Add threading, paging broken
diff --git a/src/kernel/.gdbinit b/src/kernel/.gdbinit
index 24efe1e..54e4e4c 100644
--- a/src/kernel/.gdbinit
+++ b/src/kernel/.gdbinit
@@ -1 +1,2 @@
+file kernel.elf
target remote localhost:1234
diff --git a/src/kernel/Jmk b/src/kernel/Jmk
index 5774274..c299cf1 100644
--- a/src/kernel/Jmk
+++ b/src/kernel/Jmk
@@ -36,14 +36,18 @@
multiboot.o \
vfs_initrd.o \
syscall.o \
- task.o
+ task.o \
+ task_api.o
type(custom_link)
+debug-wait: kernel.elf
+ qemu-system-i386 -s -S -kernel kernel.elf
+
debug: kernel.elf
qemu-system-i386 -s -S -kernel kernel.elf &
@echo run "target remote localhost:1234" to connect to qemu
- gdb
+ gdb $<
@pkill qemu-system-i38
qemu: kernel.elf
diff --git a/src/kernel/io.c b/src/kernel/io.c
index baa050f..0b300b5 100644
--- a/src/kernel/io.c
+++ b/src/kernel/io.c
@@ -55,8 +55,8 @@
uint strlen(char *a)
{
- int i = 0;
- for (; *a; i++)
+ uint i = 0;
+ for (; a[i]; i++)
{
}
diff --git a/src/kernel/main.c b/src/kernel/main.c
index 22d4a35..ea5200b 100644
--- a/src/kernel/main.c
+++ b/src/kernel/main.c
@@ -2,13 +2,30 @@
#include "descriptor_tables.h"
#include "io.h"
#include "log.h"
+#include "multiboot.h"
#include "paging.h"
+#include "syscall.h"
+#include "task.h"
#include "timer.h"
-#include "vga.h"
#include "vfs.h"
#include "vfs_initrd.h"
-#include "multiboot.h"
-#include "syscall.h"
+#include "vga.h"
+
+void greet()
+{
+ kprintf("Hello from get_task_id() = %d, get_process_id() = %d\n",
+ get_task_id(), get_process_id());
+}
+
+void other_thread()
+{
+ greet();
+ kprintf("Other thread returning...\n");
+ switch_task();
+
+ while (true)
+ asm volatile("hlt");
+}
int kmain(struct multiboot_info *mboot)
{
@@ -56,6 +73,16 @@
}
#endif
+ kprintf("initializing tasks\n");
+ init_tasks();
+ kprintf("\ndone initializing tasks\n");
+
+ greet();
+ spawn_thread(other_thread);
+ kprintf("thread spawned\n");
+ switch_task();
+ kprintf("Back in main thread\n");
+
asm volatile("sti");
while (true)
diff --git a/src/kernel/multiboot.c b/src/kernel/multiboot.c
index c3a3a2e..d69f56c 100644
--- a/src/kernel/multiboot.c
+++ b/src/kernel/multiboot.c
@@ -15,7 +15,7 @@
TO_VIRT(mb.cmdline, char);
kprintf("mb.mods_addr = %d, 0x%x\n", mb.mods_addr, mb.mods_addr);
- kassert((size_t)mb.mods_addr > 0xc0000000, "mb.mods_addr PHYSICAL");
+ kassert((size_t)mb.mods_addr >= 0xc0000000, "mb.mods_addr PHYSICAL");
for (int i = 0; i < mb.mods_count + 1; i++)
{
TO_VIRT(*(uint *)(mb.mods_addr+i), uint);
diff --git a/src/kernel/paging.c b/src/kernel/paging.c
index 4d0aa94..809d12c 100644
--- a/src/kernel/paging.c
+++ b/src/kernel/paging.c
@@ -5,9 +5,9 @@
#include "log.h"
#include "pic.h"
+#define NUM_FRAMES 0xffffffff / 0x1000 / 32
/* frames bitset, 0 = free, 1 = used */
-static uint frames[0xffffffff / 0x1000 / 32];
-static ulong num_frames;
+static uint frames[NUM_FRAMES];
static uint first_page_table[1024] __attribute__((aligned(4096)));
uint kernel_page_directory[1024] __attribute__((aligned(4096)));
@@ -36,7 +36,7 @@
static uint first_free_frame()
{
- for (int i = 0; i < num_frames / BITS; i++)
+ for (int i = 0; i < NUM_FRAMES / BITS; i++)
{
/*
* If there are any zeroes, ~ will yield a non-zero result,
@@ -47,10 +47,13 @@
for (int j = 0; j < BITS; j++)
{
- if ((frames[i] & 1 << j) == 0)
+ if ((frames[i] & (1 << j)) == 0)
{
/* found unused frame */
- return i * BITS + j;
+ uint frame = i * BITS + j;
+ kprintf("first_free_frame returning %d\n", frame);
+// kpanic("asdf");
+ return frame;
}
}
}
@@ -61,7 +64,7 @@
void alloc_frame(uint *page_table_entry, bool user, bool writable)
{
- if (*page_table_entry >> 12)
+ if (*page_table_entry & 1)
return; /* frame already allocated */
uint frame = first_free_frame();
@@ -83,7 +86,7 @@
