ptrace.c

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/*
 * Ptrace support for Hexagon
 *
 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#include <generated/compile.h>

#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/regset.h>
#include <linux/user.h>
#include <linux/elf.h>

#include <asm/user.h>

static int genregs_get(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           void *kbuf, void __user *ubuf)
{
    int ret;
    unsigned int dummy;
    struct pt_regs *regs = task_pt_regs(target);


    if (!regs)
        return -EIO;

    /* The general idea here is that the copyout must happen in
     * exactly the same order in which the userspace expects these
     * regs. Now, the sequence in userspace does not match the
     * sequence in the kernel, so everything past the 32 gprs
     * happens one at a time.
     */
    ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                  &regs->r00, 0, 32*sizeof(unsigned long));

#define ONEXT(KPT_REG, USR_REG) \
    if (!ret) \
        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, \
            KPT_REG, offsetof(struct user_regs_struct, USR_REG), \
            offsetof(struct user_regs_struct, USR_REG) + \
                 sizeof(unsigned long));

    /* Must be exactly same sequence as struct user_regs_struct */
    ONEXT(&regs->sa0, sa0);
    ONEXT(&regs->lc0, lc0);
    ONEXT(&regs->sa1, sa1);
    ONEXT(&regs->lc1, lc1);
    ONEXT(&regs->m0, m0);
    ONEXT(&regs->m1, m1);
    ONEXT(&regs->usr, usr);
    ONEXT(&regs->preds, p3_0);
    ONEXT(&regs->gp, gp);
    ONEXT(&regs->ugp, ugp);
    ONEXT(&pt_elr(regs), pc);
    dummy = pt_cause(regs);
    ONEXT(&dummy, cause);
    ONEXT(&pt_badva(regs), badva);

    /* Pad the rest with zeros, if needed */
    if (!ret)
        ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                    offsetof(struct user_regs_struct, pad1), -1);
    return ret;
}

static int genregs_set(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           const void *kbuf, const void __user *ubuf)
{
    int ret;
    unsigned long bucket;
    struct pt_regs *regs = task_pt_regs(target);

    if (!regs)
        return -EIO;

    ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                 &regs->r00, 0, 32*sizeof(unsigned long));

#define INEXT(KPT_REG, USR_REG) \
    if (!ret) \
        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, \
            KPT_REG, offsetof(struct user_regs_struct, USR_REG), \
            offsetof(struct user_regs_struct, USR_REG) + \
                sizeof(unsigned long));

    /* Must be exactly same sequence as struct user_regs_struct */
    INEXT(&regs->sa0, sa0);
    INEXT(&regs->lc0, lc0);
    INEXT(&regs->sa1, sa1);
    INEXT(&regs->lc1, lc1);
    INEXT(&regs->m0, m0);
    INEXT(&regs->m1, m1);
    INEXT(&regs->usr, usr);
    INEXT(&regs->preds, p3_0);
    INEXT(&regs->gp, gp);
    INEXT(&regs->ugp, ugp);
    INEXT(&pt_elr(regs), pc);

    /* CAUSE and BADVA aren't writeable. */
    INEXT(&bucket, cause);
    INEXT(&bucket, badva);

    /* Ignore the rest, if needed */
    if (!ret)
        ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                    offsetof(struct user_regs_struct, pad1), -1);

    if (ret)
        return ret;

    /*
     * This is special; SP is actually restored by the VM via the
     * special event record which is set by the special trap.
     */
    regs->hvmer.vmpsp = regs->r29;
    return 0;
}

enum hexagon_regset {
    REGSET_GENERAL,
};

static const struct user_regset hexagon_regsets[] = {
    [REGSET_GENERAL] = {
        .core_note_type = NT_PRSTATUS,
        .n = ELF_NGREG,
        .size = sizeof(unsigned long),
        .align = sizeof(unsigned long),
        .get = genregs_get,
        .set = genregs_set,
    },
};

static const struct user_regset_view hexagon_user_view = {
    .name = UTS_MACHINE,
    .e_machine = ELF_ARCH,
    .ei_osabi = ELF_OSABI,
    .regsets = hexagon_regsets,
    .n = ARRAY_SIZE(hexagon_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
    return &hexagon_user_view;
}

void ptrace_disable(struct task_struct *child)
{
    /* Boilerplate - resolves to null inline if no HW single-step */
    user_disable_single_step(child);
}

long arch_ptrace(struct task_struct *child, long request,
         unsigned long addr, unsigned long data)
{
    return ptrace_request(child, request, addr, data);
}