// SPDX-License-Identifier: GPL-2.0
/*
 * 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) 2008-2016 Helge Deller <deller@gmx.de>
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/personality.h>
#include <linux/regset.h>
#include <linux/security.h>
#include <linux/seccomp.h>
#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/audit.h>

#include <linux/uaccess.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)

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

/*
 * These are our native regset flavors.
 */
enum parisc_regset {
        REGSET_GENERAL,
        REGSET_FP
};

/*
 * 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) {
                /* 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. */
                force_sig_fault_to_task(SIGTRAP, TRAP_TRACE,
                                        (void __user *) (task_regs(task)->iaoq[0] & ~3),
                                        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 __user *datap = (unsigned long __user *)data;
        unsigned long tmp;
        long ret = -EIO;

        unsigned long user_regs_struct_size = sizeof(struct user_regs_struct);
#ifdef CONFIG_64BIT
        if (is_compat_task())
                user_regs_struct_size /= 2;
#endif

        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, datap);
                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_IAOQ0 || addr == PT_IAOQ1) {
                        data |= PRIV_USER; /* ensure userspace privilege */
                }
                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;

        case PTRACE_GETREGS:    /* Get all gp regs from the child. */
                return copy_regset_to_user(child,
                                           task_user_regset_view(current),
                                           REGSET_GENERAL,
                                           0, user_regs_struct_size,
                                           datap);

        case PTRACE_SETREGS:    /* Set all gp regs in the child. */
                return copy_regset_from_user(child,
                                             task_user_regset_view(current),
                                             REGSET_GENERAL,
                                             0, user_regs_struct_size,
                                             datap);

        case PTRACE_GETFPREGS:  /* Get the child FPU state. */
                return copy_regset_to_user(child,
                                           task_user_regset_view(current),
                                           REGSET_FP,
                                           0, sizeof(struct user_fp_struct),
                                           datap);

        case PTRACE_SETFPREGS:  /* Set the child FPU state. */
                return copy_regset_from_user(child,
                                             task_user_regset_view(current),
                                             REGSET_FP,
                                             0, sizeof(struct user_fp_struct),
                                             datap);

        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)
{
        compat_ulong_t pos;

        if (offset < 32*4)      /* gr[0..31] */
                pos = offset * 2 + 4;
        else if (offset < 32*4+32*8)    /* fr[0] ... fr[31] */
                pos = (offset - 32*4) + PT_FR0;
        else if (offset < sizeof(struct pt_regs)/2 + 32*4) /* sr[0] ... ipsw */
                pos = (offset - 32*4 - 32*8) * 2 + PT_SR0 + 4;
        else
                pos = sizeof(struct pt_regs);

        return pos;
}

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_IAOQ0+4 || addr == PT_IAOQ1+4) {
                                data |= PRIV_USER; /* ensure userspace privilege */
                        }
                        if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
                                /* Special case, fp regs are 64 bits anyway */
                                *(__u32 *) ((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;
        case PTRACE_GETREGS:
        case PTRACE_SETREGS:
        case PTRACE_GETFPREGS:
        case PTRACE_SETFPREGS:
                return arch_ptrace(child, request, addr, data);

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

        return ret;
}
#endif

long do_syscall_trace_enter(struct pt_regs *regs)
{
        if (test_thread_flag(TIF_SYSCALL_TRACE)) {
                int rc = ptrace_report_syscall_entry(regs);

                /*
                 * As tracesys_next does not set %r28 to -ENOSYS
                 * when %r20 is set to -1, initialize it here.
                 */
                regs->gr[28] = -ENOSYS;

                if (rc) {
                        /*
                         * A nonzero return code from
                         * ptrace_report_syscall_entry() tells us
                         * to prevent the syscall execution.  Skip
                         * the syscall call and the syscall restart handling.
                         *
                         * Note that the tracer may also just change
                         * regs->gr[20] to an invalid syscall number,
                         * that is handled by tracesys_next.
                         */
                        regs->gr[20] = -1UL;
                        return -1;
                }
        }

        /* Do the secure computing check after ptrace. */
        if (secure_computing() == -1)
                return -1;

#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
        if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
                trace_sys_enter(regs, regs->gr[20]);
#endif

#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);

        /*
         * 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);

#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
        if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
                trace_sys_exit(regs, regs->gr[20]);
#endif

