/*
 * Copyright (C) 2000-2007, Axis Communications AB.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/signal.h>
#include <linux/security.h>

#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <arch/hwregs/supp_reg.h>

/*
 * Determines which bits in CCS the user has access to.
 * 1 = access, 0 = no access.
 */
#define CCS_MASK 0x00087c00     /* SXNZVC */

#define SBIT_USER (1 << (S_CCS_BITNR + CCS_SHIFT))

static int put_debugreg(long pid, unsigned int regno, long data);
static long get_debugreg(long pid, unsigned int regno);
static unsigned long get_pseudo_pc(struct task_struct *child);
void deconfigure_bp(long pid);

extern unsigned long cris_signal_return_page;

/*
 * Get contents of register REGNO in task TASK.
 */
long get_reg(struct task_struct *task, unsigned int regno)
{
        /* USP is a special case, it's not in the pt_regs struct but
         * in the tasks thread struct
         */
        unsigned long ret;

        if (regno <= PT_EDA)
                ret = ((unsigned long *)task_pt_regs(task))[regno];
        else if (regno == PT_USP)
                ret = task->thread.usp;
        else if (regno == PT_PPC)
                ret = get_pseudo_pc(task);
        else if (regno <= PT_MAX)
                ret = get_debugreg(task->pid, regno);
        else
                ret = 0;

        return ret;
}

/*
 * Write contents of register REGNO in task TASK.
 */
int put_reg(struct task_struct *task, unsigned int regno, unsigned long data)
{
        if (regno <= PT_EDA)
                ((unsigned long *)task_pt_regs(task))[regno] = data;
        else if (regno == PT_USP)
                task->thread.usp = data;
        else if (regno == PT_PPC) {
                /* Write pseudo-PC to ERP only if changed. */
                if (data != get_pseudo_pc(task))
                        task_pt_regs(task)->erp = data;
        } else if (regno <= PT_MAX)
                return put_debugreg(task->pid, regno, data);
        else
                return -1;
        return 0;
}

/*
 * Called by kernel/ptrace.c when detaching.
 *
 * Make sure the single step bit is not set.
 */
void
ptrace_disable(struct task_struct *child)
{
        unsigned long tmp;

        /* Deconfigure SPC and S-bit. */
        tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
        put_reg(child, PT_CCS, tmp);
        put_reg(child, PT_SPC, 0);

        /* Deconfigure any watchpoints associated with the child. */
        deconfigure_bp(child->pid);
}


long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
        int ret;
        unsigned long __user *datap = (unsigned long __user *)data;

        switch (request) {
                /* Read word at location address. */
                case PTRACE_PEEKTEXT:
                case PTRACE_PEEKDATA: {
                        unsigned long tmp;
                        int copied;

                        ret = -EIO;

                        /* The signal trampoline page is outside the normal user-addressable
                         * space but still accessible. This is hack to make it possible to
                         * access the signal handler code in GDB.
                         */
                        if ((addr & PAGE_MASK) == cris_signal_return_page) {
                                /* The trampoline page is globally mapped, no page table to traverse.*/
                                tmp = *(unsigned long*)addr;
                        } else {
                                copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);

                                if (copied != sizeof(tmp))
                                        break;
                        }

                        ret = put_user(tmp,datap);
                        break;
                }

                /* Read the word at location address in the USER area. */
                case PTRACE_PEEKUSR: {
                        unsigned long tmp;

                        ret = -EIO;
                        if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                                break;

                        tmp = get_reg(child, addr >> 2);
                        ret = put_user(tmp, datap);
                        break;
                }

                /* Write the word at location address. */
                case PTRACE_POKETEXT:
                case PTRACE_POKEDATA:
                        ret = generic_ptrace_pokedata(child, addr, data);
                        break;

                /* Write the word at location address in the USER area. */
                case PTRACE_POKEUSR:
                        ret = -EIO;
                        if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                                break;

                        addr >>= 2;

                        if (addr == PT_CCS) {
                                /* don't allow the tracing process to change stuff like
                                 * interrupt enable, kernel/user bit, dma enables etc.
                                 */
                                data &= CCS_MASK;
                                data |= get_reg(child, PT_CCS) & ~CCS_MASK;
                        }
                        if (put_reg(child, addr, data))
                                break;
                        ret = 0;
                        break;

                case PTRACE_SYSCALL:
                case PTRACE_CONT:
                        ret = -EIO;

                        if (!valid_signal(data))
                                break;

                        /* Continue means no single-step. */
                        put_reg(child, PT_SPC, 0);

