MMU: Extra asserts to avoid future regressions

3 files changed, 110 insertions, 14 deletions

diff --git a/kernel/elf.h b/include/elf.h
index 2ad4353..f1c0f5c 100644
--- a/kernel/elf.h
+++ b/include/elf.h
@@ -1,10 +1,30 @@
 #ifndef ELF_H
 #define ELF_H
 #include <assert.h>
+#ifdef KERNEL
 #include <fs/vfs.h>
 #include <mmu.h>
+#endif
 #include <typedefs.h>
 
+#define EI_NIDENT 16
+
+#define SHN_UNDEF 0
+#define SHN_LORESERVE 0xff00
+#define SHN_LOPROC 0xff00
+#define SHN_HIPROC 0xff1f
+#define SHN_ABS 0xfff1
+#define SHN_COMMON 0xfff2
+#define SHN_HIRESERVE 0xffff
+
+#define ELF32_R_SYM(i) ((i) >> 8)
+#define ELF32_R_TYPE(i) ((unsigned char)(i))
+#define ELF32_R_INFO(s, t) (((s) << 8) + (unsigned char)(t))
+
+#define ELF32_ST_BIND(i) ((i)>>4)
+#define ELF32_ST_TYPE(i) ((i)&0xf)
+#define ELF32_ST_INFO(b,t) (((b)<<4)+((t)&0xf))
+
 #define ET_NONE 0        // No file type
 #define ET_REL 1         // Relocatable file
 #define ET_EXEC 2        // Executable file
@@ -35,6 +55,45 @@
 #define Elf32_Sword u32 // Signed large integer
 #define Elf32_Word u32  // Unsigned large integer
 
+#define STT_NOTYPE 0
+#define STT_OBJECT 1
+#define STT_FUNC 2
+#define STT_SECTION 3
+#define STT_FILE 4
+#define STT_LOPROC 13
+#define STT_HIPROC 15
+
+#define SHF_WRITE 0x1
+#define SHF_ALLOC 0x2
+#define SHF_EXECINSTR 0x4
+#define SHF_MASKPROC 0xf0000000
+
+#define ELFCLASSNONE 0
+#define ELFCLASS32 1
+#define ELFCLASS64 2
+
+#define STB_LOCAL 0
+#define STB_GLOBAL 1
+#define STB_WEAK 2
+#define STB_LOPROC 13
+#define STB_HIPROC 15
+
+#define ELFDATANONE 0
+#define ELFDATA2LSB 1
+#define ELFDATA2MSB 2
+
+#define R_386_NONE 0
+#define R_386_32 1
+#define R_386_PC32 2
+#define R_386_GOT32 3
+#define R_386_PLT32 4
+#define R_386_COPY 5
+#define R_386_GLOB_DAT 6
+#define R_386_JMP_SLOT 7
+#define R_386_RELATIVE 8
+#define R_386_GOTOFF 9
+#define R_386_GOTPC 10
+
 #define ELF_EXEC (1 << 0)
 #define ELF_WRITE (1 << 1)
 #define ELF_READ (1 << 2)
@@ -58,6 +117,37 @@ typedef struct {
   Elf32_Half e_shstrndx;
 } __attribute__((packed)) ELFHeader;
 
