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-rw-r--r--kc/core/Makefile6
-rw-r--r--kc/core/cpu.h10
-rw-r--r--kc/core/cpu/cpu.c294
-rw-r--r--kc/core/cpu/msr.c29
-rw-r--r--kc/core/cpu/msr.h15
-rw-r--r--kc/core/exceptions.h3
-rw-r--r--kc/core/kc_main.c4
7 files changed, 353 insertions, 8 deletions
diff --git a/kc/core/Makefile b/kc/core/Makefile
index 53f1cea..2b8ab8d 100644
--- a/kc/core/Makefile
+++ b/kc/core/Makefile
@@ -1,18 +1,18 @@
include ../../defaults.mk
include ../defaults.mk
-VPATH := ../../lib ../
+VPATH := ../../lib ../ cpu/
TARGET := kernel.os
.DEFAULT: $(TARGET)
-CPPFLAGS += -I../../api
+CPPFLAGS += -I../../api -I.
CFLAGS += -Wno-unused-const-variable -Wno-unused-function -fvisibility=hidden -g
SOBJS :=
GOBJS := entry_x86_64.o reloc_x86_64.o kprint.o serial.o port.o \
kc_main.o main.o memory.o memset.o memcpy.o memmove.o memcmp.o cpu.o \
- vm_tree.o exceptions.o panic.o
+ vm_tree.o exceptions.o panic.o msr.o
IOBJS :=
# __attribute__((interrupt)) requires -mgeneral-regs-only
diff --git a/kc/core/cpu.h b/kc/core/cpu.h
index 2d5e134..a8da9bf 100644
--- a/kc/core/cpu.h
+++ b/kc/core/cpu.h
@@ -1,15 +1,17 @@
#pragma once
-#include <stdint.h>
+#include "task.h"
+
+#include <stdnoreturn.h>
void cpu_init(void);
+noreturn void cpu_task_begin(void);
+void cpu_task_set(struct kc_thread *task);
+
void isr_install(int vec, void (*isr)(void), int ist, int trap);
void ist_install(int ist, void *stack);
void int_enable(void);
void int_disable(void);
-uint64_t msr_read(uint32_t index);
-void msr_write(uint32_t index, uint64_t value);
-
diff --git a/kc/core/cpu/cpu.c b/kc/core/cpu/cpu.c
new file mode 100644
index 0000000..49a88be
--- /dev/null
+++ b/kc/core/cpu/cpu.c
@@ -0,0 +1,294 @@
+#include "cpu.h"
+#include "exceptions.h"
+#include "kprint.h"
+#include "panic.h"
+#include "msr.h"
+#include "task.h"
+#include "memory.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define GDT_ENTRIES 16
+#define IDT_ENTRIES 256
+
+#define CODE_SUPER_SEG_INDEX 1
+#define CODE_USER_SEG_INDEX 2
+#define DATA_SEG_INDEX 3
+#define TASK_SEG_INDEX 4
+
+#define EFER_SCE 1
+
+#define MSR_EFER 0xc0000080
+#define MSR_STAR 0xc0000081
+#define MSR_LSTAR 0xc0000082
+#define MSR_CSTAR 0xc0000083
+#define MSR_SFMASK 0xc0000084
+
+struct dtr64
+{
+ uint16_t limit;
+ uint64_t base;
+} __attribute__((packed));
+
+struct segment_descriptor
+{
+ uint16_t limit0;
+ uint16_t base0;
+ uint8_t base16;
+ uint8_t access;
+ uint8_t flags_limit16;
+ uint8_t base24;
+} __attribute__((packed));
+
+enum segment_descriptor_type
+{
+ CODE64_SUPER_SEG,
+ CODE64_USER_SEG,
+ DATA_SEG,
+ TASK64_SEG,
+};
+
+struct gate_descriptor
+{
+ uint16_t offset0;
+ uint16_t selector;
+ uint8_t ist;
+ uint8_t access;
+ uint16_t offset16;
+ uint64_t offset32;
+} __attribute__((packed));
+
+enum gate_descriptor_type
+{
+ INT64_GATE,
+ TRAP64_GATE,
+};
+
+struct task64_segment
+{
+ uint32_t reserved0;
+ uint64_t rsp0;
+ uint64_t rsp1;
+ uint64_t rsp2;
+ uint64_t reserved1;
+ uint64_t ist[7];
+ uint16_t reserved2;
+ uint16_t iomap_base;
+};
+
+static struct segment_descriptor gdt[GDT_ENTRIES];
