a sensible source structure

The idea is that src/kernel/ is only allowed to interface with the
hardware using whatever's defined in src/arch/generic.h. I'll probably
write a small script for checking this later on.

This is a giant commit so I've probably fucked something up. It boots
fine on Bochs and QEMU, so at least there's that.

1 files changed, 0 insertions, 121 deletions

diff --git a/src/kernel/gdt.c b/src/kernel/gdt.c
deleted file mode 100644
index b0d6320..0000000
--- a/src/kernel/gdt.c
+++ /dev/null
@@ -1,121 +0,0 @@
-#include <kernel/gdt.h>
-#include <kernel/util.h>
-#include <stdint.h>
-
-extern void stack_top; // platform/boot.s
-
-struct gdt_entry {
-	uint64_t limit_low  : 16;
-	uint64_t base_low   : 24;
-	uint64_t accessed   :  1; // set by the processor
-	                          // CODE        | DATA
-	uint64_t rw         :  1; // readable?   | writeable?
-	uint64_t conforming :  1; // conforming? | expands down?
-	uint64_t code       :  1; // 1           | 0
-
-	uint64_t codeordata :  1; // 1 for everything other than TSS and LDT
-	uint64_t ring       :  2;
-	uint64_t present    :  1; // always 1
-	uint64_t limit_high :  4;
-	uint64_t available  :  1; // ???
-	uint64_t long_mode  :  1;
-	uint64_t x32        :  1;
-	uint64_t gran       :  1; // 1 - 4kb, 0 - 1b
-	uint64_t base_high  :  8;
-} __attribute__((packed));
-
-struct tss_entry {
-	uint32_t prev_tss; // unused
-	uint32_t esp0; // kernel mode stack pointer
-	uint32_t ss0;  // kernel mode stack segment
-	// total size = 0x68 (?) - 3 * sizeof(uint32_t) = 5c
-	uint8_t  _unused[0x5c];
-} __attribute__((packed));
-
-struct lgdt_arg {
-	uint16_t limit;
-	uint32_t base;
-} __attribute__((packed));
-
-static struct gdt_entry GDT[SEG_end];
-static struct tss_entry TSS;
-static struct lgdt_arg lgdt_arg; // probably doesn't need to be global
-
-static void gdt_prepare();
-static void gdt_load();
-
-
-static void gdt_prepare() {
-	GDT[SEG_null].present = 0;
-
-	GDT[SEG_r0data].limit_low  = 0xFFFF;
-	GDT[SEG_r0data].limit_high = 0xF;
-	GDT[SEG_r0data].gran       = 1; // 4KB * 0xFFFFF = (almost) 4GB
-	GDT[SEG_r0data].base_low   = 0;
-	GDT[SEG_r0data].base_high  = 0;
-	GDT[SEG_r0data].accessed   = 0;
-	GDT[SEG_r0data].rw         = 1;
-	GDT[SEG_r0data].conforming = 0;
-	GDT[SEG_r0data].code       = 0;
-	GDT[SEG_r0data].codeordata = 1;
-	GDT[SEG_r0data].ring       = 0;
-	GDT[SEG_r0data].present    = 1;
-	GDT[SEG_r0data].long_mode  = 0; // ???
-	GDT[SEG_r0data].available  = 1; // ???
-	GDT[SEG_r0data].x32        = 1;
-
-	// copy to r0 code
-	GDT[SEG_r0code] = GDT[SEG_r0data];
-	GDT[SEG_r0code].code = 1;
-
-	GDT[SEG_r3data] = GDT[SEG_r0data];
-	GDT[SEG_r3data].ring = 3;
-	GDT[SEG_r3code] = GDT[SEG_r0code];
-	GDT[SEG_r3code].ring = 3;
-
-	// tss
-	memset(&TSS, 0, sizeof(TSS));
-	TSS.ss0 = SEG_r0data << 3; // kernel data segment
-	TSS.esp0 = (uint32_t) &stack_top;
-
-	GDT[SEG_TSS].limit_low  = sizeof(TSS);
-	GDT[SEG_TSS].base_low   = (uint32_t) &TSS;
-	GDT[SEG_TSS].accessed   = 1; // 1 for TSS
-	GDT[SEG_TSS].rw         = 0; // 1 busy / 0 not busy
-	GDT[SEG_TSS].conforming = 0; // 0 for TSS
-	GDT[SEG_TSS].code       = 1; // 32bit
-	GDT[SEG_TSS].codeordata = 0; // is a system entry
-	GDT[SEG_TSS].ring       = 3;
-	GDT[SEG_TSS].present    = 1;
-	GDT[SEG_TSS].limit_high = (sizeof(TSS) >> 16) & 0xf;
-	GDT[SEG_TSS].available  = 0; // 0 for TSS
-	GDT[SEG_TSS].long_mode  = 0;
-	GDT[SEG_TSS].x32        = 0; // idk
-	GDT[SEG_TSS].gran       = 0;
-	GDT[SEG_TSS].base_high  = (((uint32_t) &TSS) >> 24) & 0xff;
-}
-
-void change_cs(int seg); // temporary
-
-static void gdt_load() {
-	lgdt_arg.limit = sizeof(GDT) - 1;
-	lgdt_arg.base = (uint32_t) &GDT;
-	asm("lgdt (%0)" 
-	    : : "r" (&lgdt_arg) : "memory");
-	asm("ltr %%ax"
-	    : : "a" (SEG_TSS << 3 | 3) : "memory");
-
-	// update all segment registers
-	change_cs(SEG_r0code << 3);
-	asm("mov %0, %%ds;"
-	    "mov %0, %%ss;"
-	    "mov %0, %%es;"
-	    "mov %0, %%fs;"
-	    "mov %0, %%gs;"
-	    : : "r" (SEG_r0data << 3) : "memory");
-}
-
-void gdt_init() {
-	gdt_prepare();
-	gdt_load();
-}