unwind.c

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		pop(&sr);
	STAT(unw.stat.script.parse_time += ia64_get_itc() - parse_start);

	script_finalize(script, &sr);
	STAT(unw.stat.script.build_time += ia64_get_itc() - start);
	return script;
}

/*
 * Apply the unwinding actions represented by OPS and update SR to
 * reflect the state that existed upon entry to the function that this
 * unwinder represents.
 */
static inline void
run_script (struct unw_script *script, struct unw_frame_info *state)
{
	struct unw_insn *ip, *limit, next_insn;
	unsigned long opc, dst, val, off;
	unsigned long *s = (unsigned long *) state;
	STAT(unsigned long start;)

	STAT(++unw.stat.script.runs; start = ia64_get_itc());
	state->flags = script->flags;
	ip = script->insn;
	limit = script->insn + script->count;
	next_insn = *ip;

	while (ip++ < limit) {
		opc = next_insn.opc;
		dst = next_insn.dst;
		val = next_insn.val;
		next_insn = *ip;

	  redo:
		switch (opc) {
		      case UNW_INSN_ADD:
			s[dst] += val;
			break;

		      case UNW_INSN_MOVE2:
			if (!s[val])
				goto lazy_init;
			s[dst+1] = s[val+1];
			s[dst] = s[val];
			break;

		      case UNW_INSN_MOVE:
			if (!s[val])
				goto lazy_init;
			s[dst] = s[val];
			break;

		      case UNW_INSN_MOVE_STACKED:
			s[dst] = (unsigned long) ia64_rse_skip_regs((unsigned long *)state->bsp,
								    val);
			break;

		      case UNW_INSN_ADD_PSP:
			s[dst] = state->psp + val;
			break;

		      case UNW_INSN_ADD_SP:
			s[dst] = state->sp + val;
			break;

		      case UNW_INSN_SETNAT_MEMSTK:
			if (!state->pri_unat_loc)
				state->pri_unat_loc = &state->sw->ar_unat;
			/* register off. is a multiple of 8, so the least 3 bits (type) are 0 */
			s[dst+1] = (*state->pri_unat_loc - s[dst]) | UNW_NAT_MEMSTK;
			break;

		      case UNW_INSN_SETNAT_TYPE:
			s[dst+1] = val;
			break;

		      case UNW_INSN_LOAD:
#if UNW_DEBUG
			if ((s[val] & (local_cpu_data->unimpl_va_mask | 0x7)) != 0
			    || s[val] < TASK_SIZE)
			{
				debug(1, "unwind: rejecting bad psp=0x%lx\n", s[val]);
				break;
			}
#endif
			s[dst] = *(unsigned long *) s[val];
			break;
		}
	}
	STAT(unw.stat.script.run_time += ia64_get_itc() - start);
	return;

  lazy_init:
	off = unw.sw_off[val];
	s[val] = (unsigned long) state->sw + off;
	if (off >= struct_offset(struct switch_stack, r4)
	    && off <= struct_offset(struct switch_stack, r7))
		/*
		 * We're initializing a general register: init NaT info, too.  Note that
		 * the offset is a multiple of 8 which gives us the 3 bits needed for
		 * the type field.
		 */
		s[val+1] = (struct_offset(struct switch_stack, ar_unat) - off) | UNW_NAT_MEMSTK;
	goto redo;
}

static int
find_save_locs (struct unw_frame_info *info)
{
	int have_write_lock = 0;
	struct unw_script *scr;

	if ((info->ip & (local_cpu_data->unimpl_va_mask | 0xf)) || info->ip < TASK_SIZE) {
		/* don't let obviously bad addresses pollute the cache */
		debug(1, "unwind: rejecting bad ip=0x%lx\n", info->ip);
		info->rp_loc = 0;
		return -1;
	}

	scr = script_lookup(info);
	if (!scr) {
		scr = build_script(info);
		if (!scr) {
			dprintk("unwind: failed to locate/build unwind script for ip %lx\n",
				info->ip);
			return -1;
		}
		have_write_lock = 1;
	}
	info->hint = scr->hint;
	info->prev_script = scr - unw.cache;

	run_script(scr, info);

	if (have_write_lock)
		write_unlock(&scr->lock);
	else
		read_unlock(&scr->lock);
	return 0;
}

int
unw_unwind (struct unw_frame_info *info)
{
	unsigned long prev_ip, prev_sp, prev_bsp;
	unsigned long ip, pr, num_regs;
	STAT(unsigned long start, flags;)
	int retval;

