From 2a20e3596a446df55cfe4b34b45b4cd8eae594db Mon Sep 17 00:00:00 2001
From: stefan <stefan@s00.xyz>
Date: Sat, 29 Apr 2023 17:37:05 -0400
Subject: some work on paging

---
 sys/include/kalloc.h |  4 +++-
 sys/include/sbi.h    |  6 +++++
 sys/include/vm.h     | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 74 insertions(+), 2 deletions(-)

(limited to 'sys/include')

diff --git a/sys/include/kalloc.h b/sys/include/kalloc.h
index 5553d94..d77eae5 100644
--- a/sys/include/kalloc.h
+++ b/sys/include/kalloc.h
@@ -1,13 +1,15 @@
 #ifndef _KALLOC_H
 #define _KALLOC_H
 
+#include <stdint.h>
+
 void *kalloc(void);
 
 void *kzalloc(void);
 
 void kfree(void *);
 
-void kalloc_init(size_t);
+void kalloc_init(uintptr_t end);
 
 void walkfree(void);
 
diff --git a/sys/include/sbi.h b/sys/include/sbi.h
index 86ca295..7430bc6 100644
--- a/sys/include/sbi.h
+++ b/sys/include/sbi.h
@@ -66,6 +66,12 @@ sbi_debug_console_write_byte(uint8_t byte)
 	sbi_ecall(0x4442434E, 0x2, 'c', 0, 0, 0, 0, 0);
 }
 
+static inline void
+sbi_remote_sfence_vma(unsigned long hart_mask, unsigned long hart_mask_base, unsigned long start_addr, unsigned long size)
+{
+	sbi_ecall(0x52464E43, 1, hart_mask, hart_mask_base, start_addr, size, 0, 0);
+}
+
 static inline void
 sbi_shutdown(void)
 {
diff --git a/sys/include/vm.h b/sys/include/vm.h
index 1883ea7..4378552 100644
--- a/sys/include/vm.h
+++ b/sys/include/vm.h
@@ -1,6 +1,70 @@
 #ifndef _VM_H
 #define _VM_H
 
-void vminit(void);
+#include <stdint.h>
+
+#define PAGEBITS_VALID    (1 << 0)
+#define PAGEBITS_R        (1 << 1)
+#define PAGEBITS_W        (1 << 2)
+#define PAGEBITS_X        (1 << 3)
+#define PAGEBITS_USER     (1 << 4)
+#define PAGEBITS_GLOBAL   (1 << 5)
+#define PAGEBITS_ACCESSED (1 << 6)
+#define PAGEBITS_DIRTY    (1 << 7)
+
+#define PAGEBITS_RO	PAGEBITS_R
+#define PAGEBITS_XO	PAGEBITS_X
+#define PAGEBITS_RW	(PAGEBITS_R | PAGEBITS_W)
+#define PAGEPITS_RX	(PAGEBITS_R | PAGEBITS_X)
+#define PAGEBITS_RWX	(PAGEBITS_R | PAGEBITS_W | PAGEBITS_X)
+
+#define MODE_SV39 	(8L << 60)
+
+typedef uint64_t pt_entry_t;
+typedef struct _pagetable {
+	pt_entry_t entries[512];
+} pagetable_t; 
+
+/* allocate kernel pagetable */ 
+void kptinit(void);
+void kptinithart(void);
+//void kptinitharts(uintptr_t mask);
+
+/* maps virtual address to physical address for @pt. */
+void vmap(pagetable_t *root, uintptr_t vaddr, uintptr_t paddr, int bits, int level);
+
+/* returns address of page table entry for @vaddr. if @alloc, next level page tables will be allocated */ 
+pt_entry_t *walkpt(pagetable_t *root, uintptr_t vaddr, int alloc);
+
+/* helper functions */
+static inline void write_satp(uintptr_t mode, uintptr_t ppn);
+static inline int pte_is_branch(pt_entry_t);
+static inline int pte_is_valid(pt_entry_t);
+
+#define PA2PTE(pa) ((uintptr_t)pa >> 2)
+#define PTE2PA(pa) ((uintptr_t)pa << 2)
+#define FLUSH_TLB() asm volatile("sfence.vma zero, zero")
+
+static inline void 
+write_satp(uintptr_t mode, uintptr_t ppn)
+{
+	FLUSH_TLB();
+	asm volatile("csrw satp, %0" : : "r"((ppn >> 12) | mode));
+	FLUSH_TLB();
+}
+
+static inline int
+pte_is_branch(pt_entry_t e)
+{
+	return ((e & PAGEBITS_RWX) == 0);
+}
+#define pte_is_leaf(e) (!pte_is_branch(e))
+
+static inline int
+pte_is_valid(pt_entry_t e)
+{
+	return (e & PAGEBITS_VALID);
+}
+
 
 #endif /* _VM_H */
-- 
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