src/target/arm_semihosting.c

   1 /***************************************************************************
   2  *   Copyright (C) 2009 by Marvell Technology Group Ltd.                   *
   3  *   Written by Nicolas Pitre <nico@marvell.com>                           *
   4  *                                                                         *
   5  *   Copyright (C) 2010 by Spencer Oliver                                  *
   6  *   spen@spen-soft.co.uk                                                  *
   7  *                                                                         *
   8  *   Copyright (C) 2016 by Square, Inc.                                    *
   9  *   Steven Stallion <stallion@squareup.com>                               *
  10  *                                                                         *
  11  *   Copyright (C) 2018 by Liviu Ionescu                                   *
  12  *   <ilg@livius.net>                                                      *
  13  *                                                                         *
  14  *   This program is free software; you can redistribute it and/or modify  *
  15  *   it under the terms of the GNU General Public License as published by  *
  16  *   the Free Software Foundation; either version 2 of the License, or     *
  17  *   (at your option) any later version.                                   *
  18  *                                                                         *
  19  *   This program is distributed in the hope that it will be useful,       *
  20  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  21  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  22  *   GNU General Public License for more details.                          *
  23  *                                                                         *
  24  *   You should have received a copy of the GNU General Public License     *
  25  *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  26  ***************************************************************************/
  27
  28 /**
  29  * @file
  30  * Hold ARM semihosting support.
  31  *
  32  * Semihosting enables code running on an ARM target to use the I/O
  33  * facilities on the host computer. The target application must be linked
  34  * against a library that forwards operation requests by using the SVC
  35  * instruction trapped at the Supervisor Call vector by the debugger.
  36  * Details can be found in chapter 8 of DUI0203I_rvct_developer_guide.pdf
  37  * from ARM Ltd.
  38  */
  39
  40 #ifdef HAVE_CONFIG_H
  41 #include "config.h"
  42 #endif
  43
  44 #include "arm.h"
  45 #include "armv4_5.h"
  46 #include "arm7_9_common.h"
  47 #include "armv7m.h"
  48 #include "armv7a.h"
  49 #include "armv8.h"
  50 #include "cortex_m.h"
  51 #include "register.h"
  52 #include "arm_opcodes.h"
  53 #include "target_type.h"
  54 #include "arm_semihosting.h"
  55 #include <helper/binarybuffer.h>
  56 #include <helper/log.h>
  57 #include <sys/stat.h>
  58
  59 static int arm_semihosting_resume(struct target *target, int *retval)
  60 {
  61         if (is_armv8(target_to_armv8(target))) {
  62                 struct armv8_common *armv8 = target_to_armv8(target);
  63                 if (armv8->last_run_control_op == ARMV8_RUNCONTROL_RESUME) {
  64                         *retval = target_resume(target, 1, 0, 0, 0);
  65                         if (*retval != ERROR_OK) {
  66                                 LOG_ERROR("Failed to resume target");
  67                                 return 0;
  68                         }
  69                 } else if (armv8->last_run_control_op == ARMV8_RUNCONTROL_STEP)
  70                         target->debug_reason = DBG_REASON_SINGLESTEP;
  71         } else {
  72                 *retval = target_resume(target, 1, 0, 0, 0);
  73                 if (*retval != ERROR_OK) {
  74                         LOG_ERROR("Failed to resume target");
  75                         return 0;
  76                 }
  77         }
  78         return 1;
  79 }
  80
  81 static int post_result(struct target *target)
  82 {
  83         struct arm *arm = target_to_arm(target);
  84
  85         if (!target->semihosting)
  86                 return ERROR_FAIL;
  87
  88         /* REVISIT this looks wrong ... ARM11 and Cortex-A8
  89          * should work this way at least sometimes.
  90          */
  91         if (is_arm7_9(target_to_arm7_9(target)) ||
  92             is_armv7a(target_to_armv7a(target))) {
  93                 uint32_t spsr;
  94
  95                 /* return value in R0 */
  96                 buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, target->semihosting->result);
  97                 arm->core_cache->reg_list[0].dirty = true;
  98
  99                 /* LR --> PC */
 100                 buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
 101                         buf_get_u32(arm_reg_current(arm, 14)->value, 0, 32));
 102                 arm->core_cache->reg_list[15].dirty = true;
 103
 104                 /* saved PSR --> current PSR */
 105                 spsr = buf_get_u32(arm->spsr->value, 0, 32);
 106
 107                 /* REVISIT should this be arm_set_cpsr(arm, spsr)
 108                  * instead of a partially unrolled version?
