ptrace.c

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/* ptrace.c: Sparc process tracing support.
 *
 * Copyright (C) 1996 David S. Miller ([e-mail])
 *
 * Based upon code written by Ross Biro, Linus Torvalds, Bob Manson,
 * and David Mosberger.
 *
 * Added Linux support -miguel (wierd, eh?, the orignal code was meant
 * to emulate SunOS).
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#define MAGIC_CONSTANT 0x80000000


/* Returning from ptrace is a bit tricky because the syscall return
 * low level code assumes any value returned which is negative and
 * is a valid errno will mean setting the condition codes to indicate
 * an error return.  This doesn't work, so we have this hook.
 */
static inline void pt_error_return(struct pt_regs *regs, unsigned long error)
{
	regs->u_regs[UREG_I0] = error;
	regs->psr |= PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static inline void pt_succ_return(struct pt_regs *regs, unsigned long value)
{
	regs->u_regs[UREG_I0] = value;
	regs->psr &= ~PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static void
pt_succ_return_linux(struct pt_regs *regs, unsigned long value, long *addr)
{
	if(put_user(value, addr))
		return pt_error_return(regs, EFAULT);
	regs->u_regs[UREG_I0] = 0;
	regs->psr &= ~PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static void
pt_os_succ_return (struct pt_regs *regs, unsigned long val, long *addr)
{
	if (current->personality == PER_SUNOS)
		pt_succ_return (regs, val);
	else
		pt_succ_return_linux (regs, val, addr);
}

/* Fuck me gently with a chainsaw... */
static inline void read_sunos_user(struct pt_regs *regs, unsigned long offset,
				   struct task_struct *tsk, long *addr)
{
	struct pt_regs *cregs = tsk->thread.kregs;
	struct thread_struct *t = &tsk->thread;
	int v;
	
	if(offset >= 1024)
		offset -= 1024; /* whee... */
	if(offset & ((sizeof(unsigned long) - 1))) {
		pt_error_return(regs, EIO);
		return;
	}
	if(offset >= 16 && offset < 784) {
		offset -= 16; offset >>= 2;
		pt_os_succ_return(regs, *(((unsigned long *)(&t->reg_window[0]))+offset), addr);
		return;
	}
	if(offset >= 784 && offset < 832) {
		offset -= 784; offset >>= 2;
		pt_os_succ_return(regs, *(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset), addr);
		return;
	}
	switch(offset) {
	case 0:
		v = t->ksp;
		break;
	case 4:
		v = t->kpc;
		break;
	case 8:
		v = t->kpsr;
		break;
	case 12:
		v = t->uwinmask;
		break;
	case 832:
		v = t->w_saved;
		break;
	case 896:
		v = cregs->u_regs[UREG_I0];
		break;
	case 900:
		v = cregs->u_regs[UREG_I1];
		break;
	case 904:
		v = cregs->u_regs[UREG_I2];
		break;
	case 908:
		v = cregs->u_regs[UREG_I3];
		break;
	case 912:
		v = cregs->u_regs[UREG_I4];
		break;
	case 916:
		v = cregs->u_regs[UREG_I5];
		break;
	case 920:
		v = cregs->u_regs[UREG_I6];
		break;
	case 924:
		if(tsk->thread.flags & MAGIC_CONSTANT)
			v = cregs->u_regs[UREG_G1];
		else
			v = 0;
		break;
	case 940:
		v = cregs->u_regs[UREG_I0];
		break;
	case 944:
		v = cregs->u_regs[UREG_I1];
		break;

	case 948:
		/* Isn't binary compatibility _fun_??? */
		if(cregs->psr & PSR_C)
			v = cregs->u_regs[UREG_I0] << 24;
		else
			v = 0;
		break;

		/* Rest of them are completely unsupported. */
	default:
		printk("%s [%d]: Wants to read user offset %ld\n",
		       current->comm, current->pid, offset);
		pt_error_return(regs, EIO);
		return;
	}
	if (current->personality == PER_SUNOS)
		pt_succ_return (regs, v);
	else
		pt_succ_return_linux (regs, v, addr);
	return;
}

static inline void write_sunos_user(struct pt_regs *regs, unsigned long offset,
				    struct task_struct *tsk)
{
	struct pt_regs *cregs = tsk->thread.kregs;
	struct thread_struct *t = &tsk->thread;
	unsigned long value = regs->u_regs[UREG_I3];

