brk.c

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#include "hal/cpu/core.h"
#include "hal/cpu/paging.h"
#include "libk/serial.h"
#include "memory/memory_utils.h"
#include "memory/phys_base_allocator.h"
#include "spinlock.h"
#include <sys/syscall.h>
intptr_t syscall_brk(void* addr)
{
    auto curr_thr = get_current_core_data()->active_thread;
    auto proc = curr_thr->process;
 
    uintptr_t old_brk = proc->heap_end;
 
    if (!addr)
        return (intptr_t)old_brk;
 
    uintptr_t new_brk = (uintptr_t)addr;
 
    if (new_brk < proc->heap_start)
        return (intptr_t)old_brk;
 
    spin_acquire(&proc->vm_lock);
 
    if (new_brk > old_brk) {
 
        uintptr_t old_page = ALIGN_UP(old_brk, PAGE_SIZE);
        uintptr_t new_page = ALIGN_UP(new_brk, PAGE_SIZE);
 
        serial2_printf("brk: from %x to %x\n", old_page, new_page);
 
        for (uintptr_t v = old_page; v < new_page; v += PAGE_SIZE) {
 
            void* phys = phys_base_alloc(1);
 
            if (!phys) {
                spin_release(&proc->vm_lock);
                return (intptr_t)old_brk;
            }
 
            vxMmap(
                curr_thr->page,
                v,
                (uintptr_t)phys,
                PAGE_PRESENT |
                PAGE_WRITABLE |
                PAGE_USER
            );
        }
    }
 
    proc->heap_end = new_brk;
 
    spin_release(&proc->vm_lock);
 
    return (intptr_t)new_brk;
}