lib/xlat_tables_v2/xlat_tables_internal.c

/*
 * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of ARM nor the names of its contributors may be used
 * to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch.h>
#include <arch_helpers.h>
#include <assert.h>
#include <cassert.h>
#include <common_def.h>
#include <debug.h>
#include <errno.h>
#include <platform_def.h>
#include <string.h>
#include <types.h>
#include <utils.h>
#include <xlat_tables_v2.h>
#ifdef AARCH32
# include "aarch32/xlat_tables_arch.h"
#else
# include "aarch64/xlat_tables_arch.h"
#endif
#include "xlat_tables_private.h"

/* Returns a pointer to the first empty translation table. */
static uint64_t *xlat_table_get_empty(xlat_ctx_t *ctx)
{
	assert(ctx->next_table < ctx->tables_num);

	return ctx->tables[ctx->next_table++];
}

/* Returns a block/page table descriptor for the given level and attributes. */
static uint64_t xlat_desc(unsigned int attr, unsigned long long addr_pa,
			  int level)
{
	uint64_t desc;
	int mem_type;

	/* Make sure that the granularity is fine enough to map this address. */
	assert((addr_pa & XLAT_BLOCK_MASK(level)) == 0);

	desc = addr_pa;
	/*
	 * There are different translation table descriptors for level 3 and the
	 * rest.
	 */
	desc |= (level == XLAT_TABLE_LEVEL_MAX) ? PAGE_DESC : BLOCK_DESC;
	/*
	 * Always set the access flag, as TF doesn't manage access flag faults.
	 * Deduce other fields of the descriptor based on the MT_NS and MT_RW
	 * memory region attributes.
	 */
	desc |= (attr & MT_NS) ? LOWER_ATTRS(NS) : 0;
	desc |= (attr & MT_RW) ? LOWER_ATTRS(AP_RW) : LOWER_ATTRS(AP_RO);
	desc |= LOWER_ATTRS(ACCESS_FLAG);

	/*
	 * Deduce shareability domain and executability of the memory region
	 * from the memory type of the attributes (MT_TYPE).
	 *
	 * Data accesses to device memory and non-cacheable normal memory are
	 * coherent for all observers in the system, and correspondingly are
	 * always treated as being Outer Shareable. Therefore, for these 2 types
	 * of memory, it is not strictly needed to set the shareability field
	 * in the translation tables.
	 */
	mem_type = MT_TYPE(attr);
	if (mem_type == MT_DEVICE) {
		desc |= LOWER_ATTRS(ATTR_DEVICE_INDEX | OSH);
		/*
		 * Always map device memory as execute-never.
		 * This is to avoid the possibility of a speculative instruction
		 * fetch, which could be an issue if this memory region
		 * corresponds to a read-sensitive peripheral.
		 */
		desc |= UPPER_ATTRS(XN);
	} else { /* Normal memory */
		/*
		 * Always map read-write normal memory as execute-never.
		 * (Trusted Firmware doesn't self-modify its code, therefore
		 * R/W memory is reserved for data storage, which must not be
		 * executable.)
		 * Note that setting the XN bit here is for consistency only.
		 * The enable_mmu_elx() function sets the SCTLR_EL3.WXN bit,
		 * which makes any writable memory region to be treated as
		 * execute-never, regardless of the value of the XN bit in the
		 * translation table.
		 *
		 * For read-only memory, rely on the MT_EXECUTE/MT_EXECUTE_NEVER
		 * attribute to figure out the value of the XN bit.
		 */
		if ((attr & MT_RW) || (attr & MT_EXECUTE_NEVER))
			desc |= UPPER_ATTRS(XN);

		if (mem_type == MT_MEMORY) {
			desc |= LOWER_ATTRS(ATTR_IWBWA_OWBWA_NTR_INDEX | ISH);
		} else {
			assert(mem_type == MT_NON_CACHEABLE);
			desc |= LOWER_ATTRS(ATTR_NON_CACHEABLE_INDEX | OSH);
		}
	}

	return desc;
}

/*
 * Enumeration of actions that can be made when mapping table entries depending
 * on the previous value in that entry and information about the region being
 * mapped.
 */
typedef enum {

