i must have done something right becuase now 0xffff_f000 points to p2 as expected, hurray

kernel-rs/Makefile

@@ -10,7 +10,7 @@ endif
 
 project	:= bluesnow
 arch	?= x86
-NASM	:= /usr/bin/nasm -f elf
+NASM	:= /usr/bin/nasm -f elf -g
 LD		:= /usr/bin/ld -m elf_i386 -L ./ -n --gc-sections
 # QEMU	:= qemu-system-x86_64 -device isa-debug-exit,iobase=0xf4,iosize=0x04 -gdb tcp::$(PORTG) -enable-kvm -monitor telnet:127.0.0.1:$(PORT),server,nowait
 QEMU	:= qemu-system-x86_64 -gdb tcp::$(PORTG) -enable-kvm -monitor telnet:127.0.0.1:$(PORT),server,nowait

kernel-rs/src/arch/x86/boot.asm

@@ -12,8 +12,8 @@ start:
 	call check_multiboot
 
 	call set_up_page_tables
-	; call enable_pse
+	call enable_pse
-	; call enable_paging
+	call enable_paging
 
 	; load the new gdt
 	lgdt [GDTR.ptr]
@@ -39,9 +39,9 @@ set_up_page_tables:
 
 .map_p2_table:
     ; map ecx-th P2 entry to a huge page that starts at address 2MiB*ecx
-    mov eax, 0x200000  ; 2MiB
+    mov eax, 0x400000  ; 4MiB
     mul ecx            ; start address of ecx-th page
-    or eax, 0b10000011 ; present + writable + huge
+    or eax, 0b10000011 ; huge + present + writable
     mov [p2_table + ecx * 4], eax ; map ecx-th entry
 
     inc ecx            ; increase counter
@@ -54,7 +54,7 @@ set_up_page_tables:
 enable_pse:
     ; enable PSE in the cr4 register
     mov eax, cr4
-    or eax, 1 << 2
+    or eax, 1 << 4
     mov cr4, eax
 
     ret
@@ -148,4 +148,3 @@ GDTR:
 .ptr:
 	DW .gdt_bottom - .gdt_top - 1	; length of the structure minus 1
 	DD .gdt_top						; pointer to top of gdt
-

kernel-rs/src/context.rs

@@ -104,8 +104,8 @@ fn context() -> &'static mut Context {
 }
 
 pub fn init(multiboot_info_addr: usize) {
-    unsafe { CONTEXT = Some(Context::new(multiboot_info_addr)) };
+    // unsafe { CONTEXT = Some(Context::new(multiboot_info_addr)) };
 
-    memory::remap_the_kernel(frame_allocator(), boot_info());
+    // memory::remap_the_kernel(frame_allocator(), boot_info());
-    self::init_screen();
+    // self::init_screen();
 }

kernel-rs/src/lib.rs

@@ -30,6 +30,7 @@ pub mod x86;
 #[no_mangle]
 pub extern fn kmain(multiboot_info_addr: usize) -> ! {
     context::init(multiboot_info_addr);
+    loop {}
     acpi::init().unwrap();
     loop { keyboard::kbd_callback(); }
 }

kernel-rs/src/memory/paging/entry.rs

@@ -1,6 +1,7 @@
 use memory::Frame;
 
 pub struct Entry(u32);
+use multiboot2::ElfSection;
 
 impl Entry {
     pub fn is_unused(&self) -> bool {
@@ -45,3 +46,21 @@ bitflags! {
         // const NO_EXECUTE =      1 << 63;
     }
 }
+
+impl EntryFlags {
+    pub fn from_elf_section_flags(section: &ElfSection) -> EntryFlags {
+        use multiboot2::ElfSectionFlags;
+
+        let mut flags = EntryFlags::empty();
+        if section.flags().contains(ElfSectionFlags::ALLOCATED) {
+            flags = flags | EntryFlags::PRESENT;
+        }
+        if section.flags().contains(ElfSectionFlags::WRITABLE) {
+            flags = flags | EntryFlags::WRITABLE;
+        }
+        // if !section.flags().contains(ElfSectionFlags::EXECUTABLE) {
+        //     flags = flags | EntryFlags::NO_EXECUTE;
+        // }
+        flags
+    }
+}

kernel-rs/src/memory/paging/mapper.rs

@@ -1,6 +1,6 @@
 use super::{VirtualAddress, PhysicalAddress, Page, ENTRY_COUNT};
 use super::entry::*;
-use super::table::{self, Table, Level2, Level1};
+use super::table::{self, Table, Level2};
 use memory::{PAGE_SIZE, Frame, FrameAllocator};
 use core::ptr::Unique;
 

kernel-rs/src/memory/paging/mod.rs

@@ -79,14 +79,20 @@ impl ActivePageTable {
                    f: F)
         where F: FnOnce(&mut Mapper)
         {
-            self.p2_mut()[ENTRY_COUNT -1].set(table.p2_frame.clone(), EntryFlags::PRESENT | EntryFlags::WRITABLE);
+            let backup = Frame::containing_address(x86::cr3());
 
