "helper/types.h"
#include "helper/bits.h"
#include "rtos_standard_stackings.h"
#include "rtos_ecos_stackings.h"
#include "server/gdb_server.h"
 
/* Unfortunately for the moment we are limited to returning the hardwired
 * register count (ARMV7M_NUM_CORE_REGS for Cortex-M) since the openocd RTOS
 * support does not yet support accessing all per-thread "stacked"
 * registers. e.g. For Cortex-M under eCos we have a per-thread BASEPRI, and for
 * all eCos targets we may have per-thread VFP/FPU register state.
 *
 * So, for the moment, we continue to use the hardwired limit for the depth of
 * the returned register description vector. The current openocd
 * rtos_standard_stackings.c just provides the main core regs for the Cortex_M*
 * targets regardless of whether FPU is present/enabled.
 *
 * However, this code is written with the expectation that we may eventually be
 * able to provide more register information ("m-system" and "vfp" for example)
 * and also with the expectation of supporting different register sets being
 * returned depending on the per-thread Cortex-M eCos contex_m for
 * example. Hence the fact that the eCos_stack_layout_*() functions below allow
 * for the stack context descriptor vector to be returned by those calls
 * allowing for eventual support where this code will potentially cache
 * different sets of register descriptors for the different shapes of contexts
 * in a *single* application/binary run-time.
 *
 * TODO: Extend openocd generic RTOS support to allow thread-specific system and
 * FPU register state to be returned. */
 
struct ecos_params;
 
static bool ecos_detect_rtos(struct target *target);
static int ecos_create(struct target *target);
static int ecos_update_threads(struct rtos *rtos);
static int ecos_get_thread_reg_list(struct rtos *rtos, int64_t thread_id, struct rtos_reg **reg_list, int *num_regs);
static int ecos_get_symbol_list_to_lookup(struct symbol_table_elem *symbol_list[]);
static int ecos_stack_layout_cortexm(struct rtos *rtos, struct ecos_params *param,
                int64_t stack_ptr, const struct rtos_register_stacking **si);
static int ecos_stack_layout_arm(struct rtos *rtos, struct ecos_params *param,
                int64_t stack_ptr, const struct rtos_register_stacking **si);
 
/* The current eCos thread IDentifier uses 0 as an unused (not a valid thread
 * ID) value. Currently the unique_id field is 16-bits, but the eCos SMP support
 * convention is that only 12-bits of the ID will be used. This
 * ECOS_MAX_THREAD_COUNT manifest is provided to limit the potential for
 * interpreting stale/inconsistent thread list state when the debug host scans
 * the thread list before the target RTOS has completed its initialisation. This
 * support will need to revisited when eCos is re-engineered to support more
 * than 16 CPU SMP setups. */
#define ECOS_MAX_THREAD_COUNT (4095)
 
struct ecos_thread_state {
    int value;
    const char *desc;
};
 
/* The status is actually a logical-OR bitmask of states: */
enum ecos_thread_state_flags {
    RUNNING    = 0, /* explicit no-bits-set value */
    SLEEPING   = BIT(0),
    COUNTSLEEP = BIT(1),
    SUSPENDED  = BIT(2),
    CREATING   = BIT(3),
    EXITED     = BIT(4),
    SLEEPSET   = (SLEEPING | COUNTSLEEP)
};
 
/* Cyg_Thread:: reason codes for wake and sleep fields: */
static const struct ecos_thread_state ecos_thread_reasons[] = {
    { 0, "NONE" }, /* normally indicates "not yet started" */
    { 1, "WAIT" }, /* wait with no timeout */
    { 2, "DELAY" }, /* simple time delay */
    { 3, "TIMEOUT" }, /* wait with timeout *or* timeout expired */
    { 4, "BREAK" }, /* forced break out of sleep */
    { 5, "DESTRUCT" }, /* wait on object being destroyed */
    { 6, "EXIT" }, /* forced termination */
    { 7, "DONE" } /* wait/delay completed */
};
 
static const char * const target_cortex_m[] = {
    "cortex_m",
    "hla_target",
    NULL
};
 
static const char * const target_arm[] = {
    "cortex_a",
    "arm7tdmi",
    "arm720t",
    "arm9tdmi",
    "arm920t",
    "arm926ejs",
    "arm946e",
    "arm966e",
    "arm11",
    NULL
};
 
/* Since individual eCos application configurations may have different thread
 * object structure layouts depending on the actual build-time enabled features
 * we provide support for applications built containing the relevant symbolic
 * support to match the actual application binary being debugged, rather than
 * relying on a set of default/fixed (and potentially incorrect)
 * offsets. However, for backwards compatibility, we do *NOT* enforce the
 * requirement for the common extra helper symbols to be present to allow the
 * fallback to the simple fixed CM3 model to avoid affecting existing users of
 * older eCos worlds. Similarly we need to provide support for per-thread
 * register context offsets, as well as for per-application-configurations,
 * since some targets can have different stacked state on a per-thread basis
 * (e.g. "cortex_m"). This is why the stacking_info is now set at run-time
 * rather than being fixed. */
 
struct ecos_params {
    const char * const *target_names; /* NULL terminated list of targets */
    int (*target_stack_layout)(struct rtos *rtos, struct ecos_params *param,
        int64_t stack_ptr, const struct rtos_register_stacking **si);
    bool flush_common;
    unsigned char pointer_width;
    unsigned char uid_width;
    unsigned char state_width;
    unsigned int thread_stack_offset;
    unsigned int thread_name_offset;
    unsigned int thread_state_offset;
    unsigned int thread_next_offset;
    unsigned int thread_uniqueid_offset;
    const struct rtos_register_stacking *stacking_info;
};
 
/* As mentioned above we provide default offset values for the "cortex_m"
 * targets for backwards compatibility with older eCos application builds and
 * previous users of this RTOS specific support that do not have the
 * configuration specific offsets provided in the symbol table. The support for
 * other targets (e.g. "cortex_a") we do expect the application to provide the
 * required symbolic information. We do not populate the stacking_info reference
 * until we have had a chance to interrogate the symbol table. */
 
static struct ecos_params ecos_params_list[] = {
    {
    .target_names = target_cortex_m,
    .pointer_width = 4,
    .uid_width = 2,
    .state_width = 4,
    .thread_stack_offset = 0x0c,
    .thread_name_offset = 0x9c,
    .thread_state_offset = 0x3c,
    .thread_next_offset = 0xa0,
    .thread_uniqueid_offset = 0x4c,
    .target_stack_layout = ecos_stack_layout_cortexm,
    .stacking_info = NULL
    },
    {
    .target_names = target_arm,
    .pointer_width = 0,
    .uid_width = 0,
    .state_width = 0,
    .thread_stack_offset = 0,
    .thread_name_offset = 0,
    .thread_state_offset = 0,
    .thread_next_offset = 0,
    .thread_uniqueid_offset = 0,
    .target_stack_layout = ecos_stack_layout_arm,
    .stacking_info = NULL
    }
};
 