+static struct gate_descriptor idt[IDT_ENTRIES];
+static struct task64_segment tss;
+
+uint64_t *get_tss_rsp0(void)
+{
+ return &tss.rsp0;
+}
+
+static void syscall_entry(void)
+{
+ kputs("system call\n");
+ halt();
+}
+
+static void set_gdt(int index,
+ uint64_t base,
+ uint64_t limit,
+ enum segment_descriptor_type type)
+{
+ gdt[index].limit0 = limit & 0xffff;
+ gdt[index].base0 = base & 0xffff;
+ gdt[index].base16 = (base >> 16) & 0xff;
+ gdt[index].flags_limit16 = (limit >> 16) & 0xf;
+ gdt[index].base24 = (base >> 24) & 0xff;
+
+ switch (type)
+ {
+ case CODE64_SUPER_SEG:
+ gdt[index].access = 0x9a;
+ gdt[index].flags_limit16 |= 0xa0;
+ break;
+ case CODE64_USER_SEG:
+ gdt[index].access = 0xfa;
+ gdt[index].flags_limit16 |= 0xa0;
+ break;
+ case DATA_SEG:
+ gdt[index].access = 0x92;
+ gdt[index].flags_limit16 |= 0xc0;
+ break;
+ case TASK64_SEG:
+ gdt[index].access = 0x89;
+ //TODO: make this cleaner i don't like it
+ gdt[index+1].limit0 = (base >> 32) & 0xffff;
+ gdt[index+1].base0 = (base >> 48) & 0xffff;
+ break;
+ };
+}
+
+static void set_idt(int vec,
+ uint16_t selector,
+ uint64_t offset,
+ enum gate_descriptor_type type)
+{
+ idt[vec].offset0 = offset & 0xffff;
+ idt[vec].selector = selector;
+ idt[vec].offset16 = (offset >> 16) & 0xffff;
+ idt[vec].offset32 = (offset >> 32) & 0xffffffff;
+
+ switch (type)
+ {
+ case INT64_GATE:
+ idt[vec].access = 0x8e;
+ break;
+ case TRAP64_GATE:
+ idt[vec].access = 0x8f;
+ break;
+ }
+}
+
+void set_ist(int vec, int ist_index)
+{
+ // non-destructively set the ist index.
+ idt[vec].access |= ist_index & 0x7;
+}
+
+static void gdt_init(void)
+{
+ set_gdt(CODE_SUPER_SEG_INDEX, 0, (uint64_t)-1, CODE64_SUPER_SEG);
+ set_gdt(CODE_USER_SEG_INDEX, 0, (uint64_t)-1, CODE64_USER_SEG);
+ set_gdt(DATA_SEG_INDEX, 0, (uint64_t)-1, DATA_SEG);
+ set_gdt(TASK_SEG_INDEX, (uint64_t)&tss, sizeof(tss) - 1, TASK64_SEG);
+
+ struct dtr64 gdtr = {sizeof(gdt) - 1, (uint64_t)&gdt};
+
+ __asm__ volatile
+ (
+ // can't have interrupts during GDT reload
+ // but don't re-enable interrupts if they were already disabled
+ "pushf\n"
+ "cli\n"
+ "lgdt %0\n"
+ "mov %w2, %%ds\n"
+ "mov %w2, %%es\n"
+ "mov %w2, %%fs\n"
+ "mov %w2, %%gs\n"
+ "mov %w2, %%ss\n"
+ // make a far return frame on the stack
+ // [ss] @rsp+8
+ // [rip] @rsp
+ "pushq %1\n"
+ "lea .Lflush(%%rip), %%rax\n"
+ "push %%rax\n"
+ // far return, now we're in the code segment
+ // defined here.
+ "lretq\n"
+ ".Lflush:\n"
+ "ltr %w3\n"
+ "popf\n"
+ // dependency on pre-boot GDT is now gone
+ :
+ : "m"(gdtr),
+ "i"(CODE_SUPER_SEG_INDEX << 3),
+ "r"(DATA_SEG_INDEX << 3),
+ "r"(TASK_SEG_INDEX << 3)
+ );
+}
+
+static void idt_init(void)
+{
+ struct dtr64 idtr = {sizeof(idt) - 1, (uint64_t)&idt};
+
+ __asm__ volatile
+ (
+ // can't have interrupts enabled during IDT reload--obviously.
+ // as with GDT don't re-enable interrupts if they were already
+ // disabled.
+ "pushf\n"
+ "cli\n"
+ "lidt %0\n"
+ "popf\n"
+ // much more straightforward than the gdt code.
+ :: "m"(idtr)
+ );
+}
+
+void cpu_init(void)
+{
+ gdt_init();
+ idt_init();
+ exceptions_init();
+
+ //TODO: fix rudimentary syscall stuff.