	/* Do nothing */
	ACTION_NONE,

	/* Write a block (or page, if in level 3) entry. */
	ACTION_WRITE_BLOCK_ENTRY,

	/*
	 * Create a new table and write a table entry pointing to it. Recurse
	 * into it for further processing.
	 */
	ACTION_CREATE_NEW_TABLE,

	/*
	 * There is a table descriptor in this entry, read it and recurse into
	 * that table for further processing.
	 */
	ACTION_RECURSE_INTO_TABLE,

} action_t;

/*
 * From the given arguments, it decides which action to take when mapping the
 * specified region.
 */
static action_t xlat_tables_map_region_action(const mmap_region_t *mm,
		const int desc_type, const unsigned long long dest_pa,
		const uintptr_t table_entry_base_va, const int level)
{
	uintptr_t mm_end_va = mm->base_va + mm->size - 1;
	uintptr_t table_entry_end_va =
			table_entry_base_va + XLAT_BLOCK_SIZE(level) - 1;

	/*
	 * The descriptor types allowed depend on the current table level.
	 */

	if ((mm->base_va <= table_entry_base_va) &&
	    (mm_end_va >= table_entry_end_va)) {

		/*
		 * Table entry is covered by region
		 * --------------------------------
		 *
		 * This means that this table entry can describe the whole
		 * translation with this granularity in principle.
		 */

		if (level == 3) {
			/*
			 * Last level, only page descriptors are allowed.
			 */
			if (desc_type == PAGE_DESC) {
				/*
				 * There's another region mapped here, don't
				 * overwrite.
				 */
				return ACTION_NONE;
			} else {
				assert(desc_type == INVALID_DESC);
				return ACTION_WRITE_BLOCK_ENTRY;
			}

		} else {

			/*
			 * Other levels. Table descriptors are allowed. Block
			 * descriptors too, but they have some limitations.
			 */

			if (desc_type == TABLE_DESC) {
				/* There's already a table, recurse into it. */
				return ACTION_RECURSE_INTO_TABLE;

			} else if (desc_type == INVALID_DESC) {
				/*
				 * There's nothing mapped here, create a new
				 * entry.
				 *
				 * Check if the destination granularity allows
				 * us to use a block descriptor or we need a
				 * finer table for it.
				 *
				 * Also, check if the current level allows block
				 * descriptors. If not, create a table instead.
				 */
				if ((dest_pa & XLAT_BLOCK_MASK(level)) ||
				    (level < MIN_LVL_BLOCK_DESC))
					return ACTION_CREATE_NEW_TABLE;
				else
					return ACTION_WRITE_BLOCK_ENTRY;

			} else {
				/*
				 * There's another region mapped here, don't
				 * overwrite.
				 */
				assert(desc_type == BLOCK_DESC);

				return ACTION_NONE;
			}
		}

	} else if ((mm->base_va <= table_entry_end_va) ||
		   (mm_end_va >= table_entry_base_va)) {

		/*
		 * Region partially covers table entry
		 * -----------------------------------
		 *
		 * This means that this table entry can't describe the whole
		 * translation, a finer table is needed.

		 * There cannot be partial block overlaps in level 3. If that
		 * happens, some of the preliminary checks when adding the
		 * mmap region failed to detect that PA and VA must at least be
		 * aligned to PAGE_SIZE.
		 */
		assert(level < 3);

		if (desc_type == INVALID_DESC) {
			/*
			 * The block is not fully covered by the region. Create
			 * a new table, recurse into it and try to map the
			 * region with finer granularity.
			 */
			return ACTION_CREATE_NEW_TABLE;

		} else {
			assert(desc_type == TABLE_DESC);
			/*
			 * The block is not fully covered by the region, but
			 * there is already a table here. Recurse into it and
			 * try to map with finer granularity.
			 *
			 * PAGE_DESC for level 3 has the same value as
			 * TABLE_DESC, but this code can't run on a level 3
			 * table because there can't be overlaps in level 3.
			 */
			return ACTION_RECURSE_INTO_TABLE;
		}
	}

	/*
	 * This table entry is outside of the region specified in the arguments,
	 * don't write anything to it.
	 */
	return ACTION_NONE;
}

