Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * Copyright (C) 2004-2006 Atmel Corporation

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#undef DEBUG

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/ptrace.h>

#include <linux/errno.h>

#include <linux/user.h>

#include <linux/security.h>

#include <linux/unistd.h>

#include <linux/notifier.h>

#include <asm/traps.h>

#include <asm/uaccess.h>

#include <asm/ocd.h>

#include <asm/mmu_context.h>

#include <linux/kdebug.h>

static struct pt_regs *get_user_regs(struct task_struct *tsk)

{

        return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +

                                  THREAD_SIZE - sizeof(struct pt_regs));

}

static void ptrace_single_step(struct task_struct *tsk)

{

        pr_debug("ptrace_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",

                 tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);

        /*

         * We can't schedule in Debug mode, so when TIF_BREAKPOINT is

         * set, the system call or exception handler will do a

         * breakpoint to enter monitor mode before returning to

         * userspace.

         *

         * The monitor code will then notice that TIF_SINGLE_STEP is

         * set and return to userspace with single stepping enabled.

         * The CPU will then enter monitor mode again after exactly

         * one instruction has been executed, and the monitor code

         * will then send a SIGTRAP to the process.

         */

        set_tsk_thread_flag(tsk, TIF_BREAKPOINT);

        set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);

}

/*

 * Called by kernel/ptrace.c when detaching

 *

 * Make sure any single step bits, etc. are not set

 */

void ptrace_disable(struct task_struct *child)

{

        clear_tsk_thread_flag(child, TIF_SINGLE_STEP);

        clear_tsk_thread_flag(child, TIF_BREAKPOINT);

}

/*

 * Read the word at offset "offset" into the task's "struct user". We

 * actually access the pt_regs struct stored on the kernel stack.

 */

static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,

                            unsigned long __user *data)

{

        unsigned long *regs;

        unsigned long value;

        if (offset & 3 || offset >= sizeof(struct user)) {

                printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);

                return -EIO;

        }

        regs = (unsigned long *)get_user_regs(tsk);

        value = 0;

        if (offset < sizeof(struct pt_regs))

                value = regs[offset / sizeof(regs[0])];

        pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",

                 tsk->comm, tsk->pid, offset, data, value);

        return put_user(value, data);

}

/*

 * Write the word "value" to offset "offset" into the task's "struct

 * user". We actually access the pt_regs struct stored on the kernel

 * stack.

 */

static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,

                             unsigned long value)

{

        unsigned long *regs;

        pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",

                        tsk->comm, tsk->pid, offset, value);

        if (offset & 3 || offset >= sizeof(struct user)) {

                pr_debug("  invalid offset 0x%08lx\n", offset);

                return -EIO;

        }

        if (offset >= sizeof(struct pt_regs))

                return 0;

        regs = (unsigned long *)get_user_regs(tsk);

        regs[offset / sizeof(regs[0])] = value;

        return 0;

}

static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)

{

        struct pt_regs *regs = get_user_regs(tsk);

        return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;

}

static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)

{

        struct pt_regs newregs;

        int ret;

        ret = -EFAULT;

        if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {

                struct pt_regs *regs = get_user_regs(tsk);

                ret = -EINVAL;

                if (valid_user_regs(&newregs)) {

                        *regs = newregs;

                        ret = 0;

                }

        }

        return ret;

}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)

{

        int ret;

        pr_debug("ptrace: Enabling monitor mode...\n");

        ocd_write(DC, ocd_read(DC) | (1 << OCD_DC_MM_BIT)

                        | (1 << OCD_DC_DBE_BIT));

        switch (request) {

        /* Read the word at location addr in the child process */

        case PTRACE_PEEKTEXT:

        case PTRACE_PEEKDATA:

                ret = generic_ptrace_peekdata(child, addr, data);

                break;

        case PTRACE_PEEKUSR:

                ret = ptrace_read_user(child, addr,

                                       (unsigned long __user *)data);

                break;

        /* Write the word in data at location addr */

        case PTRACE_POKETEXT:

        case PTRACE_POKEDATA:

                ret = generic_ptrace_pokedata(child, addr, data);

                break;

        case PTRACE_POKEUSR:

                ret = ptrace_write_user(child, addr, data);

                break;

        /* continue and stop at next (return from) syscall */

        case PTRACE_SYSCALL:

        /* restart after signal */

        case PTRACE_CONT:

                ret = -EIO;

                if (!valid_signal(data))

                        break;

                if (request == PTRACE_SYSCALL)

                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                else

                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                child->exit_code = data;

                /* XXX: Are we sure no breakpoints are active here? */

                wake_up_process(child);

                ret = 0;

                break;

        /*

         * Make the child exit. Best I can do is send it a

         * SIGKILL. Perhaps it should be put in the status that it

         * wants to exit.

         */

        case PTRACE_KILL:

                ret = 0;

                if (child->exit_state == EXIT_ZOMBIE)

                        break;

                child->exit_code = SIGKILL;

                wake_up_process(child);

                break;

        /*

         * execute single instruction.