#define ECOS_NUM_PARAMS ARRAY_SIZE(ecos_params_list)
 
/* To eventually allow for more than just the ARMV7M_NUM_CORE_REGS to be
 * returned by the Cortex-M support, and to avoid run-time lookups we manually
 * maintain our own mapping for the supplied stack register vector entries. This
 * enum needs to match the rtos_ecos_regoff_cortexm[] vector. Admittedly the
 * initial indices just match the corresponding ARMV7M_R* definitions, but after
 * the base registers the ARMV7M_* number space does not match the vector we
 * wish to populate in this eCos support code. */
enum ecos_reglist_cortexm {
    ECOS_REGLIST_R0 = 0,
    ECOS_REGLIST_R1,
    ECOS_REGLIST_R2,
    ECOS_REGLIST_R3,
    ECOS_REGLIST_R4,
    ECOS_REGLIST_R5,
    ECOS_REGLIST_R6,
    ECOS_REGLIST_R7,
    ECOS_REGLIST_R8,
    ECOS_REGLIST_R9,
    ECOS_REGLIST_R10,
    ECOS_REGLIST_R11,
    ECOS_REGLIST_R12,
    ECOS_REGLIST_R13,
    ECOS_REGLIST_R14,
    ECOS_REGLIST_PC,
    ECOS_REGLIST_XPSR,  /* ARMV7M_NUM_CORE_REGS */
    ECOS_REGLIST_BASEPRI,
    ECOS_REGLIST_FPSCR, /* Following for FPU contexts */
    ECOS_REGLIST_D0,
    ECOS_REGLIST_D1,
    ECOS_REGLIST_D2,
    ECOS_REGLIST_D3,
    ECOS_REGLIST_D4,
    ECOS_REGLIST_D5,
    ECOS_REGLIST_D6,
    ECOS_REGLIST_D7,
    ECOS_REGLIST_D8,
    ECOS_REGLIST_D9,
    ECOS_REGLIST_D10,
    ECOS_REGLIST_D11,
    ECOS_REGLIST_D12,
    ECOS_REGLIST_D13,
    ECOS_REGLIST_D14,
    ECOS_REGLIST_D15
};
 
#define ECOS_CORTEXM_BASE_NUMREGS (ARMV7M_NUM_CORE_REGS)
 
/* NOTE: The offsets in this vector are overwritten by the architecture specific
 * layout functions depending on the specific application configuration. The
 * ordering of this vector MUST match eCos_reglist. */
static struct stack_register_offset rtos_ecos_regoff_cortexm[] = {
    { ARMV7M_R0,      -1, 32 }, /* r0            */
    { ARMV7M_R1,      -1, 32 }, /* r1            */
    { ARMV7M_R2,      -1, 32 }, /* r2            */
    { ARMV7M_R3,      -1, 32 }, /* r3            */
    { ARMV7M_R4,      -1, 32 }, /* r4            */
    { ARMV7M_R5,      -1, 32 }, /* r5            */
    { ARMV7M_R6,      -1, 32 }, /* r6            */
    { ARMV7M_R7,      -1, 32 }, /* r7            */
    { ARMV7M_R8,      -1, 32 }, /* r8            */
    { ARMV7M_R9,      -1, 32 }, /* r9            */
    { ARMV7M_R10,     -1, 32 }, /* r10           */
    { ARMV7M_R11,     -1, 32 }, /* r11           */
    { ARMV7M_R12,     -1, 32 }, /* r12           */
    { ARMV7M_R13,     -1, 32 }, /* sp            */
    { ARMV7M_R14,     -1, 32 }, /* lr            */
    { ARMV7M_PC,      -1, 32 }, /* pc            */
    { ARMV7M_XPSR,    -1, 32 }, /* xPSR          */
    { ARMV7M_BASEPRI, -1, 32 },     /* BASEPRI       */
    { ARMV7M_FPSCR,   -1, 32 },     /* FPSCR         */
    { ARMV7M_D0,      -1, 64 },     /* D0  (S0/S1)   */
    { ARMV7M_D1,      -1, 64 },     /* D1  (S2/S3)   */
    { ARMV7M_D2,      -1, 64 },     /* D2  (S4/S5)   */
    { ARMV7M_D3,      -1, 64 },     /* D3  (S6/S7)   */
    { ARMV7M_D4,      -1, 64 },     /* D4  (S8/S9)   */
    { ARMV7M_D5,      -1, 64 },     /* D5  (S10/S11) */
    { ARMV7M_D6,      -1, 64 },     /* D6  (S12/S13) */
    { ARMV7M_D7,      -1, 64 },     /* D7  (S14/S15) */
    { ARMV7M_D8,      -1, 64 },     /* D8  (S16/S17) */
    { ARMV7M_D9,      -1, 64 },     /* D9  (S18/S19) */
    { ARMV7M_D10,     -1, 64 },     /* D10 (S20/S21) */
    { ARMV7M_D11,     -1, 64 },     /* D11 (S22/S23) */
    { ARMV7M_D12,     -1, 64 },     /* D12 (S24/S25) */
    { ARMV7M_D13,     -1, 64 },     /* D13 (S26/S27) */
    { ARMV7M_D14,     -1, 64 },     /* D14 (S28/S29) */
    { ARMV7M_D15,     -1, 64 },     /* D15 (S30/S31) */
};
 
static struct stack_register_offset rtos_ecos_regoff_arm[] = {
    { 0,  -1, 32 },     /* r0       */
    { 1,  -1, 32 },     /* r1       */
    { 2,  -1, 32 },     /* r2       */
    { 3,  -1, 32 },     /* r3       */
    { 4,  -1, 32 },     /* r4       */
    { 5,  -1, 32 },     /* r5       */
    { 6,  -1, 32 },     /* r6       */
    { 7,  -1, 32 },     /* r7       */
    { 8,  -1, 32 },     /* r8       */
    { 9,  -1, 32 },     /* r9       */
    { 10, -1, 32 },     /* r10      */
    { 11, -1, 32 },     /* r11 (fp) */
    { 12, -1, 32 },     /* r12 (ip) */
    { 13, -1, 32 },     /* sp (r13) */
    { 14, -1, 32 },     /* lr (r14) */
    { 15, -1, 32 },     /* pc (r15) */
    { 16, -1, 32 },     /* xPSR     */
};
 
static struct rtos_register_stacking rtos_ecos_stacking = {
    .stack_registers_size = 0,
    .stack_growth_direction = -1,
    .num_output_registers = 0,
    .calculate_process_stack = NULL,    /* stack_alignment */
    .register_offsets = NULL
};
 
