ptrace_64.c

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/*
 * Copyright 2003 PathScale, Inc.
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 *
 * Licensed under the GPL
 */

#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/errno.h>
#define __FRAME_OFFSETS
#include <asm/ptrace.h>
#include <asm/uaccess.h>

/*
 * determines which flags the user has access to.
 * 1 = access 0 = no access
 */
#define FLAG_MASK 0x44dd5UL

static const int reg_offsets[] =
{
    [R8 >> 3] = HOST_R8,
    [R9 >> 3] = HOST_R9,
    [R10 >> 3] = HOST_R10,
    [R11 >> 3] = HOST_R11,
    [R12 >> 3] = HOST_R12,
    [R13 >> 3] = HOST_R13,
    [R14 >> 3] = HOST_R14,
    [R15 >> 3] = HOST_R15,
    [RIP >> 3] = HOST_IP,
    [RSP >> 3] = HOST_SP,
    [RAX >> 3] = HOST_AX,
    [RBX >> 3] = HOST_BX,
    [RCX >> 3] = HOST_CX,
    [RDX >> 3] = HOST_DX,
    [RSI >> 3] = HOST_SI,
    [RDI >> 3] = HOST_DI,
    [RBP >> 3] = HOST_BP,
    [CS >> 3] = HOST_CS,
    [SS >> 3] = HOST_SS,
    [FS_BASE >> 3] = HOST_FS_BASE,
    [GS_BASE >> 3] = HOST_GS_BASE,
    [DS >> 3] = HOST_DS,
    [ES >> 3] = HOST_ES,
    [FS >> 3] = HOST_FS,
    [GS >> 3] = HOST_GS,
    [EFLAGS >> 3] = HOST_EFLAGS,
    [ORIG_RAX >> 3] = HOST_ORIG_AX,
};

int putreg(struct task_struct *child, int regno, unsigned long value)
{
#ifdef TIF_IA32
    /*
     * Some code in the 64bit emulation may not be 64bit clean.
     * Don't take any chances.
     */
    if (test_tsk_thread_flag(child, TIF_IA32))
        value &= 0xffffffff;
#endif
    switch (regno) {
    case R8:
    case R9:
    case R10:
    case R11:
    case R12:
    case R13:
    case R14:
    case R15:
    case RIP:
    case RSP:
    case RAX:
    case RBX:
    case RCX:
    case RDX:
    case RSI:
    case RDI:
    case RBP:
    case ORIG_RAX:
        break;

    case FS:
    case GS:
    case DS:
    case ES:
    case SS:
    case CS:
        if (value && (value & 3) != 3)
            return -EIO;
        value &= 0xffff;
        break;

    case FS_BASE:
    case GS_BASE:
        if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
            return -EIO;
        break;

    case EFLAGS:
        value &= FLAG_MASK;
        child->thread.regs.regs.gp[HOST_EFLAGS] |= value;
        return 0;

    default:
        panic("Bad register in putreg(): %d\n", regno);
    }

    child->thread.regs.regs.gp[reg_offsets[regno >> 3]] = value;
    return 0;
}

int poke_user(struct task_struct *child, long addr, long data)
{
    if ((addr & 3) || addr < 0)
        return -EIO;

    if (addr < MAX_REG_OFFSET)
        return putreg(child, addr, data);
    else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
        (addr <= offsetof(struct user, u_debugreg[7]))) {
        addr -= offsetof(struct user, u_debugreg[0]);
        addr = addr >> 2;
        if ((addr == 4) || (addr == 5))
            return -EIO;
        child->thread.arch.debugregs[addr] = data;
        return 0;
    }
    return -EIO;
}

unsigned long getreg(struct task_struct *child, int regno)
{
    unsigned long mask = ~0UL;
#ifdef TIF_IA32
    if (test_tsk_thread_flag(child, TIF_IA32))
        mask = 0xffffffff;
#endif
    switch (regno) {
    case R8:
    case R9:
    case R10:
    case R11:
    case R12:
    case R13:
    case R14:
    case R15:
    case RIP:
    case RSP:
    case RAX:
    case RBX:
    case RCX:
    case RDX:
    case RSI:
    case RDI:
    case RBP:
    case ORIG_RAX:
    case EFLAGS:
    case FS_BASE:
    case GS_BASE:
        break;
    case FS:
    case GS:
    case DS:
    case ES:
    case SS:
    case CS:
        mask = 0xffff;
        break;
    default:
        panic("Bad register in getreg: %d\n", regno);
    }
    return mask & child->thread.regs.regs.gp[reg_offsets[regno >> 3]];
}

int peek_user(struct task_struct *child, long addr, long data)
{
    /* read the word at location addr in the USER area. */
    unsigned long tmp;

    if ((addr & 3) || addr < 0)
        return -EIO;

    tmp = 0;  /* Default return condition */
    if (addr < MAX_REG_OFFSET)
        tmp = getreg(child, addr);
    else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
        (addr <= offsetof(struct user, u_debugreg[7]))) {
        addr -= offsetof(struct user, u_debugreg[0]);
        addr = addr >> 2;
        tmp = child->thread.arch.debugregs[addr];
    }
    return put_user(tmp, (unsigned long *) data);
}

/* XXX Mostly copied from sys-i386 */
int is_syscall(unsigned long addr)
{
    unsigned short instr;
    int n;

    n = copy_from_user(&instr, (void __user *) addr, sizeof(instr));
    if (n) {
        /*
         * access_process_vm() grants access to vsyscall and stub,
         * while copy_from_user doesn't. Maybe access_process_vm is
         * slow, but that doesn't matter, since it will be called only
         * in case of singlestepping, if copy_from_user failed.
         */
        n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
        if (n != sizeof(instr)) {
            printk("is_syscall : failed to read instruction from "
                   "0x%lx\n", addr);
            return 1;
        }
    }
    /* sysenter */
    return instr == 0x050f;
}

static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
{
    int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
    long fpregs[HOST_FP_SIZE];

    BUG_ON(sizeof(*buf) != sizeof(fpregs));
    err = save_fp_registers(userspace_pid[cpu], fpregs);
    if (err)
        return err;

    n = copy_to_user(buf, fpregs, sizeof(fpregs));
    if (n > 0)
        return -EFAULT;

    return n;
}

static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
{
    int n, cpu = ((struct thread_info *) child->stack)->cpu;
    long fpregs[HOST_FP_SIZE];

    BUG_ON(sizeof(*buf) != sizeof(fpregs));
    n = copy_from_user(fpregs, buf, sizeof(fpregs));
    if (n > 0)
        return -EFAULT;

    return restore_fp_registers(userspace_pid[cpu], fpregs);
}

long subarch_ptrace(struct task_struct *child, long request,
            unsigned long addr, unsigned long data)
{
    int ret = -EIO;
    void __user *datap = (void __user *) data;

    switch (request) {
    case PTRACE_GETFPREGS: /* Get the child FPU state. */
        ret = get_fpregs(datap, child);
        break;
    case PTRACE_SETFPREGS: /* Set the child FPU state. */
        ret = set_fpregs(datap, child);
        break;
    case PTRACE_ARCH_PRCTL:
        /* XXX Calls ptrace on the host - needs some SMP thinking */
        ret = arch_prctl(child, data, (void __user *) addr);
        break;
    }

    return ret;
}