Opening a TFTP file stream

Makefile

@@ -13,8 +13,11 @@ config.mk: | config.default.mk
 boot.bin: boot.elf
 	objcopy -O binary --only-section=.text boot.elf $@
 
-boot.elf: lboot.o fernlader.ld
-	$(LD) $(LDFLAGS) -o $@ lboot.o
+boot.elf: lboot.o loader.o fernlader.ld
+	$(LD) $(LDFLAGS) -o $@ lboot.o loader.o
 
-.S.o:
+lboot.o: lboot.S
 	$(CC) $(CFLAGS) -c -o $@ $(@:.o=.S)
+
+loader.o: loader.c
+	$(CC) $(CFLAGS) -m64 -Os -c -o $@ $(@:.o=.c)

bootboot.h

@@ -0,0 +1,155 @@
+/*
+ * bootboot.h
+ * https://gitlab.com/bztsrc/bootboot
+ *
+ * Copyright (C) 2017 - 2021 bzt (bztsrc@gitlab)
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * This file is part of the BOOTBOOT Protocol package.
+ * @brief The BOOTBOOT structure
+ *
+ */
+
+#ifndef _BOOTBOOT_H_
+#define _BOOTBOOT_H_
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+#ifndef _MSC_VER
+#define _pack __attribute__((packed))
+#else
+#define _pack
+#pragma pack(push)
+#pragma pack(1)
+#endif
+
+#define BOOTBOOT_MAGIC "BOOT"
+
+/* default virtual addresses for level 0 and 1 static loaders */
+#define BOOTBOOT_MMIO   0xfffffffff8000000  /* memory mapped IO virtual address */
+#define BOOTBOOT_FB     0xfffffffffc000000  /* frame buffer virtual address */
+#define BOOTBOOT_INFO   0xffffffffffe00000  /* bootboot struct virtual address */
+#define BOOTBOOT_ENV    0xffffffffffe01000  /* environment string virtual address */
+#define BOOTBOOT_CORE   0xffffffffffe02000  /* core loadable segment start */
+
+/* minimum protocol level:
+ *  hardcoded kernel name, static kernel memory addresses */
+#define PROTOCOL_MINIMAL 0
+/* static protocol level:
+ *  kernel name parsed from environment, static kernel memory addresses */
+#define PROTOCOL_STATIC  1
+/* dynamic protocol level:
+ *  kernel name parsed, kernel memory addresses from ELF or PE symbols */
+#define PROTOCOL_DYNAMIC 2
+/* big-endian flag */
+#define PROTOCOL_BIGENDIAN 0x80
+
+/* loader types, just informational */
+#define LOADER_BIOS     (0<<2)
+#define LOADER_UEFI     (1<<2)
+#define LOADER_RPI      (2<<2)
+#define LOADER_COREBOOT (3<<2)
+
+/* framebuffer pixel format, only 32 bits supported */
+#define FB_ARGB   0
+#define FB_RGBA   1
+#define FB_ABGR   2
+#define FB_BGRA   3
+
+/* mmap entry, type is stored in least significant tetrad (half byte) of size
+ * this means size described in 16 byte units (not a problem, most modern
+ * firmware report memory in pages, 4096 byte units anyway). */
+typedef struct {
+  uint64_t   ptr;
+  uint64_t   size;
+} _pack MMapEnt;
+#define MMapEnt_Ptr(a)  ((a)->ptr)
+#define MMapEnt_Size(a) ((a)->size & 0xFFFFFFFFFFFFFFF0)
+#define MMapEnt_Type(a) ((a)->size & 0xF)
+#define MMapEnt_IsFree(a) (((a)->size&0xF)==1)
+
+#define MMAP_USED     0   /* don't use. Reserved or unknown regions */
+#define MMAP_FREE     1   /* usable memory */
+#define MMAP_ACPI     2   /* acpi memory, volatile and non-volatile as well */
+#define MMAP_MMIO     3   /* memory mapped IO region */
+
+#define INITRD_MAXSIZE 16 /* Mb */
+
+typedef struct {
+  /* first 64 bytes is platform independent */
+  uint8_t    magic[4];    /* 'BOOT' magic */
+  uint32_t   size;        /* length of bootboot structure, minimum 128 */
+  uint8_t    protocol;    /* 1, static addresses, see PROTOCOL_* and LOADER_* above */
+  uint8_t    fb_type;     /* framebuffer type, see FB_* above */
+  uint16_t   numcores;    /* number of processor cores */
+  uint16_t   bspid;       /* Bootsrap processor ID (Local APIC Id on x86_64) */
+  int16_t    timezone;    /* in minutes -1440..1440 */
+  uint8_t    datetime[8]; /* in BCD yyyymmddhhiiss UTC (independent to timezone) */
+  uint64_t   initrd_ptr;  /* ramdisk image position and size */
+  uint64_t   initrd_size;
+  uint64_t   fb_ptr;      /* framebuffer pointer and dimensions */
+  uint32_t   fb_size;
+  uint32_t   fb_width;
+  uint32_t   fb_height;
+  uint32_t   fb_scanline;
+
+  /* the rest (64 bytes) is platform specific */
+  union {
+    struct {
+      uint64_t acpi_ptr;
+      uint64_t smbi_ptr;
+      uint64_t efi_ptr;
+      uint64_t mp_ptr;
+      uint64_t unused0;
+      uint64_t unused1;
+      uint64_t unused2;
+      uint64_t unused3;
+    } x86_64;
+    struct {
+      uint64_t acpi_ptr;
+      uint64_t mmio_ptr;
+      uint64_t efi_ptr;
+      uint64_t unused0;
+      uint64_t unused1;
+      uint64_t unused2;
+      uint64_t unused3;
+      uint64_t unused4;
+    } aarch64;
+  } arch;
+
+  /* from 128th byte, MMapEnt[], more records may follow */
+  MMapEnt    mmap;
+  /* use like this:
+   * MMapEnt *mmap_ent = &bootboot.mmap; mmap_ent++;
+   * until you reach bootboot->size, while(mmap_ent < bootboot + bootboot->size) */
+} _pack BOOTBOOT;
+
+#ifdef _MSC_VER
+#pragma pack(pop)
+#endif
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif

