/*
 *  arch/s390/kernel/ptrace.c
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *
 *  Based on PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/m68k/kernel/ptrace.c"
 *  Copyright (C) 1994 by Hamish Macdonald
 *  Taken from linux/kernel/ptrace.c and modified for M680x0.
 *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 *
 * Modified by Cort Dougan (cort@cs.nmt.edu) 
 *
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file README.legal in the main directory of
 * this archive for more details.
 */

#include <stddef.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>

#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#ifdef CONFIG_S390_SUPPORT
#include "linux32.h"
#else
#define parent_31bit 0
#endif


void FixPerRegisters(struct task_struct *task)
{
        struct pt_regs *regs = __KSTK_PTREGS(task);
        per_struct *per_info=
                        (per_struct *)&task->thread.per_info;

        per_info->control_regs.bits.em_instruction_fetch =
                per_info->single_step | per_info->instruction_fetch;
        
        if (per_info->single_step) {
                per_info->control_regs.bits.starting_addr=0;
#ifdef CONFIG_S390_SUPPORT
                if (current->thread.flags & S390_FLAG_31BIT) {
                        per_info->control_regs.bits.ending_addr=0x7fffffffUL;
                }
                else 
#endif      
                {
                per_info->control_regs.bits.ending_addr=-1L;
                }
        } else {
                per_info->control_regs.bits.starting_addr=
                        per_info->starting_addr;
                per_info->control_regs.bits.ending_addr=
                        per_info->ending_addr;
        }
        /* if any of the control reg tracing bits are on 
           we switch on per in the psw */
        if (per_info->control_regs.words.cr[0] & PER_EM_MASK)
                regs->psw.mask |= PSW_PER_MASK;
        else
                regs->psw.mask &= ~PSW_PER_MASK;
        if (per_info->control_regs.bits.storage_alt_space_ctl)
                task->thread.user_seg |= USER_STD_MASK;
        else
                task->thread.user_seg &= ~USER_STD_MASK;
}

void set_single_step(struct task_struct *task)
{
        per_struct *per_info= (per_struct *) &task->thread.per_info;    
        
        per_info->single_step = 1;  /* Single step */
        FixPerRegisters (task);
}

void clear_single_step(struct task_struct *task)
{
        per_struct *per_info= (per_struct *) &task->thread.per_info;

        per_info->single_step = 0;
        FixPerRegisters (task);
}

int ptrace_usercopy(addr_t realuseraddr, addr_t copyaddr, int len,
                    int tofromuser, int writeuser, unsigned long mask)
{
        unsigned long *realuserptr, *copyptr;
        unsigned long tempuser;
        int retval;

        retval = 0;
        realuserptr = (unsigned long *) realuseraddr;
        copyptr = (unsigned long *) copyaddr;

        if (writeuser && realuserptr == NULL)
                return 0;

        if (mask != -1L) {
                tempuser = *realuserptr;
                if (!writeuser) {
                        tempuser &= mask;
                        realuserptr = &tempuser;
                }
        }
        if (tofromuser) {
                if (writeuser) {
                        retval = copy_from_user(realuserptr, copyptr, len);
                } else {
                        if (realuserptr == NULL)
                                retval = clear_user(copyptr, len);
                        else
                                retval = copy_to_user(copyptr,realuserptr,len);
                }      
                retval = retval ? -EFAULT : 0;
        } else {
                if (writeuser)
                        memcpy(realuserptr, copyptr, len);
                else
                        memcpy(copyptr, realuserptr, len);
        }
        if (mask != -1L && writeuser)
                *realuserptr = (*realuserptr & mask) | (tempuser & ~mask);
        return retval;
}