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


/*
 * regset functions.
 */

static int fpr_get(struct task_struct *target,
                     const struct user_regset *regset,
                     struct membuf to)
{
        struct pt_regs *regs = task_regs(target);

        return membuf_write(&to, regs->fr, ELF_NFPREG * sizeof(__u64));
}

static int fpr_set(struct task_struct *target,
                     const struct user_regset *regset,
                     unsigned int pos, unsigned int count,
                     const void *kbuf, const void __user *ubuf)
{
        struct pt_regs *regs = task_regs(target);
        const __u64 *k = kbuf;
        const __u64 __user *u = ubuf;
        __u64 reg;

        pos /= sizeof(reg);
        count /= sizeof(reg);

        if (kbuf)
                for (; count > 0 && pos < ELF_NFPREG; --count)
                        regs->fr[pos++] = *k++;
        else
                for (; count > 0 && pos < ELF_NFPREG; --count) {
                        if (__get_user(reg, u++))
                                return -EFAULT;
                        regs->fr[pos++] = reg;
                }

        kbuf = k;
        ubuf = u;
        pos *= sizeof(reg);
        count *= sizeof(reg);
        user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                                  ELF_NFPREG * sizeof(reg), -1);
        return 0;
}

#define RI(reg) (offsetof(struct user_regs_struct,reg) / sizeof(long))

static unsigned long get_reg(struct pt_regs *regs, int num)
{
        switch (num) {
        case RI(gr[0]) ... RI(gr[31]):  return regs->gr[num - RI(gr[0])];
        case RI(sr[0]) ... RI(sr[7]):   return regs->sr[num - RI(sr[0])];
        case RI(iasq[0]):               return regs->iasq[0];
        case RI(iasq[1]):               return regs->iasq[1];
        case RI(iaoq[0]):               return regs->iaoq[0];
        case RI(iaoq[1]):               return regs->iaoq[1];
        case RI(sar):                   return regs->sar;
        case RI(iir):                   return regs->iir;
        case RI(isr):                   return regs->isr;
        case RI(ior):                   return regs->ior;
        case RI(ipsw):                  return regs->ipsw;
        case RI(cr27):                  return regs->cr27;
        case RI(cr0):                   return mfctl(0);
        case RI(cr24):                  return mfctl(24);
        case RI(cr25):                  return mfctl(25);
        case RI(cr26):                  return mfctl(26);
        case RI(cr28):                  return mfctl(28);
        case RI(cr29):                  return mfctl(29);
        case RI(cr30):                  return mfctl(30);
        case RI(cr31):                  return mfctl(31);
        case RI(cr8):                   return mfctl(8);
        case RI(cr9):                   return mfctl(9);
        case RI(cr12):                  return mfctl(12);
        case RI(cr13):                  return mfctl(13);
        case RI(cr10):                  return mfctl(10);
        case RI(cr15):                  return mfctl(15);
        default:                        return 0;
        }
}

static void set_reg(struct pt_regs *regs, int num, unsigned long val)
{
        switch (num) {
        case RI(gr[0]): /*
                         * PSW is in gr[0].
                         * 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.
                         */
                        val &= USER_PSW_BITS;
                        regs->gr[0] &= ~USER_PSW_BITS;
                        regs->gr[0] |= val;
                        return;
        case RI(gr[1]) ... RI(gr[31]):
                        regs->gr[num - RI(gr[0])] = val;
                        return;
        case RI(iaoq[0]):
        case RI(iaoq[1]):
                        /* set 2 lowest bits to ensure userspace privilege: */
                        regs->iaoq[num - RI(iaoq[0])] = val | PRIV_USER;
                        return;
        case RI(sar):   regs->sar = val;
                        return;
        default:        return;
#if 0
        /* do not allow to change any of the following registers (yet) */
        case RI(sr[0]) ... RI(sr[7]):   return regs->sr[num - RI(sr[0])];
        case RI(iasq[0]):               return regs->iasq[0];
        case RI(iasq[1]):               return regs->iasq[1];
        case RI(iir):                   return regs->iir;
        case RI(isr):                   return regs->isr;
        case RI(ior):                   return regs->ior;
        case RI(ipsw):                  return regs->ipsw;
        case RI(cr27):                  return regs->cr27;
        case cr0, cr24, cr25, cr26, cr27, cr28, cr29, cr30, cr31;
        case cr8, cr9, cr12, cr13, cr10, cr15;
#endif
        }
}

static int gpr_get(struct task_struct *target,
                     const struct user_regset *regset,
                     struct membuf to)
{
        struct pt_regs *regs = task_regs(target);
        unsigned int pos;

        for (pos = 0; pos < ELF_NGREG; pos++)
                membuf_store(&to, get_reg(regs, pos));
        return 0;
}

static int gpr_set(struct task_struct *target,
                     const struct user_regset *regset,
                     unsigned int pos, unsigned int count,
                     const void *kbuf, const void __user *ubuf)
{
        struct pt_regs *regs = task_regs(target);
        const unsigned long *k = kbuf;
        const unsigned long __user *u = ubuf;
        unsigned long reg;