fernlader.cfg

@@ -0,0 +1 @@
+kernel=sys/core

fernlader.ld

@@ -1,6 +1,7 @@
 SECTIONS {
-    . = 0x7C00;
-    .text : {
-        *(*)
+    .text 0x7C00: {
+        lboot.o(.text*, .data*)
+        loader.o(.text*, .data*, .bss*)
     }
+    memmap = ALIGN(8);
 }

lboot.S

@@ -4,8 +4,22 @@
             .text
             .code16
 
+            .macro      pxe_call, opcode
+            mov         %sp, %bx
+            push        %ss
+            push        %bx
+            push        $\opcode
+            lcall       *pxe_api
+            add         $6, %sp
+            mov         %sp, %bx
+            or          %ss:(%bx), %ax
+            jnz         _pcerr
+            .endm
+
+            // _start: entry point
 _start:     cli
             cld
+            mov         %sp, %bp
 
             // we keep our text and data close to each other
             xor         %ax, %ax
@@ -16,6 +30,18 @@ _start:     cli
             mov         $msg_start, %si
             call        print
 
+            mov         %ss:4(%bp), %si
+            mov         %ss:6(%bp), %ax
+            mov         %ax, %es
+            .set        PXE_MAGIC, 0x45585021
+            cmpl        $PXE_MAGIC, %es:(%si)
+            je          1f
+            mov         $msg_pserr, %si
+            call        print
+            jmp         hang
+1:          mov         %es:16(%si), %eax
+            mov         %eax, pxe_api
+
             mov         $msg_a20, %si
             call        print
             call        enable_a20
@@ -24,10 +50,39 @@ _start:     cli
             call        print
             call        unreal
 
