ptrace.c

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/*
 * Kernel support for the ptrace() and syscall tracing interfaces.
 *
 * Copyright (C) 1999-2000 Hewlett-Packard Co
 * Copyright (C) 1999-2000 David Mosberger-Tang <[e-mail]>
 *
 * Derived from the x86 and Alpha versions.  Most of the code in here
 * could actually be factored into a common set of routines.
 */
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/smp_lock.h>
#include <linux/user.h>

#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/ptrace_offsets.h>
#include <asm/rse.h>
#include <asm/system.h>
#include <asm/uaccess.h>

/*
 * Bits in the PSR that we allow ptrace() to change:
 *	be, up, ac, mfl, mfh (the user mask; five bits total)
 *	db (debug breakpoint fault; one bit)
 *	id (instruction debug fault disable; one bit)
 *	dd (data debug fault disable; one bit)
 *	ri (restart instruction; two bits)
 *	is (instruction set; one bit)
 */
#define IPSR_WRITE_MASK \
	(IA64_PSR_UM | IA64_PSR_DB | IA64_PSR_IS | IA64_PSR_ID | IA64_PSR_DD | IA64_PSR_RI)
#define IPSR_READ_MASK	IPSR_WRITE_MASK

#ifdef CONFIG_IA64_NEW_UNWIND

#define PTRACE_DEBUG	1

#if PTRACE_DEBUG
# define dprintk(format...)	printk(format)
# define inline
#else
# define dprintk(format...)
#endif

/*
 * Collect the NaT bits for r1-r31 from scratch_unat and return a NaT
 * bitset where bit i is set iff the NaT bit of register i is set.
 */
unsigned long
ia64_get_scratch_nat_bits (struct pt_regs *pt, unsigned long scratch_unat)
{
#	define GET_BITS(first, last, unat)						\
	({										\
		unsigned long bit = ia64_unat_pos(&pt->r##first);			\
		unsigned long mask = ((1UL << (last - first + 1)) - 1) << first;	\
		(ia64_rotl(unat, first) >> bit) & mask;					\
	})
	unsigned long val;

	val  = GET_BITS( 1,  3, scratch_unat);
	val |= GET_BITS(12, 15, scratch_unat);
	val |= GET_BITS( 8, 11, scratch_unat);
	val |= GET_BITS(16, 31, scratch_unat);
	return val;

#	undef GET_BITS
}

/*
 * Set the NaT bits for the scratch registers according to NAT and
 * return the resulting unat (assuming the scratch registers are
 * stored in PT).
 */
unsigned long
ia64_put_scratch_nat_bits (struct pt_regs *pt, unsigned long nat)
{
	unsigned long scratch_unat;

#	define PUT_BITS(first, last, nat)					\
	({									\
		unsigned long bit = ia64_unat_pos(&pt->r##first);		\
		unsigned long mask = ((1UL << (last - first + 1)) - 1) << bit;	\
		(ia64_rotr(nat, first) << bit) & mask;				\
	})
	scratch_unat  = PUT_BITS( 1,  3, nat);
	scratch_unat |= PUT_BITS(12, 15, nat);
	scratch_unat |= PUT_BITS( 8, 11, nat);
	scratch_unat |= PUT_BITS(16, 31, nat);

	return scratch_unat;

#	undef PUT_BITS
}

#else /* !CONFIG_IA64_NEW_UNWIND */

/*
 * Collect the NaT bits for r1-r31 from sw->caller_unat and
 * sw->ar_unat and return a NaT bitset where bit i is set iff the NaT
 * bit of register i is set.
 */
long
ia64_get_nat_bits (struct pt_regs *pt, struct switch_stack *sw)
{
#	define GET_BITS(str, first, last, unat)						\
	({										\
		unsigned long bit = ia64_unat_pos(&str->r##first);			\
		unsigned long mask = ((1UL << (last - first + 1)) - 1) << first;	\
		(ia64_rotl(unat, first) >> bit) & mask;					\
	})
	unsigned long val;

	val  = GET_BITS(pt,  1,  3, sw->caller_unat);
	val |= GET_BITS(pt, 12, 15, sw->caller_unat);
	val |= GET_BITS(pt,  8, 11, sw->caller_unat);
	val |= GET_BITS(pt, 16, 31, sw->caller_unat);
	val |= GET_BITS(sw,  4,  7, sw->ar_unat);
	return val;

