ptrace.c

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/*
 * linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 * these modifications are Copyright 2004-2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2
 */

#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/regset.h>
#include <linux/signal.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/asm-offsets.h>
#include <asm/dma.h>
#include <asm/fixed_code.h>
#include <asm/cacheflush.h>
#include <asm/mem_map.h>
#include <asm/mmu_context.h>

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Get contents of register REGNO in task TASK.
 */
static inline long
get_reg(struct task_struct *task, unsigned long regno,
    unsigned long __user *datap)
{
    long tmp;
    struct pt_regs *regs = task_pt_regs(task);

    if (regno & 3 || regno > PT_LAST_PSEUDO)
        return -EIO;

    switch (regno) {
    case PT_TEXT_ADDR:
        tmp = task->mm->start_code;
        break;
    case PT_TEXT_END_ADDR:
        tmp = task->mm->end_code;
        break;
    case PT_DATA_ADDR:
        tmp = task->mm->start_data;
        break;
    case PT_USP:
        tmp = task->thread.usp;
        break;
    default:
        if (regno < sizeof(*regs)) {
            void *reg_ptr = regs;
            tmp = *(long *)(reg_ptr + regno);
        } else
            return -EIO;
    }

    return put_user(tmp, datap);
}

/*
 * Write contents of register REGNO in task TASK.
 */
static inline int
put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
{
    struct pt_regs *regs = task_pt_regs(task);

    if (regno & 3 || regno > PT_LAST_PSEUDO)
        return -EIO;

    switch (regno) {
    case PT_PC:
        /*********************************************************************/
        /* At this point the kernel is most likely in exception.             */
        /* The RETX register will be used to populate the pc of the process. */
        /*********************************************************************/
        regs->retx = data;
        regs->pc = data;
        break;
    case PT_RETX:
        break;      /* regs->retx = data; break; */
    case PT_USP:
        regs->usp = data;
        task->thread.usp = data;
        break;
    case PT_SYSCFG: /* don't let userspace screw with this */
        if ((data & ~1) != 0x6)
            pr_warning("ptrace: ignore syscfg write of %#lx\n", data);
        break;      /* regs->syscfg = data; break; */
    default:
        if (regno < sizeof(*regs)) {
            void *reg_offset = regs;
            *(long *)(reg_offset + regno) = data;
        }
        /* Ignore writes to pseudo registers */
    }

    return 0;
}

/*
 * check that an address falls within the bounds of the target process's memory mappings
 */
int
is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long len)
{
    struct vm_area_struct *vma;
    struct sram_list_struct *sraml;

    /* overflow */
    if (start + len < start)
        return -EIO;

    vma = find_vma(child->mm, start);
    if (vma && start >= vma->vm_start && start + len <= vma->vm_end)
            return 0;

    for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next)
        if (start >= (unsigned long)sraml->addr
            && start + len < (unsigned long)sraml->addr + sraml->length)
            return 0;

    if (start >= FIXED_CODE_START && start + len < FIXED_CODE_END)
        return 0;

#ifdef CONFIG_APP_STACK_L1
    if (child->mm->context.l1_stack_save)
        if (start >= (unsigned long)l1_stack_base &&
            start + len < (unsigned long)l1_stack_base + l1_stack_len)
            return 0;
#endif

    return -EIO;
}

/*
 * retrieve the contents of Blackfin userspace general registers
 */
static int genregs_get(struct task_struct *target,
               const struct user_regset *regset,
               unsigned int pos, unsigned int count,
               void *kbuf, void __user *ubuf)
{
    struct pt_regs *regs = task_pt_regs(target);
    int ret;

    /* This sucks ... */
    regs->usp = target->thread.usp;

    ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                  regs, 0, sizeof(*regs));
    if (ret < 0)
        return ret;

    return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                    sizeof(*regs), -1);
}

/*
 * update the contents of the Blackfin userspace general registers
 */
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)
{
    struct pt_regs *regs = task_pt_regs(target);
    int ret;

    /* Don't let people set SYSCFG (it's at the end of pt_regs) */
    ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                 regs, 0, PT_SYSCFG);
    if (ret < 0)
        return ret;

    /* This sucks ... */
    target->thread.usp = regs->usp;
    /* regs->retx = regs->pc; */

    return user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                    PT_SYSCFG, -1);
}

/*
 * Define the register sets available on the Blackfin under Linux
 */
enum bfin_regset {
    REGSET_GENERAL,
};

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

static const struct user_regset_view user_bfin_native_view = {
    .name      = "Blackfin",
    .e_machine = EM_BLACKFIN,
    .regsets   = bfin_regsets,
    .n         = ARRAY_SIZE(bfin_regsets),
};