-            mov         $msg_fin, %si
+            mov         $msg_getmap, %si
             call        print
-1:          hlt
-            jmp         1b
+            call        get_map
+
+            mov         $msg_mkheap, %si
+            call        print
+            call        make_heap
+
+            mov         $msg_paging, %si
+            call        print
+            call        paging
+
+            .set        PXE_GET_CACHED_INFO, 0x0071
+            push        $0
+            push        %cs
+            push        $tx_buf
+            push        $1024
+            push        $2
+            push        $0
+            pxe_call    PXE_GET_CACHED_INFO
+            add         $12, %sp
+            mov         tx_buf+20, %eax
+            mov         %eax, server_ip
+
+            mov         $msg_read, %si
+            call        print
+            call        read_file
+
+            mov         $msg_long, %si
+            call        print
+            call        long
+
+            jmp         hang
 
             .set        COM1,       0x3F8
             .macro      com1_write  offset=0, byte
@@ -36,6 +91,7 @@ _start:     cli
             outb        %al, %dx
             .endm
 
+            // init_com1: Set up COM1 port for debug output
 init_com1:  com1_write  1, 0x00 // clear interrupts
             com1_write  3, 0x80 // set DLAB to 1
             com1_write  0, 0x0C // 9600 baud rate
@@ -43,51 +99,256 @@ init_com1:  com1_write  1, 0x00 // clear interrupts
             com1_write  3, 0x07 // 8 bit data + 1 parity bit
             ret
 
+            // enable_a20: Allow use of 'high' memory
 enable_a20: // TODO more thorough implementation
             inb         $0x92, %al
             or          $2, %al
             outb        %al, $0x92
             ret
 
+            // unreal: Enter unreal mode
 unreal:     push        %ds
-            lgdt        gdt_ptr
+            lgdt        gdt16_ptr
 
             mov         %cr0, %eax
             or          $0x01, %al
             mov         %eax, %cr0
-            ljmp        $0x8, $1f
+            ljmp        $0x8, $_urprot
 
-1:          mov         $0x10, %cx
+_urprot:    mov         $0x10, %cx
             mov         %cx, %ds
             
             and         $0xFE, %al
             mov         %eax, %cr0
-            ljmp        $0x0, $2f
+            ljmp        $0x0, $_urunreal
 