+typedef struct {
+  Elf32_Addr r_offset;
+  Elf32_Word r_info;
+} Elf32_Rel;
+
+typedef struct {
+  Elf32_Word st_name;
+  Elf32_Addr st_value;
+  Elf32_Word st_size;
+  unsigned char st_info;
+  unsigned char st_other;
+  Elf32_Half st_shndx;
+} Elf32_Sym;
+
+typedef struct {
+  unsigned char e_ident[EI_NIDENT];
+  Elf32_Half e_type;
+  Elf32_Half e_machine;
+  Elf32_Word e_version;
+  Elf32_Addr e_entry;
+  Elf32_Off e_phoff;
+  Elf32_Off e_shoff;
+  Elf32_Word e_flags;
+  Elf32_Half e_ehsize;
+  Elf32_Half e_phentsize;
+  Elf32_Half e_phnum;
+  Elf32_Half e_shentsize;
+  Elf32_Half e_shnum;
+  Elf32_Half e_shstrndx;
+} Elf32_Ehdr;
+
 // Section header
 typedef struct {
   Elf32_Word sh_name;
diff --git a/kernel/arch/i386/mmu.c b/kernel/arch/i386/mmu.c
index 6fd00b6..9a00f52 100644
--- a/kernel/arch/i386/mmu.c
+++ b/kernel/arch/i386/mmu.c
@@ -115,7 +115,7 @@ void mmu_free_pages(void *a, u32 n) {
   for (; n > 0; n--) {
     Page *p = get_page(a, NULL, PAGE_NO_ALLOCATE, 0);
     p->present = 0;
-    write_to_frame(p->frame * 0x1000, 0);
+    (void)write_to_frame(p->frame * 0x1000, 0);
     a += 0x1000;
   }
 }
@@ -141,9 +141,14 @@ int get_free_frame(u32 *frame) {
   return 0;
 }
 
-void write_to_frame(u32 frame_address, u8 on) {
+int write_to_frame(u32 frame_address, u8 on) {
   u32 frame = frame_address / 0x1000;
   if (on) {
+    int frame_is_used = (0 != (tmp_small_frames[INDEX_FROM_BIT(frame)] &
+          ((u32)0x1 << OFFSET_FROM_BIT(frame))));
+    if (frame_is_used) {
+      return 0;
+    }
     num_allocated_frames++;
     tmp_small_frames[INDEX_FROM_BIT(frame)] |=
         ((u32)0x1 << OFFSET_FROM_BIT(frame));
@@ -153,6 +158,7 @@ void write_to_frame(u32 frame_address, u8 on) {
     tmp_small_frames[INDEX_FROM_BIT(frame)] &=
         ~((u32)0x1 << OFFSET_FROM_BIT(frame));
   }
+  return 1;
 }
 
 PageDirectory *get_active_pagedirectory(void) {
@@ -176,7 +182,7 @@ PageTable *clone_table(u32 src_index, PageDirectory *src_directory,
       kmalloc_align_free(new_table, sizeof(PageTable));
       return NULL;
     }
-    write_to_frame(frame_address * 0x1000, 1);
+    assert(write_to_frame(frame_address * 0x1000, 1));
     new_table->pages[i].frame = frame_address;
 
     new_table->pages[i].present |= src->pages[i].present;
@@ -369,7 +375,7 @@ void *mmu_map_user_frames(void *const ptr, size_t s) {
     p->user = !is_kernel;
     p->frame = (uintptr_t)(ptr + i * 0x1000) / 0x1000;
     kprintf("mapped user frame: %x\n", p->frame);
-    write_to_frame((uintptr_t)ptr + i * 0x1000, 1);
+    (void)write_to_frame((uintptr_t)ptr + i * 0x1000, 1);
   }
   return r;
 }
@@ -386,7 +392,7 @@ void *mmu_map_frames(void *const ptr, size_t s) {
     p->rw = rw;
     p->user = !is_kernel;
     p->frame = (uintptr_t)(ptr + i * 0x1000) / 0x1000;
-    write_to_frame((uintptr_t)ptr + i * 0x1000, 1);
+    (void)write_to_frame((uintptr_t)ptr + i * 0x1000, 1);
   }
   return r;
 }
@@ -401,7 +407,7 @@ int allocate_frame(Page *page, int rw, int is_kernel) {
   if (!get_free_frame(&frame_address)) {
     return 0;
   }
-  write_to_frame(frame_address * 0x1000, 1);
+  assert(write_to_frame(frame_address * 0x1000, 1));
 
