arm64: demand_paging: add support for on-demand mappings
This makes ARM64 compatible with K_MEM_MAP_UNPAGED.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
diff --git a/arch/arm64/core/mmu.c b/arch/arm64/core/mmu.c
index 85bae34..a914916 100644
--- a/arch/arm64/core/mmu.c
+++ b/arch/arm64/core/mmu.c
@@ -243,8 +243,15 @@
static void set_pte_block_desc(uint64_t *pte, uint64_t desc, unsigned int level)
{
- if (desc) {
- desc |= (level == XLAT_LAST_LEVEL) ? PTE_PAGE_DESC : PTE_BLOCK_DESC;
+ if (level != XLAT_LAST_LEVEL) {
+ desc |= PTE_BLOCK_DESC;
+ } else if (!IS_ENABLED(CONFIG_DEMAND_PAGING) || (desc & PTE_BLOCK_DESC_AF) != 0) {
+ desc |= PTE_PAGE_DESC;
+ } else {
+ /*
+ * Demand paging configured and AF unset: leave the descriptor
+ * type to "invalid" as in arch_mem_page_out().
+ */
}
*pte = desc;
debug_show_pte(pte, level);
@@ -677,6 +684,11 @@
/* the access flag */
desc |= PTE_BLOCK_DESC_AF;
+ if (IS_ENABLED(CONFIG_DEMAND_PAGING) && (attrs & MT_PAGED_OUT) != 0) {
+ /* set it up for demand paging like arch_mem_page_out() */
+ desc &= ~PTE_BLOCK_DESC_AF;
+ desc |= PTE_BLOCK_DESC_AP_RO;
+ }
/* memory attribute index field */
mem_type = MT_TYPE(attrs);
@@ -1090,6 +1102,10 @@
entry_flags |= MT_RW_AP_ELx;
}
+ if (IS_ENABLED(CONFIG_DEMAND_PAGING) && (flags & K_MEM_MAP_UNPAGED) != 0) {
+ entry_flags |= MT_PAGED_OUT;
+ }
+
return add_map(ptables, "generic", phys, (uintptr_t)virt, size, entry_flags);
}
diff --git a/include/zephyr/arch/arm64/arm_mmu.h b/include/zephyr/arch/arm64/arm_mmu.h
index 7b6ce32..450a823 100644
--- a/include/zephyr/arch/arm64/arm_mmu.h
+++ b/include/zephyr/arch/arm64/arm_mmu.h
@@ -45,6 +45,7 @@
* attrs[7] : Mirror RO/RW permissions to EL0
* attrs[8] : Overwrite existing mapping if any
* attrs[9] : non-Global mapping (nG)
+ * attrs[10]: Paged-out mapping
*
*/
#define MT_PERM_SHIFT 3U
@@ -54,6 +55,7 @@
#define MT_RW_AP_SHIFT 7U
#define MT_NO_OVERWRITE_SHIFT 8U
#define MT_NON_GLOBAL_SHIFT 9U
+#define MT_PAGED_OUT_SHIFT 10U
#define MT_RO (0U << MT_PERM_SHIFT)
#define MT_RW (1U << MT_PERM_SHIFT)
@@ -75,6 +77,8 @@
#define MT_G (0U << MT_NON_GLOBAL_SHIFT)
#define MT_NG (1U << MT_NON_GLOBAL_SHIFT)
+#define MT_PAGED_OUT (1U << MT_PAGED_OUT_SHIFT)
+
#define MT_P_RW_U_RW (MT_RW | MT_RW_AP_ELx | MT_P_EXECUTE_NEVER | MT_U_EXECUTE_NEVER)
#define MT_P_RW_U_NA (MT_RW | MT_RW_AP_EL_HIGHER | MT_P_EXECUTE_NEVER | MT_U_EXECUTE_NEVER)
#define MT_P_RO_U_RO (MT_RO | MT_RW_AP_ELx | MT_P_EXECUTE_NEVER | MT_U_EXECUTE_NEVER)
@@ -95,6 +99,13 @@
#define ARCH_DATA_PAGE_DIRTY BIT(2)
#define ARCH_DATA_PAGE_NOT_MAPPED BIT(3)
+/*
+ * Special unpaged "location" tags (highest possible descriptor physical
+ * address values unlikely to conflict with backing store locations)
+ */
+#define ARCH_UNPAGED_ANON_ZERO 0x0000fffffffff000
+#define ARCH_UNPAGED_ANON_UNINIT 0x0000ffffffffe000
+
#ifndef _ASMLANGUAGE
/* Region definition data structure */
