westeros: Preperations for VMM. Housekeeping.

Signed-off-by: TunaCici <[email protected]>

Kernel/Arch/ARM64/Entry.S

@@ -25,10 +25,6 @@ _start:
 	ldr     x2, =end_entry
 	mov     x3, #0x00
 
-	/* Register vector tables */
-	adr	x0, vector_table
-	msr	vbar_el1, x0
-
 	/* Enable access to FPU & Advanced SIMD (NEON) */
 	mrs	x0, CPACR_EL1
 	orr	x0, x0, #(0x3 << 20)

Kernel/Main.c

@@ -20,14 +20,12 @@
 #include "Memory/Physical.h"
 #include "Memory/Virtual.h"
 
-/* Kernel physical start & end addresses */
-extern uint64_t kstart;
-extern uint64_t kend;
+extern uint64_t kend; /* in Kernel/kerne.ld */
+extern uint64_t vector_table; /* in Kernel/Arch/ARM64/Vector.S */
 
 void kmain(void)
 {
-        volatile const uint8_t *kernel_start = (uint8_t*) &kstart;
-        volatile const uint8_t *kernel_end = (uint8_t*) &kend;
+        const void *kernel_end = &kend;
 
         uint64_t mem_start = 0x0;
         uint64_t mem_end = 0x0;
@@ -53,6 +51,10 @@ void kmain(void)
                 wfi();
         }
 
+        /* X. Setup vector tables */
+        MSR("vbar_el1", vector_table);
+        isb();
+
         /* 1. Init BootMem */
         klog("[kmain] Initializing early memory manager...\n");
 

Kernel/Start.c

@@ -18,9 +18,6 @@
 
 extern void kmain(void);
 
-extern uint64_t kstart;
-extern uint64_t kend;
-
 void _halt(const char *s)
 {
         klog("Halting due to: %s", s);
@@ -38,10 +35,6 @@ void start(void)
         const char      *_cpuModel  = "Cortex A-72";
         const uint32_t  _coreCount =  2u;
 
-        /* Symbols. Defined in Kernel/kernel.ld */
-        const uint64_t *kernelBase = (uint64_t*) &kstart;
-        const uint64_t *kernelEnd = (uint64_t*) &kend;
-
         klog("WesterOS early boot stage\n");
         klog("Running sanity checks...\n");
 
@@ -129,9 +122,6 @@ void start(void)
                 kprintf("Unmasked\n");
         }
 
-        MRS("VBAR_EL1", val64);
-        klog("---- Vector Table: 0x%lx\n", val64);
-
         /* -------- Machine Layout -------- */
         klog("QEMU ARM Virt Machine memory layout:\n");
 
@@ -163,13 +153,6 @@ void start(void)
                 DTB_START, DTB_END
         );
 
-        klog ("---- Kernel: 0x%p - 0x%p (system)\n",
-                kernelBase,
-                kernelEnd
-        );
-
-        val64 = (kernelEnd - kernelBase);
-        klog("WesterOS kernel size: %lu bytes\n", val64);
 
         klog("Everything's OK. Calling the Kernel now...\n");
         kmain();

Kernel/kernel.ld

@@ -9,76 +9,85 @@ OUTPUT_ARCH(aarch64)
 ENTRY(_start)
 
 ENTRY_INIT_STACK_SIZE = 0x2000; /* 8 KiB */
+KERNEL_VMA_BASE = 0xFFFF000000000000; /* TTBR1_EL1 lower boundary */
 
 SECTIONS
 {
-        /* the entry point, before enabling paging. The code to enable paing
-         * needs to have the same virtual/physical address. Entry.S and Start.c
-         * run in this initial setting.
+        /*
+         * The entry point, before enabling paging.
+         * The code to enable paging needs to have the same VA & PA.
+         * Only Entry.S and Start.c run in this initial setting.
          */
 
-        /* QEMU loads DTB at 0x00000000_40000000. So we skip 1MiB */
+        /* QEMU loads DTB at 0x00000000_40000000. So we skip over it (1MiB) */
         . = 0x40100000;
-        PROVIDE (kstart = .);
-
-        .start_sec : {
+
+        .start_sec :
+        {
+                _start_sec = .;
+
                 Build/Entry.o(.text)
-                Build/Vector.o(.text)
                 Build/Start.o(.text .text.*)
 
                 Build/Entry.o(.rodata .rodata.*)
-                Build/Vector.o(.rodata .rodata.*)
                 Build/Start.o(.rodata .rodata.*)
 
                 Build/Entry.o(.data .data.*)
-                Build/Vector.o(.data .data.*)
                 Build/Start.o(.data .data.*)
 
                 PROVIDE(edata_entry = .);
 
                 Build/Entry.o(.bss .bss.* COMMON)
-                Build/Vector.o(.bss .bss.* COMMON)
                 Build/Start.o(.bss .bss.* COMMON)
 
-                /* Reserve space for stack */
+                /* Reserve stack space for kernel */
                 . = ALIGN(0x1000);
                 . += ENTRY_INIT_STACK_SIZE;
 
                 PROVIDE (init_stktop = .);
 
                 PROVIDE(end_entry = .);
-                . += 0x1000;
+                . = ALIGN(0x1000);
         }
 
-        /* the kernel executes at the higher address space, but loaded
-        at the lower memory (0x30000) */
+        /*
+         * Kernel has two adresses:
+         * Load Memory Address (LMA): right after '.start_sec'
+         * Virtual Memory Address (VMA): right after 'KERNEL_VMA_BASE'
+         *
+         * https://sourceware.org/binutils/docs/ld/Basic-Script-Concepts.html
+         */
+
+        /* . = KERNEL_VMA_BASE; */ 
 
-        .text : { /** here to make code also copied into phymem **/
+        .text : AT(ADDR(.start_sec) + SIZEOF(.start_sec))
+        {
+                _code = .;
                 *(.text .text.* .gnu.linkonce.t.*)
+                *(.rodata*)
+                . = ALIGN(0x1000);
         }
 
-        PROVIDE(etext = .);	/* Define the 'etext' symbol to this value */
-
-        .rodata : {
-                *(.rodata .rodata.* .gnu.linkonce.r.*)
-        }
-
-        /* aligned the data to a (4K) page, so it can be assigned
-        different protection than the code*/
-        . = ALIGN(0x1000);
-
-        PROVIDE (data_start = .);
-
-        .data : {
+        .data : AT(ADDR(.text) + SIZEOF(.text))
+        {
+                _data = .;
                 *(.data .data.*)
+                . = ALIGN(0x1000);
         }
 
-        PROVIDE (edata = .);
+        .eh_frame : AT(ADDR(.data) + SIZEOF(.data))
+        {
+                _ehframe = .;
+                *(.eh_frame)
+                . = ALIGN(0x1000);
+        }
 
-        .bss : {
+        .bss : AT(ADDR(.eh_frame) + SIZEOF(.eh_frame))
+        {
+                _bss = .;
                 *(.bss .bss.* COMMON)
+                . = ALIGN(0x1000);
         }
 
-        . = ALIGN(0x1000);
         PROVIDE (kend = .);
 }