 109                  */
 110
 111                 buf_set_u32(arm->cpsr->value, 0, 32, spsr);
 112                 arm->cpsr->dirty = true;
 113                 arm->core_mode = spsr & 0x1f;
 114                 if (spsr & 0x20)
 115                         arm->core_state = ARM_STATE_THUMB;
 116
 117         } else if (is_armv8(target_to_armv8(target))) {
 118                 if (arm->core_state == ARM_STATE_AARCH64) {
 119                         /* return value in R0 */
 120                         buf_set_u64(arm->core_cache->reg_list[0].value, 0, 64, target->semihosting->result);
 121                         arm->core_cache->reg_list[0].dirty = true;
 122
 123                         uint64_t pc = buf_get_u64(arm->core_cache->reg_list[32].value, 0, 64);
 124                         buf_set_u64(arm->pc->value, 0, 64, pc + 4);
 125                         arm->pc->dirty = true;
 126                 }
 127         } else {
 128                 /* resume execution, this will be pc+2 to skip over the
 129                  * bkpt instruction */
 130
 131                 /* return result in R0 */
 132                 buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, target->semihosting->result);
 133                 arm->core_cache->reg_list[0].dirty = true;
 134         }
 135
 136         return ERROR_OK;
 137 }
 138
 139 /**
 140  * Initialize ARM semihosting support.
 141  *
 142  * @param target Pointer to the ARM target to initialize.
 143  * @return An error status if there is a problem during initialization.
 144  */
 145 int arm_semihosting_init(struct target *target)
 146 {
 147         struct arm *arm = target_to_arm(target);
 148         assert(arm->setup_semihosting);
 149         semihosting_common_init(target, arm->setup_semihosting, post_result);
 150
 151         return ERROR_OK;
 152 }
 153
 154 /**
 155  * Checks for and processes an ARM semihosting request.  This is meant
 156  * to be called when the target is stopped due to a debug mode entry.
 157  * If the value 0 is returned then there was nothing to process. A non-zero
 158  * return value signifies that a request was processed and the target resumed,
 159  * or an error was encountered, in which case the caller must return
 160  * immediately.
 161  *
 162  * @param target Pointer to the ARM target to process.  This target must
 163  *      not represent an ARMv6-M or ARMv7-M processor.
 164  * @param retval Pointer to a location where the return code will be stored
 165  * @return non-zero value if a request was processed or an error encountered
 166  */
 167 int arm_semihosting(struct target *target, int *retval)
 168 {
 169         struct arm *arm = target_to_arm(target);
 170         struct armv7a_common *armv7a = target_to_armv7a(target);
 171         uint32_t pc, lr, spsr;
 172         struct reg *r;
 173
 174         struct semihosting *semihosting = target->semihosting;
 175         if (!semihosting)
 176                 return 0;
 177
 178         if (!semihosting->is_active)
 179                 return 0;
 180
 181         if (is_arm7_9(target_to_arm7_9(target)) ||
 182             is_armv7a(armv7a)) {
 183                 uint32_t vbar = 0x00000000;
 184
 185                 if (arm->core_mode != ARM_MODE_SVC)
 186                         return 0;
 187
 188                 if (is_armv7a(armv7a)) {
 189                         struct arm_dpm *dpm = armv7a->arm.dpm;
 190
 191                         *retval = dpm->prepare(dpm);
 192                         if (*retval == ERROR_OK) {
 193                                 *retval = dpm->instr_read_data_r0(dpm,
 194                                                                  ARMV4_5_MRC(15, 0, 0, 12, 0, 0),
 195                                                                  &vbar);
 196
 197                                 dpm->finish(dpm);
 198
 199                                 if (*retval != ERROR_OK)
 200                                         return 1;
 201                         } else {
 202                                 return 1;
 203                         }
 204                 }
 205
 206                 /* Check for PC == 0x00000008 or 0xffff0008: Supervisor Call vector. */
 207                 r = arm->pc;
 208                 pc = buf_get_u32(r->value, 0, 32);
 209                 if (pc != (vbar + 0x00000008) && pc != 0xffff0008)
 210                         return 0;
 211
 212                 r = arm_reg_current(arm, 14);
 213                 lr = buf_get_u32(r->value, 0, 32);
 214
 215                 /* Core-specific code should make sure SPSR is retrieved
 216                  * when the above checks pass...