/* To avoid the run-time cost of matching explicit symbol names we push the
 * lookup offsets to this *manually* maintained enumeration which must match the
 * ecos_symbol_list[] order below. */
enum ecos_symbol_values {
    ECOS_VAL_THREAD_LIST = 0,
    ECOS_VAL_CURRENT_THREAD_PTR,
    ECOS_VAL_COMMON_THREAD_NEXT_OFF,
    ECOS_VAL_COMMON_THREAD_NEXT_SIZE,
    ECOS_VAL_COMMON_THREAD_STATE_OFF,
    ECOS_VAL_COMMON_THREAD_STATE_SIZE,
    ECOS_VAL_COMMON_THREAD_SLEEP_OFF,
    ECOS_VAL_COMMON_THREAD_SLEEP_SIZE,
    ECOS_VAL_COMMON_THREAD_WAKE_OFF,
    ECOS_VAL_COMMON_THREAD_WAKE_SIZE,
    ECOS_VAL_COMMON_THREAD_ID_OFF,
    ECOS_VAL_COMMON_THREAD_ID_SIZE,
    ECOS_VAL_COMMON_THREAD_NAME_OFF,
    ECOS_VAL_COMMON_THREAD_NAME_SIZE,
    ECOS_VAL_COMMON_THREAD_PRI_OFF,
    ECOS_VAL_COMMON_THREAD_PRI_SIZE,
    ECOS_VAL_COMMON_THREAD_STACK_OFF,
    ECOS_VAL_COMMON_THREAD_STACK_SIZE,
    ECOS_VAL_CORTEXM_THREAD_SAVED,
    ECOS_VAL_CORTEXM_CTX_THREAD_SIZE,
    ECOS_VAL_CORTEXM_CTX_TYPE_OFF,
    ECOS_VAL_CORTEXM_CTX_TYPE_SIZE,
    ECOS_VAL_CORTEXM_CTX_BASEPRI_OFF,
    ECOS_VAL_CORTEXM_CTX_BASEPRI_SIZE,
    ECOS_VAL_CORTEXM_CTX_SP_OFF,
    ECOS_VAL_CORTEXM_CTX_SP_SIZE,
    ECOS_VAL_CORTEXM_CTX_REG_OFF,
    ECOS_VAL_CORTEXM_CTX_REG_SIZE,
    ECOS_VAL_CORTEXM_CTX_PC_OFF,
    ECOS_VAL_CORTEXM_CTX_PC_SIZE,
    ECOS_VAL_CORTEXM_VAL_EXCEPTION,
    ECOS_VAL_CORTEXM_VAL_THREAD,
    ECOS_VAL_CORTEXM_VAL_INTERRUPT,
    ECOS_VAL_CORTEXM_VAL_FPU,
    ECOS_VAL_CORTEXM_CTX_FPSCR_OFF,
    ECOS_VAL_CORTEXM_CTX_FPSCR_SIZE,
    ECOS_VAL_CORTEXM_CTX_S_OFF,
    ECOS_VAL_CORTEXM_CTX_S_SIZE,
    ECOS_VAL_ARM_REGSIZE,
    ECOS_VAL_ARM_CTX_R0_OFF,
    ECOS_VAL_ARM_CTX_R1_OFF,
    ECOS_VAL_ARM_CTX_R2_OFF,
    ECOS_VAL_ARM_CTX_R3_OFF,
    ECOS_VAL_ARM_CTX_R4_OFF,
    ECOS_VAL_ARM_CTX_R5_OFF,
    ECOS_VAL_ARM_CTX_R6_OFF,
    ECOS_VAL_ARM_CTX_R7_OFF,
    ECOS_VAL_ARM_CTX_R8_OFF,
    ECOS_VAL_ARM_CTX_R9_OFF,
    ECOS_VAL_ARM_CTX_R10_OFF,
    ECOS_VAL_ARM_CTX_FP_OFF,
    ECOS_VAL_ARM_CTX_IP_OFF,
    ECOS_VAL_ARM_CTX_SP_OFF,
    ECOS_VAL_ARM_CTX_LR_OFF,
    ECOS_VAL_ARM_CTX_PC_OFF,
    ECOS_VAL_ARM_CTX_CPSR_OFF,
    ECOS_VAL_ARM_FPUSIZE,
    ECOS_VAL_ARM_CTX_FPSCR_OFF,
    ECOS_VAL_ARM_SCOUNT,
    ECOS_VAL_ARM_CTX_SVEC_OFF,
    ECOS_VAL_ARM_VFPCOUNT,
    ECOS_VAL_ARM_CTX_VFPVEC_OFF
};
 
struct symbols {
    const char *name;
    const char * const *target_names; /* non-NULL when for a specific architecture */
    bool optional;
};
 