	STAT(local_irq_save(flags); ++unw.stat.api.unwinds; start = ia64_get_itc());

	prev_ip = info->ip;
	prev_sp = info->sp;
	prev_bsp = info->bsp;

	/* restore the ip */
	if (!info->rp_loc) {
		debug(1, "unwind: failed to locate return link (ip=0x%lx)!\n", info->ip);
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}
	ip = info->ip = *info->rp_loc;
	if (ip < GATE_ADDR + PAGE_SIZE) {
		/*
		 * We don't have unwind info for the gate page, so we consider that part
		 * of user-space for the purpose of unwinding.
		 */
		debug(1, "unwind: reached user-space (ip=0x%lx)\n", ip);
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}

	/* restore the cfm: */
	if (!info->pfs_loc) {
		dprintk("unwind: failed to locate ar.pfs!\n");
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}
	info->cfm_loc = info->pfs_loc;

	/* restore the bsp: */
	pr = info->pr;
	num_regs = 0;
	if ((info->flags & UNW_FLAG_INTERRUPT_FRAME)) {
		if ((pr & (1UL << pNonSys)) != 0)
			num_regs = *info->cfm_loc & 0x7f;		/* size of frame */
		info->pfs_loc =
			(unsigned long *) (info->sp + 16 + struct_offset(struct pt_regs, ar_pfs));
	} else
		num_regs = (*info->cfm_loc >> 7) & 0x7f;	/* size of locals */
	info->bsp = (unsigned long) ia64_rse_skip_regs((unsigned long *) info->bsp, -num_regs);
	if (info->bsp < info->regstk.limit || info->bsp > info->regstk.top) {
		dprintk("unwind: bsp (0x%lx) out of range [0x%lx-0x%lx]\n",
			info->bsp, info->regstk.limit, info->regstk.top);
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}

	/* restore the sp: */
	info->sp = info->psp;
	if (info->sp < info->memstk.top || info->sp > info->memstk.limit) {
		dprintk("unwind: sp (0x%lx) out of range [0x%lx-0x%lx]\n",
			info->sp, info->memstk.top, info->memstk.limit);
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}

	if (info->ip == prev_ip && info->sp == prev_sp && info->bsp == prev_bsp) {
		dprintk("unwind: ip, sp, bsp remain unchanged; stopping here (ip=0x%lx)\n", ip);
		STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
		return -1;
	}

	/* as we unwind, the saved ar.unat becomes the primary unat: */
	info->pri_unat_loc = info->unat_loc;

	/* finally, restore the predicates: */
	unw_get_pr(info, &info->pr);

	retval = find_save_locs(info);
	STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
	return retval;
}

int
unw_unwind_to_user (struct unw_frame_info *info)
{
	unsigned long ip;

	while (unw_unwind(info) >= 0) {
		if (unw_get_rp(info, &ip) < 0) {
			unw_get_ip(info, &ip);
			dprintk("unwind: failed to read return pointer (ip=0x%lx)\n", ip);
			return -1;
		}
		/*
		 * We don't have unwind info for the gate page, so we consider that part
		 * of user-space for the purpose of unwinding.
		 */
		if (ip < GATE_ADDR + PAGE_SIZE)
			return 0;
	}
	unw_get_ip(info, &ip);
	dprintk("unwind: failed to unwind to user-level (ip=0x%lx)\n", ip);
	return -1;
}

void
unw_init_frame_info (struct unw_frame_info *info, struct task_struct *t, struct switch_stack *sw)
{
	unsigned long rbslimit, rbstop, stklimit, stktop, sol;
	STAT(unsigned long start, flags;)

	STAT(local_irq_save(flags); ++unw.stat.api.inits; start = ia64_get_itc());

	/*
	 * Subtle stuff here: we _could_ unwind through the
	 * switch_stack frame but we don't want to do that because it
	 * would be slow as each preserved register would have to be
	 * processed.  Instead, what we do here is zero out the frame
	 * info and start the unwind process at the function that
	 * created the switch_stack frame.  When a preserved value in
	 * switch_stack needs to be accessed, run_script() will
	 * initialize the appropriate pointer on demand.
	 */
	memset(info, 0, sizeof(*info));

	rbslimit = (unsigned long) t + IA64_RBS_OFFSET;
	rbstop   = sw->ar_bspstore;
	if (rbstop - (unsigned long) t >= IA64_STK_OFFSET)
		rbstop = rbslimit;

	stklimit = (unsigned long) t + IA64_STK_OFFSET;
	stktop   = (unsigned long) sw - 16;
	if (stktop <= rbstop)
		stktop = rbstop;

