/****************************************************************************
 * arch/arm/src/armv6-m/arm_hardfault.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <debug.h>

#include <irq.h>

#include "nvic.h"
#include "arm_internal.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#ifdef CONFIG_DEBUG_HARDFAULT_ALERT
#  define hfalert(format, ...) _alert(format, ##__VA_ARGS__)
#else
#  define hfalert(x...)
#endif

#ifdef CONFIG_DEBUG_HARDFAULT_INFO
#  define hfinfo(format, ...)  _info(format, ##__VA_ARGS__)
#else
#  define hfinfo(x...)
#endif

#define INSN_SVC0        0xdf00 /* insn: svc 0 */

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: arm_hardfault
 *
 * Description:
 *   This is Hard Fault exception handler.  It also catches SVC call
 *   exceptions that are performed in bad contexts.
 *
 ****************************************************************************/

int arm_hardfault(int irq, void *context, void *arg)
{
  uint32_t *regs = (uint32_t *)context;

  /* Get the value of the program counter where the fault occurred */

  uint16_t *pc = (uint16_t *)regs[REG_PC] - 1;

  /* Check if the pc lies in known FLASH memory.
   * REVISIT:  What if the PC lies in "unknown" external memory?
   */

#ifdef CONFIG_BUILD_PROTECTED
  /* In the kernel build, SVCalls are expected in either the base, kernel
   * FLASH region or in the user FLASH region.
   */

  if (((uintptr_t)pc >= (uintptr_t)_stext &&
       (uintptr_t)pc <  (uintptr_t)_etext) ||
      ((uintptr_t)pc >= (uintptr_t)USERSPACE->us_textstart &&
       (uintptr_t)pc <  (uintptr_t)USERSPACE->us_textend))
#else
  /* SVCalls are expected only from the base, kernel FLASH region */

  if ((uintptr_t)pc >= (uintptr_t)_stext &&
      (uintptr_t)pc <  (uintptr_t)_etext)
#endif
    {
      /* Fetch the instruction that caused the Hard fault */

      uint16_t insn = *pc;
      hfinfo("  PC: %p INSN: %04x\n", pc, insn);

      /* If this was the instruction 'svc 0', then forward processing
       * to the SVCall handler
       */

      if (insn == INSN_SVC0)
        {
          hfinfo("Forward SVCall\n");
          return arm_svcall(irq, context, NULL);
        }
    }

#if defined(CONFIG_DEBUG_HARDFAULT_ALERT)
  /* Dump some hard fault info */

  hfalert("\nHard Fault:\n");
  hfalert("  IRQ: %d regs: %p\n", irq, regs);
  hfalert("  PRIMASK: %08x IPSR: %08x\n",
          getprimask(), getipsr());
#endif

  up_irq_save();
  hfalert("PANIC!!! Hard fault\n");
  PANIC_WITH_REGS("panic", context);
  return OK; /* Won't get here */
}