#define ECOSSYM(_n, _o, _t) { .name = _n, .optional = (_o), .target_names = _t }
 
/* Some of offset/size helper symbols are common to all eCos
 * targets. Unfortunately, for historical reasons, some information is in
 * architecture specific namespaces leading to some duplication and a larger
 * vector below. */
static const struct symbols ecos_symbol_list[] = {
    ECOSSYM("Cyg_Thread::thread_list", false, NULL),
    ECOSSYM("Cyg_Scheduler_Base::current_thread", false, NULL),
    /* Following symbols *are* required for generic application-specific
     * configuration support, but we mark as optional for backwards
     * compatibility with the previous fixed Cortex-M3 only RTOS plugin
     * implementation. */
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.list_next", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.list_next", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.state", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.state", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.sleep_reason", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.sleep_reason", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.wake_reason", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.wake_reason", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.unique_id", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.unique_id", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.name", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.name", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.priority", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.priority", true, NULL),
    ECOSSYM("__ecospro_syminfo.off.cyg_thread.stack_ptr", true, NULL),
    ECOSSYM("__ecospro_syminfo.size.cyg_thread.stack_ptr", true, NULL),
    /* optional Cortex-M: */
    ECOSSYM("__ecospro_syminfo.cortexm.thread.saved", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.Thread", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.type", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.type", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.basepri", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.basepri", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.sp", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.sp", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.r", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.r", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.pc", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.pc", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.value.HAL_SAVEDREGISTERS.EXCEPTION", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.value.HAL_SAVEDREGISTERS.THREAD", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.value.HAL_SAVEDREGISTERS.INTERRUPT", true, target_cortex_m),
    /* optional Cortex-M with H/W FPU configured: */
    ECOSSYM("__ecospro_syminfo.value.HAL_SAVEDREGISTERS.WITH_FPU", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.fpscr", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.fpscr", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.off.HAL_SavedRegisters.u.thread.s", true, target_cortex_m),
    ECOSSYM("__ecospro_syminfo.size.HAL_SavedRegisters.u.thread.s", true, target_cortex_m),
    /* optional ARM: */
    ECOSSYM("ARMREG_SIZE", true, target_arm),
    ECOSSYM("armreg_r0", true, target_arm),
    ECOSSYM("armreg_r1", true, target_arm),
    ECOSSYM("armreg_r2", true, target_arm),
    ECOSSYM("armreg_r3", true, target_arm),
    ECOSSYM("armreg_r4", true, target_arm),
    ECOSSYM("armreg_r5", true, target_arm),
    ECOSSYM("armreg_r6", true, target_arm),
    ECOSSYM("armreg_r7", true, target_arm),
    ECOSSYM("armreg_r8", true, target_arm),
    ECOSSYM("armreg_r9", true, target_arm),
    ECOSSYM("armreg_r10", true, target_arm),
    ECOSSYM("armreg_fp", true, target_arm),
    ECOSSYM("armreg_ip", true, target_arm),
    ECOSSYM("armreg_sp", true, target_arm),
    ECOSSYM("armreg_lr", true, target_arm),
    ECOSSYM("armreg_pc", true, target_arm),
    ECOSSYM("armreg_cpsr", true, target_arm),
    /* optional ARM FPU common: */
    ECOSSYM("ARMREG_FPUCONTEXT_SIZE", true, target_arm),
    ECOSSYM("armreg_fpscr", true, target_arm),
    /* optional ARM FPU single-precision: */
    ECOSSYM("ARMREG_S_COUNT", true, target_arm),
    ECOSSYM("armreg_s_vec", true, target_arm),
    /* optional ARM FPU double-precision: */
    ECOSSYM("ARMREG_VFP_COUNT", true, target_arm),
    ECOSSYM("armreg_vfp_vec", true, target_arm),
};
 
const struct rtos_type ecos_rtos = {
    .name = "eCos",
 
    .detect_rtos = ecos_detect_rtos,
    .create = ecos_create,
    .update_threads = ecos_update_threads,
    .get_thread_reg_list = ecos_get_thread_reg_list,
    .get_symbol_list_to_lookup = ecos_get_symbol_list_to_lookup,
 
};
 
static symbol_address_t ecos_value(struct rtos *rtos, unsigned int idx)
{
    if (idx < ARRAY_SIZE(ecos_symbol_list))
        return rtos->symbols[idx].address;
 
    /* We do not terminate, just return 0 in this case. */
    LOG_ERROR("eCos: Invalid symbol index %u", idx);
    return 0;
}
 
#define XMLENTRY(_c, _s) { .xc = (_c), .rs = (_s), .rlen = (sizeof(_s) - 1) }
 
static const struct {
    char xc;
    const char *rs;
    size_t rlen;
} xmlchars[] = {
    XMLENTRY('<', "&lt;"),
    XMLENTRY('&', "&amp;"),
    XMLENTRY('>', "&gt;"),
    XMLENTRY('\'', "&apos;"),
    XMLENTRY('"', "&quot;")
};
 
static bool ecos_escape_string(const char *raw, char *out, size_t limit)
{
    static const char *tokens = "<&>\'\"";
    bool escaped = false;
 
    if (!out || !limit)
        return false;
 
    (void)memset(out, '\0', limit);
 
    while (raw && *raw && limit) {
        size_t lok = strcspn(raw, tokens);
        if (lok) {
            size_t tocopy;
            tocopy = ((limit < lok) ? limit : lok);
            (void)memcpy(out, raw, tocopy);
            limit -= tocopy;
            out += tocopy;
            raw += lok;
            continue;
        }
 
        char *fidx = strchr(tokens, *raw);
        if (!fidx) {
            /* Should never happen assuming xmlchars
             * vector and tokens string match. */
            LOG_ERROR("eCos: Unexpected XML char %c", *raw);
            continue;
        }
 
        uint32_t cidx = (fidx - tokens);
        size_t tocopy = xmlchars[cidx].rlen;
        if (limit < tocopy)
            break;
 
        escaped = true;
        (void)memcpy(out, xmlchars[cidx].rs, tocopy);
        limit -= tocopy;
        out += tocopy;
        raw++;
    }
 
    return escaped;
}
 
static int ecos_check_app_info(struct rtos *rtos, struct ecos_params *param)
{
    if (!rtos || !param)
        return -1;
 
    if (param->flush_common) {
        if (debug_level >= LOG_LVL_DEBUG) {
            for (unsigned int idx = 0; idx < ARRAY_SIZE(ecos_symbol_list); idx++) {
                LOG_DEBUG("eCos: %s 0x%016" PRIX64 " %s",
                    rtos->symbols[idx].optional ? "OPTIONAL" : "        ",
                    rtos->symbols[idx].address, rtos->symbols[idx].symbol_name);
            }
        }
 