#	undef GET_BITS
}

/*
 * Store the NaT bitset NAT in pt->caller_unat and sw->ar_unat.
 */
void
ia64_put_nat_bits (struct pt_regs *pt, struct switch_stack *sw, unsigned long nat)
{
#	define PUT_BITS(str, first, last, nat)					\
	({									\
		unsigned long bit = ia64_unat_pos(&str->r##first);		\
		unsigned long mask = ((1UL << (last - first + 1)) - 1) << bit;	\
		(ia64_rotr(nat, first) << bit) & mask;				\
	})
	sw->caller_unat  = PUT_BITS(pt,  1,  3, nat);
	sw->caller_unat |= PUT_BITS(pt, 12, 15, nat);
	sw->caller_unat |= PUT_BITS(pt,  8, 11, nat);
	sw->caller_unat |= PUT_BITS(pt, 16, 31, nat);
	sw->ar_unat      = PUT_BITS(sw,  4,  7, nat);

#	undef PUT_BITS
}

#endif /* !CONFIG_IA64_NEW_UNWIND */

#define IA64_MLX_TEMPLATE	0x2
#define IA64_MOVL_OPCODE	6

void
ia64_increment_ip (struct pt_regs *regs)
{
	unsigned long w0, ri = ia64_psr(regs)->ri + 1;

	if (ri > 2) {
		ri = 0;
		regs->cr_iip += 16;
	} else if (ri == 2) {
		get_user(w0, (char *) regs->cr_iip + 0);
		if (((w0 >> 1) & 0xf) == IA64_MLX_TEMPLATE) {
			/*
			 * rfi'ing to slot 2 of an MLX bundle causes
			 * an illegal operation fault.  We don't want
			 * that to happen...
			 */
			ri = 0;
			regs->cr_iip += 16;
		}
	}
	ia64_psr(regs)->ri = ri;
}

void
ia64_decrement_ip (struct pt_regs *regs)
{
	unsigned long w0, ri = ia64_psr(regs)->ri - 1;

	if (ia64_psr(regs)->ri == 0) {
		regs->cr_iip -= 16;
		ri = 2;
		get_user(w0, (char *) regs->cr_iip + 0);
		if (((w0 >> 1) & 0xf) == IA64_MLX_TEMPLATE) {
			/*
			 * rfi'ing to slot 2 of an MLX bundle causes
			 * an illegal operation fault.  We don't want
			 * that to happen...
			 */
			ri = 1;
		}
	}
	ia64_psr(regs)->ri = ri;
}

/*
 * This routine is used to read an rnat bits that are stored on the
 * kernel backing store.  Since, in general, the alignment of the user
 * and kernel are different, this is not completely trivial.  In
 * essence, we need to construct the user RNAT based on up to two
 * kernel RNAT values and/or the RNAT value saved in the child's
 * pt_regs.
 *
 * user rbs
 *
 * +--------+ <-- lowest address
 * | slot62 |
 * +--------+
 * |  rnat  | 0x....1f8
 * +--------+
 * | slot00 | \
 * +--------+ |
 * | slot01 | > child_regs->ar_rnat
 * +--------+ |
 * | slot02 | /				kernel rbs
 * +--------+ 				+--------+
 *	    <- child_regs->ar_bspstore	| slot61 | <-- krbs
 * +- - - - +				+--------+
 *					| slot62 |
 * +- - - - +				+--------+
 *					|  rnat	 |
 * +- - - - +				+--------+
 *   vrnat				| slot00 |
 * +- - - - +				+--------+
 *					=	 =
 *					+--------+
 *					| slot00 | \
 *					+--------+ |
 *					| slot01 | > child_stack->ar_rnat
 *					+--------+ |
 *					| slot02 | /
 *					+--------+
 *						  <--- child_stack->ar_bspstore
 *
 * The way to think of this code is as follows: bit 0 in the user rnat
 * corresponds to some bit N (0 <= N <= 62) in one of the kernel rnat
 * value.  The kernel rnat value holding this bit is stored in
 * variable rnat0.  rnat1 is loaded with the kernel rnat value that
 * form the upper bits of the user rnat value.
 *
 * Boundary cases:
 *
 * o when reading the rnat "below" the first rnat slot on the kernel
 *   backing store, rnat0/rnat1 are set to 0 and the low order bits
 *   are merged in from pt->ar_rnat.
 *
 * o when reading the rnat "above" the last rnat slot on the kernel
 *   backing store, rnat0/rnat1 gets its value from sw->ar_rnat.
 */
static unsigned long
get_rnat (struct pt_regs *pt, struct switch_stack *sw,
	  unsigned long *krbs, unsigned long *urnat_addr)
{
	unsigned long rnat0 = 0, rnat1 = 0, urnat = 0, *slot0_kaddr, kmask = ~0UL;
	unsigned long *kbsp, *ubspstore, *rnat0_kaddr, *rnat1_kaddr, shift;
	long num_regs;

