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-rw-r--r--kernel/boot/init/boot.s6
-rw-r--r--kernel/include/common.h13
-rw-r--r--kernel/include/mm/virtual_mm.h5
-rw-r--r--kernel/kernel/kernel.c4
-rw-r--r--kernel/mm/physical_mm/physical_mm.c2
-rw-r--r--kernel/mm/virtual_mm/virtual_mm.c43
6 files changed, 48 insertions, 25 deletions
diff --git a/kernel/boot/init/boot.s b/kernel/boot/init/boot.s
index a1a6ee5..8a134c4 100644
--- a/kernel/boot/init/boot.s
+++ b/kernel/boot/init/boot.s
@@ -28,9 +28,9 @@
/*
Declare a multiboot header that marks the program as a kernel. These are magic
values that are documented in the multiboot standard. The bootloader will
- search for this signature in the first 8 KiB of the kernel file, aligned at a
+ search for this signature in the first 8KiB of the kernel file, aligned at a
32-bit boundary. The signature is in its own section so the header can be
- forced to be within the first 8 KiB of the kernel file.
+ forced to be within the first 8KiB of the kernel file.
*/
.section .multiboot
.align 4
@@ -53,7 +53,7 @@
.section .bss
.align 16
stack_bottom:
-.skip 16384 # 16 KiB
+.skip 16384 # 16KiB
stack_top:
/*
diff --git a/kernel/include/common.h b/kernel/include/common.h
index 2e1faa3..7f7f50f 100644
--- a/kernel/include/common.h
+++ b/kernel/include/common.h
@@ -36,4 +36,17 @@
halt(); \
}
+#define ASSERT(condition) \
+ { \
+ if (!(condition)) { \
+ printk("ASSERTION FAILED", \
+ "[%s]:%lu IS RENDERED FALSE.", \
+ __func__, \
+ __LINE__); \
+ /* TODO: We should probably remove this exit() eventually */ \
+ exit(); \
+ halt(); \
+ } \
+ }
+
#endif
diff --git a/kernel/include/mm/virtual_mm.h b/kernel/include/mm/virtual_mm.h
index 6bd5178..c0eb237 100644
--- a/kernel/include/mm/virtual_mm.h
+++ b/kernel/include/mm/virtual_mm.h
@@ -40,7 +40,7 @@
#define PDE_FRAME(x) ((x) &0xFFFFF000)
#define PDE_IS_PRESENT(pd_entry) ((*pd_entry) & 1)
-#define GET_PDE_FRAME(virtual_address) (((uint32_t) virtual_address) >> 22)
+#define GET_PD_INDEX(virtual_address) (((uint32_t) virtual_address) >> 22)
#define PDE_GET_TABLE(pd_entry) ((*pd_entry) & ~0xfff)
#define PTE_PRESENT(x) x
@@ -58,7 +58,8 @@
#define PTE_FRAME(x) ((x) << 12)
#define PTE_IS_PRESENT(pt_entry) ((*pt_entry) & 1)
-#define GET_PTE_FRAME(virtual_address) \
+#define GET_PTE_FRAME(x) ((x) >> 12)
+#define GET_PT_INDEX(virtual_address) \
((((uint32_t) virtual_address) >> 12) & 0x3ff)
#define ADD_ATTRIB(entry, attribute) (*entry |= (attribute))
diff --git a/kernel/kernel/kernel.c b/kernel/kernel/kernel.c
index f41f48e..7a7f95f 100644
--- a/kernel/kernel/kernel.c
+++ b/kernel/kernel/kernel.c
@@ -48,8 +48,8 @@ kernel_main(uint32_t magic, multiboot_info_t *multiboot_info)
printk("\nKernel", "Started.");
- virtual_mm_map_page((void *) 0x0C00000, (void *) 0x3000);
- virtual_mm_find_free_virtual_addresses(2);
+ // virtual_mm_map_page((void *) 0x0C00000, (void *) 0x3000);
+ virtual_mm_find_free_virtual_addresses(10000);
exit();
halt(); /* If exit() fails (on real hardware) */
diff --git a/kernel/mm/physical_mm/physical_mm.c b/kernel/mm/physical_mm/physical_mm.c
index ed89316..801ce7b 100644
--- a/kernel/mm/physical_mm/physical_mm.c
+++ b/kernel/mm/physical_mm/physical_mm.c
@@ -72,7 +72,7 @@ physical_mm_initialize_region(uint32_t start, uint32_t length)
if (physical_mm_test_bit(bit, memory_map))
physical_mm_set_usable(bit++, &total_free_blocks, memory_map);
- /* First block is always used (first 64 KiB) */
+ /* First block is always used (first 64KiB) */
if (!physical_mm_test_bit(0, memory_map))
physical_mm_set_used(0, &total_free_blocks, memory_map);
}