-2:          pop         %ds
+_urunreal:  pop         %ds
             ret
 
+            // get_map: Retrieve memory map using e820 BIOS function
+get_map:     mov         %ds, %ax
+            mov         %ax, %es
+            mov         $memmap, %di
+            xor         %ebx, %ebx
+            mov         $0x534D4150, %edx // e820 magic number
+_gmnext:    movl        $0, 20(%di)
+            mov         $24, %ecx
+            mov         $0xE820, %eax
+            int         $0x15
+            jc          _gmdone
+            test        %ebx, %ebx
+            jz          _gmdone
+            add         $24, %di
+            jmp         _gmnext
+_gmdone:    add         $24, %di
+            mov         %di, memmap_end
+            ret
+
+            // paging: Set up initial page tables for long mode
+paging:     mov         $4*4096, %ecx
+            call        alloc
+            mov         %eax, pd_ptr
+            mov         $4096, %ecx
+            call        alloc
+            mov         %eax, pdp_ptr
+            mov         $4096, %ecx
+            call        alloc
+            mov         %eax, pml4_ptr
+
+            // fill PDEs with identity map < 4Gb
+            mov         pd_ptr, %edi
+            xor         %ecx, %ecx
+_pgnext:    mov         %ecx, %eax
+            shl         $21, %eax
+            or          $0b10000011, %eax
+            movl        %eax, 0(%edi)
+            movl        $0,   4(%edi)
+            add         $8, %edi
+            inc         %ecx
+            cmp         $4*512, %ecx
+            jne         _pgnext
+
+            // link to PDs in PDP
+            mov         pdp_ptr, %edi
+            mov         pd_ptr, %eax
+            orl         $0b11, %eax
+
+            movl        %eax,  0(%edi)
+            movl        $0,    4(%edi)
+            add         $0x1000, %eax
+            movl        %eax,  8(%edi)
+            movl        $0,   12(%edi)
+            add         $0x1000, %eax
+            movl        %eax, 16(%edi)
+            movl        $0,   20(%edi)
+            add         $0x1000, %eax
+            movl        %eax, 24(%edi)
+            movl        $0,   28(%edi)
+
+            // link to PDP in PML4
+            mov         pml4_ptr, %edi
+            mov         pdp_ptr, %eax
+            orl         $0b11, %eax
+            movl        %eax, 0(%edi)
+            movl        $0,   4(%edi)
+
+            ret
+
+            // make_heap: find a memory range suitable for heap usage
+make_heap:  mov         $memmap-24, %si
+_mhnext:    add         $24, %si
+            cmp         memmap_end, %si
+            jae         _mhdone
+
+            cmpl        $1, 16(%si)
+            jne         _mhnext
+            
+            cmpl        $0, 4(%si)
+            ja          _mhnext
+            
+            mov         0(%si), %ebx
+            mov         8(%si), %ecx
+
+            // find end of range, clip to 4Gb
+            add         %ebx, %ecx
+            jnc         1f
+            mov         $0xFFFFFFFF, %ecx
+
+            // handle wraparound if length > 4Gb
+1:          cmpl        $0, 12(%si)
+            je          1f
+            mov         $0xFFFFFFFF, %ecx
+
+            // adjust base to above 1Mb, above the bootloader
+1:          cmp         $0x10000, %ebx
+            jae         1f
+            mov         $0x10000, %ebx
+
+            // align to 4Kb boundaries
+1:          add         $0xFFF, %ebx
+            and         $0xFFFFF000, %ebx
+            and         $0xFFFFF000, %ecx
+
+            sub         %ebx, %ecx
+            cmp         heap_size, %ecx
+            jbe         _mhnext
+
+            mov         %ebx, heap_start
+            mov         %ecx, heap_size
+            jmp         _mhnext
+
+_mhdone:    ret
+
+            // alloc: take ECX bytes from heap, return ptr in EAX
+            // The allocation does not get marked in the memmap.
+            // No realignment is performed, so only alloc aligned sizes.
+alloc:      cmp         heap_size, %ecx
+            ja          _aerr
+            mov         heap_start, %eax
+            add         %ecx, heap_start
+            sub         %ecx, heap_size
+            ret
+_aerr:      mov         $msg_aerr, %si
+            call        print
+            jmp         hang
+
+read_file:  
+            .set        PXE_TFTP_OPEN, 0x0020
+            push        $1024
+            push        $0x4500
+            sub         $128, %sp
+
+            mov         $fn_config, %esi
+            mov         %ss, %ax
+            mov         %ax, %es
+            mov         %esp, %edi
+            mov         $fn_config_l, %ecx
+            rep movsb
+
+            push        $0
+            push        $0
+
+            sub         $4, %sp
+            mov         %sp, %di
+            mov         server_ip+0, %al
+            mov         %al, %ss:0(%di)
+            mov         server_ip+1, %al
+            mov         %al, %ss:1(%di)
+            mov         server_ip+2, %al
+            mov         %al, %ss:2(%di)
+            mov         server_ip+3, %al
+            mov         %al, %ss:3(%di)
+
+            push        $0
+            pxe_call    PXE_TFTP_OPEN
+            add         $14+128, %sp
+
+            ret
+
+            // print: print NUL-terminated string pointed to by SI
 print:      xor         %bx, %bx
 
-1:          mov         $COM1+5, %dx
+_prnext:    mov         $COM1+5, %dx
             inb         %dx, %al
             test        $0x20, %al
-            jz          1b
+            jz          _prnext
 
             lodsb
             or          %al, %al
-            jz          2f
+            jz          _prdone
 
             mov         $COM1, %dx
             outb        %al, %dx
 
             mov         $0x0E, %ah
             int         $0x10
-            jmp         1b
+            jmp         _prnext
 