        /* If "__ecospro_syminfo.size.cyg_thread.list_next" is non-zero then we
         * expect all of the generic thread structure symbols to have been
         * provided. */
        symbol_address_t thread_next_size = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_NEXT_SIZE);
        if (thread_next_size != 0) {
            param->pointer_width = thread_next_size;
            param->uid_width = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_ID_SIZE);
            param->state_width = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_STATE_SIZE);
            param->thread_stack_offset = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_STACK_OFF);
            param->thread_name_offset = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_NAME_OFF);
            param->thread_state_offset = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_STATE_OFF);
            param->thread_next_offset = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_NEXT_OFF);
            param->thread_uniqueid_offset = ecos_value(rtos, ECOS_VAL_COMMON_THREAD_ID_OFF);
        }
 
        if (param->uid_width != sizeof(uint16_t)) {
            /* Currently all eCos configurations use a 16-bit field to hold the
             * unique thread ID. */
            LOG_WARNING("eCos: Unexpected unique_id width %" PRIu8, param->uid_width);
            param->uid_width = (unsigned char)sizeof(uint16_t);
        }
 
        param->stacking_info = NULL;
        param->flush_common = false;
    }
 
    return ERROR_OK;
}
 
/* The Cortex-M eCosPro "thread" contexts have a "type" indicator, which tracks
 * the context state of (THREAD | EXCEPTION | INTERRUPT) and whether FPU
 * registers are saved.
 *
 * For thread-aware debugging from GDB we are only interested in THREAD states
 * and so do not need to implement support for INTERRUPT or EXCEPTION thread
 * contexts since this code does not expose those stack contexts via the
 * constructed thread list support. */
static int ecos_stack_layout_cortexm(struct rtos *rtos,
        struct ecos_params *param, int64_t stack_ptr,
        const struct rtos_register_stacking **si)
{
    int retval = ERROR_OK;
 
    /* CONSIDER: We could return
     * ecos_value(rtos, ECOS_VAL_CORTEXM_THREAD_SAVED) as the actual PC
     * address of a context switch, with the LR being set to the context PC
     * field to give a true representation of where the thread switch
     * occurs. However that would require extending the common
     * rtos_generic_stack_read() code with suitable support for applying a
     * supplied value, or just implementing our own version of that code that
     * can inject data into what is passed onwards to GDB. */
 
    /* UPDATE: When we can return VFP register state then we will NOT be
     * basing the cached state on the single param->stacking_info value,
     * since we will need a different stacking_info structure returned for
     * each thread type when FPU support is enabled. The use of the single
     * param->stacking_info is a holder whilst we are limited to the fixed
     * ARMV7M_NUM_CORE_REGS set of descriptors. */
 
    if (!param->stacking_info &&
        ecos_value(rtos, ECOS_VAL_CORTEXM_THREAD_SAVED) &&
        ecos_value(rtos, ECOS_VAL_CORTEXM_VAL_THREAD)) {
        unsigned char numoutreg = ECOS_CORTEXM_BASE_NUMREGS;
 
        rtos_ecos_stacking.stack_registers_size = ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_THREAD_SIZE);
        rtos_ecos_stacking.calculate_process_stack = rtos_generic_stack_align8;
        rtos_ecos_stacking.register_offsets = rtos_ecos_regoff_cortexm;
 
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R0].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x00);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R1].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x04);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R2].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x08);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R3].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x0C);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R4].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x10);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R5].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x14);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R6].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x18);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R7].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x1C);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R8].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x20);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R9].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x24);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R10].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x28);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R11].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x2C);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R12].offset = (ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_REG_OFF) + 0x30);
        /* Rather than using the stacked ECOS_VAL_CORTEXM_CTX_SP_OFF
         * value we force the reported sp to be after the stacked
         * register context. */
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R13].offset = -2;
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_R14].offset = -1;
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_PC].offset = ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_PC_OFF);
        rtos_ecos_regoff_cortexm[ECOS_REGLIST_XPSR].offset = -1;
 
        param->stacking_info = &rtos_ecos_stacking;
 
        /* Common Cortex-M thread register offsets for the current
         * symbol table: */
        if (retval == ERROR_OK && param->stacking_info) {
            if (numoutreg > ECOS_REGLIST_BASEPRI) {
                rtos_ecos_regoff_cortexm[ECOS_REGLIST_BASEPRI].offset =
                    ecos_value(rtos, ECOS_VAL_CORTEXM_CTX_BASEPRI_OFF);
            }
 
            rtos_ecos_stacking.num_output_registers = numoutreg;
        }
    }
 
    if (si)
        *si = param->stacking_info;
 
    return retval;
}
 
static int ecos_stack_layout_arm(struct rtos *rtos, struct ecos_params *param,
        int64_t stack_ptr, const struct rtos_register_stacking **si)
{
    int retval = ERROR_OK;
 
    if (!param->stacking_info && ecos_value(rtos, ECOS_VAL_ARM_REGSIZE)) {
        /* When OpenOCD is extended to allow FPU registers to be returned from a
         * stacked thread context we can check:
         *      if (0 != ecos_value(rtos, ECOS_VAL_ARM_FPUSIZE)) { FPU }
         * for presence of FPU registers in the context. */
 
        rtos_ecos_stacking.stack_registers_size = ecos_value(rtos, ECOS_VAL_ARM_REGSIZE);
        rtos_ecos_stacking.num_output_registers = ARRAY_SIZE(rtos_ecos_regoff_arm);
        rtos_ecos_stacking.register_offsets = rtos_ecos_regoff_arm;
 
        rtos_ecos_regoff_arm[0].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R0_OFF);
        rtos_ecos_regoff_arm[1].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R1_OFF);
        rtos_ecos_regoff_arm[2].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R2_OFF);
        rtos_ecos_regoff_arm[3].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R3_OFF);
        rtos_ecos_regoff_arm[4].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R4_OFF);
        rtos_ecos_regoff_arm[5].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R5_OFF);
        rtos_ecos_regoff_arm[6].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R6_OFF);
        rtos_ecos_regoff_arm[7].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R7_OFF);
        rtos_ecos_regoff_arm[8].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R8_OFF);
        rtos_ecos_regoff_arm[9].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R9_OFF);
        rtos_ecos_regoff_arm[10].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_R10_OFF);
        rtos_ecos_regoff_arm[11].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_FP_OFF);
        rtos_ecos_regoff_arm[12].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_IP_OFF);
        rtos_ecos_regoff_arm[13].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_SP_OFF);
        rtos_ecos_regoff_arm[14].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_LR_OFF);
        rtos_ecos_regoff_arm[15].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_PC_OFF);
        rtos_ecos_regoff_arm[16].offset = ecos_value(rtos, ECOS_VAL_ARM_CTX_CPSR_OFF);
 
        param->stacking_info = &rtos_ecos_stacking;
    }
 
    if (si)
        *si = param->stacking_info;
 
    return retval;
}
 
/* We see this function called on a new connection, it looks like before and
 * after the "tar rem"/"tar extended-remote". It might be the only point we can
 * decide to cache information (to check if the symbol table has changed). */
static int ecos_update_threads(struct rtos *rtos)
{
    int retval;
    int tasks_found = 0;
    int thread_list_size = 0;
    struct ecos_params *param;
 
    if (!rtos)
        return -1;
 
