ptrace.c

linux-2.6.15.6

/* ptrace.c: Sparc process tracing support.
 *
 * Copyright (C) 1996 David S. Miller ([e-mail])
 * Copyright (C) 1997 Jakub Jelinek ([e-mail])
 *
 * Based upon code written by Ross Biro, Linus Torvalds, Bob Manson,
 * and David Mosberger.
 *
 * Added Linux support -miguel (weird, eh?, the original 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 <linux/security.h>
#include <linux/seccomp.h>
#include <linux/audit.h>
#include <linux/signal.h>

#include <asm/asi.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/psrcompat.h>
#include <asm/visasm.h>
#include <asm/spitfire.h>
#include <asm/page.h>
#include <asm/cpudata.h>

/* 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->tstate |= (TSTATE_ICARRY | TSTATE_XCARRY);
	regs->tpc = regs->tnpc;
	regs->tnpc += 4;
}

static inline void pt_succ_return(struct pt_regs *regs, unsigned long value)
{
	regs->u_regs[UREG_I0] = value;
	regs->tstate &= ~(TSTATE_ICARRY | TSTATE_XCARRY);
	regs->tpc = regs->tnpc;
	regs->tnpc += 4;
}

static inline void
pt_succ_return_linux(struct pt_regs *regs, unsigned long value, void __user *addr)
{
	if (test_thread_flag(TIF_32BIT)) {
		if (put_user(value, (unsigned int __user *) addr)) {
			pt_error_return(regs, EFAULT);
			return;
		}
	} else {
		if (put_user(value, (long __user *) addr)) {
			pt_error_return(regs, EFAULT);
			return;
		}
	}
	regs->u_regs[UREG_I0] = 0;
	regs->tstate &= ~(TSTATE_ICARRY | TSTATE_XCARRY);
	regs->tpc = regs->tnpc;
	regs->tnpc += 4;
}

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

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

#ifdef DEBUG_PTRACE
char *pt_rq [] = {
	/* 0  */ "TRACEME", "PEEKTEXT", "PEEKDATA", "PEEKUSR",
	/* 4  */ "POKETEXT", "POKEDATA", "POKEUSR", "CONT",
	/* 8  */ "KILL", "SINGLESTEP", "SUNATTACH", "SUNDETACH",
	/* 12 */ "GETREGS", "SETREGS", "GETFPREGS", "SETFPREGS",
	/* 16 */ "READDATA", "WRITEDATA", "READTEXT", "WRITETEXT",
	/* 20 */ "GETFPAREGS", "SETFPAREGS", "unknown", "unknown",
	/* 24 */ "SYSCALL", ""
};
#endif

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
	/* nothing to do */
}

/* To get the necessary page struct, access_process_vm() first calls
 * get_user_pages().  This has done a flush_dcache_page() on the
 * accessed page.  Then our caller (copy_{to,from}_user_page()) did
 * to memcpy to read/write the data from that page.
 *
 * Now, the only thing we have to do is:
 * 1) flush the D-cache if it's possible than an illegal alias
 *    has been created
 * 2) flush the I-cache if this is pre-cheetah and we did a write
 */
void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
			 unsigned long uaddr, void *kaddr,
			 unsigned long len, int write)
{
	BUG_ON(len > PAGE_SIZE);

#ifdef DCACHE_ALIASING_POSSIBLE
	/* If bit 13 of the kernel address we used to access the
	 * user page is the same as the virtual address that page
	 * is mapped to in the user's address space, we can skip the
	 * D-cache flush.
	 */
	if ((uaddr ^ (unsigned long) kaddr) & (1UL << 13)) {
		unsigned long start = __pa(kaddr);
		unsigned long end = start + len;
		unsigned long dcache_line_size;

		dcache_line_size = local_cpu_data().dcache_line_size;

		if (tlb_type == spitfire) {
			for (; start < end; start += dcache_line_size)
				spitfire_put_dcache_tag(start & 0x3fe0, 0x0);
		} else {
			start &= ~(dcache_line_size - 1);
			for (; start < end; start += dcache_line_size)
				__asm__ __volatile__(
					"stxa %%g0, [%0] %1\n\t"
					"membar #Sync"
					: /* no outputs */
					: "r" (start),
					"i" (ASI_DCACHE_INVALIDATE));
		}
	}
#endif
	if (write && tlb_type == spitfire) {
		unsigned long start = (unsigned long) kaddr;
		unsigned long end = start + len;
		unsigned long icache_line_size;

		icache_line_size = local_cpu_data().icache_line_size;

		for (; start < end; start += icache_line_size)
			flushi(start);
	}
}

asmlinkage void do_ptrace(struct pt_regs *regs)
{
	int request = regs->u_regs[UREG_I0];
	pid_t 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;
	int ret;

	if (test_thread_flag(TIF_32BIT)) {
		addr &= 0xffffffffUL;
		data &= 0xffffffffUL;
		addr2 &= 0xffffffffUL;
	}
	lock_kernel();
#ifdef DEBUG_PTRACE
	{
		char *s;

		if ((request >= 0) && (request <= 24))
			s = pt_rq [request];
		else
			s = "unknown";

		if (request == PTRACE_POKEDATA && data == 0x91d02001){
			printk ("do_ptrace: breakpoint pid=%d, addr=%016lx addr2=%016lx\n",
				pid, addr, addr2);
		} else 
			printk("do_ptrace: rq=%s(%d) pid=%d addr=%016lx data=%016lx addr2=%016lx\n",
			       s, request, pid, addr, data, addr2);
	}
#endif
	if (request == PTRACE_TRACEME) {
		int ret;

