[PATCH] ppc64: Add ptrace data breakpoint support

[wandboard.git] / arch / ppc64 / kernel / process.c

/*
 *  linux/arch/ppc64/kernel/process.c
 *
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995  Linus Torvalds
 *
 *  Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
 *  Paul Mackerras (paulus@cs.anu.edu.au)
 *
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/init_task.h>
#include <linux/prctl.h>
#include <linux/ptrace.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/utsname.h>
#include <linux/kprobes.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/prom.h>
#include <asm/ppcdebug.h>
#include <asm/machdep.h>
#include <asm/iSeries/HvCallHpt.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/time.h>
#include <asm/plpar_wrappers.h>

#ifndef CONFIG_SMP
struct task_struct *last_task_used_math = NULL;
struct task_struct *last_task_used_altivec = NULL;
#endif

/*
 * Make sure the floating-point register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_fp_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                /*
                 * We need to disable preemption here because if we didn't,
                 * another process could get scheduled after the regs->msr
                 * test but before we have finished saving the FP registers
                 * to the thread_struct.  That process could take over the
                 * FPU, and then when we get scheduled again we would store
                 * bogus values for the remaining FP registers.
                 */
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_FP) {
#ifdef CONFIG_SMP
                        /*
                         * This should only ever be called for current or
                         * for a stopped child process.  Since we save away
                         * the FP register state on context switch on SMP,
                         * there is something wrong if a stopped child appears
                         * to still have its FP state in the CPU registers.
                         */
                        BUG_ON(tsk != current);
#endif
                        giveup_fpu(current);
                }
                preempt_enable();
        }
}

void enable_kernel_fp(void)
{
        WARN_ON(preemptible());

#ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
                giveup_fpu(current);
        else
                giveup_fpu(NULL);       /* just enables FP for kernel */
#else
        giveup_fpu(last_task_used_math);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_fp);

int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
{
        if (!tsk->thread.regs)
                return 0;
        flush_fp_to_thread(current);

        memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));

        return 1;
}

#ifdef CONFIG_ALTIVEC

void enable_kernel_altivec(void)
{
        WARN_ON(preemptible());

#ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
                giveup_altivec(current);
        else
                giveup_altivec(NULL);   /* just enables FP for kernel */
#else
        giveup_altivec(last_task_used_altivec);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_altivec);

/*
 * Make sure the VMX/Altivec register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_altivec_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_VEC) {
#ifdef CONFIG_SMP
                        BUG_ON(tsk != current);
#endif
                        giveup_altivec(current);
                }
                preempt_enable();
        }
}

int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
{
        flush_altivec_to_thread(current);
        memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
        return 1;
}

#endif /* CONFIG_ALTIVEC */

static void set_dabr_spr(unsigned long val)
{
        mtspr(SPRN_DABR, val);
}

int set_dabr(unsigned long dabr)
{
        int ret = 0;

        if (firmware_has_feature(FW_FEATURE_XDABR)) {
                /* We want to catch accesses from kernel and userspace */
                unsigned long flags = H_DABRX_KERNEL|H_DABRX_USER;
                ret = plpar_set_xdabr(dabr, flags);
        } else if (firmware_has_feature(FW_FEATURE_DABR)) {
                ret = plpar_set_dabr(dabr);
        } else {
                set_dabr_spr(dabr);
        }

        return ret;
}

DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
static DEFINE_PER_CPU(unsigned long, current_dabr);

struct task_struct *__switch_to(struct task_struct *prev,
                                struct task_struct *new)
{
        struct thread_struct *new_thread, *old_thread;
        unsigned long flags;
        struct task_struct *last;

#ifdef CONFIG_SMP
        /* avoid complexity of lazy save/restore of fpu
         * by just saving it every time we switch out if
         * this task used the fpu during the last quantum.
         * 
         * If it tries to use the fpu again, it'll trap and
         * reload its fp regs.  So we don't have to do a restore
         * every switch, just a save.
         *  -- Cort
         */
        if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
                giveup_fpu(prev);
#ifdef CONFIG_ALTIVEC
        if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
                giveup_altivec(prev);
#endif /* CONFIG_ALTIVEC */
#endif /* CONFIG_SMP */