	kbsp = (unsigned long *) sw->ar_bspstore;
	ubspstore = (unsigned long *) pt->ar_bspstore;
	/*
	 * First, figure out which bit number slot 0 in user-land maps
	 * to in the kernel rnat.  Do this by figuring out how many
	 * register slots we're beyond the user's backingstore and
	 * then computing the equivalent address in kernel space.
	 */
	num_regs = ia64_rse_num_regs(ubspstore, urnat_addr + 1);
	slot0_kaddr = ia64_rse_skip_regs(krbs, num_regs);
	shift = ia64_rse_slot_num(slot0_kaddr);
	rnat1_kaddr = ia64_rse_rnat_addr(slot0_kaddr);
	rnat0_kaddr = rnat1_kaddr - 64;

	if (ubspstore + 63 > urnat_addr) {
		/* some bits need to be merged in from pt->ar_rnat */
		kmask = ~((1UL << ia64_rse_slot_num(ubspstore)) - 1);
		urnat = (pt->ar_rnat & ~kmask);
	} 
	if (rnat0_kaddr >= kbsp) {
		rnat0 = sw->ar_rnat;
	} else if (rnat0_kaddr > krbs) {
		rnat0 = *rnat0_kaddr;
	}
	if (rnat1_kaddr >= kbsp) {
		rnat1 = sw->ar_rnat;
	} else if (rnat1_kaddr > krbs) {
		rnat1 = *rnat1_kaddr;
	}
	urnat |= ((rnat1 << (63 - shift)) | (rnat0 >> shift)) & kmask;
	return urnat;
}

/*
 * The reverse of get_rnat.
 */
static void
put_rnat (struct pt_regs *pt, struct switch_stack *sw,
	  unsigned long *krbs, unsigned long *urnat_addr, unsigned long urnat)
{
	unsigned long rnat0 = 0, rnat1 = 0, rnat = 0, *slot0_kaddr, kmask = ~0UL, mask;
	unsigned long *kbsp, *ubspstore, *rnat0_kaddr, *rnat1_kaddr, shift;
	long num_regs;

	kbsp = (unsigned long *) sw->ar_bspstore;
	ubspstore = (unsigned long *) pt->ar_bspstore;
	/*
	 * First, figure out which bit number slot 0 in user-land maps
	 * to in the kernel rnat.  Do this by figuring out how many
	 * register slots we're beyond the user's backingstore and
	 * then computing the equivalent address in kernel space.
	 */
	num_regs = (long) ia64_rse_num_regs(ubspstore, urnat_addr + 1);
	slot0_kaddr = ia64_rse_skip_regs(krbs, num_regs);
	shift = ia64_rse_slot_num(slot0_kaddr);
	rnat1_kaddr = ia64_rse_rnat_addr(slot0_kaddr);
	rnat0_kaddr = rnat1_kaddr - 64;

	if (ubspstore + 63 > urnat_addr) {
		/* some bits need to be place in pt->ar_rnat: */
		kmask = ~((1UL << ia64_rse_slot_num(ubspstore)) - 1);
		pt->ar_rnat = (pt->ar_rnat & kmask) | (rnat & ~kmask);
	} 
	/*
	 * Note: Section 11.1 of the EAS guarantees that bit 63 of an
	 * rnat slot is ignored. so we don't have to clear it here.
	 */
	rnat0 = (urnat << shift);
	mask = ~0UL << shift;
	if (rnat0_kaddr >= kbsp) {
		sw->ar_rnat = (sw->ar_rnat & ~mask) | (rnat0 & mask);
	} else if (rnat0_kaddr > krbs) {
		*rnat0_kaddr = ((*rnat0_kaddr & ~mask) | (rnat0 & mask));
	}

