/*
 * Kernel support for the ptrace() and syscall tracing interfaces.
 *
 * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
 * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
 * Copyright (C) 2008 Helge Deller <deller@gmx.de>
 */

#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/tracehook.h>
#include <linux/user.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/seccomp.h>
#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/audit.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/asm-offsets.h>

/* PSW bits we allow the debugger to modify */
#define USER_PSW_BITS   (PSW_N | PSW_B | PSW_V | PSW_CB)

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *task)
{
        clear_tsk_thread_flag(task, TIF_SINGLESTEP);
        clear_tsk_thread_flag(task, TIF_BLOCKSTEP);

        /* make sure the trap bits are not set */
        pa_psw(task)->r = 0;
        pa_psw(task)->t = 0;
        pa_psw(task)->h = 0;
        pa_psw(task)->l = 0;
}

/*
 * The following functions are called by ptrace_resume() when
 * enabling or disabling single/block tracing.
 */
void user_disable_single_step(struct task_struct *task)
{
        ptrace_disable(task);
}

void user_enable_single_step(struct task_struct *task)
{
        clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
        set_tsk_thread_flag(task, TIF_SINGLESTEP);

        if (pa_psw(task)->n) {
                struct siginfo si;

                /* Nullified, just crank over the queue. */
                task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
                task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
                task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
                pa_psw(task)->n = 0;
                pa_psw(task)->x = 0;
                pa_psw(task)->y = 0;
                pa_psw(task)->z = 0;
                pa_psw(task)->b = 0;
                ptrace_disable(task);
                /* Don't wake up the task, but let the
                   parent know something happened. */
                si.si_code = TRAP_TRACE;
                si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
                si.si_signo = SIGTRAP;
                si.si_errno = 0;
                force_sig_info(SIGTRAP, &si, task);
                /* notify_parent(task, SIGCHLD); */
                return;
        }

        /* Enable recovery counter traps.  The recovery counter
         * itself will be set to zero on a task switch.  If the
         * task is suspended on a syscall then the syscall return
         * path will overwrite the recovery counter with a suitable
         * value such that it traps once back in user space.  We
         * disable interrupts in the tasks PSW here also, to avoid
         * interrupts while the recovery counter is decrementing.
         */
        pa_psw(task)->r = 1;
        pa_psw(task)->t = 0;
        pa_psw(task)->h = 0;
        pa_psw(task)->l = 0;
}

void user_enable_block_step(struct task_struct *task)
{
        clear_tsk_thread_flag(task, TIF_SINGLESTEP);
        set_tsk_thread_flag(task, TIF_BLOCKSTEP);

        /* Enable taken branch trap. */
        pa_psw(task)->r = 0;
        pa_psw(task)->t = 1;
        pa_psw(task)->h = 0;
        pa_psw(task)->l = 0;
}

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        unsigned long tmp;
        long ret = -EIO;

        switch (request) {

        /* Read the word at location addr in the USER area.  For ptraced
           processes, the kernel saves all regs on a syscall. */
        case PTRACE_PEEKUSR:
                if ((addr & (sizeof(unsigned long)-1)) ||
                     addr >= sizeof(struct pt_regs))
                        break;
                tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
                ret = put_user(tmp, (unsigned long __user *) data);
                break;

        /* Write the word at location addr in the USER area.  This will need
           to change when the kernel no longer saves all regs on a syscall.
           FIXME.  There is a problem at the moment in that r3-r18 are only
           saved if the process is ptraced on syscall entry, and even then
           those values are overwritten by actual register values on syscall
           exit. */
        case PTRACE_POKEUSR:
                /* Some register values written here may be ignored in
                 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
                 * r31/r31+4, and not with the values in pt_regs.
                 */
                if (addr == PT_PSW) {
                        /* Allow writing to Nullify, Divide-step-correction,
                         * and carry/borrow bits.
                         * BEWARE, if you set N, and then single step, it won't
                         * stop on the nullified instruction.
                         */
                        data &= USER_PSW_BITS;
                        task_regs(child)->gr[0] &= ~USER_PSW_BITS;
                        task_regs(child)->gr[0] |= data;
                        ret = 0;
                        break;
                }

                if ((addr & (sizeof(unsigned long)-1)) ||
                     addr >= sizeof(struct pt_regs))
                        break;
                if ((addr >= PT_GR1 && addr <= PT_GR31) ||
                                addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
                                (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
                                addr == PT_SAR) {
                        *(unsigned long *) ((char *) task_regs(child) + addr) = data;
                        ret = 0;
                }
                break;