diff --git a/kernel/mm/virtual_mm/virtual_mm.c b/kernel/mm/virtual_mm/virtual_mm.c
index 929b37d..4153065 100644
--- a/kernel/mm/virtual_mm/virtual_mm.c
+++ b/kernel/mm/virtual_mm/virtual_mm.c
@@ -89,7 +89,7 @@ virtual_mm_initialize(void)
void
virtual_mm_map_page(void *physical_address, void *virtual_address)
{
- uint32_t *pd_entry = &current_page_directory[GET_PDE_FRAME(virtual_address)];
+ uint32_t *pd_entry = &current_page_directory[GET_PD_INDEX(virtual_address)];
uint32_t *table = 0;
/* If the pd_entry isn't present, allocate a block for it, zero the table,
@@ -106,16 +106,18 @@ virtual_mm_map_page(void *physical_address, void *virtual_address)
} else
table = (uint32_t *) PDE_GET_TABLE(pd_entry);
- uint32_t *pt_entry = &table[GET_PTE_FRAME(virtual_address)];
- if (PTE_IS_PRESENT(pt_entry))
- ASSERT_NOT_REACHED(); /* TODO: Mapping previously mapped memory */
+ uint32_t *pt_entry = &table[GET_PT_INDEX(virtual_address)];
+ if (PTE_IS_PRESENT(pt_entry)) {
+ printk("debug", "Mapping previously mapped memory: 0x%x", pt_entry);
+ ASSERT_NOT_REACHED();
+ }
*pt_entry = PTE_FRAME((uint32_t) physical_address) | PTE_PRESENT(1)
| PTE_WRITABLE(1);
}
ALWAYS_INLINE uint32_t *
-get_table(uint32_t *pd_entry)
+get_or_make_table(uint32_t *pd_entry)
{
uint32_t *table;
if (!PDE_IS_PRESENT(pd_entry)) {
@@ -123,8 +125,8 @@ get_table(uint32_t *pd_entry)
if (!table)
ASSERT_NOT_REACHED();
- for (uint32_t _ = 0; _ < 1024; _++)
- table[_] = 0;
+ for (uint32_t i = 0; i < 1024; i++)
+ table[i] = 0x0;
*pd_entry = PDE_FRAME((uint32_t) table) | PDE_PRESENT(1) | PDE_WRITABLE(1);
} else
@@ -136,33 +138,38 @@ get_table(uint32_t *pd_entry)
ALWAYS_INLINE void
virtual_mm_find_free_virtual_addresses(uint32_t n)
{
- for (uint32_t i = 0; i < PAGE_DIRECTORY_SIZE; i++) {
- uint32_t current_pd_index = i;
- uint32_t *pd_entry = &current_page_directory[current_pd_index];
- uint32_t *table = get_table(pd_entry);
+ /* Skip the first page directory, we don't wanna touch the first 4MiB. */
+ for (uint32_t i = 1; i < PAGE_DIRECTORY_SIZE; i++) {
+ uint32_t *pd_entry = &current_page_directory[i];
+ uint32_t *table = get_or_make_table(pd_entry);
for (uint32_t j = 0; j < PAGE_TABLE_SIZE; j++) {
uint32_t *pt_entry = &table[j];
if (PTE_IS_PRESENT(pt_entry))
continue;
- /* We found our starting pt_entry */
+ /* We found our starting pt_entry */
printk("debug", "Starting: 0x%x", pt_entry);
uint32_t count = 0;
for (uint32_t k = j; k <= PAGE_TABLE_SIZE; k++) {
/* If we overflow, switch to the consecutive page directory entry */
if (k == PAGE_TABLE_SIZE) {
- pd_entry = &current_page_directory[++current_pd_index];
- table = get_table(pd_entry);
+ if (++i == PAGE_DIRECTORY_SIZE)
+ ASSERT_NOT_REACHED(); /* Ran out of pd_entries */
+
+ pd_entry = &current_page_directory[i];
printk("debug", "Switching pd_entry: 0x%x", pd_entry);
+
+ table = get_or_make_table(pd_entry);
k = 0;
}
+ /* If page table entry is already used, break from the current loop */
uint32_t *pt_entry = &table[k];
if (PTE_IS_PRESENT(pt_entry)) {
- count = 0;
- current_pd_index = i;
- pd_entry = &current_page_directory[current_pd_index];
+ /* Since we have some used address at some point between j and count,
+ * we can't find n consecutive free addresses in between j and the
+ * used block (j + count + 1) */
j += count;
break;
}
@@ -170,6 +177,8 @@ virtual_mm_find_free_virtual_addresses(uint32_t n)
// printk("debug", "Found page: 0x%x", &table[k]);
count++;
if (count == n) {
+ /* TODO: Convert this into a virtual_address using the pd_index &
+ * pt_index */
printk("debug", "Found starting page at: 0x%x", &table[j]);
return;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-22 15:28:09 +0000