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Forbid block descriptors in initial xlat table levels

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In AArch64, depending on the granularity of the translation tables,
level 0 and/or level 1 of the translation tables may not support block
descriptors, only table descriptors.

This patch introduces a check to make sure that, even if theoretically
it could be possible to create a block descriptor to map a big memory
region, a new subtable will be created to describe its mapping.

Change-Id: Ieb9c302206bfa33fbaf0cdc6a5a82516d32ae2a7
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
This commit is contained in:
Antonio Nino Diaz 2016-12-13 15:02:31 +00:00
parent e60e74bd26
commit 2240f45b1a
2 changed files with 32 additions and 1 deletions
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3
lib/xlat_tables/xlat_tables_common.c
View File

@ -353,7 +353,8 @@ static mmap_region_t *init_xlation_table_inner(mmap_region_t *mm,
if (mm->base_va > base_va + level_size - 1) {
/* Next region is after this area. Nothing to map yet */
desc = INVALID_DESC;
} else {
/* Make sure that the current level allows block descriptors */
} else if (level >= XLAT_BLOCK_LEVEL_MIN) {
/*
* Try to get attributes of this area. It will fail if
* there are partially overlapping regions. On success,

30
lib/xlat_tables/xlat_tables_private.h
View File

@ -58,6 +58,36 @@ CASSERT(IS_POWER_OF_TWO(PLAT_VIRT_ADDR_SPACE_SIZE),
CASSERT(IS_POWER_OF_TWO(PLAT_PHY_ADDR_SPACE_SIZE),
assert_valid_phy_addr_space_size);
/*
* In AArch32 state, the MMU only supports 4KB page granularity, which means
* that the first translation table level is either 1 or 2. Both of them are
* allowed to have block and table descriptors. See section G4.5.6 of the
* ARMv8-A Architecture Reference Manual (DDI 0487A.k) for more information.
*
* In AArch64 state, the MMU may support 4 KB, 16 KB and 64 KB page
* granularity. For 4KB granularity, a level 0 table descriptor doesn't support
* block translation. For 16KB, the same thing happens to levels 0 and 1. For
* 64KB, same for level 1. See section D4.3.1 of the ARMv8-A Architecture
* Reference Manual (DDI 0487A.k) for more information.
*
* The define below specifies the first table level that allows block
* descriptors.
*/
#ifdef AARCH32
# define XLAT_BLOCK_LEVEL_MIN 1
#else /* if AArch64 */
# if PAGE_SIZE == (4*1024) /* 4KB */
# define XLAT_BLOCK_LEVEL_MIN 1
# else /* 16KB or 64KB */
# define XLAT_BLOCK_LEVEL_MIN 2
# endif
#endif /* AARCH32 */
void print_mmap(void);
void init_xlation_table(uintptr_t base_va, uint64_t *table,
int level, uintptr_t *max_va,