        pos /= sizeof(reg);
        count /= sizeof(reg);

        if (kbuf)
                for (; count > 0 && pos < ELF_NGREG; --count)
                        set_reg(regs, pos++, *k++);
        else
                for (; count > 0 && pos < ELF_NGREG; --count) {
                        if (__get_user(reg, u++))
                                return -EFAULT;
                        set_reg(regs, pos++, reg);
                }

        kbuf = k;
        ubuf = u;
        pos *= sizeof(reg);
        count *= sizeof(reg);
        user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                                  ELF_NGREG * sizeof(reg), -1);
        return 0;
}

static const struct user_regset native_regsets[] = {
        [REGSET_GENERAL] = {
                USER_REGSET_NOTE_TYPE(PRSTATUS), .n = ELF_NGREG,
                .size = sizeof(long), .align = sizeof(long),
                .regset_get = gpr_get, .set = gpr_set
        },
        [REGSET_FP] = {
                USER_REGSET_NOTE_TYPE(PRFPREG), .n = ELF_NFPREG,
                .size = sizeof(__u64), .align = sizeof(__u64),
                .regset_get = fpr_get, .set = fpr_set
        }
};

static const struct user_regset_view user_parisc_native_view = {
        .name = "parisc", .e_machine = ELF_ARCH, .ei_osabi = ELFOSABI_LINUX,
        .regsets = native_regsets, .n = ARRAY_SIZE(native_regsets)
};

#ifdef CONFIG_64BIT
static int gpr32_get(struct task_struct *target,
                     const struct user_regset *regset,
                     struct membuf to)
{
        struct pt_regs *regs = task_regs(target);
        unsigned int pos;

        for (pos = 0; pos < ELF_NGREG; pos++)
                membuf_store(&to, (compat_ulong_t)get_reg(regs, pos));

        return 0;
}

static int gpr32_set(struct task_struct *target,
                     const struct user_regset *regset,
                     unsigned int pos, unsigned int count,
                     const void *kbuf, const void __user *ubuf)
{
        struct pt_regs *regs = task_regs(target);
        const compat_ulong_t *k = kbuf;
        const compat_ulong_t __user *u = ubuf;
        compat_ulong_t reg;

        pos /= sizeof(reg);
        count /= sizeof(reg);

        if (kbuf)
                for (; count > 0 && pos < ELF_NGREG; --count)
                        set_reg(regs, pos++, *k++);
        else
                for (; count > 0 && pos < ELF_NGREG; --count) {
                        if (__get_user(reg, u++))
                                return -EFAULT;
                        set_reg(regs, pos++, reg);
                }

        kbuf = k;
        ubuf = u;
        pos *= sizeof(reg);
        count *= sizeof(reg);
        user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                                  ELF_NGREG * sizeof(reg), -1);
        return 0;
}

/*
 * These are the regset flavors matching the 32bit native set.
 */
static const struct user_regset compat_regsets[] = {
        [REGSET_GENERAL] = {
                USER_REGSET_NOTE_TYPE(PRSTATUS), .n = ELF_NGREG,
                .size = sizeof(compat_long_t), .align = sizeof(compat_long_t),
                .regset_get = gpr32_get, .set = gpr32_set
        },
        [REGSET_FP] = {
                USER_REGSET_NOTE_TYPE(PRFPREG), .n = ELF_NFPREG,
                .size = sizeof(__u64), .align = sizeof(__u64),
                .regset_get = fpr_get, .set = fpr_set
        }
};

static const struct user_regset_view user_parisc_compat_view = {
        .name = "parisc", .e_machine = EM_PARISC, .ei_osabi = ELFOSABI_LINUX,
        .regsets = compat_regsets, .n = ARRAY_SIZE(compat_regsets)
};
#endif  /* CONFIG_64BIT */

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
        BUILD_BUG_ON(sizeof(struct user_regs_struct)/sizeof(long) != ELF_NGREG);
        BUILD_BUG_ON(sizeof(struct user_fp_struct)/sizeof(__u64) != ELF_NFPREG);
#ifdef CONFIG_64BIT
        if (is_compat_task())
                return &user_parisc_compat_view;
#endif
        return &user_parisc_native_view;
}


/* HAVE_REGS_AND_STACK_ACCESS_API feature */

struct pt_regs_offset {
        const char *name;
        int offset;
};