#if defined(CONFIG_ALTIVEC) && !defined(CONFIG_SMP)
        /* Avoid the trap.  On smp this this never happens since
         * we don't set last_task_used_altivec -- Cort
         */
        if (new->thread.regs && last_task_used_altivec == new)
                new->thread.regs->msr |= MSR_VEC;
#endif /* CONFIG_ALTIVEC */

        if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
                set_dabr(new->thread.dabr);
                __get_cpu_var(current_dabr) = new->thread.dabr;
        }

        flush_tlb_pending();

        new_thread = &new->thread;
        old_thread = &current->thread;

        /* Collect purr utilization data per process and per processor
         * wise purr is nothing but processor time base
         */
        if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
                struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
                long unsigned start_tb, current_tb;
                start_tb = old_thread->start_tb;
                cu->current_tb = current_tb = mfspr(SPRN_PURR);
                old_thread->accum_tb += (current_tb - start_tb);
                new_thread->start_tb = current_tb;
        }

        local_irq_save(flags);
        last = _switch(old_thread, new_thread);

        local_irq_restore(flags);

        return last;
}

static int instructions_to_print = 16;

static void show_instructions(struct pt_regs *regs)
{
        int i;
        unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
                        sizeof(int));

        printk("Instruction dump:");

        for (i = 0; i < instructions_to_print; i++) {
                int instr;

                if (!(i % 8))
                        printk("\n");

                if (((REGION_ID(pc) != KERNEL_REGION_ID) &&
                     (REGION_ID(pc) != VMALLOC_REGION_ID)) ||
                     __get_user(instr, (unsigned int *)pc)) {
                        printk("XXXXXXXX ");
                } else {
                        if (regs->nip == pc)
                                printk("<%08x> ", instr);
                        else
                                printk("%08x ", instr);
                }

                pc += sizeof(int);
        }

        printk("\n");
}

void show_regs(struct pt_regs * regs)
{
        int i;
        unsigned long trap;

        printk("NIP: %016lX XER: %08X LR: %016lX CTR: %016lX\n",
               regs->nip, (unsigned int)regs->xer, regs->link, regs->ctr);
        printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
               regs, regs->trap, print_tainted(), system_utsname.release);
        printk("MSR: %016lx EE: %01x PR: %01x FP: %01x ME: %01x "
               "IR/DR: %01x%01x CR: %08X\n",
               regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
               regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
               regs->msr&MSR_IR ? 1 : 0,
               regs->msr&MSR_DR ? 1 : 0,
               (unsigned int)regs->ccr);
        trap = TRAP(regs);
        printk("DAR: %016lx DSISR: %016lx\n", regs->dar, regs->dsisr);
        printk("TASK: %p[%d] '%s' THREAD: %p",
               current, current->pid, current->comm, current->thread_info);

#ifdef CONFIG_SMP
        printk(" CPU: %d", smp_processor_id());
#endif /* CONFIG_SMP */

        for (i = 0; i < 32; i++) {
                if ((i % 4) == 0) {
                        printk("\n" KERN_INFO "GPR%02d: ", i);
                }

                printk("%016lX ", regs->gpr[i]);
                if (i == 13 && !FULL_REGS(regs))
                        break;
        }
        printk("\n");
        /*
         * Lookup NIP late so we have the best change of getting the
         * above info out without failing
         */
        printk("NIP [%016lx] ", regs->nip);
        print_symbol("%s\n", regs->nip);
        printk("LR [%016lx] ", regs->link);
        print_symbol("%s\n", regs->link);
        show_stack(current, (unsigned long *)regs->gpr[1]);
        if (!user_mode(regs))
                show_instructions(regs);
}

void exit_thread(void)
{
        kprobe_flush_task(current);

#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
        if (last_task_used_altivec == current)
                last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#endif /* CONFIG_SMP */
}

void flush_thread(void)
{
        struct thread_info *t = current_thread_info();

        kprobe_flush_task(current);
        if (t->flags & _TIF_ABI_PENDING)
                t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);

#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
        if (last_task_used_altivec == current)
                last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#endif /* CONFIG_SMP */

        if (current->thread.dabr) {
                current->thread.dabr = 0;
                set_dabr(0);
        }
}

void
release_thread(struct task_struct *t)
{
}


/*
 * This gets called before we allocate a new thread and copy
 * the current task into it.
 */
void prepare_to_copy(struct task_struct *tsk)
{
        flush_fp_to_thread(current);
        flush_altivec_to_thread(current);
}