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

        return ret;
}


#ifdef CONFIG_COMPAT

/* This function is needed to translate 32 bit pt_regs offsets in to
 * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
 * will request offset 12 if it wants gr3, but the lower 32 bits of
 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
 * This code relies on a 32 bit pt_regs being comprised of 32 bit values
 * except for the fp registers which (a) are 64 bits, and (b) follow
 * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
 * being 64 bit in both cases.
 */

static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
{
        if (offset < 0)
                return sizeof(struct pt_regs);
        else if (offset <= 32*4)        /* gr[0..31] */
                return offset * 2 + 4;
        else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
                return offset + 32*4;
        else if (offset < sizeof(struct pt_regs)/2 + 32*4)
                return offset * 2 + 4 - 32*8;
        else
                return sizeof(struct pt_regs);
}

long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                        compat_ulong_t addr, compat_ulong_t data)
{
        compat_uint_t tmp;
        long ret = -EIO;

        switch (request) {

        case PTRACE_PEEKUSR:
                if (addr & (sizeof(compat_uint_t)-1))
                        break;
                addr = translate_usr_offset(addr);
                if (addr >= sizeof(struct pt_regs))
                        break;

                tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
                ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
                break;

        /* Write the word at location addr in the USER area.  This will need
           to change when the kernel no longer saves all regs on a syscall.
           FIXME.  There is a problem at the moment in that r3-r18 are only
           saved if the process is ptraced on syscall entry, and even then
           those values are overwritten by actual register values on syscall
           exit. */
        case PTRACE_POKEUSR:
                /* Some register values written here may be ignored in
                 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
                 * r31/r31+4, and not with the values in pt_regs.
                 */
                if (addr == PT_PSW) {
                        /* Since PT_PSW==0, it is valid for 32 bit processes
                         * under 64 bit kernels as well.
                         */
                        ret = arch_ptrace(child, request, addr, data);
                } else {
                        if (addr & (sizeof(compat_uint_t)-1))
                                break;
                        addr = translate_usr_offset(addr);
                        if (addr >= sizeof(struct pt_regs))
                                break;
                        if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
                                /* Special case, fp regs are 64 bits anyway */
                                *(__u64 *) ((char *) task_regs(child) + addr) = data;
                                ret = 0;
                        }
                        else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
                                        addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
                                        addr == PT_SAR+4) {
                                /* Zero the top 32 bits */
                                *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
                                *(__u32 *) ((char *) task_regs(child) + addr) = data;
                                ret = 0;
                        }
                }
                break;

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

        return ret;
}
#endif

long do_syscall_trace_enter(struct pt_regs *regs)
{
        /* Do the secure computing check first. */
        if (secure_computing() == -1)
                return -1;

        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
            tracehook_report_syscall_entry(regs)) {
                /*
                 * Tracing decided this syscall should not happen or the
                 * debugger stored an invalid system call number. Skip
                 * the system call and the system call restart handling.
                 */
                regs->gr[20] = -1UL;
                goto out;
        }

#ifdef CONFIG_64BIT
        if (!is_compat_task())
                audit_syscall_entry(regs->gr[20], regs->gr[26], regs->gr[25],
                                    regs->gr[24], regs->gr[23]);
        else
#endif
                audit_syscall_entry(regs->gr[20] & 0xffffffff,
                        regs->gr[26] & 0xffffffff,
                        regs->gr[25] & 0xffffffff,
                        regs->gr[24] & 0xffffffff,
                        regs->gr[23] & 0xffffffff);

out:
        /*
         * Sign extend the syscall number to 64bit since it may have been
         * modified by a compat ptrace call
         */
        return (int) ((u32) regs->gr[20]);
}

void do_syscall_trace_exit(struct pt_regs *regs)
{
        int stepping = test_thread_flag(TIF_SINGLESTEP) ||
                test_thread_flag(TIF_BLOCKSTEP);

        audit_syscall_exit(regs);

        if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall_exit(regs, stepping);
}