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#include <kernel/arch/generic.h>
#include <kernel/mem/alloc.h>
#include <kernel/mem/virt.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/vfs/mount.h>
#include <shared/mem.h>
#include <stdint.h>
struct process *process_first;
struct process *process_current;
static uint32_t next_pid = 0;
struct process *process_seed(void) {
struct process *proc = kmalloc(sizeof *proc);
proc->pages = pagedir_new();
proc->state = PS_RUNNING;
proc->sibling = NULL;
proc->child = NULL;
proc->parent = NULL;
proc->mount = vfs_mount_seed();
proc->id = next_pid++;
proc->handled_req = NULL;
proc->controlled = NULL;
process_first = proc;
for (int i = 0; i < HANDLE_MAX; i++)
proc->handles[i].type = HANDLE_EMPTY;
// map the stack to the last page in memory
pagedir_map(proc->pages, (userptr_t)~PAGE_MASK, page_alloc(1), true, true);
proc->regs.esp = (userptr_t) ~0xF;
// map the kernel
// yup, .text is writeable too. the plan is to not map the kernel
// into user memory at all, but i'll implement that later. TODO
for (size_t p = 0x100000; p < (size_t)&_bss_end; p += PAGE_SIZE)
pagedir_map(proc->pages, (userptr_t)p, (void*)p, false, true);
// the kernel still has to load the executable code and set EIP
return proc;
}
struct process *process_fork(struct process *parent) {
struct process *child = kmalloc(sizeof *child);
memcpy(child, parent, sizeof *child);
child->pages = pagedir_copy(parent->pages);
child->sibling = parent->child;
child->child = NULL;
child->parent = parent;
parent->child = child;
parent->handled_req = NULL; // TODO control this with a flag
child->id = next_pid++;
return child;
}
void process_free(struct process *p) {
assert(p->state == PS_DEADER);
pagedir_free(p->pages);
if (p->child) { // TODO
// panic_invalid_state();
return;
}
if (p->parent && p->parent->child == p) {
p->parent->child = p->sibling;
} else {
// this would be simpler if siblings were a doubly linked list
struct process *prev = p->parent->child;
while (prev->sibling != p) {
prev = prev->sibling;
assert(prev);
}
prev->sibling = p->sibling;
}
kfree(p);
}
void process_switch(struct process *proc) {
assert(proc->state == PS_RUNNING);
process_current = proc;
pagedir_switch(proc->pages);
sysexit(proc->regs);
}
_Noreturn void process_switch_any(void) {
struct process *found = process_find(PS_RUNNING);
if (found) process_switch(found);
process_idle();
}
_Noreturn void process_idle(void) {
struct process *procs[16];
size_t len = process_find_multiple(PS_WAITS4IRQ, procs, 16);
if (len == 0) {
mem_debugprint();
cpu_shutdown();
}
for (;;) {
for (size_t i = 0; i < len; i++) {
if (procs[i]->waits4irq.ready()) {
/* if this is entered during the first iteration, it indicates a
* kernel bug. this should be logged. TODO? */
procs[i]->waits4irq.callback(procs[i]);
process_switch_any();
}
}
cpu_pause();
}
}
struct process *process_next(struct process *p) {
/* is a weird depth-first search, the search order is:
* 1
* / \
* 2 5
* /| |\
* 3 4 6 7
*/
if (!p) return NULL;
if (p->child) return p->child;
if (p->sibling) return p->sibling;
/* looking at the diagram above - we're at 4, want to find 5 */
while (!p->sibling) {
p = p->parent;
if (!p) return NULL;
}
return p->sibling;
}
struct process *process_find(enum process_state target) {
struct process *result = NULL;
process_find_multiple(target, &result, 1);
return result;
}
size_t process_find_multiple(enum process_state target, struct process **buf, size_t max) {
size_t i = 0;
for (struct process *p = process_first;
i < max && p;
p = process_next(p))
{
if (p->state == target) buf[i++] = p;
}
return i;
}
handle_t process_find_handle(struct process *proc) {
handle_t handle;
for (handle = 0; handle < HANDLE_MAX; handle++) {
if (proc->handles[handle].type == HANDLE_EMPTY)
break;
}
if (handle == HANDLE_MAX) handle = -1;
return handle;
}
void process_transition(struct process *p, enum process_state state) {
enum process_state last = p->state;
p->state = state;
switch (state) {
case PS_RUNNING:
assert(last != PS_DEAD && last != PS_DEADER);
break;
case PS_DEAD:
assert(last == PS_RUNNING);
break;
case PS_DEADER:
assert(last == PS_DEAD);
process_free(p);
break;
case PS_WAITS4CHILDDEATH:
case PS_WAITS4FS:
case PS_WAITS4REQUEST:
assert(last == PS_RUNNING);
break;
case PS_WAITS4IRQ:
assert(last == PS_WAITS4FS);
break;
}
}
void process_kill(struct process *proc, int ret) {
// TODO kill children
process_transition(proc, PS_DEAD);
proc->death_msg = ret;
process_try2collect(proc);
if (proc == process_first) {
kprintf("init killed, quitting...");
mem_debugprint();
cpu_shutdown();
}
}
int process_try2collect(struct process *dead) {
struct process *parent = dead->parent;
int ret;
assert(dead->state == PS_DEAD);
switch (parent->state) {
case PS_WAITS4CHILDDEATH:
ret = dead->death_msg;
regs_savereturn(&parent->regs, ret);
process_transition(parent, PS_RUNNING);
process_transition(dead, PS_DEADER);
return ret;
default:
return -1; // this return value isn't used anywhere
// TODO enforce that, somehow? idk
}
}
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