/*
 * Recursive function that writes to the translation tables and maps the
 * specified region.
 */
static void xlat_tables_map_region(xlat_ctx_t *ctx, mmap_region_t *mm,
				   const uintptr_t table_base_va,
				   uint64_t *const table_base,
				   const int table_entries,
				   const int level)
{
	assert(level >= ctx->base_level && level <= XLAT_TABLE_LEVEL_MAX);

	uintptr_t mm_end_va = mm->base_va + mm->size - 1;

	uintptr_t table_idx_va;
	unsigned long long table_idx_pa;

	uint64_t *subtable;
	uint64_t desc;

	int table_idx;

	if (mm->base_va > table_base_va) {
		/* Find the first index of the table affected by the region. */
		table_idx_va = mm->base_va & ~XLAT_BLOCK_MASK(level);

		table_idx = (table_idx_va - table_base_va) >>
			    XLAT_ADDR_SHIFT(level);

		assert(table_idx < table_entries);
	} else {
		/* Start from the beginning of the table. */
		table_idx_va = table_base_va;
		table_idx = 0;
	}

	while (table_idx < table_entries) {

		desc = table_base[table_idx];

		table_idx_pa = mm->base_pa + table_idx_va - mm->base_va;

		action_t action = xlat_tables_map_region_action(mm,
			desc & DESC_MASK, table_idx_pa, table_idx_va, level);

		if (action == ACTION_WRITE_BLOCK_ENTRY) {

			table_base[table_idx] =
				xlat_desc(mm->attr, table_idx_pa, level);

		} else if (action == ACTION_CREATE_NEW_TABLE) {

			subtable = xlat_table_get_empty(ctx);
			assert(subtable != NULL);
			/* Recurse to write into subtable */
			xlat_tables_map_region(ctx, mm, table_idx_va, subtable,
					       XLAT_TABLE_ENTRIES, level + 1);
			/* Point to new subtable from this one. */
			table_base[table_idx] =
					TABLE_DESC | (unsigned long)subtable;

		} else if (action == ACTION_RECURSE_INTO_TABLE) {

			subtable = (uint64_t *)(uintptr_t)(desc & TABLE_ADDR_MASK);
			/* Recurse to write into subtable */
			xlat_tables_map_region(ctx, mm, table_idx_va, subtable,
					       XLAT_TABLE_ENTRIES, level + 1);

		} else {

			assert(action == ACTION_NONE);

		}

		table_idx++;
		table_idx_va += XLAT_BLOCK_SIZE(level);

		/* If reached the end of the region, exit */
		if (mm_end_va <= table_idx_va)
			break;
	}
}

void print_mmap(mmap_region_t *const mmap)
{
#if LOG_LEVEL >= LOG_LEVEL_VERBOSE
	tf_printf("mmap:\n");
	mmap_region_t *mm = mmap;

	while (mm->size) {
		tf_printf(" VA:%p  PA:0x%llx  size:0x%zx  attr:0x%x\n",
				(void *)mm->base_va, mm->base_pa,
				mm->size, mm->attr);
		++mm;
	};
	tf_printf("\n");
#endif
}

/*
 * Function that verifies that a region can be mapped.
 * Returns:
 *        0: Success, the mapping is allowed.
 *   EINVAL: Invalid values were used as arguments.
 *   ERANGE: The memory limits were surpassed.
 *   ENOMEM: There is not enough memory in the mmap array.
 *    EPERM: Region overlaps another one in an invalid way.
 */
static int mmap_add_region_check(xlat_ctx_t *ctx, unsigned long long base_pa,
				 uintptr_t base_va, size_t size,
				 unsigned int attr)
{
	mmap_region_t *mm = ctx->mmap;
	unsigned long long end_pa = base_pa + size - 1;
	uintptr_t end_va = base_va + size - 1;

	if (!IS_PAGE_ALIGNED(base_pa) || !IS_PAGE_ALIGNED(base_va) ||
			!IS_PAGE_ALIGNED(size))
		return -EINVAL;

	/* Check for overflows */
	if ((base_pa > end_pa) || (base_va > end_va))
		return -ERANGE;

	if ((base_va + (uintptr_t)size - (uintptr_t)1) > ctx->va_max_address)
		return -ERANGE;

	if ((base_pa + (unsigned long long)size - 1ULL) > ctx->pa_max_address)
		return -ERANGE;