    /* wipe out previous thread details if any */
    rtos_free_threadlist(rtos);
 
    if (!rtos->rtos_specific_params)
        return -3;
 
    param = rtos->rtos_specific_params;
 
    if (!rtos->symbols) {
        /* NOTE: We only see this when connecting from GDB the first
         * time before the application image is loaded. So it is not a
         * hook for detecting an application change. */
        param->flush_common = true;
        LOG_ERROR("No symbols for eCos");
        return -4;
    }
 
    retval = ecos_check_app_info(rtos, param);
    if (retval != ERROR_OK)
        return retval;
 
    if (rtos->symbols[ECOS_VAL_THREAD_LIST].address == 0) {
        LOG_ERROR("Don't have the thread list head");
        return -2;
    }
 
    /* determine the number of current threads */
    uint32_t thread_list_head = rtos->symbols[ECOS_VAL_THREAD_LIST].address;
    uint32_t thread_index;
    target_read_buffer(rtos->target,
        thread_list_head,
        param->pointer_width,
        (uint8_t *) &thread_index);
    uint32_t first_thread = thread_index;
 
    /* Even if 0==first_thread indicates a system with no defined eCos
     * threads, instead of early exiting here we fall through the code to
     * allow the creation of a faked "Current Execution" descriptor as
     * needed. */
 
    if (first_thread) {
        /* Since the OpenOCD RTOS support can attempt to obtain thread
         * information on initial connection when the system *may* have
         * undefined memory state it is possible for a simple thread count scan
         * to produce invalid results. To avoid blocking indefinitely when
         * encountering an invalid closed loop we limit the number of threads to
         * the maximum possible, and if we pass that limit then something is
         * wrong so treat the system as having no threads defined. */
        do {
            thread_list_size++;
            if (thread_list_size > ECOS_MAX_THREAD_COUNT) {
                /* Treat as "no threads" case: */
                first_thread = 0;
                thread_list_size = 0;
                break;
            }
            retval = target_read_buffer(rtos->target,
                    thread_index + param->thread_next_offset,
                    param->pointer_width,
                    (uint8_t *)&thread_index);
            if (retval != ERROR_OK)
                return retval;
        } while (thread_index != first_thread);
    }
 
    /* read the current thread id */
    rtos->current_thread = 0;
 
    uint32_t current_thread_addr;
    retval = target_read_buffer(rtos->target,
            rtos->symbols[ECOS_VAL_CURRENT_THREAD_PTR].address,
            param->pointer_width,
            (uint8_t *)&current_thread_addr);
    if (retval != ERROR_OK) {
        LOG_ERROR("Reading active thread address");
        return retval;
    }
 
    if (current_thread_addr) {
        uint16_t id = 0;
        retval = target_read_buffer(rtos->target,
                current_thread_addr + param->thread_uniqueid_offset,
                param->uid_width,
                (uint8_t *)&id);
        if (retval != ERROR_OK) {
            LOG_ERROR("Could not read eCos current thread from target");
            return retval;
        }
        rtos->current_thread = (threadid_t)id;
    }
 
    if (thread_list_size == 0 || rtos->current_thread == 0) {
        /* Either : No RTOS threads - there is always at least the current execution though */
        /* OR     : No current thread - all threads suspended - show the current execution
         * of idling */
        static const char tmp_str[] = "Current Execution";
        thread_list_size++;
        tasks_found++;
        rtos->thread_details = malloc(
                sizeof(struct thread_detail) * thread_list_size);
        /* 1 is a valid eCos thread id, so we return 0 for this faked
         * "current" CPU state: */
        rtos->thread_details->threadid = 0;
        rtos->thread_details->exists = true;
        rtos->thread_details->extra_info_str = NULL;
        rtos->thread_details->thread_name_str = malloc(sizeof(tmp_str));
        strcpy(rtos->thread_details->thread_name_str, tmp_str);
 
        /* Early exit if current CPU state our only "thread": */
        if (thread_list_size == 1) {
            rtos->thread_count = 1;
            return ERROR_OK;
        }
    } else {
        /* create space for new thread details */
        rtos->thread_details = malloc(
                sizeof(struct thread_detail) * thread_list_size);
    }
 
    /* loop over all threads */
    thread_index = first_thread;
    do {
        #define ECOS_THREAD_NAME_STR_SIZE (200)
        char tmp_str[ECOS_THREAD_NAME_STR_SIZE];
        uint32_t name_ptr = 0;
        uint32_t prev_thread_ptr;
 
        /* Save the thread ID. For eCos the thread has a unique ID distinct from
         * the thread_index descriptor pointer. We present this scheduler ID
         * instead of the descriptor memory address. */
        uint16_t thread_id = 0;
        retval = target_read_buffer(rtos->target,
                thread_index + param->thread_uniqueid_offset,
                param->uid_width,
                (uint8_t *)&thread_id);
        if (retval != ERROR_OK) {
            LOG_ERROR("Could not read eCos thread id from target");
            return retval;
        }
        rtos->thread_details[tasks_found].threadid = thread_id;
 
        /* Read the name pointer */
        retval = target_read_buffer(rtos->target,
                thread_index + param->thread_name_offset,
                param->pointer_width,
                (uint8_t *)&name_ptr);
        if (retval != ERROR_OK) {
            LOG_ERROR("Could not read eCos thread name pointer from target");
            return retval;
        }
 
        /* Read the thread name */
        retval =
            target_read_buffer(rtos->target,
                name_ptr,
                ECOS_THREAD_NAME_STR_SIZE,
                (uint8_t *)&tmp_str);
        if (retval != ERROR_OK) {
            LOG_ERROR("Error reading thread name from eCos target");
            return retval;
        }
        tmp_str[ECOS_THREAD_NAME_STR_SIZE-1] = '\x00';
 