 217                  */
 218                 if (!arm->spsr->valid) {
 219                         LOG_ERROR("SPSR not valid!");
 220                         *retval = ERROR_FAIL;
 221                         return 1;
 222                 }
 223
 224                 spsr = buf_get_u32(arm->spsr->value, 0, 32);
 225
 226                 /* check instruction that triggered this trap */
 227                 if (spsr & (1 << 5)) {
 228                         /* was in Thumb (or ThumbEE) mode */
 229                         uint8_t insn_buf[2];
 230                         uint16_t insn;
 231
 232                         *retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
 233                         if (*retval != ERROR_OK)
 234                                 return 1;
 235                         insn = target_buffer_get_u16(target, insn_buf);
 236
 237                         /* SVC 0xab */
 238                         if (insn != 0xDFAB)
 239                                 return 0;
 240                 } else if (spsr & (1 << 24)) {
 241                         /* was in Jazelle mode */
 242                         return 0;
 243                 } else {
 244                         /* was in ARM mode */
 245                         uint8_t insn_buf[4];
 246                         uint32_t insn;
 247
 248                         *retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
 249                         if (*retval != ERROR_OK)
 250                                 return 1;
 251                         insn = target_buffer_get_u32(target, insn_buf);
 252
 253                         /* SVC 0x123456 */
 254                         if (insn != 0xEF123456)
 255                                 return 0;
 256                 }
 257         } else if (is_armv7m(target_to_armv7m(target))) {
 258                 uint16_t insn;
 259
 260                 if (target->debug_reason != DBG_REASON_BREAKPOINT)
 261                         return 0;
 262
 263                 r = arm->pc;
 264                 pc = buf_get_u32(r->value, 0, 32);
 265
 266                 pc &= ~1;
 267                 *retval = target_read_u16(target, pc, &insn);
 268                 if (*retval != ERROR_OK)
 269                         return 1;
 270
 271                 /* bkpt 0xAB */
 272                 if (insn != 0xBEAB)
 273                         return 0;
 274         } else if (is_armv8(target_to_armv8(target))) {
 275                 if (target->debug_reason != DBG_REASON_BREAKPOINT)
 276                         return 0;
 277
 278                 if (arm->core_state == ARM_STATE_AARCH64) {
 279                         uint32_t insn = 0;
 280                         r = arm->pc;
 281                         uint64_t pc64 = buf_get_u64(r->value, 0, 64);
 282                         *retval = target_read_u32(target, pc64, &insn);
 283
 284                         if (*retval != ERROR_OK)
 285                                 return 1;
 286
 287                         /* bkpt 0xAB */
 288                         if (insn != 0xD45E0000)
 289                                 return 0;
 290                 } else
 291                         return 1;
 292         } else {
 293                 LOG_ERROR("Unsupported semi-hosting Target");
 294                 return 0;
 295         }
 296
 297         /* Perform semihosting if we are not waiting on a fileio
 298          * operation to complete.
 299          */
 300         if (!semihosting->hit_fileio) {
 301                 if (is_armv8(target_to_armv8(target)) &&
 302                                 arm->core_state == ARM_STATE_AARCH64) {
 303                         /* Read op and param from register x0 and x1 respectively. */
 304                         semihosting->op = buf_get_u64(arm->core_cache->reg_list[0].value, 0, 64);
 305                         semihosting->param = buf_get_u64(arm->core_cache->reg_list[1].value, 0, 64);
 306                         semihosting->word_size_bytes = 8;
 307                 } else {
 308                         /* Read op and param from register r0 and r1 respectively. */
 309                         semihosting->op = buf_get_u32(arm->core_cache->reg_list[0].value, 0, 32);
 310                         semihosting->param = buf_get_u32(arm->core_cache->reg_list[1].value, 0, 32);
 311                         semihosting->word_size_bytes = 4;
 312                 }
 313
 314                 /* Check for ARM operation numbers. */
 315                 if (0 <= semihosting->op && semihosting->op <= 0x31) {
 316                         *retval = semihosting_common(target);
 317                         if (*retval != ERROR_OK) {
 318                                 LOG_ERROR("Failed semihosting operation");
 319                                 return 0;
 320                         }
 321                 } else {
 322                         /* Unknown operation number, not a semihosting call. */
 323                         return 0;
 324                 }
 325         }
 326
 327         /* Resume if target it is resumable and we are not waiting on a fileio
 328          * operation to complete:
 329          */
 330         if (semihosting->is_resumable && !semihosting->hit_fileio)
 331                 return arm_semihosting_resume(target, retval);
 332
 333         return 0;
 334 }