/*
 * Copy a thread..
 */
int
copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
            unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
        unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;

        /* Copy registers */
        sp -= sizeof(struct pt_regs);
        childregs = (struct pt_regs *) sp;
        *childregs = *regs;
        if ((childregs->msr & MSR_PR) == 0) {
                /* for kernel thread, set stackptr in new task */
                childregs->gpr[1] = sp + sizeof(struct pt_regs);
                p->thread.regs = NULL;  /* no user register state */
                clear_ti_thread_flag(p->thread_info, TIF_32BIT);
        } else {
                childregs->gpr[1] = usp;
                p->thread.regs = childregs;
                if (clone_flags & CLONE_SETTLS) {
                        if (test_thread_flag(TIF_32BIT))
                                childregs->gpr[2] = childregs->gpr[6];
                        else
                                childregs->gpr[13] = childregs->gpr[6];
                }
        }
        childregs->gpr[3] = 0;  /* Result from fork() */
        sp -= STACK_FRAME_OVERHEAD;

        /*
         * The way this works is that at some point in the future
         * some task will call _switch to switch to the new task.
         * That will pop off the stack frame created below and start
         * the new task running at ret_from_fork.  The new task will
         * do some house keeping and then return from the fork or clone
         * system call, using the stack frame created above.
         */
        sp -= sizeof(struct pt_regs);
        kregs = (struct pt_regs *) sp;
        sp -= STACK_FRAME_OVERHEAD;
        p->thread.ksp = sp;
        if (cpu_has_feature(CPU_FTR_SLB)) {
                unsigned long sp_vsid = get_kernel_vsid(sp);

                sp_vsid <<= SLB_VSID_SHIFT;
                sp_vsid |= SLB_VSID_KERNEL;
                if (cpu_has_feature(CPU_FTR_16M_PAGE))
                        sp_vsid |= SLB_VSID_L;

                p->thread.ksp_vsid = sp_vsid;
        }

        /*
         * The PPC64 ABI makes use of a TOC to contain function 
         * pointers.  The function (ret_from_except) is actually a pointer
         * to the TOC entry.  The first entry is a pointer to the actual
         * function.
         */
        kregs->nip = *((unsigned long *)ret_from_fork);

        return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp)
{
        unsigned long entry, toc, load_addr = regs->gpr[2];

        /* fdptr is a relocated pointer to the function descriptor for
         * the elf _start routine.  The first entry in the function
         * descriptor is the entry address of _start and the second
         * entry is the TOC value we need to use.
         */
        set_fs(USER_DS);
        __get_user(entry, (unsigned long __user *)fdptr);
        __get_user(toc, (unsigned long __user *)fdptr+1);

        /* Check whether the e_entry function descriptor entries
         * need to be relocated before we can use them.
         */
        if (load_addr != 0) {
                entry += load_addr;
                toc   += load_addr;
        }

        /*
         * If we exec out of a kernel thread then thread.regs will not be
         * set. Do it now.
         */
        if (!current->thread.regs) {
                unsigned long childregs = (unsigned long)current->thread_info +
                                                THREAD_SIZE;
                childregs -= sizeof(struct pt_regs);
                current->thread.regs = (struct pt_regs *)childregs;
        }

        regs->nip = entry;
        regs->gpr[1] = sp;
        regs->gpr[2] = toc;
        regs->msr = MSR_USER64;
#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = 0;
#endif /* CONFIG_SMP */
        memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
        current->thread.fpscr = 0;
#ifdef CONFIG_ALTIVEC
#ifndef CONFIG_SMP
        if (last_task_used_altivec == current)
                last_task_used_altivec = 0;
#endif /* CONFIG_SMP */
        memset(current->thread.vr, 0, sizeof(current->thread.vr));
        current->thread.vscr.u[0] = 0;
        current->thread.vscr.u[1] = 0;
        current->thread.vscr.u[2] = 0;
        current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
        current->thread.vrsave = 0;
        current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
}
EXPORT_SYMBOL(start_thread);

int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
        struct pt_regs *regs = tsk->thread.regs;

        if (val > PR_FP_EXC_PRECISE)
                return -EINVAL;
        tsk->thread.fpexc_mode = __pack_fe01(val);
        if (regs != NULL && (regs->msr & MSR_FP) != 0)
                regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
                        | tsk->thread.fpexc_mode;
        return 0;
}