	/* Check that there is space in the mmap array */
	if (ctx->mmap[ctx->mmap_num - 1].size != 0)
		return -ENOMEM;

	/* Check for PAs and VAs overlaps with all other regions */
	for (mm = ctx->mmap; mm->size; ++mm) {

		uintptr_t mm_end_va = mm->base_va + mm->size - 1;

		/*
		 * Check if one of the regions is completely inside the other
		 * one.
		 */
		int fully_overlapped_va =
			((base_va >= mm->base_va) && (end_va <= mm_end_va)) ||
			((mm->base_va >= base_va) && (mm_end_va <= end_va));

		/*
		 * Full VA overlaps are only allowed if both regions are
		 * identity mapped (zero offset) or have the same VA to PA
		 * offset. Also, make sure that it's not the exact same area.
		 * This can only be done with locked regions.
		 */
		if (fully_overlapped_va) {

			if ((mm->base_va - mm->base_pa) != (base_va - base_pa))
				return -EPERM;

			if ((base_va == mm->base_va) && (size == mm->size))
				return -EPERM;

		} else {
			/*
			 * If the regions do not have fully overlapping VAs,
			 * then they must have fully separated VAs and PAs.
			 * Partial overlaps are not allowed
			 */

			unsigned long long mm_end_pa =
						     mm->base_pa + mm->size - 1;

			int separated_pa =
				(end_pa < mm->base_pa) || (base_pa > mm_end_pa);
			int separated_va =
				(end_va < mm->base_va) || (base_va > mm_end_va);

			if (!(separated_va && separated_pa))
				return -EPERM;
		}
	}

	return 0;
}

void mmap_add_region_ctx(xlat_ctx_t *ctx, mmap_region_t *mm)
{
	mmap_region_t *mm_cursor = ctx->mmap;
	mmap_region_t *mm_last = mm_cursor + ctx->mmap_num;
	unsigned long long end_pa = mm->base_pa + mm->size - 1;
	uintptr_t end_va = mm->base_va + mm->size - 1;
	int ret;

	/* Ignore empty regions */
	if (!mm->size)
		return;

	ret = mmap_add_region_check(ctx, mm->base_pa, mm->base_va, mm->size,
				    mm->attr);
	if (ret != 0) {
		ERROR("mmap_add_region_check() failed. error %d\n", ret);
		assert(0);
		return;
	}

	/*
	 * Find correct place in mmap to insert new region.
	 *
	 * 1 - Lower region VA end first.
	 * 2 - Smaller region size first.
	 *
	 * VA  0                                   0xFF
	 *
	 * 1st |------|
	 * 2nd |------------|
	 * 3rd                 |------|
	 * 4th                            |---|
	 * 5th                                   |---|
	 * 6th                            |----------|
	 * 7th |-------------------------------------|
	 *
	 * This is required for overlapping regions only. It simplifies adding
	 * regions with the loop in xlat_tables_init_internal because the outer
	 * ones won't overwrite block or page descriptors of regions added
	 * previously.
	 */

	while ((mm_cursor->base_va + mm_cursor->size - 1) < end_va
	       && mm_cursor->size)
		++mm_cursor;

	while ((mm_cursor->base_va + mm_cursor->size - 1 == end_va)
	       && (mm_cursor->size < mm->size))
		++mm_cursor;

	/* Make room for new region by moving other regions up by one place */
	memmove(mm_cursor + 1, mm_cursor,
		(uintptr_t)mm_last - (uintptr_t)mm_cursor);

	/*
	 * Check we haven't lost the empty sentinel from the end of the array.
	 * This shouldn't happen as we have checked in mmap_add_region_check
	 * that there is free space.
	 */
	assert(mm_last->size == 0);

	mm_cursor->base_pa = mm->base_pa;
	mm_cursor->base_va = mm->base_va;
	mm_cursor->size = mm->size;
	mm_cursor->attr = mm->attr;

	if (end_pa > ctx->max_pa)
		ctx->max_pa = end_pa;
	if (end_va > ctx->max_va)
		ctx->max_va = end_va;
}