+            // map temp page to current p2
+            let p2_table = temporary_page.map_table_frame(backup.clone(), self);
+
+            // overwrite recrusive map
+            self.p2_mut()[1023].set(table.p2_frame.clone(), EntryFlags::PRESENT | EntryFlags::WRITABLE);
             //TODO tlb flush all
 
-            // execute f in the nex context
+            // execute f in the new context
             f(self);
 
             // TODO restore recursive mapping to original p2 table
+            p2_table[1023].set(backup, EntryFlags::PRESENT | EntryFlags::WRITABLE);
         }
 
     pub fn switch(&mut self, new_table: InactivePageTable) -> InactivePageTable {
@@ -127,6 +133,7 @@ impl InactivePageTable {
 }
 
 pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
+    -> ActivePageTable
     where A: FrameAllocator
 {
     let mut temporary_page = TemporaryPage::new(Page { number: 0xcafe },
@@ -139,6 +146,11 @@ pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
     };
 
     active_table.with(&mut new_table, &mut temporary_page, |mapper| {
+
+        // identity map the VGA text buffer
+        let vga_buffer_frame = Frame::containing_address(0xb8000);
+        mapper.identity_map(vga_buffer_frame, EntryFlags::WRITABLE, allocator);
+
         let elf_sections_tag = boot_info.elf_sections_tag()
             .expect("Memory map tag required");
 
@@ -155,8 +167,7 @@ pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
             println!("mapping section at addr: {:#x}, size: {:#x}",
                      section.start_address(), section.size());
 
-            let flags = EntryFlags::WRITABLE; //TODO use real section flags
+            let flags = EntryFlags::from_elf_section_flags(&section);
-
             let start_frame = Frame::containing_address(section.start_address() as usize);
             let end_frame = Frame::containing_address(section.end_address() as usize - 1);
             for frame in Frame::range_inclusive(start_frame, end_frame) {
@@ -164,9 +175,6 @@ pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
             }
         }
 
-        let vga_buffer_frame = Frame::containing_address(0xb8000);
-        mapper.identity_map(vga_buffer_frame, EntryFlags::WRITABLE, allocator);
-
         let multiboot_start = Frame::containing_address(boot_info.start_address());
         let multiboot_end = Frame::containing_address(boot_info.end_address() - 1);
         for frame in Frame::range_inclusive(multiboot_start, multiboot_end) {
@@ -175,7 +183,14 @@ pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
     });
 
     let old_table = active_table.switch(new_table);
-    println!("new table!");
+
+    let old_p2_page  = Page::containing_address(
+        old_table.p2_frame.start_address()
+        );
+    active_table.unmap(old_p2_page, allocator);
+    println!("guard page at {:#x}", old_p2_page.start_address());
+
+    active_table
 }
 
 pub fn test_paging<A>(allocator: &mut A)

kernel-rs/src/memory/paging/table.rs

@@ -55,8 +55,7 @@ impl<L> Table<L> where L: HierarchicalLevel
                 "mapping code does not support huge pages");
                 let frame = allocator.allocate_frame().expect("no frames available");
                 self[index].set(frame, EntryFlags::PRESENT | EntryFlags::WRITABLE);
-                panic!("wtf");
+                self.next_table_mut(index).expect("next_table_mut gave None").zero()
-                self.next_table_mut(index).expect("real wtf now").zero()
             }
             self.next_table_mut(index).expect("no next table 2")
         }

kernel-rs/src/vga/mod.rs

@@ -165,11 +165,10 @@ impl Writer {
 
     pub fn flush(&mut self) {
         let slice = unsafe { core::slice::from_raw_parts_mut(0xb8000 as *mut u8, 4000) };
-
+        // let cr0 = x86::cr0() & !(1 << 31);
-        let cr0 = x86::cr0() & !(1 << 31);
+        // unsafe { x86::cr0_write(cr0); }
-        unsafe { x86::cr0_write(cr0); }
         slice.as_mut().clone_from_slice(&self.buffer);
-        unsafe { x86::cr0_write(cr0 | (1 << 31)); }
+        // unsafe { x86::cr0_write(cr0 | (1 << 31)); }
         self.flush_cursor();
     }
 

kernel-rs/x86-bluesnow.json

@@ -1,6 +1,9 @@
 {
 	"arch": "x86",
+
+	"_comment": "http://llvm.org/docs/LangRef.html#data-layout",
 	"data-layout": "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128",
+
 	"llvm-target": "i686-unknown-none",
 	"linker-flavor": "gcc",
 	"no-compiler-rt": true,