#ifdef CONFIG_S390_SUPPORT

typedef struct
{
        __u32 cr[3];
} per_cr_words32  __attribute__((packed));

typedef struct
{
        __u16          perc_atmid;          /* 0x096 */
        __u32          address;             /* 0x098 */
        __u8           access_id;           /* 0x0a1 */
} per_lowcore_words32  __attribute__((packed));

typedef struct
{
        union {
                per_cr_words32   words;
        } control_regs  __attribute__((packed));
        /*
         * Use these flags instead of setting em_instruction_fetch
         * directly they are used so that single stepping can be
         * switched on & off while not affecting other tracing
         */
        unsigned  single_step       : 1;
        unsigned  instruction_fetch : 1;
        unsigned                    : 30;
        /*
         * These addresses are copied into cr10 & cr11 if single
         * stepping is switched off
         */
        __u32     starting_addr;
        __u32     ending_addr;
        union {
                per_lowcore_words32 words;
        } lowcore; 
} per_struct32 __attribute__((packed));

struct user_regs_struct32
{
        _psw_t32 psw;
        u32 gprs[NUM_GPRS];
        u32 acrs[NUM_ACRS];
        u32 orig_gpr2;
        s390_fp_regs fp_regs;
        /*
         * These per registers are in here so that gdb can modify them
         * itself as there is no "official" ptrace interface for hardware
         * watchpoints. This is the way intel does it.
         */
        per_struct32 per_info;
        u32  ieee_instruction_pointer; 
        /* Used to give failing instruction back to user for ieee exceptions */
};

struct user32 {
                                  /* We start with the registers, to mimic the way that "memory" is returned
                                   from the ptrace(3,...) function.  */
  struct user_regs_struct32 regs; /* Where the registers are actually stored */
                                  /* The rest of this junk is to help gdb figure out what goes where */
  u32 u_tsize;                    /* Text segment size (pages). */
  u32 u_dsize;                    /* Data segment size (pages). */
  u32 u_ssize;                    /* Stack segment size (pages). */
  u32 start_code;                 /* Starting virtual address of text. */
  u32 start_stack;                /* Starting virtual address of stack area.
                                   This is actually the bottom of the stack,
                                   the top of the stack is always found in the
                                   esp register.  */
  s32 signal;                     /* Signal that caused the core dump. */
  u32 u_ar0;                      /* Used by gdb to help find the values for */
                                  /* the registers. */
  u32 magic;                      /* To uniquely identify a core file */
  char u_comm[32];                /* User command that was responsible */
};


#define PT32_PSWMASK  0x0
#define PT32_PSWADDR  0x04
#define PT32_GPR0     0x08
#define PT32_GPR15    0x44
#define PT32_ACR0     0x48
#define PT32_ACR15    0x84
#define PT32_ORIGGPR2 0x88
#define PT32_FPC      0x90
#define PT32_FPR0_HI  0x98
#define PT32_FPR15_LO 0x114
#define PT32_CR_9     0x118
#define PT32_CR_11    0x120
#define PT32_IEEE_IP  0x13C
#define PT32_LASTOFF  PT32_IEEE_IP
#define PT32_ENDREGS  0x140-1
#define U32OFFSETOF(member) offsetof(struct user32,regs.member)
#define U64OFFSETOF(member) offsetof(struct user,regs.member)
#define U6432DIFF(member) (U64OFFSETOF(member) - U32OFFSETOF(member))
#define PT_SINGLE_STEP   (PT_CR_11+8)
#define PT32_SINGLE_STEP (PT32_CR_11+4)

#endif /* CONFIG_S390_SUPPORT */

int copy_user(struct task_struct *task,saddr_t useraddr, addr_t copyaddr,
              int len, int tofromuser, int writingtouser)
{
        int copylen=0,copymax;
        addr_t  realuseraddr;
        saddr_t enduseraddr;
        unsigned long mask;
#ifdef CONFIG_S390_SUPPORT
        int     parent_31bit=current->thread.flags & S390_FLAG_31BIT;
        int     skip;
#endif
        enduseraddr=useraddr+len;
        if ((useraddr<0||useraddr&3||enduseraddr&3)||
#ifdef CONFIG_S390_SUPPORT
            (parent_31bit && enduseraddr > sizeof(struct user32)) ||
#endif
            enduseraddr > sizeof(struct user))
                return (-EIO);

