#define VTCR_EL2_COMMON_BITS (VTCR_EL2_SH0_INNER | VTCR_EL2_ORGN0_WBWA | \
VTCR_EL2_IRGN0_WBWA | VTCR_EL2_RES1)
- #ifdef CONFIG_ARM64_64K_PAGES
/*
- * Stage2 translation configuration:
- * 64kB pages (TG0 = 1)
- * 2 level page tables (SL = 1)
+ * VTCR_EL2:SL0 indicates the entry level for Stage2 translation.
+ * Interestingly, it depends on the page size.
+ * See D.10.2.121, VTCR_EL2, in ARM DDI 0487C.a
+ *
+ * -----------------------------------------
+ * | Entry level | 4K | 16K/64K |
+ * ------------------------------------------
+ * | Level: 0 | 2 | - |
+ * ------------------------------------------
+ * | Level: 1 | 1 | 2 |
+ * ------------------------------------------
+ * | Level: 2 | 0 | 1 |
+ * ------------------------------------------
+ * | Level: 3 | - | 0 |
+ * ------------------------------------------
+ *
+ * The table roughly translates to :
+ *
+ * SL0(PAGE_SIZE, Entry_level) = TGRAN_SL0_BASE - Entry_Level
+ *
+ * Where TGRAN_SL0_BASE is a magic number depending on the page size:
+ * TGRAN_SL0_BASE(4K) = 2
+ * TGRAN_SL0_BASE(16K) = 3
+ * TGRAN_SL0_BASE(64K) = 3
+ * provided we take care of ruling out the unsupported cases and
+ * Entry_Level = 4 - Number_of_levels.
+ *
*/
- #define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SL0_LVL1)
- #define VTTBR_X_TGRAN_MAGIC 38
+ #ifdef CONFIG_ARM64_64K_PAGES
+
+ #define VTCR_EL2_TGRAN VTCR_EL2_TG0_64K
+ #define VTCR_EL2_TGRAN_SL0_BASE 3UL
+
#elif defined(CONFIG_ARM64_16K_PAGES)
- /*
- * Stage2 translation configuration:
- * 16kB pages (TG0 = 2)
- * 2 level page tables (SL = 1)
- */
- #define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_16K | VTCR_EL2_SL0_LVL1)
- #define VTTBR_X_TGRAN_MAGIC 42
+
+ #define VTCR_EL2_TGRAN VTCR_EL2_TG0_16K
+ #define VTCR_EL2_TGRAN_SL0_BASE 3UL
+
#else /* 4K */
- /*
- * Stage2 translation configuration:
- * 4kB pages (TG0 = 0)
- * 3 level page tables (SL = 1)
- */
- #define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SL0_LVL1)
- #define VTTBR_X_TGRAN_MAGIC 37
+
+ #define VTCR_EL2_TGRAN VTCR_EL2_TG0_4K
+ #define VTCR_EL2_TGRAN_SL0_BASE 2UL
+
#endif
- #define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS)
- #define VTTBR_X (VTTBR_X_TGRAN_MAGIC - VTCR_EL2_T0SZ_IPA)
+ #define VTCR_EL2_LVLS_TO_SL0(levels) \
+ ((VTCR_EL2_TGRAN_SL0_BASE - (4 - (levels))) << VTCR_EL2_SL0_SHIFT)
+ #define VTCR_EL2_SL0_TO_LVLS(sl0) \
+ ((sl0) + 4 - VTCR_EL2_TGRAN_SL0_BASE)
+ #define VTCR_EL2_LVLS(vtcr) \
+ VTCR_EL2_SL0_TO_LVLS(((vtcr) & VTCR_EL2_SL0_MASK) >> VTCR_EL2_SL0_SHIFT)
+
+ #define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN)
+ #define VTCR_EL2_IPA(vtcr) (64 - ((vtcr) & VTCR_EL2_T0SZ_MASK))
+
+ /*
+ * ARM VMSAv8-64 defines an algorithm for finding the translation table
+ * descriptors in section D4.2.8 in ARM DDI 0487C.a.
+ *
+ * The algorithm defines the expectations on the translation table
+ * addresses for each level, based on PAGE_SIZE, entry level
+ * and the translation table size (T0SZ). The variable "x" in the
+ * algorithm determines the alignment of a table base address at a given
+ * level and thus determines the alignment of VTTBR:BADDR for stage2
+ * page table entry level.
+ * Since the number of bits resolved at the entry level could vary
+ * depending on the T0SZ, the value of "x" is defined based on a
+ * Magic constant for a given PAGE_SIZE and Entry Level. The
+ * intermediate levels must be always aligned to the PAGE_SIZE (i.e,
+ * x = PAGE_SHIFT).
+ *
+ * The value of "x" for entry level is calculated as :
+ * x = Magic_N - T0SZ
+ *
+ * where Magic_N is an integer depending on the page size and the entry
+ * level of the page table as below:
+ *
+ * --------------------------------------------
+ * | Entry level | 4K 16K 64K |
+ * --------------------------------------------
+ * | Level: 0 (4 levels) | 28 | - | - |
+ * --------------------------------------------
+ * | Level: 1 (3 levels) | 37 | 31 | 25 |
+ * --------------------------------------------
+ * | Level: 2 (2 levels) | 46 | 42 | 38 |
+ * --------------------------------------------
+ * | Level: 3 (1 level) | - | 53 | 51 |
+ * --------------------------------------------
+ *
+ * We have a magic formula for the Magic_N below:
+ *
+ * Magic_N(PAGE_SIZE, Level) = 64 - ((PAGE_SHIFT - 3) * Number_of_levels)
+ *
+ * where Number_of_levels = (4 - Level). We are only interested in the
+ * value for Entry_Level for the stage2 page table.
+ *
+ * So, given that T0SZ = (64 - IPA_SHIFT), we can compute 'x' as follows:
+ *
+ * x = (64 - ((PAGE_SHIFT - 3) * Number_of_levels)) - (64 - IPA_SHIFT)
+ * = IPA_SHIFT - ((PAGE_SHIFT - 3) * Number of levels)
+ *
+ * Here is one way to explain the Magic Formula:
+ *
+ * x = log2(Size_of_Entry_Level_Table)
+ *
+ * Since, we can resolve (PAGE_SHIFT - 3) bits at each level, and another
+ * PAGE_SHIFT bits in the PTE, we have :
+ *
+ * Bits_Entry_level = IPA_SHIFT - ((PAGE_SHIFT - 3) * (n - 1) + PAGE_SHIFT)
+ * = IPA_SHIFT - (PAGE_SHIFT - 3) * n - 3
+ * where n = number of levels, and since each pointer is 8bytes, we have:
+ *
+ * x = Bits_Entry_Level + 3
+ * = IPA_SHIFT - (PAGE_SHIFT - 3) * n
+ *
+ * The only constraint here is that, we have to find the number of page table
+ * levels for a given IPA size (which we do, see stage2_pt_levels())
+ */
+ #define ARM64_VTTBR_X(ipa, levels) ((ipa) - ((levels) * (PAGE_SHIFT - 3)))
- #define VTTBR_BADDR_MASK (((UL(1) << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_X)
+#define VTTBR_CNP_BIT (UL(1))
#define VTTBR_VMID_SHIFT (UL(48))
#define VTTBR_VMID_MASK(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT)
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