#if LOG_LEVEL >= LOG_LEVEL_VERBOSE

/* Print the attributes of the specified block descriptor. */
static void xlat_desc_print(uint64_t desc)
{
	int mem_type_index = ATTR_INDEX_GET(desc);

	if (mem_type_index == ATTR_IWBWA_OWBWA_NTR_INDEX) {
		tf_printf("MEM");
	} else if (mem_type_index == ATTR_NON_CACHEABLE_INDEX) {
		tf_printf("NC");
	} else {
		assert(mem_type_index == ATTR_DEVICE_INDEX);
		tf_printf("DEV");
	}

	tf_printf(LOWER_ATTRS(AP_RO) & desc ? "-RO" : "-RW");
	tf_printf(LOWER_ATTRS(NS) & desc ? "-NS" : "-S");
	tf_printf(UPPER_ATTRS(XN) & desc ? "-XN" : "-EXEC");
}

static const char * const level_spacers[] = {
	"",
	"  ",
	"    ",
	"      "
};

/*
 * Recursive function that reads the translation tables passed as an argument
 * and prints their status.
 */
static void xlat_tables_print_internal(const uintptr_t table_base_va,
		uint64_t *const table_base, const int table_entries,
		const int level)
{
	assert(level <= XLAT_TABLE_LEVEL_MAX);

	uint64_t desc;
	uintptr_t table_idx_va = table_base_va;
	int table_idx = 0;

	size_t level_size = XLAT_BLOCK_SIZE(level);

	while (table_idx < table_entries) {

		desc = table_base[table_idx];

		if ((desc & DESC_MASK) == INVALID_DESC) {

			tf_printf("%sVA:%p size:0x%zx\n",
				  level_spacers[level],
				  (void *)table_idx_va, level_size);

		} else {

			/*
			 * Check if this is a table or a block. Tables are only
			 * allowed in levels other than 3, but DESC_PAGE has the
			 * same value as DESC_TABLE, so we need to check.
			 */
			if (((desc & DESC_MASK) == TABLE_DESC) &&
					(level < XLAT_TABLE_LEVEL_MAX)) {
				/*
				 * Do not print any PA for a table descriptor,
				 * as it doesn't directly map physical memory
				 * but instead points to the next translation
				 * table in the translation table walk.
				 */
				tf_printf("%sVA:%p size:0x%zx\n",
					  level_spacers[level],
					  (void *)table_idx_va, level_size);

				uintptr_t addr_inner = desc & TABLE_ADDR_MASK;

				xlat_tables_print_internal(table_idx_va,
					(uint64_t *)addr_inner,
					XLAT_TABLE_ENTRIES, level+1);
			} else {
				tf_printf("%sVA:%p PA:0x%llx size:0x%zx ",
					  level_spacers[level],
					  (void *)table_idx_va,
					  (unsigned long long)(desc & TABLE_ADDR_MASK),
					  level_size);
				xlat_desc_print(desc);
				tf_printf("\n");
			}
		}

		table_idx++;
		table_idx_va += level_size;
	}
}

#endif /* LOG_LEVEL >= LOG_LEVEL_VERBOSE */

void xlat_tables_print(xlat_ctx_t *ctx)
{
#if LOG_LEVEL >= LOG_LEVEL_VERBOSE
	xlat_tables_print_internal(0, ctx->base_table, ctx->base_table_entries,
				   ctx->base_level);
#endif /* LOG_LEVEL >= LOG_LEVEL_VERBOSE */
}

void init_xlation_table(xlat_ctx_t *ctx)
{
	mmap_region_t *mm = ctx->mmap;

	/* All tables must be zeroed before mapping any region. */

	for (int i = 0; i < ctx->base_table_entries; i++)
		ctx->base_table[i] = INVALID_DESC;

	for (int j = 0; j < ctx->tables_num; j++) {
		for (int i = 0; i < XLAT_TABLE_ENTRIES; i++)
			ctx->tables[j][i] = INVALID_DESC;
	}

	while (mm->size)
		xlat_tables_map_region(ctx, mm++, 0, ctx->base_table,
				ctx->base_table_entries, ctx->base_level);

	ctx->initialized = 1;
}