-2:          ret
+_prdone:    ret
 
-gdt:        // entry 0: null descriptor
+            // long: Enter long mode
+long:       
+            // Enable PAE
+            mov         %cr4, %eax
+            or          $0b100000, %eax
+            mov         %eax, %cr4
+
+            // Load page table
+            mov         pml4_ptr, %eax
+            mov         %eax, %cr3
+
+            // Enable long mode
+            .set        IA32_EFER,  0xC0000080
+            mov         $IA32_EFER, %ecx
+            rdmsr
+            or          $0x100, %eax
+            wrmsr
+
+            // Enable protected mode + paging
+            mov         %cr0, %eax
+            or          $0x80000001, %eax
+            mov         %eax, %cr0
+
+            // Linearize stack address
+            mov         %ss, %eax
+            shl         $4, %eax
+            add         %eax, %esp
+            mov         %esp, %ebp
+
+            // Load long mode GDT, switch to 64-bit CS
+            lgdt        gdt64_ptr
+            ljmp        $0x8, $trampo64
+
+            // hang: sleep indefinitely
+hang:       hlt
+            jmp         hang
+
+_pcerr:     mov         $msg_pcerr, %si
+            call        print
+            jmp         hang
+
+            // gdt16: Protected mode / Unreal mode 16-bit GDT
+gdt16:      // entry 0: null descriptor
             .word       0
             .word       0
             .byte       0
@@ -108,11 +369,77 @@ gdt:        // entry 0: null descriptor
             .byte       0b10010010
             .byte       0x8F
             .byte       0
-            .set        gdt_size, .-gdt
-gdt_ptr:    .word       gdt_size-1
-            .long       gdt
+            .set        gdt16_size, .-gdt16
+gdt16_ptr:  .word       gdt16_size-1
+            .long       gdt16
 
+            // gdt64: Long mode 64-bit GDT
+gdt64:      // entry 0: null descriptor
+            .quad       0
+            // entry 1: code segment
+            .word       0
+            .word       0
+            .byte       0
+            .byte       0x98
+            .byte       0x60
+            .byte       0
+            // entry 2: data segment
+            .word       0
+            .word       0
+            .byte       0
+            .byte       0x92
+            .byte       0x00
+            .byte       0
+            .set        gdt64_size, .-gdt64
+gdt64_ptr:  .word       gdt64_size-1
+            .quad       gdt64
+
+            // Messages to print
 msg_start:  .asciz      "Netboot via fernlader v1 ...\r\n"
 msg_a20:    .asciz      " * Enabling A20\r\n"
 msg_unreal: .asciz      " * Unreal Mode\r\n"
-msg_fin:    .asciz      "Finished.\r\n"
+msg_getmap: .asciz      " * Memory Map\r\n"
+msg_mkheap: .asciz      " * Making Space\r\n"
+msg_paging: .asciz      " * Paging\r\n"
+msg_read:   .asciz      " * Retrieving\r\n"
+msg_long:   .asciz      " * Long Mode\r\n"
+msg_pserr:  .asciz      "panic: Missing !PXE structure.\r\n"
+msg_pcerr:  .asciz      "panic: PXE call failed.\r\n"
+msg_aerr:   .asciz      "panic: Out of heap space.\r\n"
+
+fn_config:  .asciz      "fernlader.cfg"
+            .set        fn_config_l, .-fn_config
+
+pxe_api:    .long       0
+server_ip:  .space      4
+
+heap_start: .long       0
+heap_size:  .long       0
+
+            // Long mode initial page tables
+pd_ptr:     .long       0
+pdp_ptr:    .long       0
+pml4_ptr:   .long       0
+
+            // Points to the end of the memory map
+memmap_end: .word       0
+
+tx_buf:     .space      1024
+
+            .code64
+            // trampo64: Trampoline function to load long-mode segments
+            // before entering the loader.
+trampo64:   
+            mov         $0x10, %eax
+            mov         %eax, %ds
+            mov         %eax, %es
+            mov         %eax, %fs
+            mov         %eax, %gs
+            mov         %eax, %ss
+            jmp         loader_main
+
+            // ToDo List:
+            // - Sorting the memmap
+            // - Sanitizing the memmap
+            // - Translating the memmap to bootboot format
+            // - Parsing a config file

loader.c

@@ -0,0 +1,5 @@
+void
+loader_main(void)
+{
+	for (;;) {}
+}

run-qemu.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-qemu-system-x86_64 -netdev user,id=n1,net=10.0.0.5/24,tftp=netboot,bootfile=/boot.bin -device virtio-net-pci,netdev=n1
+qemu-system-x86_64 -netdev user,id=n1,net=10.0.0.5/24,tftp=.,bootfile=/boot.bin -device virtio-net-pci,netdev=n1,bootindex=0 "$@"