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/*
* Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/errno.h>
#include <mu/process.h>
#include <mu/mmu.h>
#include <vm/phys.h>
#include <lib/string.h>
#define STACK_TOP 0xBFFFFFFF
#define GDT_KERNCODE 0x08
#define GDT_KERNDATA 0x10
#define GDT_USERCODE 0x18
#define GDT_USERDATA 0x20
int
mu_process_init(struct process *process, uintptr_t ip, int flags)
{
struct trapframe *tf;
struct pcb *pcb;
uintptr_t stack_base;
uint8_t cs, ds;
int error;
if (process == NULL) {
return -EINVAL;
}
pcb = &process->pcb;
tf = &pcb->tf;
error = mu_pmap_forkvas(&pcb->vas);
if (error < 0) {
return error;
}
/* Allocate a new stack */
stack_base = vm_phys_alloc(1);
if (stack_base == 0) {
vm_phys_free(pcb->vas.cr3, 1);
return -ENOMEM;
}
/* Get the segment selectors based on mode */
if (ISSET(flags, PROC_KERN)) {
cs = GDT_KERNCODE;
ds = GDT_KERNDATA;
} else {
cs = GDT_USERCODE | 3;
ds = GDT_USERDATA | 3;
}
memset(tf, 0, sizeof(*tf));
tf->rip = ip;
tf->rflags = 0x202;
tf->cs = cs;
tf->ss = ds;
/* Map out the stack */
error = mu_pmap_map(
&pcb->vas,
stack_base,
STACK_TOP,
PROT_READ | PROT_WRITE,
PAGESIZE_4K
);
if (error < 0) {
vm_phys_free(stack_base, 1);
vm_phys_free(pcb->vas.cr3, 1);
return error;
}
tf->rsp = ALIGN_DOWN(STACK_TOP + (PAGESIZE - 1), 16);
return 0;
}
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