for (uint i = 0; i < 1024 * 0x1000; i += 0x1000)
{
- set_frame(page + i);
+ set_frame(i);
}
dir[table] = 0b10000011;
@@ -93,7 +96,7 @@
{
if (dir[table] >> 12)
{
- return (uint *)(size_t)(dir[table] ^ 0xfff);
+ return (uint *)(size_t)PHYS_TO_VIRT((dir[table] ^ 0xfff));
}
uint *page_table = kmalloc_a(sizeof(uint[1024]));
@@ -129,6 +132,9 @@
uint *table = get_or_create_table(dir, (size_t)virt >> 22, false, false);
alloc_frame(&table[page], false, false);
+
+ kprintf("alloc_page table[page] = %d (0x%x)\n", table[page], table[page]);
+ return;
}
void alloc_kernel_page_range(uint *from, uint *to)
diff --git a/src/kernel/task.c b/src/kernel/task.c
index 3d27850..4e71174 100644
--- a/src/kernel/task.c
+++ b/src/kernel/task.c
@@ -1,22 +1,35 @@
#include "task.h"
#include "alloc.h"
#include "io.h"
+#include "log.h"
#include "paging.h"
struct process processes[1024] = {0};
struct ll_task_i *first_task = NULL, *last_task = NULL, *current_task = NULL;
+static uint next_task_id = 0;
-void init_tasks(uint kernel_esp, uint kernel_ebp, uint kernel_eip)
+void _init_tasks(uint kernel_esp, uint kernel_ebp, uint kernel_eip)
{
asm volatile("cli");
+ kprintf("_init_tasks\n");
+
processes[0] = (struct process){
.exists = true,
.id = 0,
.ring = 0,
.uid = 0,
+ .page_directory_p = VIRT_TO_PHYS(kernel_page_directory),
+ // Obviously this isn't the actual stack position, but we want it to
+ // grow down from 4 gb so we will pretend that the first task has its
+ // stack at exactly 4gb and work from there. Because the new stack will
+ // be mapped to any random frame, it doesn't actually matter where we
+ // put it, we just want somewhere that won't collide with any user space
+ // stuff or our heap.
+ .last_stack_pos = 0xFFFFF000,
};
strcpy(processes[0].name, "kernel");
+ kprintf("in _init_tasks, strlen of 'kernel' is %d\n", strlen("kernel"));
first_task = last_task = current_task = malloc(sizeof(struct ll_task_i));
@@ -26,10 +39,11 @@
.esp = kernel_esp,
.ebp = kernel_ebp,
.eip = kernel_eip,
- .kernel = true,
- .page_directory = kernel_page_directory,
+ .id = next_task_id++,
};
+ kprintf("Returning from _init_tasks\n");
+
asm volatile("sti");
}
@@ -51,7 +65,82 @@
return current_task->task.proc->id;
}
-void spawn_thread(void (* function)(void *data), void *data)
+void spawn_thread(void (*function)())
{
+ asm volatile("cli");
+ struct process *proc = current_task->task.proc;
+ // Virtual address of page directory (in kernel memory)
+ uint *dir_v = PHYS_TO_VIRT(proc->page_directory_p);
+ // Virtual location of new stack
+ uint new_stack_base_v = proc->last_stack_pos = proc->last_stack_pos - 0x1000;
+
+ // Alloc a new page in the current process mapping to the new stack
+ alloc_page(dir_v, (void *)new_stack_base_v);
+
+ // <TEST>: see if we can assign to the new stack memory (ie: did mapping succeed)
+ uint *base = (uint *)new_stack_base_v;
+
+ kprintf("base = 0x%x\n", base);
+
+ *base = 0;
+ kpanic("in spawn_thread\n");
+ // </TEST>
+
+ struct ll_task_i *ll_task = malloc(sizeof(struct ll_task_i));
+ memset(ll_task, 0, sizeof(struct ll_task_i));
+ struct task *task = &ll_task->task;
+
+ task->proc = proc;
+ task->id = next_task_id++;
+ task->ebp = task->esp = new_stack_base_v;
+ task->eip = (uint)function;
+
+ last_task->next = ll_task;
+ last_task = ll_task;
+
+ asm volatile("sti");
+}
+
+extern void _switch_to_task(uint page_directory, uint eip, uint ebp, uint esp);
+
+void switch_to_task(struct task *task)
+{
+ _switch_to_task(task->proc->page_directory_p, task->eip, task->ebp,
+ task->esp);
+ __builtin_unreachable();
+}
+
+// WARNING: do not call this manually, it will clobber everything
+// except esp, ebp, and eip (obviously). Use switch_task in task_api.s
+// instead.