   page->present = 1;
   page->rw = rw;
@@ -430,7 +436,7 @@ void mmu_free_pagedirectory(PageDirectory *pd) {
       if (!page->frame) {
         continue;
       }
-      write_to_frame(((u32)page->frame) * 0x1000, 0);
+      (void)write_to_frame(((u32)page->frame) * 0x1000, 0);
     }
     kmalloc_align_free(pd->tables[i], sizeof(PageTable));
     pd->tables[i] = NULL;
@@ -451,7 +457,7 @@ void mmu_free_address_range(void *ptr, size_t length, PageDirectory *pd) {
     if (!page->frame) {
       continue;
     }
-    write_to_frame(((u32)page->frame) * 0x1000, 0);
+    (void)write_to_frame(((u32)page->frame) * 0x1000, 0);
     page->present = 0;
     page->rw = 0;
     page->user = 0;
@@ -485,7 +491,7 @@ void mmu_map_physical(void *dst, PageDirectory *d, void *physical,
     p->rw = 1;
     p->user = 1;
     p->frame = (uintptr_t)physical / PAGE_SIZE;
-    write_to_frame((uintptr_t)physical, 1);
+    (void)write_to_frame((uintptr_t)physical, 1);
   }
 }
 
@@ -651,7 +657,7 @@ void paging_init(u64 memsize, multiboot_info_t *mb) {
         (multiboot_memory_map_t *)(mb->mmap_addr + 0xc0000000);
     for (size_t length = 0; length < mb->mmap_length;) {
       if (MULTIBOOT_MEMORY_AVAILABLE == map->type) {
-        num_of_frames = max(num_of_frames, map->addr + map->len);
+        num_of_frames = max(num_of_frames, map->addr + map->len + 0x1000);
         for (size_t i = 0; i < map->len; i += 0x20000) {
           u32 frame = (map->addr + i) / 0x1000;
           if (frame < (num_array_frames * 32)) {
@@ -682,14 +688,14 @@ void paging_init(u64 memsize, multiboot_info_t *mb) {
 
     // Loop through the pages in the table
     PageTable *table = kernel_directory->tables[i];
-    write_to_frame(kernel_directory->physical_tables[i], 1);
+    (void)write_to_frame(kernel_directory->physical_tables[i], 1);
     for (size_t j = 0; j < 1024; j++) {
       if (!table->pages[j].present) {
         continue;
       }
       // Add the frame to our bitmap to ensure it does not get used by
       // another newly created page.
-      write_to_frame(table->pages[j].frame * 0x1000, 1);
+      (void)write_to_frame(table->pages[j].frame * 0x1000, 1);
     }
   }
 
@@ -725,7 +731,7 @@ void paging_init(u64 memsize, multiboot_info_t *mb) {
         for (size_t i = 0; i < map->len - 0x1000; i += 0x20000) {
           u32 frame = (map->addr + i) / 0x1000;
           if (frame > (num_array_frames * 32)) {
-            assert(INDEX_FROM_BIT(frame) <= num_of_frames);
+            assert(INDEX_FROM_BIT(frame) < num_of_frames);
             tmp_small_frames[INDEX_FROM_BIT(frame)] = 0;
           }
         }
diff --git a/kernel/includes/mmu.h b/kernel/includes/mmu.h
index 83ea6e0..a248b8a 100644
--- a/kernel/includes/mmu.h
+++ b/kernel/includes/mmu.h
@@ -64,7 +64,7 @@ PageDirectory *clone_directory(PageDirectory *original);
 void *virtual_to_physical(void *address, PageDirectory *directory);
 void *ksbrk(size_t s);
 void *ksbrk_physical(size_t s, void **physical);
-void write_to_frame(u32 frame_address, u8 on);
+int write_to_frame(u32 frame_address, u8 on);
 
 Page *get_page(void *ptr, PageDirectory *directory, int create_new_page,
                int set_user);