                        if (!get_debugreg(child->pid, PT_BP_CTRL)) {
                                unsigned long tmp;
                                /* If no h/w bp configured, disable S bit. */
                                tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
                                put_reg(child, PT_CCS, tmp);
                        }

                        if (request == PTRACE_SYSCALL) {
                                set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                        }
                        else {
                                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                        }

                        child->exit_code = data;

                        /* TODO: make sure any pending breakpoint is killed */
                        wake_up_process(child);
                        ret = 0;

                        break;

                /* Make the child exit by sending it a sigkill. */
                case PTRACE_KILL:
                        ret = 0;

                        if (child->exit_state == EXIT_ZOMBIE)
                                break;

                        child->exit_code = SIGKILL;

                        /* Deconfigure single-step and h/w bp. */
                        ptrace_disable(child);

                        /* TODO: make sure any pending breakpoint is killed */
                        wake_up_process(child);
                        break;

                /* Set the trap flag. */
                case PTRACE_SINGLESTEP: {
                        unsigned long tmp;
                        ret = -EIO;

                        /* Set up SPC if not set already (in which case we have
                           no other choice but to trust it). */
                        if (!get_reg(child, PT_SPC)) {
                                /* In case we're stopped in a delay slot. */
                                tmp = get_reg(child, PT_ERP) & ~1;
                                put_reg(child, PT_SPC, tmp);
                        }
                        tmp = get_reg(child, PT_CCS) | SBIT_USER;
                        put_reg(child, PT_CCS, tmp);

                        if (!valid_signal(data))
                                break;

                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                        /* TODO: set some clever breakpoint mechanism... */

                        child->exit_code = data;
                        wake_up_process(child);
                        ret = 0;
                        break;

                }

                /* Get all GP registers from the child. */
                case PTRACE_GETREGS: {
                        int i;
                        unsigned long tmp;

                        for (i = 0; i <= PT_MAX; i++) {
                                tmp = get_reg(child, i);

                                if (put_user(tmp, datap)) {
                                        ret = -EFAULT;
                                        goto out_tsk;
                                }

                                datap++;
                        }

                        ret = 0;
                        break;
                }

                /* Set all GP registers in the child. */
                case PTRACE_SETREGS: {
                        int i;
                        unsigned long tmp;

                        for (i = 0; i <= PT_MAX; i++) {
                                if (get_user(tmp, datap)) {
                                        ret = -EFAULT;
                                        goto out_tsk;
                                }

                                if (i == PT_CCS) {
                                        tmp &= CCS_MASK;
                                        tmp |= get_reg(child, PT_CCS) & ~CCS_MASK;
                                }

                                put_reg(child, i, tmp);
                                datap++;
                        }

                        ret = 0;
                        break;
                }

                default:
                        ret = ptrace_request(child, request, addr, data);
                        break;
        }

out_tsk:
        return ret;
}

void do_syscall_trace(void)
{
        if (!test_thread_flag(TIF_SYSCALL_TRACE))
                return;

        if (!(current->ptrace & PT_PTRACED))
                return;

        /* the 0x80 provides a way for the tracing parent to distinguish
           between a syscall stop and SIGTRAP delivery */
        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
                                 ? 0x80 : 0));

        /*
         * This isn't the same as continuing with a signal, but it will do for
         * normal use.
         */
        if (current->exit_code) {
                send_sig(current->exit_code, current, 1);
                current->exit_code = 0;
        }
}

/* Returns the size of an instruction that has a delay slot. */

static int insn_size(struct task_struct *child, unsigned long pc)
{
  unsigned long opcode;
  int copied;
  int opsize = 0;

  /* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
  copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
  if (copied != sizeof(opcode))
    return 0;

  switch ((opcode & 0x0f00) >> 8) {
  case 0x0:
  case 0x9:
  case 0xb:
          opsize = 2;
          break;
  case 0xe:
  case 0xf:
          opsize = 6;
          break;
  case 0xd:
          /* Could be 4 or 6; check more bits. */
          if ((opcode & 0xff) == 0xff)
                  opsize = 4;
          else
                  opsize = 6;
          break;
  default:
          panic("ERROR: Couldn't find size of opcode 0x%lx at 0x%lx\n",
                opcode, pc);
  }

  return opsize;
}

static unsigned long get_pseudo_pc(struct task_struct *child)
{
        /* Default value for PC is ERP. */
        unsigned long pc = get_reg(child, PT_ERP);

        if (pc & 0x1) {
                unsigned long spc = get_reg(child, PT_SPC);
                /* Delay slot bit set. Report as stopped on proper
                   instruction. */
                if (spc) {
                        /* Rely on SPC if set. FIXME: We might want to check
                           that EXS indicates we stopped due to a single-step
                           exception. */
                        pc = spc;
                } else {
                        /* Calculate the PC from the size of the instruction
                           that the delay slot we're in belongs to. */
                        pc += insn_size(child, pc & ~1) - 1;
                }
        }
        return pc;
}

static long bp_owner = 0;