        /* Since eCos can have arbitrary C string names we can sometimes
         * get an internal warning from GDB about "not well-formed
         * (invalid token)" since the XML post-processing done by GDB on
         * the OpenOCD returned response containing the thread strings
         * is not escaped. For example the eCos kernel testsuite
         * application tm_basic uses the thread name "<<NULL>>" which
         * will trigger this failure unless escaped. */
        if (tmp_str[0] == '\x00') {
            snprintf(tmp_str, ECOS_THREAD_NAME_STR_SIZE, "NoName:[0x%08" PRIX32 "]", thread_index);
        } else {
            /* The following is a workaround to avoid any issues
             * from arbitrary eCos thread names causing GDB/OpenOCD
             * issues. We limit the escaped thread name passed to
             * GDB to the same length as the un-escaped just to
             * avoid overly long strings. */
            char esc_str[ECOS_THREAD_NAME_STR_SIZE];
            bool escaped = ecos_escape_string(tmp_str, esc_str, sizeof(esc_str));
            if (escaped)
                strcpy(tmp_str, esc_str);
        }
 
        rtos->thread_details[tasks_found].thread_name_str =
            malloc(strlen(tmp_str)+1);
        strcpy(rtos->thread_details[tasks_found].thread_name_str, tmp_str);
 
        /* Read the thread status */
        int64_t thread_status = 0;
        retval = target_read_buffer(rtos->target,
                thread_index + param->thread_state_offset,
                param->state_width,
                (uint8_t *)&thread_status);
        if (retval != ERROR_OK) {
            LOG_ERROR("Error reading thread state from eCos target");
            return retval;
        }
 
        /* The thread_status is a BITMASK */
        char state_desc[21];        /* Enough for "suspended+countsleep\0" maximum */
 
        if (thread_status & SUSPENDED)
            strcpy(state_desc, "suspended+");
        else
            state_desc[0] = '\0';
 
        switch (thread_status & ~SUSPENDED) {
        case RUNNING:
            if (thread_index == current_thread_addr)
                strcat(state_desc, "running");
            else if (thread_status & SUSPENDED)
                state_desc[9] = '\0';   /* Drop '+' from "suspended+" */
            else
                strcat(state_desc, "ready");
            break;
        case SLEEPING:
            strcat(state_desc, "sleeping");
            break;
        case SLEEPSET:
        case COUNTSLEEP:
            strcat(state_desc, "counted sleep");
            break;
        case CREATING:
            strcpy(state_desc, "creating");
            break;
        case EXITED:
            strcpy(state_desc, "exited");
            break;
        default:
            strcpy(state_desc, "unknown state");
            break;
        }
 
        /* For the moment we do not bother decoding the wake reason for the
         * active "running" thread, but it is useful providing the sleep reason
         * for stacked threads. */
        int64_t sleep_reason = 0; /* sleep reason */
 
        if (thread_index != current_thread_addr &&
            ecos_value(rtos, ECOS_VAL_COMMON_THREAD_SLEEP_SIZE)) {
            retval = target_read_buffer(rtos->target,
                (thread_index + ecos_value(rtos, ECOS_VAL_COMMON_THREAD_SLEEP_OFF)),
                ecos_value(rtos, ECOS_VAL_COMMON_THREAD_SLEEP_SIZE),
                (uint8_t *)&sleep_reason);
            if (retval != ERROR_OK) {
                LOG_ERROR("Error reading thread sleep reason from eCos target");
                return retval;
            }
            if (sleep_reason < 0 ||
                sleep_reason > (int64_t)ARRAY_SIZE(ecos_thread_reasons)) {
                sleep_reason = 0;
            }
        }
 
        /* We do not display anything for the Cyg_Thread::NONE reason */
        size_t tr_extra = 0;
        const char *reason_desc = NULL;
        if (sleep_reason)
            reason_desc = ecos_thread_reasons[sleep_reason].desc;
        if (reason_desc)
            tr_extra = 2 + strlen(reason_desc) + 1;
 
        /* Display thread priority if available: */
        int64_t priority = 0;
        size_t pri_extra = 0;
        if (ecos_value(rtos, ECOS_VAL_COMMON_THREAD_PRI_SIZE)) {
            retval = target_read_buffer(rtos->target,
                (thread_index + ecos_value(rtos, ECOS_VAL_COMMON_THREAD_PRI_OFF)),
                ecos_value(rtos, ECOS_VAL_COMMON_THREAD_PRI_SIZE),
                (uint8_t *)&priority);
            if (retval != ERROR_OK) {
                LOG_ERROR("Error reading thread priority from eCos target");
                return retval;
            }
            pri_extra = (12 + 20); /* worst-case ", Priority: " */
        }
 
        size_t eilen = (8 + strlen(state_desc) + tr_extra + pri_extra);
        char *eistr = malloc(eilen);
        /* We do not need to treat a malloc failure as a fatal error here since
         * the code below will just not report extra thread information if NULL,
         * thus allowing all of the threads to be enumerated even with reduced
         * information when the host is low on memory. However... */
        if (!eistr) {
            LOG_ERROR("OOM allocating extra information buffer");
            return ERROR_FAIL;
        }
 
        int soff = snprintf(eistr, eilen, "State: %s", state_desc);
        if (tr_extra && reason_desc)
            soff += snprintf(&eistr[soff], (eilen - soff), " (%s)", reason_desc);
        if (pri_extra)
            (void)snprintf(&eistr[soff], (eilen - soff), ", Priority: %" PRId64 "", priority);
        rtos->thread_details[tasks_found].extra_info_str = eistr;
 
        rtos->thread_details[tasks_found].exists = true;
 
        tasks_found++;
        prev_thread_ptr = thread_index;
 
        /* Get the location of the next thread structure. */
        thread_index = rtos->symbols[ECOS_VAL_THREAD_LIST].address;
        retval = target_read_buffer(rtos->target,
                prev_thread_ptr + param->thread_next_offset,
                param->pointer_width,
                (uint8_t *) &thread_index);
        if (retval != ERROR_OK) {
            LOG_ERROR("Error reading next thread pointer in eCos thread list");
            return retval;
        }
    } while (thread_index != first_thread);
 
    rtos->thread_count = tasks_found;
    return ERROR_OK;
}
 
static int ecos_get_thread_reg_list(struct rtos *rtos, int64_t thread_id,
        struct rtos_reg **reg_list, int *num_regs)
{
    int retval;
    struct ecos_params *param;
 
    if (!rtos)
        return -1;
 
    if (thread_id == 0)
        return -2;
 
    if (!rtos->rtos_specific_params)
        return -3;
 
    param = rtos->rtos_specific_params;
 
    retval = ecos_check_app_info(rtos, param);
    if (retval != ERROR_OK)
        return retval;
 