#define REG_OFFSET_NAME(r)    {.name = #r, .offset = offsetof(struct pt_regs, r)}
#define REG_OFFSET_INDEX(r,i) {.name = #r#i, .offset = offsetof(struct pt_regs, r[i])}
#define REG_OFFSET_END {.name = NULL, .offset = 0}

static const struct pt_regs_offset regoffset_table[] = {
        REG_OFFSET_INDEX(gr,0),
        REG_OFFSET_INDEX(gr,1),
        REG_OFFSET_INDEX(gr,2),
        REG_OFFSET_INDEX(gr,3),
        REG_OFFSET_INDEX(gr,4),
        REG_OFFSET_INDEX(gr,5),
        REG_OFFSET_INDEX(gr,6),
        REG_OFFSET_INDEX(gr,7),
        REG_OFFSET_INDEX(gr,8),
        REG_OFFSET_INDEX(gr,9),
        REG_OFFSET_INDEX(gr,10),
        REG_OFFSET_INDEX(gr,11),
        REG_OFFSET_INDEX(gr,12),
        REG_OFFSET_INDEX(gr,13),
        REG_OFFSET_INDEX(gr,14),
        REG_OFFSET_INDEX(gr,15),
        REG_OFFSET_INDEX(gr,16),
        REG_OFFSET_INDEX(gr,17),
        REG_OFFSET_INDEX(gr,18),
        REG_OFFSET_INDEX(gr,19),
        REG_OFFSET_INDEX(gr,20),
        REG_OFFSET_INDEX(gr,21),
        REG_OFFSET_INDEX(gr,22),
        REG_OFFSET_INDEX(gr,23),
        REG_OFFSET_INDEX(gr,24),
        REG_OFFSET_INDEX(gr,25),
        REG_OFFSET_INDEX(gr,26),
        REG_OFFSET_INDEX(gr,27),
        REG_OFFSET_INDEX(gr,28),
        REG_OFFSET_INDEX(gr,29),
        REG_OFFSET_INDEX(gr,30),
        REG_OFFSET_INDEX(gr,31),
        REG_OFFSET_INDEX(sr,0),
        REG_OFFSET_INDEX(sr,1),
        REG_OFFSET_INDEX(sr,2),
        REG_OFFSET_INDEX(sr,3),
        REG_OFFSET_INDEX(sr,4),
        REG_OFFSET_INDEX(sr,5),
        REG_OFFSET_INDEX(sr,6),
        REG_OFFSET_INDEX(sr,7),
        REG_OFFSET_INDEX(iasq,0),
        REG_OFFSET_INDEX(iasq,1),
        REG_OFFSET_INDEX(iaoq,0),
        REG_OFFSET_INDEX(iaoq,1),
        REG_OFFSET_NAME(cr27),
        REG_OFFSET_NAME(ksp),
        REG_OFFSET_NAME(kpc),
        REG_OFFSET_NAME(sar),
        REG_OFFSET_NAME(iir),
        REG_OFFSET_NAME(isr),
        REG_OFFSET_NAME(ior),
        REG_OFFSET_NAME(ipsw),
        REG_OFFSET_END,
};

/**
 * regs_query_register_offset() - query register offset from its name
 * @name:       the name of a register
 *
 * regs_query_register_offset() returns the offset of a register in struct
 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 */
int regs_query_register_offset(const char *name)
{
        const struct pt_regs_offset *roff;
        for (roff = regoffset_table; roff->name != NULL; roff++)
                if (!strcmp(roff->name, name))
                        return roff->offset;
        return -EINVAL;
}

/**
 * regs_query_register_name() - query register name from its offset
 * @offset:     the offset of a register in struct pt_regs.
 *
 * regs_query_register_name() returns the name of a register from its
 * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
 */
const char *regs_query_register_name(unsigned int offset)
{
        const struct pt_regs_offset *roff;
        for (roff = regoffset_table; roff->name != NULL; roff++)
                if (roff->offset == offset)
                        return roff->name;
        return NULL;
}

/**
 * regs_within_kernel_stack() - check the address in the stack
 * @regs:      pt_regs which contains kernel stack pointer.
 * @addr:      address which is checked.
 *
 * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 * If @addr is within the kernel stack, it returns true. If not, returns false.
 */
int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
        return ((addr & ~(THREAD_SIZE - 1))  ==
                (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
}

/**
 * regs_get_kernel_stack_nth() - get Nth entry of the stack
 * @regs:       pt_regs which contains kernel stack pointer.
 * @n:          stack entry number.
 *
 * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 * is specified by @regs. If the @n th entry is NOT in the kernel stack,
 * this returns 0.
 */
unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
{
        unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);

        addr -= n;

        if (!regs_within_kernel_stack(regs, (unsigned long)addr))
                return 0;

        return *addr;
}