#ifdef CONFIG_S390_SUPPORT
        if(parent_31bit)
        {
                if(useraddr != PT32_PSWMASK)
                {
                        if (useraddr == PT32_PSWADDR)
                                useraddr = PT_PSWADDR+4;
                        else if(useraddr <= PT32_GPR15)
                                useraddr = ((useraddr-PT32_GPR0)*2) + PT_GPR0+4;
                        else if(useraddr <= PT32_ACR15)
                                useraddr += PT_ACR0-PT32_ACR0;
                        else if(useraddr == PT32_ORIGGPR2)
                                useraddr = PT_ORIGGPR2+4;
                        else if(useraddr <= PT32_FPR15_LO)
                                useraddr += PT_FPR0-PT32_FPR0_HI;
                        else if(useraddr <= PT32_CR_11)
                                useraddr = ((useraddr-PT32_CR_9)*2) + PT_CR_9+4;
                        else if(useraddr ==  PT32_SINGLE_STEP)
                                useraddr = PT_SINGLE_STEP; 
                        else if(useraddr <= U32OFFSETOF(per_info.ending_addr))  
                                useraddr = (((useraddr-U32OFFSETOF(per_info.starting_addr)))*2) + 
                                        U64OFFSETOF(per_info.starting_addr)+4;
                        else if( useraddr == U32OFFSETOF(per_info.lowcore.words.perc_atmid))
                                useraddr = U64OFFSETOF(per_info.lowcore.words.perc_atmid);
                        else if( useraddr == U32OFFSETOF(per_info.lowcore.words.address))
                                useraddr = U64OFFSETOF(per_info.lowcore.words.address)+4;
                        else if(useraddr == U32OFFSETOF(per_info.lowcore.words.access_id))
                                useraddr = U64OFFSETOF(per_info.lowcore.words.access_id);
                        else if(useraddr == PT32_IEEE_IP)
                                useraddr = PT_IEEE_IP+4;
                }
        }
#endif /* CONFIG_S390_SUPPORT */

        while(len>0)
        {
#ifdef CONFIG_S390_SUPPORT
                skip=0;
#endif
                mask=PSW_ADDR_MASK;
                if(useraddr<PT_FPC)
                {
                        realuseraddr=((addr_t) __KSTK_PTREGS(task)) + useraddr;
                        if(useraddr<(PT_PSWMASK+8))
                        {
                                if(parent_31bit)
                                {
                                        copymax=PT_PSWMASK+4;
#ifdef CONFIG_S390_SUPPORT
                                        skip=8;
#endif
                                }
                                else
                                {
                                        copymax=PT_PSWMASK+8;
                                }
                                if(writingtouser)
                                        mask=PSW_MASK_DEBUGCHANGE;
                        }
                        else if(useraddr<(PT_PSWADDR+8))
                        {
                                copymax=PT_PSWADDR+8;
                                mask=PSW_ADDR_DEBUGCHANGE;
#ifdef CONFIG_S390_SUPPORT
                                if(parent_31bit)
                                        skip=4;
#endif