	info->regstk.limit = rbslimit;
	info->regstk.top   = rbstop;
	info->memstk.limit = stklimit;
	info->memstk.top   = stktop;
	info->task = t;
	info->sw  = sw;
	info->sp = info->psp = (unsigned long) (sw + 1) - 16;
	info->cfm_loc = &sw->ar_pfs;
	sol = (*info->cfm_loc >> 7) & 0x7f;
	info->bsp = (unsigned long) ia64_rse_skip_regs((unsigned long *) info->regstk.top, -sol);
	info->ip = sw->b0;
	info->pr = sw->pr;

	find_save_locs(info);
	STAT(unw.stat.api.init_time += ia64_get_itc() - start; local_irq_restore(flags));
}

void
unw_init_from_blocked_task (struct unw_frame_info *info, struct task_struct *t)
{
	struct switch_stack *sw = (struct switch_stack *) (t->thread.ksp + 16);

	unw_init_frame_info(info, t, sw);
}

static void
init_unwind_table (struct unw_table *table, const char *name, unsigned long segment_base,
		   unsigned long gp, const void *table_start, const void *table_end)
{
	const struct unw_table_entry *start = table_start, *end = table_end;

	table->name = name;
	table->segment_base = segment_base;
	table->gp = gp;
	table->start = segment_base + start[0].start_offset;
	table->end = segment_base + end[-1].end_offset;
	table->array = start;
	table->length = end - start;
}

void *
unw_add_unwind_table (const char *name, unsigned long segment_base, unsigned long gp,
		      const void *table_start, const void *table_end)
{
	const struct unw_table_entry *start = table_start, *end = table_end;
	struct unw_table *table;
	unsigned long flags;

	if (end - start <= 0) {
		dprintk("unwind: ignoring attempt to insert empty unwind table\n");
		return 0;
	}

	table = kmalloc(sizeof(*table), GFP_USER);
	if (!table)
		return 0;

	init_unwind_table(table, name, segment_base, gp, table_start, table_end);

	spin_lock_irqsave(&unw.lock, flags);
	{
		/* keep kernel unwind table at the front (it's searched most commonly): */
		table->next = unw.tables->next;
		unw.tables->next = table;
	}
	spin_unlock_irqrestore(&unw.lock, flags);

	return table;
}

void
unw_remove_unwind_table (void *handle)
{
	struct unw_table *table, *prev;
	struct unw_script *tmp;
	unsigned long flags;
	long index;

	if (!handle) {
		dprintk("unwind: ignoring attempt to remove non-existent unwind table\n");
		return;
	}

	table = handle;
	if (table == &unw.kernel_table) {
		dprintk("unwind: sorry, freeing the kernel's unwind table is a no-can-do!\n");
		return;
	}

	spin_lock_irqsave(&unw.lock, flags);
	{
		/* first, delete the table: */

		for (prev = (struct unw_table *) &unw.tables; prev; prev = prev->next)
			if (prev->next == table)
				break;
		if (!prev) {
			dprintk("unwind: failed to find unwind table %p\n", (void *) table);
			spin_unlock_irqrestore(&unw.lock, flags);
			return;
		}
		prev->next = table->next;
	}
	spin_unlock_irqrestore(&unw.lock, flags);

	/* next, remove hash table entries for this table */

	for (index = 0; index <= UNW_HASH_SIZE; ++index) {
		tmp = unw.cache + unw.hash[index];
		if (unw.hash[index] >= UNW_CACHE_SIZE
		    || tmp->ip < table->start || tmp->ip >= table->end)
			continue;

		write_lock(&tmp->lock);
		{
			if (tmp->ip >= table->start && tmp->ip < table->end) {
				unw.hash[index] = tmp->coll_chain;
				tmp->ip = 0;
			}
		}
		write_unlock(&tmp->lock);
	}

	kfree(table);
}

void
unw_create_gate_table (void)
{
	extern char __start_gate_section[], __stop_gate_section[];
	unsigned long *lp, start, end, segbase = unw.kernel_table.segment_base;
	const struct unw_table_entry *entry, *first;
	size_t info_size, size;
	char *info;

	start = (unsigned long) __start_gate_section - segbase;
	end   = (unsigned long) __stop_gate_section - segbase;
	size  = 0;
	first = lookup(&unw.kernel_table, start);

	for (entry = first; entry->start_offset < end; ++entry)
		size += 3*8 + 8 + 8*UNW_LENGTH(*(u64 *) (segbase + entry->info_offset));
	size += 8;	/* reserve space for "end of table" marker */