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

void user_enable_single_step(struct task_struct *child)
{
    struct pt_regs *regs = task_pt_regs(child);
    regs->syscfg |= SYSCFG_SSSTEP;

    set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
    struct pt_regs *regs = task_pt_regs(child);
    regs->syscfg &= ~SYSCFG_SSSTEP;

    clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

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

    switch (request) {
        /* when I and D space are separate, these will need to be fixed. */
    case PTRACE_PEEKDATA:
        pr_debug("ptrace: PEEKDATA\n");
        /* fall through */
    case PTRACE_PEEKTEXT:   /* read word at location addr. */
        {
            unsigned long tmp = 0;
            int copied = 0, to_copy = sizeof(tmp);

            ret = -EIO;
            pr_debug("ptrace: PEEKTEXT at addr 0x%08lx + %i\n", addr, to_copy);
            if (is_user_addr_valid(child, addr, to_copy) < 0)
                break;
            pr_debug("ptrace: user address is valid\n");

            switch (bfin_mem_access_type(addr, to_copy)) {
            case BFIN_MEM_ACCESS_CORE:
            case BFIN_MEM_ACCESS_CORE_ONLY:
                copied = access_process_vm(child, addr, &tmp,
                                           to_copy, 0);
                if (copied)
                    break;

                /* hrm, why didn't that work ... maybe no mapping */
                if (addr >= FIXED_CODE_START &&
                    addr + to_copy <= FIXED_CODE_END) {
                    copy_from_user_page(0, 0, 0, &tmp, paddr, to_copy);
                    copied = to_copy;
                } else if (addr >= BOOT_ROM_START) {
                    memcpy(&tmp, paddr, to_copy);
                    copied = to_copy;
                }

                break;
            case BFIN_MEM_ACCESS_DMA:
                if (safe_dma_memcpy(&tmp, paddr, to_copy))
                    copied = to_copy;
                break;
            case BFIN_MEM_ACCESS_ITEST:
                if (isram_memcpy(&tmp, paddr, to_copy))
                    copied = to_copy;
                break;
            default:
                copied = 0;
                break;
            }

            pr_debug("ptrace: copied size %d [0x%08lx]\n", copied, tmp);
            if (copied == to_copy)
                ret = put_user(tmp, datap);
            break;
        }

        /* when I and D space are separate, this will have to be fixed. */
    case PTRACE_POKEDATA:
        pr_debug("ptrace: PTRACE_PEEKDATA\n");
        /* fall through */
    case PTRACE_POKETEXT:   /* write the word at location addr. */
        {
            int copied = 0, to_copy = sizeof(data);

            ret = -EIO;
            pr_debug("ptrace: POKETEXT at addr 0x%08lx + %i bytes %lx\n",
                     addr, to_copy, data);
            if (is_user_addr_valid(child, addr, to_copy) < 0)
                break;
            pr_debug("ptrace: user address is valid\n");

            switch (bfin_mem_access_type(addr, to_copy)) {
            case BFIN_MEM_ACCESS_CORE:
            case BFIN_MEM_ACCESS_CORE_ONLY:
                copied = access_process_vm(child, addr, &data,
                                           to_copy, 1);
                break;
            case BFIN_MEM_ACCESS_DMA:
                if (safe_dma_memcpy(paddr, &data, to_copy))
                    copied = to_copy;
                break;
            case BFIN_MEM_ACCESS_ITEST:
                if (isram_memcpy(paddr, &data, to_copy))
                    copied = to_copy;
                break;
            default:
                copied = 0;
                break;
            }

            pr_debug("ptrace: copied size %d\n", copied);
            if (copied == to_copy)
                ret = 0;
            break;
        }

    case PTRACE_PEEKUSR:
        switch (addr) {
#ifdef CONFIG_BINFMT_ELF_FDPIC  /* backwards compat */
        case PT_FDPIC_EXEC:
            request = PTRACE_GETFDPIC;
            addr = PTRACE_GETFDPIC_EXEC;
            goto case_default;
        case PT_FDPIC_INTERP:
            request = PTRACE_GETFDPIC;
            addr = PTRACE_GETFDPIC_INTERP;
            goto case_default;
#endif
        default:
            ret = get_reg(child, addr, datap);
        }
        pr_debug("ptrace: PEEKUSR reg %li with %#lx = %i\n", addr, data, ret);
        break;

    case PTRACE_POKEUSR:
        ret = put_reg(child, addr, data);
        pr_debug("ptrace: POKEUSR reg %li with %li = %i\n", addr, data, ret);
        break;

    case PTRACE_GETREGS:
        pr_debug("ptrace: PTRACE_GETREGS\n");
        return copy_regset_to_user(child, &user_bfin_native_view,
                       REGSET_GENERAL,
                       0, sizeof(struct pt_regs),
                       datap);

    case PTRACE_SETREGS:
        pr_debug("ptrace: PTRACE_SETREGS\n");
        return copy_regset_from_user(child, &user_bfin_native_view,
                         REGSET_GENERAL,
                         0, sizeof(struct pt_regs),
                         datap);

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

    return ret;
}

asmlinkage int syscall_trace_enter(struct pt_regs *regs)
{
    int ret = 0;

    if (test_thread_flag(TIF_SYSCALL_TRACE))
        ret = tracehook_report_syscall_entry(regs);

    return ret;
}

asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
    int step;

    step = test_thread_flag(TIF_SINGLESTEP);
    if (step || test_thread_flag(TIF_SYSCALL_TRACE))
        tracehook_report_syscall_exit(regs, step);
}