	if(offset >= 1024)
		offset -= 1024; /* whee... */
	if(offset & ((sizeof(unsigned long) - 1)))
		goto failure;
	if(offset >= 16 && offset < 784) {
		offset -= 16; offset >>= 2;
		*(((unsigned long *)(&t->reg_window[0]))+offset) = value;
		goto success;
	}
	if(offset >= 784 && offset < 832) {
		offset -= 784; offset >>= 2;
		*(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset) = value;
		goto success;
	}
	switch(offset) {
	case 896:
		cregs->u_regs[UREG_I0] = value;
		break;
	case 900:
		cregs->u_regs[UREG_I1] = value;
		break;
	case 904:
		cregs->u_regs[UREG_I2] = value;
		break;
	case 908:
		cregs->u_regs[UREG_I3] = value;
		break;
	case 912:
		cregs->u_regs[UREG_I4] = value;
		break;
	case 916:
		cregs->u_regs[UREG_I5] = value;
		break;
	case 920:
		cregs->u_regs[UREG_I6] = value;
		break;
	case 924:
		cregs->u_regs[UREG_I7] = value;
		break;
	case 940:
		cregs->u_regs[UREG_I0] = value;
		break;
	case 944:
		cregs->u_regs[UREG_I1] = value;
		break;

		/* Rest of them are completely unsupported or "no-touch". */
	default:
		printk("%s [%d]: Wants to write user offset %ld\n",
		       current->comm, current->pid, offset);
		goto failure;
	}
success:
	pt_succ_return(regs, 0);
	return;
failure:
	pt_error_return(regs, EIO);
	return;
}

/* #define ALLOW_INIT_TRACING */
/* #define DEBUG_PTRACE */

#ifdef DEBUG_PTRACE
char *pt_rq [] = {
"TRACEME",
"PEEKTEXT",
"PEEKDATA",
"PEEKUSR",
"POKETEXT",
"POKEDATA",
"POKEUSR",
"CONT",
"KILL",
"SINGLESTEP",
"SUNATTACH",
"SUNDETACH",
"GETREGS",
"SETREGS",
"GETFPREGS",
"SETFPREGS",
"READDATA",
"WRITEDATA",
"READTEXT",
"WRITETEXT",
"GETFPAREGS",
"SETFPAREGS",
""
};
#endif

asmlinkage void do_ptrace(struct pt_regs *regs)
{
	unsigned long request = regs->u_regs[UREG_I0];
	unsigned long pid = regs->u_regs[UREG_I1];
	unsigned long addr = regs->u_regs[UREG_I2];
	unsigned long data = regs->u_regs[UREG_I3];
	unsigned long addr2 = regs->u_regs[UREG_I4];
	struct task_struct *child;

	lock_kernel();
#ifdef DEBUG_PTRACE
	{
		char *s;

		if ((request > 0) && (request < 21))
			s = pt_rq [request];
		else
			s = "unknown";

		if (request == PTRACE_POKEDATA && data == 0x91d02001){
			printk ("do_ptrace: breakpoint pid=%d, addr=%08lx addr2=%08lx\n",
				pid, addr, addr2);
		} else 
			printk("do_ptrace: rq=%s(%d) pid=%d addr=%08lx data=%08lx addr2=%08lx\n",
			       s, (int) request, (int) pid, addr, data, addr2);
	}
#endif
	if(request == PTRACE_TRACEME) {
		/* are we already being traced? */
		if (current->ptrace & PT_PTRACED) {
			pt_error_return(regs, EPERM);
			goto out;
		}
		/* set the ptrace bit in the process flags. */
		current->ptrace |= PT_PTRACED;
		pt_succ_return(regs, 0);
		goto out;
	}
#ifndef ALLOW_INIT_TRACING
	if(pid == 1) {
		/* Can't dork with init. */
		pt_error_return(regs, EPERM);
		goto out;
	}
#endif
	if(!(child = find_task_by_pid(pid))) {
		pt_error_return(regs, ESRCH);
		goto out;
	}

	if ((current->personality == PER_SUNOS && request == PTRACE_SUNATTACH)
	    || (current->personality != PER_SUNOS && request == PTRACE_ATTACH)) {
		unsigned long flags;

		if(child == current) {
			/* Try this under SunOS/Solaris, bwa haha
			 * You'll never be able to kill the process. ;-)
			 */
			pt_error_return(regs, EPERM);
			goto out;
		}
		if((!child->dumpable ||
		    (current->uid != child->euid) ||
		    (current->uid != child->uid) ||
		    (current->uid != child->suid) ||
		    (current->gid != child->egid) ||
		    (current->gid != child->sgid) ||