		/* are we already being traced? */
		if (current->ptrace & PT_PTRACED) {
			pt_error_return(regs, EPERM);
			goto out;
		}
		ret = security_ptrace(current->parent, current);
		if (ret) {
			pt_error_return(regs, -ret);
			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
	read_lock(&tasklist_lock);
	child = find_task_by_pid(pid);
	if (child)
		get_task_struct(child);
	read_unlock(&tasklist_lock);

	if (!child) {
		pt_error_return(regs, ESRCH);
		goto out;
	}

	if ((current->personality == PER_SUNOS && request == PTRACE_SUNATTACH)
	    || (current->personality != PER_SUNOS && request == PTRACE_ATTACH)) {
		if (ptrace_attach(child)) {
			pt_error_return(regs, EPERM);
			goto out_tsk;
		}
		pt_succ_return(regs, 0);
		goto out_tsk;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (ret < 0) {
		pt_error_return(regs, -ret);
		goto out_tsk;
	}

	if (!(test_thread_flag(TIF_32BIT))	&&
	    ((request == PTRACE_READDATA64)		||
	     (request == PTRACE_WRITEDATA64)		||
	     (request == PTRACE_READTEXT64)		||
	     (request == PTRACE_WRITETEXT64)		||
	     (request == PTRACE_PEEKTEXT64)		||
	     (request == PTRACE_POKETEXT64)		||
	     (request == PTRACE_PEEKDATA64)		||
	     (request == PTRACE_POKEDATA64))) {
		addr = regs->u_regs[UREG_G2];
		addr2 = regs->u_regs[UREG_G3];
		request -= 30; /* wheee... */
	}

	switch(request) {
	case PTRACE_PEEKTEXT: /* read word at location addr. */ 
	case PTRACE_PEEKDATA: {
		unsigned long tmp64;
		unsigned int tmp32;
		int res, copied;

		res = -EIO;
		if (test_thread_flag(TIF_32BIT)) {
			copied = access_process_vm(child, addr,
						   &tmp32, sizeof(tmp32), 0);
			tmp64 = (unsigned long) tmp32;
			if (copied == sizeof(tmp32))
				res = 0;
		} else {
			copied = access_process_vm(child, addr,
						   &tmp64, sizeof(tmp64), 0);
			if (copied == sizeof(tmp64))
				res = 0;
		}
		if (res < 0)
			pt_error_return(regs, -res);
		else
			pt_os_succ_return(regs, tmp64, (void __user *) data);
		goto out_tsk;
	}

	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA: {
		unsigned long tmp64;
		unsigned int tmp32;
		int copied, res = -EIO;

		if (test_thread_flag(TIF_32BIT)) {
			tmp32 = data;
			copied = access_process_vm(child, addr,
						   &tmp32, sizeof(tmp32), 1);
			if (copied == sizeof(tmp32))
				res = 0;
		} else {
			tmp64 = data;
			copied = access_process_vm(child, addr,
						   &tmp64, sizeof(tmp64), 1);
			if (copied == sizeof(tmp64))
				res = 0;
		}
		if (res < 0)
			pt_error_return(regs, -res);
		else
			pt_succ_return(regs, res);
		goto out_tsk;
	}

	case PTRACE_GETREGS: {
		struct pt_regs32 __user *pregs =
			(struct pt_regs32 __user *) addr;
		struct pt_regs *cregs = child->thread_info->kregs;
		int rval;

		if (__put_user(tstate_to_psr(cregs->tstate), (&pregs->psr)) ||
		    __put_user(cregs->tpc, (&pregs->pc)) ||
		    __put_user(cregs->tnpc, (&pregs->npc)) ||
		    __put_user(cregs->y, (&pregs->y))) {
			pt_error_return(regs, EFAULT);
			goto out_tsk;
		}
		for (rval = 1; rval < 16; rval++)
			if (__put_user(cregs->u_regs[rval], (&pregs->u_regs[rval - 1]))) {
				pt_error_return(regs, EFAULT);
				goto out_tsk;
			}
		pt_succ_return(regs, 0);
#ifdef DEBUG_PTRACE
		printk ("PC=%lx nPC=%lx o7=%lx\n", cregs->tpc, cregs->tnpc, cregs->u_regs [15]);
#endif
		goto out_tsk;
	}