Function _unmap_area

libcpu/risc-v/common64/mmu.c:249–300

Unmaps a virtual address range (1GB/2MB/4KB according to actual page level) from the page table. */

/* Unmaps a virtual address range (1GB/2MB/4KB according to actual page level) from the page table. */
static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr)
{
    rt_ubase_t loop_va = __UMASKVALUE((rt_ubase_t)v_addr, PAGE_OFFSET_MASK);
    size_t unmapped = 0;

    int i = 0;
    rt_ubase_t lvl_off[3];
    rt_ubase_t *lvl_entry[3];
    lvl_off[0] = (rt_ubase_t)GET_L1(loop_va);
    lvl_off[1] = (rt_ubase_t)GET_L2(loop_va);
    lvl_off[2] = (rt_ubase_t)GET_L3(loop_va);
    unmapped = 1 << (ARCH_PAGE_SHIFT + ARCH_INDEX_WIDTH * 2ul);

    rt_ubase_t *pentry;
    lvl_entry[i] = ((rt_ubase_t *)aspace->page_table + lvl_off[i]);
    pentry = lvl_entry[i];

    /* check if lvl_entry[0] is valid. if no, return 0 directly. */
    if (!PTE_USED(*pentry))
    {
        return 0;
    }

    /* find leaf page table entry */
    while (PTE_USED(*pentry) && !PAGE_IS_LEAF(*pentry))
    {
        i += 1;

        if (i >= 3)
        {
            unmapped = 0;
            break;
        }

        lvl_entry[i] = ((rt_ubase_t *)PPN_TO_VPN(GET_PADDR(*pentry), PV_OFFSET) +
                        lvl_off[i]);
        pentry = lvl_entry[i];
        unmapped >>= ARCH_INDEX_WIDTH;
    }

    /* clear PTE & setup its */
    if (PTE_USED(*pentry))
    {
        _unmap_pte(pentry, lvl_entry, i);
    }
    else
    {
        unmapped = 0; /* invalid pte, return 0. */
    }

    return unmapped;
}

/**
 * @brief Unmaps a range of virtual memory addresses from the specified address space.