/* Reachable from exit_thread in signal.c, so not static. */
void deconfigure_bp(long pid)
{
        int bp;

        /* Only deconfigure if the pid is the owner. */
        if (bp_owner != pid)
                return;

        for (bp = 0; bp < 6; bp++) {
                unsigned long tmp;
                /* Deconfigure start and end address (also gets rid of ownership). */
                put_debugreg(pid, PT_BP + 3 + (bp * 2), 0);
                put_debugreg(pid, PT_BP + 4 + (bp * 2), 0);

                /* Deconfigure relevant bits in control register. */
                tmp = get_debugreg(pid, PT_BP_CTRL) & ~(3 << (2 + (bp * 4)));
                put_debugreg(pid, PT_BP_CTRL, tmp);
        }
        /* No owner now. */
        bp_owner = 0;
}

static int put_debugreg(long pid, unsigned int regno, long data)
{
        int ret = 0;
        register int old_srs;

#ifdef CONFIG_ETRAX_KGDB
        /* Ignore write, but pretend it was ok if value is 0
           (we don't want POKEUSR/SETREGS failing unnessecarily). */
        return (data == 0) ? ret : -1;
#endif

        /* Simple owner management. */
        if (!bp_owner)
                bp_owner = pid;
        else if (bp_owner != pid) {
                /* Ignore write, but pretend it was ok if value is 0
                   (we don't want POKEUSR/SETREGS failing unnessecarily). */
                return (data == 0) ? ret : -1;
        }

        /* Remember old SRS. */
        SPEC_REG_RD(SPEC_REG_SRS, old_srs);
        /* Switch to BP bank. */
        SUPP_BANK_SEL(BANK_BP);

        switch (regno - PT_BP) {
        case 0:
                SUPP_REG_WR(0, data); break;
        case 1:
        case 2:
                if (data)
                        ret = -1;
                break;
        case 3:
                SUPP_REG_WR(3, data); break;
        case 4:
                SUPP_REG_WR(4, data); break;
        case 5:
                SUPP_REG_WR(5, data); break;
        case 6:
                SUPP_REG_WR(6, data); break;
        case 7:
                SUPP_REG_WR(7, data); break;
        case 8:
                SUPP_REG_WR(8, data); break;
        case 9:
                SUPP_REG_WR(9, data); break;
        case 10:
                SUPP_REG_WR(10, data); break;
        case 11:
                SUPP_REG_WR(11, data); break;
        case 12:
                SUPP_REG_WR(12, data); break;
        case 13:
                SUPP_REG_WR(13, data); break;
        case 14:
                SUPP_REG_WR(14, data); break;
        default:
                ret = -1;
                break;
        }

        /* Restore SRS. */
        SPEC_REG_WR(SPEC_REG_SRS, old_srs);
        /* Just for show. */
        NOP();
        NOP();
        NOP();

        return ret;
}

static long get_debugreg(long pid, unsigned int regno)
{
        register int old_srs;
        register long data;

        if (pid != bp_owner) {
                return 0;
        }

        /* Remember old SRS. */
        SPEC_REG_RD(SPEC_REG_SRS, old_srs);
        /* Switch to BP bank. */
        SUPP_BANK_SEL(BANK_BP);

        switch (regno - PT_BP) {
        case 0:
                SUPP_REG_RD(0, data); break;
        case 1:
        case 2:
                /* error return value? */
                data = 0;
                break;
        case 3:
                SUPP_REG_RD(3, data); break;
        case 4:
                SUPP_REG_RD(4, data); break;
        case 5:
                SUPP_REG_RD(5, data); break;
        case 6:
                SUPP_REG_RD(6, data); break;
        case 7:
                SUPP_REG_RD(7, data); break;
        case 8:
                SUPP_REG_RD(8, data); break;
        case 9:
                SUPP_REG_RD(9, data); break;
        case 10:
                SUPP_REG_RD(10, data); break;
        case 11:
                SUPP_REG_RD(11, data); break;
        case 12:
                SUPP_REG_RD(12, data); break;
        case 13:
                SUPP_REG_RD(13, data); break;
        case 14:
                SUPP_REG_RD(14, data); break;
        default:
                /* error return value? */
                data = 0;
        }

        /* Restore SRS. */
        SPEC_REG_WR(SPEC_REG_SRS, old_srs);
        /* Just for show. */
        NOP();
        NOP();
        NOP();

        return data;
}