    /* We can get memory access errors reported by this function on
     * re-connecting to a board with stale thread information in memory. The
     * initial ecos_update_threads() is called twice and may read
     * stale/invalid information depending on the memory state. This happens
     * as part of the "target remote" connection so cannot be avoided by GDB
     * scripting. It is not critical and allowing the application to run and
     * initialise its BSS etc. will allow correct thread and register
     * information to be obtained. This really only affects debug sessions
     * where "info thr" is used before the initial run-time initialisation
     * has occurred. */
 
    /* Find the thread with that thread id */
    uint16_t id = 0;
    uint32_t thread_list_head = rtos->symbols[ECOS_VAL_THREAD_LIST].address;
    uint32_t thread_index;
    target_read_buffer(rtos->target, thread_list_head, param->pointer_width,
            (uint8_t *)&thread_index);
    bool done = false;
    while (!done) {
        retval = target_read_buffer(rtos->target,
                thread_index + param->thread_uniqueid_offset,
                param->uid_width,
                (uint8_t *)&id);
        if (retval != ERROR_OK) {
            LOG_ERROR("Error reading unique id from eCos thread 0x%08" PRIX32 "", thread_index);
            return retval;
        }
 
        if (id == thread_id) {
            done = true;
            break;
        }
        target_read_buffer(rtos->target,
            thread_index + param->thread_next_offset,
            param->pointer_width,
            (uint8_t *) &thread_index);
    }
 
    if (done) {
        /* Read the stack pointer */
        int64_t stack_ptr = 0;
        retval = target_read_buffer(rtos->target,
                thread_index + param->thread_stack_offset,
                param->pointer_width,
                (uint8_t *)&stack_ptr);
        if (retval != ERROR_OK) {
            LOG_ERROR("Error reading stack frame from eCos thread");
            return retval;
        }
 
        if (!stack_ptr) {
            LOG_ERROR("NULL stack pointer in thread %" PRIu64, thread_id);
            return -5;
        }
 
        const struct rtos_register_stacking *stacking_info = NULL;
        if (param->target_stack_layout) {
            retval = param->target_stack_layout(rtos, param, stack_ptr, &stacking_info);
            if (retval != ERROR_OK) {
                LOG_ERROR("Error reading stack layout for eCos thread");
                return retval;
            }
        }
        if (!stacking_info)
            stacking_info = &rtos_ecos_cortex_m3_stacking;
 
        return rtos_generic_stack_read(rtos->target,
            stacking_info,
            stack_ptr,
            reg_list,
            num_regs);
    }
 
    return -1;
}
 
/* NOTE: This is only called once when the first GDB connection is made to
 * OpenOCD and not on subsequent connections (when the application symbol table
 * may have changed, affecting the offsets of critical fields and the stacked
 * context shape). */
static int ecos_get_symbol_list_to_lookup(struct symbol_table_elem *symbol_list[])
{
    unsigned int i;
    *symbol_list = calloc(
            ARRAY_SIZE(ecos_symbol_list), sizeof(struct symbol_table_elem));
 
    /* If the target reference was passed into this function we could limit
     * the symbols we need to lookup to the target_type_name(target) based
     * range. For the moment we need to provide a single vector with all of
     * the symbols across all of the supported architectures. */
    for (i = 0; i < ARRAY_SIZE(ecos_symbol_list); i++) {
        (*symbol_list)[i].symbol_name = ecos_symbol_list[i].name;
        (*symbol_list)[i].optional = ecos_symbol_list[i].optional;
    }
 
    return 0;
}
 
/* NOTE: Only called by rtos.c:rtos_qsymbol() when auto-detecting the RTOS. If
 * the target configuration uses the explicit "-rtos" config option then this
 * detection routine is NOT called. */
static bool ecos_detect_rtos(struct target *target)
{
    if ((target->rtos->symbols) &&
            (target->rtos->symbols[ECOS_VAL_THREAD_LIST].address != 0)) {
        /* looks like eCos */
        return true;
    }
    return false;
}
 
/* Since we should never have 0 as a valid eCos thread ID we use $Hg0 as the
 * indicator of a new session as regards flushing any cached state. */
static int ecos_packet_hook(struct connection *connection,
        const char *packet, int packet_size)
{
    int64_t current_threadid;
 
    if (packet[0] == 'H' && packet[1] == 'g') {
        int numscan = sscanf(packet, "Hg%16" SCNx64, &current_threadid);
        if (numscan == 1 && current_threadid == 0) {
            struct target *target = get_target_from_connection(connection);
            if (target && target->rtos && target->rtos->rtos_specific_params) {
                struct ecos_params *param;
                param = target->rtos->rtos_specific_params;
                param->flush_common = true;
            }
        }
    }
 
    return rtos_thread_packet(connection, packet, packet_size);
}
 
/* Called at start of day when eCos detected or specified in config file. */
static int ecos_create(struct target *target)
{
    for (unsigned int i = 0; i < ARRAY_SIZE(ecos_params_list); i++) {
        const char * const *tnames = ecos_params_list[i].target_names;
        while (*tnames) {
            if (strcmp(*tnames, target_type_name(target)) == 0) {
                /* LOG_DEBUG("eCos: matched target \"%s\"", target_type_name(target)); */
                target->rtos->rtos_specific_params = (void *)&ecos_params_list[i];
                ecos_params_list[i].flush_common = true;
                ecos_params_list[i].stacking_info = NULL;
                target->rtos->current_thread = 0;
                target->rtos->thread_details = NULL;
 
                /* We use the $Hg0 packet as a new GDB connection "start-of-day" hook to
                 * force a re-cache of information. It is possible for a single OpenOCD
                 * session to be connected to a target with multiple GDB debug sessions
                 * started/stopped. With eCos it is possible for those GDB sessions to
                 * present applications with different offsets within a thread
                 * descriptor for fields used by this module, and for the stacked
                 * context within the connected target architecture to differ between
                 * applications and even between threads in a single application. So we
                 * need to ensure any information we cache is flushed on an application
                 * change, and GDB referencing an invalid eCos thread ID (0) is a good
                 * enough point, since we can accept the re-cache hit if that packet
                 * appears during an established session, whilst benefiting from not
                 * re-loading information on every update_threads or get_thread_reg_list
                 * call. */
                target->rtos->gdb_thread_packet = ecos_packet_hook;
                /* We do not currently use the target->rtos->gdb_target_for_threadid
                 * hook. */
                return 0;
            }
            tnames++;
        }
    }
 
    LOG_ERROR("Could not find target in eCos compatibility list");
    return -1;
}