	rnat1 = (urnat >> (63 - shift));
	mask = ~0UL >> (63 - shift);
	if (rnat1_kaddr >= kbsp) {
		sw->ar_rnat = (sw->ar_rnat & ~mask) | (rnat1 & mask);
	} else if (rnat1_kaddr > krbs) {
		*rnat1_kaddr = ((*rnat1_kaddr & ~mask) | (rnat1 & mask));
	}
}

long
ia64_peek (struct pt_regs *regs, struct task_struct *child, unsigned long addr, long *val)
{
	unsigned long *bspstore, *krbs, krbs_num_regs, regnum, *rbs_end, *laddr;
	struct switch_stack *child_stack;
	struct pt_regs *child_regs;
	size_t copied;
	long ret;

	laddr = (unsigned long *) addr;
	child_regs = ia64_task_regs(child);
#ifdef CONFIG_IA64_NEW_UNWIND
	child_stack = (struct switch_stack *) (child->thread.ksp + 16);
#else
	child_stack = (struct switch_stack *) child_regs - 1;
#endif
	bspstore = (unsigned long *) child_regs->ar_bspstore;
	krbs = (unsigned long *) child + IA64_RBS_OFFSET/8;
	krbs_num_regs = ia64_rse_num_regs(krbs, (unsigned long *) child_stack->ar_bspstore);
	rbs_end = ia64_rse_skip_regs(bspstore, krbs_num_regs);
	if (laddr >= bspstore && laddr <= ia64_rse_rnat_addr(rbs_end)) {
		/*
		 * Attempt to read the RBS in an area that's actually
		 * on the kernel RBS => read the corresponding bits in
		 * the kernel RBS.
		 */
		if (ia64_rse_is_rnat_slot(laddr))
			ret = get_rnat(child_regs, child_stack, krbs, laddr);
		else {
			regnum = ia64_rse_num_regs(bspstore, laddr);
			laddr = ia64_rse_skip_regs(krbs, regnum);
			if (regnum >= krbs_num_regs) {
				ret = 0;
			} else {
				if  ((unsigned long) laddr >= (unsigned long) high_memory) {
					printk("yikes: trying to access long at %p\n",
					       (void *) laddr);
					return -EIO;
				}
				ret = *laddr;
			}
		}
	} else {
		copied = access_process_vm(child, addr, &ret, sizeof(ret), 0);
		if (copied != sizeof(ret))
			return -EIO;
	}
	*val = ret;
	return 0;
}

long
ia64_poke (struct pt_regs *regs, struct task_struct *child, unsigned long addr, long val)
{
	unsigned long *bspstore, *krbs, krbs_num_regs, regnum, *rbs_end, *laddr;
	struct switch_stack *child_stack;
	struct pt_regs *child_regs;

	laddr = (unsigned long *) addr;
	child_regs = ia64_task_regs(child);
#ifdef CONFIG_IA64_NEW_UNWIND
	child_stack = (struct switch_stack *) (child->thread.ksp + 16);
#else
	child_stack = (struct switch_stack *) child_regs - 1;
#endif
	bspstore = (unsigned long *) child_regs->ar_bspstore;
	krbs = (unsigned long *) child + IA64_RBS_OFFSET/8;
	krbs_num_regs = ia64_rse_num_regs(krbs, (unsigned long *) child_stack->ar_bspstore);
	rbs_end = ia64_rse_skip_regs(bspstore, krbs_num_regs);
	if (laddr >= bspstore && laddr <= ia64_rse_rnat_addr(rbs_end)) {
		/*
		 * Attempt to write the RBS in an area that's actually
		 * on the kernel RBS => write the corresponding bits
		 * in the kernel RBS.
		 */
		if (ia64_rse_is_rnat_slot(laddr))
			put_rnat(child_regs, child_stack, krbs, laddr, val);
		else {