Changeset 948e85b in mainline for kernel/arch/ia32/src/boot/multiboot.S

Timestamp:

2018-11-13T20:22:20Z (5 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Children:

33ef2f2

Parents:

87db879

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2018-10-24 15:05:32)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2018-11-13 20:22:20)

Message:

Allocate non-PSE page tables statically

File:

• kernel/arch/ia32/src/boot/multiboot.S (modified) (3 diffs)

kernel/arch/ia32/src/boot/multiboot.S

@@ -220 +220 @@
         movl %ecx, %cr4
 
-        call calc_kernel_end
-        call find_mem_for_pt
-
-        mov kernel_end, %esi
-        mov free_area, %ecx
-
-        cmpl %esi, %ecx
-        jbe use_kernel_end
-
-                mov %ecx, %esi
-
-                /* Align address down to 4k */
-                andl $(~(PAGE_SIZE - 1)), %esi
-
-        use_kernel_end:
-
-                /* Align address to 4k */
-                addl $(PAGE_SIZE - 1), %esi
-                andl $(~(PAGE_SIZE - 1)), %esi
-
-                /* Allocate space for page tables */
-                movl %esi, pt_loc
-                movl $KA2PA(ballocs), %edi
-
-                movl %esi, (%edi)
-                addl $4, %edi
-                movl $(2 * 1024 * 1024), (%edi)
-
-                /* Fill page tables */
-                xorl %ecx, %ecx
-                xorl %ebx, %ebx
-
-                floop_pt:
-                        movl $(PTE_RW | PTE_P), %eax
-                        orl %ebx, %eax
-                        movl %eax, (%esi, %ecx, 4)
-                        addl $PAGE_SIZE, %ebx
-
-                        incl %ecx
-                        cmpl $(512 * 1024), %ecx
-
-                        jl floop_pt
-
-                /* Fill page directory */
-                movl $(page_directory + 0), %esi
-                movl $(page_directory + 2048), %edi
-                xorl %ecx, %ecx
-                movl pt_loc, %ebx
-
-                floop:
-                        movl $(PDE_RW | PDE_P), %eax
-                        orl %ebx, %eax
-
-                        /* Mapping 0x00000000 + %ecx * 4M => 0x00000000 + %ecx * 4M */
-                        movl %eax, (%esi, %ecx, 4)
-
-                        /* Mapping 0x80000000 + %ecx * 4M => 0x00000000 + %ecx * 4M */
-                        movl %eax, (%edi, %ecx, 4)
-                        addl $PAGE_SIZE, %ebx
-
-                        incl %ecx
-                        cmpl $512, %ecx
-
-                        jl floop
-
-                movl %esi, %cr3
-
-                movl %cr0, %ebx
-                orl $CR0_PG, %ebx  /* paging on */
-                movl %ebx, %cr0
-
-                ret
+        /* Allocate space for page tables */
+        // TODO: we shouldn't need to put this allocation in ballocs,
+        //       since it's static.
+        movl $KA2PA(ballocs), %edi
+        movl $page_tables, 0(%edi)
+        movl $(2 * 1024 * 1024), 4(%edi)
+
+        /* Fill page tables */
+        xorl %ecx, %ecx
+        xorl %ebx, %ebx
+        mov $page_tables, %esi
+
+        floop_pt:
+                movl $(PTE_RW | PTE_P), %eax
+                orl %ebx, %eax
+                movl %eax, (%esi, %ecx, 4)
+                addl $PAGE_SIZE, %ebx
+
+                incl %ecx
+                cmpl $(512 * 1024), %ecx
+
+                jl floop_pt
+
+        /* Fill page directory */
+        movl $(page_directory + 0), %esi
+        movl $(page_directory + 2048), %edi
+        xorl %ecx, %ecx
+        movl $page_tables, %ebx
+
+        floop:
+                movl $(PDE_RW | PDE_P), %eax
+                orl %ebx, %eax
+
+                /* Mapping 0x00000000 + %ecx * 4M => 0x00000000 + %ecx * 4M */
+                movl %eax, (%esi, %ecx, 4)
+
+                /* Mapping 0x80000000 + %ecx * 4M => 0x00000000 + %ecx * 4M */
+                movl %eax, (%edi, %ecx, 4)
+                addl $PAGE_SIZE, %ebx
+
+                incl %ecx
+                cmpl $512, %ecx
+
+                jl floop
+
+        movl %esi, %cr3
+
+        movl %cr0, %ebx
+        orl $CR0_PG, %ebx  /* paging on */
+        movl %ebx, %cr0
+
+        ret
 FUNCTION_END(map_kernel_non_pse)
-
-/** Calculate unmapped address of the end of the kernel. */
-calc_kernel_end:
-        movl $KA2PA(kdata_end), %edi
-        movl %edi, kernel_end
-        ret
-
-// TODO: remove this cruft
-
-/** Find free 2M (+4k for alignment) region where to store page tables */
-find_mem_for_pt:
-        /* Check if multiboot info is present */
-        cmpl $MULTIBOOT_LOADER_MAGIC, multiboot_eax
-        je check_multiboot_map
-
-                ret
-
-        check_multiboot_map:
-
-                /* Copy address of the multiboot info to ebx */
-                movl multiboot_ebx, %ebx
-
-                /* Check if memory map flag is present */
-                movl (%ebx), %edx
-                andl $MULTIBOOT_INFO_FLAGS_MMAP, %edx
-                jnz use_multiboot_map
-
-                        ret
-
-        use_multiboot_map:
-
-                /* Copy address of the memory map to edx */
-                movl MULTIBOOT_INFO_OFFSET_MMAP_ADDR(%ebx), %edx
-                movl %edx, %ecx
-
-                addl MULTIBOOT_INFO_OFFSET_MMAP_LENGTH(%ebx), %ecx
-
-                /* Find a free region at least 2M in size */
-                check_memmap_loop:
-
-                        /* Is this a free region? */
-                        cmpl $MEMMAP_MEMORY_AVAILABLE, MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_TYPE(%edx)
-                        jnz next_region
-
-                        /* Check size */
-                        cmpl $0, MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_SIZE + 4(%edx)
-                        jnz next_region
-                        cmpl $(2 * 1024 * 1024 + PAGE_SIZE), MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_SIZE(%edx)
-                        jbe next_region
-
-                        cmpl $0, MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_BASE_ADDRESS + 4(%edx)
-                        jz found_region
-
-                next_region:
-
-                        cmp %ecx, %edx
-                        jbe next_region_do
-
-                                ret
-
-                next_region_do:
-
-                        addl MULTIBOOT_MEMMAP_OFFSET_SIZE(%edx), %edx
-                        addl $MULTIBOOT_MEMMAP_SIZE_SIZE, %edx
-                        jmp check_memmap_loop
-
-                found_region:
-
-                        /* Use end of the found region */
-                        mov MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_BASE_ADDRESS(%edx), %ecx
-                        add MULTIBOOT_MEMMAP_OFFSET_MM_INFO + E820MEMMAP_OFFSET_SIZE(%edx), %ecx
-                        sub $(2 * 1024 * 1024), %ecx
-                        mov %ecx, free_area
-
-                        ret
 
 /** Print string to EGA display (in light green).
@@ -600 +505 @@
 
 .align 4096
+page_tables:
+        .space 2*1024*1024;
+
+.align 4096
 page_directory:
         .space 4096, 0
@@ -611 +520 @@
 
 SYMBOL(multiboot_ebx)
-        .long 0
-
-pt_loc:
-        .long 0
-kernel_end:
-        .long 0
-free_area:
         .long 0