int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
        unsigned int val;

        val = __unpack_fe01(tsk->thread.fpexc_mode);
        return put_user(val, (unsigned int __user *) adr);
}

int sys_clone(unsigned long clone_flags, unsigned long p2, unsigned long p3,
              unsigned long p4, unsigned long p5, unsigned long p6,
              struct pt_regs *regs)
{
        unsigned long parent_tidptr = 0;
        unsigned long child_tidptr = 0;

        if (p2 == 0)
                p2 = regs->gpr[1];      /* stack pointer for child */

        if (clone_flags & (CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
                           CLONE_CHILD_CLEARTID)) {
                parent_tidptr = p3;
                child_tidptr = p5;
                if (test_thread_flag(TIF_32BIT)) {
                        parent_tidptr &= 0xffffffff;
                        child_tidptr &= 0xffffffff;
                }
        }

        return do_fork(clone_flags, p2, regs, 0,
                    (int __user *)parent_tidptr, (int __user *)child_tidptr);
}

int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
             unsigned long p4, unsigned long p5, unsigned long p6,
             struct pt_regs *regs)
{
        return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
}

int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
              unsigned long p4, unsigned long p5, unsigned long p6,
              struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1], regs, 0,
                    NULL, NULL);
}

int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
               unsigned long a3, unsigned long a4, unsigned long a5,
               struct pt_regs *regs)
{
        int error;
        char * filename;
        
        filename = getname((char __user *) a0);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        flush_fp_to_thread(current);
        flush_altivec_to_thread(current);
        error = do_execve(filename, (char __user * __user *) a1,
                                    (char __user * __user *) a2, regs);
  
        if (error == 0) {
                task_lock(current);
                current->ptrace &= ~PT_DTRACE;
                task_unlock(current);
        }
        putname(filename);

out:
        return error;
}

static int kstack_depth_to_print = 64;

static int validate_sp(unsigned long sp, struct task_struct *p,
                       unsigned long nbytes)
{
        unsigned long stack_page = (unsigned long)p->thread_info;

        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

#ifdef CONFIG_IRQSTACKS
        stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

        stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;
#endif

        return 0;
}

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long ip, sp;
        int count = 0;

        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        sp = p->thread.ksp;
        if (!validate_sp(sp, p, 112))
                return 0;

        do {
                sp = *(unsigned long *)sp;
                if (!validate_sp(sp, p, 112))
                        return 0;
                if (count > 0) {
                        ip = *(unsigned long *)(sp + 16);
                        if (!in_sched_functions(ip))
                                return ip;
                }
        } while (count++ < 16);
        return 0;
}
EXPORT_SYMBOL(get_wchan);

void show_stack(struct task_struct *p, unsigned long *_sp)
{
        unsigned long ip, newsp, lr;
        int count = 0;
        unsigned long sp = (unsigned long)_sp;
        int firstframe = 1;

        if (sp == 0) {
                if (p) {
                        sp = p->thread.ksp;
                } else {
                        sp = __get_SP();
                        p = current;
                }
        }

        lr = 0;
        printk("Call Trace:\n");
        do {
                if (!validate_sp(sp, p, 112))
                        return;

                _sp = (unsigned long *) sp;
                newsp = _sp[0];
                ip = _sp[2];
                if (!firstframe || ip != lr) {
                        printk("[%016lx] [%016lx] ", sp, ip);
                        print_symbol("%s", ip);
                        if (firstframe)
                                printk(" (unreliable)");
                        printk("\n");
                }
                firstframe = 0;

                /*
                 * See if this is an exception frame.
                 * We look for the "regshere" marker in the current frame.
                 */
                if (validate_sp(sp, p, sizeof(struct pt_regs) + 400)
                    && _sp[12] == 0x7265677368657265ul) {
                        struct pt_regs *regs = (struct pt_regs *)
                                (sp + STACK_FRAME_OVERHEAD);
                        printk("--- Exception: %lx", regs->trap);
                        print_symbol(" at %s\n", regs->nip);
                        lr = regs->link;
                        print_symbol("    LR = %s\n", lr);
                        firstframe = 1;
                }

                sp = newsp;
        } while (count++ < kstack_depth_to_print);
}

void dump_stack(void)
{
        show_stack(current, (unsigned long *)__get_SP());
}
EXPORT_SYMBOL(dump_stack);