                        }
                        else
                        {
#ifdef CONFIG_S390_SUPPORT
                                if(parent_31bit && useraddr <= PT_GPR15+4)
                                {
                                        copymax=useraddr+4;
                                        if(useraddr<PT_GPR15+4)
                                                skip=4;
                                }
                                else
#endif
                                        copymax=PT_FPC;
                        }
                }
                else if(useraddr<(PT_FPR15+sizeof(freg_t)))
                {
                        copymax=(PT_FPR15+sizeof(freg_t));
                        realuseraddr=(addr_t)&(((u8 *)&task->thread.fp_regs)[useraddr-PT_FPC]);
                }
                else if(useraddr<sizeof(struct user_regs_struct))
                {
#ifdef CONFIG_S390_SUPPORT
                        if( parent_31bit && useraddr <= PT_IEEE_IP+4)
                        {
                                switch(useraddr)
                                {
                                case PT_CR_11+4:
                                case U64OFFSETOF(per_info.ending_addr)+4:
                                case U64OFFSETOF(per_info.lowcore.words.address)+4:
                                        copymax=useraddr+4;
                                        break;
                                case  PT_SINGLE_STEP:
                                case  U64OFFSETOF(per_info.lowcore.words.perc_atmid):
                                        /* We copy 2 bytes in excess for the atmid member this also gets around */
                                        /* alignment for this member in 32 bit */
                                        skip=8;
                                        copymax=useraddr+4;
                                        break;
                                default: 
                                        copymax=useraddr+4;
                                        skip=4;
                                }
                        }
                        else
#endif
                        {
                                copymax=sizeof(struct user_regs_struct);
                        }
                        realuseraddr=(addr_t)&(((u8 *)&task->thread.per_info)[useraddr-PT_CR_9]);
                }
                else 
                {
                        copymax=sizeof(struct user);
                        realuseraddr=(addr_t)NULL;
                }
                copylen=copymax-useraddr;
                copylen=(copylen>len ? len:copylen);
                if(ptrace_usercopy(realuseraddr,copyaddr,copylen,tofromuser,writingtouser,mask))
                        return (-EIO);
                copyaddr+=copylen;
                len-=copylen;
                useraddr+=copylen
#if CONFIG_S390_SUPPORT
                        +skip
#endif
                        ;
        }
        FixPerRegisters(task);
        return(0);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
        /* make sure the single step bit is not set. */
        clear_single_step(child);
}

typedef struct
{
__u32   len;
__u32   kernel_addr;
__u32   process_addr;
} ptrace_area_emu31;


asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
{
        struct task_struct *child;
        int ret = -EPERM;
        int copied;
#ifdef CONFIG_S390_SUPPORT
        int           parent_31bit;
        int           sizeof_parent_long;
        u8            *dataptr;
#else
#define sizeof_parent_long 8
#define dataptr (u8 *)&data
#endif
        lock_kernel();
        if (request == PTRACE_TRACEME) 
        {
                /* are we already being traced? */
                if (current->ptrace & PT_PTRACED)
                        goto out;
                /* set the ptrace bit in the process flags. */
                current->ptrace |= PT_PTRACED;
                ret = 0;
                goto out;
        }
        ret = -ESRCH;
        read_lock(&tasklist_lock);
        child = find_task_by_pid(pid);
        if (child)
                get_task_struct(child);
        read_unlock(&tasklist_lock);
        if (!child)
                goto out;
        ret = -EPERM;
        if (pid == 1)           /* you may not mess with init */
                goto out_tsk;
        if (request == PTRACE_ATTACH) 
        {
                ret = ptrace_attach(child);
                goto out_tsk;
        }
        ret = -ESRCH;
        // printk("child=%lX child->flags=%lX",child,child->flags);
        /* I added child!=current line so we can get the */
        /* ieee_instruction_pointer from the user structure DJB */
        if(child!=current)
        {
                if (!(child->ptrace & PT_PTRACED))
                        goto out_tsk;
                if (child->state != TASK_STOPPED) 
                {
                        if (request != PTRACE_KILL)
                                goto out_tsk;
                }
                if (child->p_pptr != current)
                        goto out_tsk;
        }
#ifdef CONFIG_S390_SUPPORT
        parent_31bit=(current->thread.flags & S390_FLAG_31BIT);
        sizeof_parent_long=(parent_31bit ? 4:8);
        dataptr=&(((u8 *)&data)[parent_31bit ? 4:0]);
#endif
        switch (request) 
        {
                /* If I and D space are separate, these will need to be fixed. */
        case PTRACE_PEEKTEXT: /* read word at location addr. */ 
        case PTRACE_PEEKDATA: 
        {
                u8 tmp[8];
                copied = access_process_vm(child, addr, tmp, sizeof_parent_long, 0);
                ret = -EIO;
                if (copied != sizeof_parent_long)
                        break;
                ret = copy_to_user((void *)data,tmp,sizeof_parent_long);
                ret = ret ? -EFAULT : 0;
                break;
        