+
+ uint64_t lstar_bits = (uintptr_t)syscall_entry;
+ msr_write(MSR_LSTAR, lstar_bits);
+
+ union
+ {
+ struct
+ {
+ uint32_t eip32;
+ uint8_t syscall_ss;
+ uint8_t syscall_cs;
+ uint8_t sysret_ss;
+ uint8_t sysret_cs;
+ }
+ fields;
+ uint64_t raw;
+ }
+ star_bits =
+ {
+ {
+ 0,
+ DATA_SEG_INDEX,
+ CODE_SUPER_SEG_INDEX,
+ DATA_SEG_INDEX,
+ CODE_USER_SEG_INDEX
+ }
+ };
+
+ msr_write(MSR_STAR, star_bits.raw);
+
+ uint64_t efer_bits = msr_read(MSR_EFER);
+ efer_bits |= EFER_SCE; // enable syscall extensions
+ msr_write(MSR_EFER, efer_bits);
+}
+
+void exceptions_init(void)
+{
+ isr_install(GENERAL_PROTECTION_VECTOR, &general_protection_isr, 0, 0);
+ isr_install(PAGE_FAULT_VECTOR, &page_fault_isr, 0, 0);
+}
+
+void isr_install(int vec, void (*isr)(void), int trap, int ist)
+{
+ enum gate_descriptor_type type = INT64_GATE;
+
+ if (trap)
+ {
+ type = TRAP64_GATE;
+ }
+
+ set_idt(vec, CODE_SUPER_SEG_INDEX << 3, (uint64_t)isr, type);
+ if (ist)
+ {
+ set_ist(vec, ist);
+ }
+}
+
+void ist_install(int ist, void *stack)
+{
+ tss.ist[ist] = (uint64_t)stack;
+}
+
+void int_enable(void)
+{
+ __asm__ ("sti");
+}
+
+void int_disable(void)
+{
+ __asm__ ("cli");
+}
+
diff --git a/kc/core/cpu/msr.c b/kc/core/cpu/msr.c
new file mode 100644
index 0000000..2efdd7d
--- /dev/null
+++ b/kc/core/cpu/msr.c
@@ -0,0 +1,29 @@
+#include "msr.h"
+
+uint64_t msr_read(uint32_t index)
+{
+ uint32_t low;
+ uint32_t high;
+
+ __asm__ volatile
+ (
+ "rdmsr\n\t"
+ : "=a"(low), "=d"(high)
+ : "c"(index)
+ );
+
+ return ((uint64_t)high << 32)|low;
+}
+
+void msr_write(uint32_t index, uint64_t value)
+{
+ uint32_t low = value & 0xffffffff;
+ uint32_t high = value >> 32;
+
+ __asm__ volatile
+ (
+ "wrmsr\n\t"
+ :: "a"(low), "d"(high), "c"(index)
+ );
+}
+
diff --git a/kc/core/cpu/msr.h b/kc/core/cpu/msr.h
new file mode 100644
index 0000000..a5014da
--- /dev/null
+++ b/kc/core/cpu/msr.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stdint.h>
+
+#define EFER_SCE 1
+
+#define MSR_EFER 0xc0000080
+#define MSR_STAR 0xc0000081
+#define MSR_LSTAR 0xc0000082
+#define MSR_CSTAR 0xc0000083
+#define MSR_SFMASK 0xc0000084
+
+uint64_t msr_read(uint32_t index);
+void msr_write(uint32_t index, uint64_t value);
+
diff --git a/kc/core/exceptions.h b/kc/core/exceptions.h
index 5d22284..11696d5 100644
--- a/kc/core/exceptions.h
+++ b/kc/core/exceptions.h
@@ -1,7 +1,10 @@
#pragma once
extern void page_fault_isr(void);
+extern void general_protection_isr(void);
+#define GENERAL_PROTECTION_VECTOR 0xd
#define PAGE_FAULT_VECTOR 0xe
void exceptions_init(void);
+
diff --git a/kc/core/kc_main.c b/kc/core/kc_main.c
index d8ccc11..1eb07da 100644
--- a/kc/core/kc_main.c
+++ b/kc/core/kc_main.c
@@ -10,9 +10,11 @@
#include <stddef.h>
#include <stdint.h>
+//TODO: initialize vm before cpu?
+// alternatively, split memory and/or cpu initialization steps
+
unsigned long kc_main(struct kc_boot_data *data)
{
- (void)data;
cpu_init();
serial_init();
kputs("<hacker voice> i'm in 3333\r\n");
generated by cgit v1.3.1-1-g115d (git 2.54.0) at 2026-07-22 22:42:17 +0000