diff options
Diffstat (limited to 'src/arch/arm/armv7')
| -rw-r--r-- | src/arch/arm/armv7/mmu.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/src/arch/arm/armv7/mmu.c b/src/arch/arm/armv7/mmu.c index 727da5cf72..8c2f78c4d0 100644 --- a/src/arch/arm/armv7/mmu.c +++ b/src/arch/arm/armv7/mmu.c @@ -97,13 +97,17 @@ typedef uint64_t pte_t; typedef uint32_t pte_t; #endif /* CONFIG_ARM_LPAE */ +/* We set the first PTE to a sentinel value that cannot occur naturally (has + * attributes set but bits [1:0] are 0 -> unmapped) to mark unused subtables. */ +#define ATTR_UNUSED 0xBADbA6E0 +#define SUBTABLE_PTES (1 << (BLOCK_SHIFT - PAGE_SHIFT)) + /* * mask/shift/size for pages and blocks */ #define PAGE_SHIFT 12 #define PAGE_SIZE (1UL << PAGE_SHIFT) #define BLOCK_SIZE (1UL << BLOCK_SHIFT) -#define SUBTABLE_SIZE ((1 << (BLOCK_SHIFT - PAGE_SHIFT)) * sizeof(pte_t)) /* * MAIR Index @@ -113,7 +117,6 @@ typedef uint32_t pte_t; #define MAIR_INDX_WB 2 static pte_t *const ttb_buff = (void *)_ttb; -static int used_tables = 0; /* Not all boards want to use subtables and declare them in memlayout.ld. This * outputs two 0x00000000 symbols if they don't, making _ttb_subtables_size 0. @@ -156,12 +159,17 @@ static void mmu_fill_table(pte_t *table, u32 start_idx, u32 end_idx, static pte_t *mmu_create_subtable(pte_t *pgd_entry) { - if (used_tables >= _ttb_subtables_size / SUBTABLE_SIZE) - die("Not enough room for another sub-pagetable!"); + pte_t *table = (pte_t *)_ttb_subtables; + + /* Find unused subtable (first PTE == ATTR_UNUSED). */ + while (table[0] != ATTR_UNUSED) { + table += SUBTABLE_PTES; + if ((pte_t *)_ettb_subtables - table <= 0) + die("Not enough room for another sub-pagetable!"); + } /* We assume that *pgd_entry must already be a valid block mapping. */ uintptr_t start_addr = (uintptr_t)(*pgd_entry & BLOCK_MASK); - pte_t *table = (void *)(_ttb_subtables + used_tables++ * SUBTABLE_SIZE); printk(BIOS_DEBUG, "Creating new subtable @%p for [%#.8x:%#.8lx)\n", table, start_addr, start_addr + BLOCK_SIZE); @@ -172,8 +180,7 @@ static pte_t *mmu_create_subtable(pte_t *pgd_entry) attr = ((attr & ~(1 << 4)) | (1 << 0)); if (attr & ATTR_BLOCK) attr = (attr & ~ATTR_BLOCK) | ATTR_PAGE; - mmu_fill_table(table, 0, SUBTABLE_SIZE / sizeof(pte_t), - start_addr, PAGE_SHIFT, attr); + mmu_fill_table(table, 0, SUBTABLE_PTES, start_addr, PAGE_SHIFT, attr); /* Replace old entry in upper level table to point at subtable. */ *pgd_entry = (pte_t)(uintptr_t)table | ATTR_NEXTLEVEL; @@ -265,6 +272,11 @@ void mmu_config_range(u32 start_mb, u32 size_mb, enum dcache_policy policy) */ void mmu_init(void) { + /* Initially mark all subtables as unused (first PTE == ATTR_UNUSED). */ + pte_t *table = (pte_t *)_ttb_subtables; + for (; (pte_t *)_ettb_subtables - table > 0; table += SUBTABLE_PTES) + table[0] = ATTR_UNUSED; + if (CONFIG_ARM_LPAE) { pte_t *const pgd_buff = (pte_t*)(_ttb + 16*KiB); pte_t *pmd = ttb_buff; |