+void _do_switch_task(uint eip, uint ebp, uint esp)
+{
+ // sti is called in switch_to_task
+ asm volatile("cli");
+
+ kprintf("\nin _do_switch_task(%d, %d, %d)\n", eip, ebp, esp);
+
+ // save context for this task
+ current_task->task.ebp = ebp;
+ current_task->task.esp = esp;
+ current_task->task.eip = eip;
+
+ if (current_task->next == NULL)
+ {
+ // Start from the first task if there are more tasks, or just return
+ if (current_task == first_task)
+ return; // No context switch necessary
+
+ current_task = first_task;
+ }
+ else
+ {
+ // Continue the next task
+ current_task = current_task->next;
+ }
+
+ kprintf("Will switch to task id %d\n", current_task->task.id);
+
+ switch_to_task(¤t_task->task);
}
diff --git a/src/kernel/task.h b/src/kernel/task.h
index e70fd6d..c31162e 100644
--- a/src/kernel/task.h
+++ b/src/kernel/task.h
@@ -6,10 +6,15 @@
struct process
{
bool exists;
- int id;
+ int id; // kernel uses pid 0, which cannot exit
int ring;
int uid;
char name[32];
+ uint page_directory_p;
+ // most recent (bottom) stack used by a task, next
+ // stack should be under this one.
+ // NOTE: must be PAGE ALIGNED
+ uint last_stack_pos;
};
struct task
@@ -18,8 +23,6 @@
struct process *proc;
uint stack_top_p; // stack frame PHYSICAL address
uint esp, ebp, eip;
- uint *page_directory;
- bool kernel;
};
struct ll_task_i
@@ -31,7 +34,7 @@
// extern struct process processes[1024];
// extern struct ll_task_i *first_task, *current_task;
-void init_tasks(uint kernel_esp, uint kernel_ebp, uint kernel_eip);
+extern void init_tasks();
struct process *get_process(uint pid);
int get_process_id();
@@ -40,4 +43,5 @@
// For compatibility I guess
#define getpid get_process_id
-void spawn_thread(void (* function)(void *data), void *data);
+void spawn_thread(void (*function)());
+extern void switch_task();
diff --git a/src/kernel/task_api.s b/src/kernel/task_api.s
new file mode 100644
index 0000000..686ddaa
--- /dev/null
+++ b/src/kernel/task_api.s
@@ -0,0 +1,39 @@
+ [bits 32]
+ [extern _do_switch_task]
+ [global switch_task]
+switch_task:
+ pusha ; Save everything
+ push esp ; Arguments for _do_switch_task(eip, ebp, esp)
+ push ebp
+ push .after
+ call _do_switch_task
+.after:
+ popa ; Reset everything
+ xor eax, eax ; Return 0
+ ret
+
+ [global _switch_to_task]
+_switch_to_task: ; (page_directory, eip, ebp, esp)
+ add esp, 4 ; We don't care about the return address
+ pop eax ; Instruction pointer
+ pop ebp ; Frame pointer
+ pop ebx ; Stack pointer
+ pop ecx ; Page directory
+
+ mov esp, ebx ; Reset old stack
+
+ mov cr3, ecx ; Set page directory
+ sti
+ jmp eax ; Jump back to code
+
+ [extern _init_tasks]
+ [global init_tasks]
+init_tasks:
+ lea eax, [esp + 4] ; Stack pointer before call
+ mov ebx, [esp] ; Return address
+ push ebx ; eip
+ push ebp ; ebp
+ push eax ; esp
+ call _init_tasks
+ add esp, 12
+ ret