	unw.gate_table = alloc_bootmem(size);
	if (!unw.gate_table) {
		unw.gate_table_size = 0;
		printk("unwind: unable to create unwind data for gate page!\n");
		return;
	}
	unw.gate_table_size = size;

	lp = unw.gate_table;
	info = (char *) unw.gate_table + size;

	for (entry = first; entry->start_offset < end; ++entry, lp += 3) {
		info_size = 8 + 8*UNW_LENGTH(*(u64 *) (segbase + entry->info_offset));
		info -= info_size;
		memcpy(info, (char *) segbase + entry->info_offset, info_size);

		lp[0] = entry->start_offset - start + GATE_ADDR;	/* start */
		lp[1] = entry->end_offset - start + GATE_ADDR;		/* end */
		lp[2] = info - (char *) unw.gate_table;			/* info */
	}
	*lp = 0;	/* end-of-table marker */
}

void
unw_init (void)
{
	extern int ia64_unw_start, ia64_unw_end, __gp;
	extern void unw_hash_index_t_is_too_narrow (void);
	long i, off;

	if (8*sizeof(unw_hash_index_t) < UNW_LOG_HASH_SIZE)
		unw_hash_index_t_is_too_narrow();

	unw.sw_off[unw.preg_index[UNW_REG_PRI_UNAT_GR]] = SW(AR_UNAT);
	unw.sw_off[unw.preg_index[UNW_REG_BSPSTORE]] = SW(AR_BSPSTORE);
	unw.sw_off[unw.preg_index[UNW_REG_PFS]] = SW(AR_UNAT);
	unw.sw_off[unw.preg_index[UNW_REG_RP]] = SW(B0);
	unw.sw_off[unw.preg_index[UNW_REG_UNAT]] = SW(AR_UNAT);
	unw.sw_off[unw.preg_index[UNW_REG_PR]] = SW(PR);
	unw.sw_off[unw.preg_index[UNW_REG_LC]] = SW(AR_LC);
	unw.sw_off[unw.preg_index[UNW_REG_FPSR]] = SW(AR_FPSR);
	for (i = UNW_REG_R4, off = SW(R4); i <= UNW_REG_R7; ++i, off += 8)
		unw.sw_off[unw.preg_index[i]] = off;
	for (i = UNW_REG_B1, off = SW(B1); i <= UNW_REG_B5; ++i, off += 8)
		unw.sw_off[unw.preg_index[i]] = off;
	for (i = UNW_REG_F2, off = SW(F2); i <= UNW_REG_F5; ++i, off += 16)
		unw.sw_off[unw.preg_index[i]] = off;
	for (i = UNW_REG_F16, off = SW(F16); i <= UNW_REG_F31; ++i, off += 16)
		unw.sw_off[unw.preg_index[i]] = off;

	for (i = 0; i < UNW_CACHE_SIZE; ++i) {
		if (i > 0)
			unw.cache[i].lru_chain = (i - 1);
		unw.cache[i].coll_chain = -1;
		unw.cache[i].lock = RW_LOCK_UNLOCKED;
	}
	unw.lru_head = UNW_CACHE_SIZE - 1;
	unw.lru_tail = 0;

	init_unwind_table(&unw.kernel_table, "kernel", KERNEL_START, (unsigned long) &__gp,
			  &ia64_unw_start, &ia64_unw_end);
}

/*
 * This system call copies the unwind data into the buffer pointed to by BUF and returns
 * the size of the unwind data.  If BUF_SIZE is smaller than the size of the unwind data
 * or if BUF is NULL, nothing is copied, but the system call still returns the size of the
 * unwind data.
 *
 * The first portion of the unwind data contains an unwind table and rest contains the
 * associated unwind info (in no particular order).  The unwind table consists of a table
 * of entries of the form:
 *
 *	u64 start;	(64-bit address of start of function)
 *	u64 end;	(64-bit address of start of function)
 *	u64 info;	(BUF-relative offset to unwind info)
 *
 * The end of the unwind table is indicated by an entry with a START address of zero.
 *
 * Please see the IA-64 Software Conventions and Runtime Architecture manual for details
 * on the format of the unwind info.
 *
 * ERRORS
 *	EFAULT	BUF points outside your accessible address space.
 */
asmlinkage long
sys_getunwind (void *buf, size_t buf_size)
{
	if (buf && buf_size >= unw.gate_table_size)
		if (copy_to_user(buf, unw.gate_table, unw.gate_table_size) != 0)
			return -EFAULT;
	return unw.gate_table_size;
}