        }
                /* read the word at location addr in the USER area. */
        case PTRACE_PEEKUSR:
                ret=copy_user(child,addr,data,sizeof_parent_long,1,0);
                break;

                /* If I and D space are separate, this will have to be fixed. */
        case PTRACE_POKETEXT: /* write the word at location addr. */
        case PTRACE_POKEDATA:
                ret = 0;
                if (access_process_vm(child, addr,dataptr, sizeof_parent_long, 1) == sizeof_parent_long)
                        break;
                ret = -EIO;
                break;

        case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
                ret=copy_user(child,addr,(addr_t)dataptr,sizeof_parent_long,0,1);
                break;

        case PTRACE_SYSCALL:    /* continue and stop at next (return from) syscall */
        case PTRACE_CONT:        /* restart after signal. */
                ret = -EIO;
                if ((unsigned long) data >= _NSIG)
                        break;
                if (request == PTRACE_SYSCALL)
                        child->ptrace |= PT_TRACESYS;
                else
                        child->ptrace &= ~PT_TRACESYS;
                child->exit_code = data;
                /* make sure the single step bit is not set. */
                clear_single_step(child);
                wake_up_process(child);
                ret = 0;
                break;

/*
 * make the child exit.  Best I can do is send it a sigkill. 
 * perhaps it should be put in the status that it wants to 
 * exit.
 */
        case PTRACE_KILL:
                ret = 0;
                if (child->state == TASK_ZOMBIE) /* already dead */
                        break;
                child->exit_code = SIGKILL;
                clear_single_step(child);
                wake_up_process(child);
                /* make sure the single step bit is not set. */
                break;

        case PTRACE_SINGLESTEP:  /* set the trap flag. */
                ret = -EIO;
                if ((unsigned long) data >= _NSIG)
                        break;
                child->ptrace &= ~PT_TRACESYS;
                child->exit_code = data;
                set_single_step(child);
                /* give it a chance to run. */
                wake_up_process(child);
                ret = 0;
                break;

        case PTRACE_DETACH:  /* detach a process that was attached. */
                ret = ptrace_detach(child, data);
                break;

        case PTRACE_PEEKUSR_AREA:
        case PTRACE_POKEUSR_AREA:
                if(parent_31bit)
                {
                        ptrace_area_emu31   parea; 
                        if(copy_from_user(&parea,(void *)addr,sizeof(parea))==0)
                                ret=copy_user(child,parea.kernel_addr,parea.process_addr,
                                              parea.len,1,(request==PTRACE_POKEUSR_AREA));
                        else ret = -EFAULT;
                }
                else
                {
                        ptrace_area   parea; 
                        if(copy_from_user(&parea,(void *)addr,sizeof(parea))==0)
                                ret=copy_user(child,parea.kernel_addr,parea.process_addr,
                                              parea.len,1,(request==PTRACE_POKEUSR_AREA));
                        else ret = -EFAULT;
                }
                break;
        default:
                ret = -EIO;
                break;
        }
 out_tsk:
        free_task_struct(child);
 out:
        unlock_kernel();
        return ret;
}



asmlinkage void syscall_trace(void)
{
        lock_kernel();
        if ((current->ptrace & (PT_PTRACED|PT_TRACESYS))
            != (PT_PTRACED|PT_TRACESYS))
                goto out;
        current->exit_code = SIGTRAP;
        set_current_state(TASK_STOPPED);
        notify_parent(current, SIGCHLD);
        schedule();
        /*
         * this isn't the same as continuing with a signal, but it will do
         * for normal use.  strace only continues with a signal if the
         * stopping signal is not SIGTRAP.  -brl
         */
        if (current->exit_code) {
                send_sig(current->exit_code, current, 1);
                current->exit_code = 0;
        }
 out:
        unlock_kernel();
}