         */

        case PTRACE_SINGLESTEP:

                ret = -EIO;

                if (!valid_signal(data))

                        break;

                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                ptrace_single_step(child);

                child->exit_code = data;

                wake_up_process(child);

                ret = 0;

                break;

        case PTRACE_GETREGS:

                ret = ptrace_getregs(child, (void __user *)data);

                break;

        case PTRACE_SETREGS:

                ret = ptrace_setregs(child, (const void __user *)data);

                break;

        default:

                ret = ptrace_request(child, request, addr, data);

                break;

        }

        return ret;

}

asmlinkage void syscall_trace(void)

{

        if (!test_thread_flag(TIF_SYSCALL_TRACE))

                return;

        if (!(current->ptrace & PT_PTRACED))

                return;

        /* The 0x80 provides a way for the tracing parent to

         * distinguish between a syscall stop and SIGTRAP delivery */

        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)

                                 ? 0x80 : 0));

        /*

         * this isn't the same as continuing with a signal, but it

         * will do for normal use.  strace only continues with a

         * signal if the stopping signal is not SIGTRAP.  -brl

         */

        if (current->exit_code) {

                pr_debug("syscall_trace: sending signal %d to PID %u\n",

                         current->exit_code, current->pid);

                send_sig(current->exit_code, current, 1);

                current->exit_code = 0;

        }

}

/*

 * debug_trampoline() is an assembly stub which will store all user

 * registers on the stack and execute a breakpoint instruction.

 *

 * If we single-step into an exception handler which runs with

 * interrupts disabled the whole time so it doesn't have to check for

 * pending work, its return address will be modified so that it ends

 * up returning to debug_trampoline.

 *

 * If the exception handler decides to store the user context and

 * enable interrupts after all, it will restore the original return

 * address and status register value. Before it returns, it will

 * notice that TIF_BREAKPOINT is set and execute a breakpoint

 * instruction.

 */

extern void debug_trampoline(void);

asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)

{

        struct thread_info      *ti;

        unsigned long           trampoline_addr;

        u32                     status;

        u32                     ctrl;

        int                     code;

        status = ocd_read(DS);

        ti = current_thread_info();

        code = TRAP_BRKPT;

        pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",

                        status, regs->pc, regs->sr, ti->flags);

        if (!user_mode(regs)) {

                unsigned long   die_val = DIE_BREAKPOINT;

                if (status & (1 << OCD_DS_SSS_BIT))

                        die_val = DIE_SSTEP;

                if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)

                                == NOTIFY_STOP)

                        return regs;

                if ((status & (1 << OCD_DS_SWB_BIT))

                                && test_and_clear_ti_thread_flag(

                                        ti, TIF_BREAKPOINT)) {

                        /*

                         * Explicit breakpoint from trampoline or

                         * exception/syscall/interrupt handler.

                         *

                         * The real saved regs are on the stack right

                         * after the ones we saved on entry.

                         */

                        regs++;

                        pr_debug("  -> TIF_BREAKPOINT done, adjusted regs:"

                                        "PC=0x%08lx SR=0x%08lx\n",

                                        regs->pc, regs->sr);

                        BUG_ON(!user_mode(regs));

                        if (test_thread_flag(TIF_SINGLE_STEP)) {

                                pr_debug("Going to do single step...\n");

                                return regs;

                        }

                        /*

                         * No TIF_SINGLE_STEP means we're done

                         * stepping over a syscall. Do the trap now.

                         */

                        code = TRAP_TRACE;

                } else if ((status & (1 << OCD_DS_SSS_BIT))

                                && test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {

                        pr_debug("Stepped into something, "

                                        "setting TIF_BREAKPOINT...\n");

                        set_ti_thread_flag(ti, TIF_BREAKPOINT);

                        /*

                         * We stepped into an exception, interrupt or

                         * syscall handler. Some exception handlers

                         * don't check for pending work, so we need to

                         * set up a trampoline just in case.

                         *

                         * The exception entry code will undo the

                         * trampoline stuff if it does a full context

                         * save (which also means that it'll check for

                         * pending work later.)

                         */

                        if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {

                                trampoline_addr

                                        = (unsigned long)&debug_trampoline;

                                pr_debug("Setting up trampoline...\n");

                                ti->rar_saved = sysreg_read(RAR_EX);

                                ti->rsr_saved = sysreg_read(RSR_EX);

                                sysreg_write(RAR_EX, trampoline_addr);

                                sysreg_write(RSR_EX, (MODE_EXCEPTION

                                                        | SR_EM | SR_GM));

                                BUG_ON(ti->rsr_saved & MODE_MASK);

                        }

                        /*

                         * If we stepped into a system call, we

                         * shouldn't do a single step after we return

                         * since the return address is right after the

                         * "scall" instruction we were told to step

                         * over.

                         */

                        if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {

                                pr_debug("Supervisor; no single step\n");

                                clear_ti_thread_flag(ti, TIF_SINGLE_STEP);

                        }

                        ctrl = ocd_read(DC);

                        ctrl &= ~(1 << OCD_DC_SS_BIT);

                        ocd_write(DC, ctrl);

                        return regs;

                } else {

                        printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",

                                        status);

                        printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);

                        die("Unhandled debug trap in kernel mode",

                                        regs, SIGTRAP);

                }

        } else if (status & (1 << OCD_DS_SSS_BIT)) {

                /* Single step in user mode */

                code = TRAP_TRACE;

                ctrl = ocd_read(DC);

                ctrl &= ~(1 << OCD_DC_SS_BIT);

                ocd_write(DC, ctrl);

        }

        pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",

                        code, regs->pc, regs->sr);

        clear_thread_flag(TIF_SINGLE_STEP);

        _exception(SIGTRAP, regs, code, instruction_pointer(regs));

        return regs;

}