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[libcpu][risc-v]处理mmu.c中_unmap_area函数的几处潜在风险或问题 #10107

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Merged
Rbb666 merged 2 commits into from
Mar 17, 2025
Merged

[libcpu][risc-v]处理mmu.c中_unmap_area函数的几处潜在风险或问题 #10107

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112d2be
[libcpu][risc-v]remove unused parameter 'size' for func _unmap_area.
GorrayLi Mar 13, 2025
06a6cca
[libcpu][risc-v]add code for handling exception scenarios in _unmap_a…
GorrayLi Mar 13, 2025
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27 changes: 22 additions & 5 deletions libcpu/risc-v/common64/mmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@
#define USER_VADDR_START 0
#endif

static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr, size_t size);
static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr);

static void *current_mmu_table = RT_NULL;

Expand Down Expand Up @@ -198,7 +198,7 @@ void *rt_hw_mmu_map(struct rt_aspace *aspace, void *v_addr, void *p_addr,
while (unmap_va != v_addr)
{
MM_PGTBL_LOCK(aspace);
_unmap_area(aspace, unmap_va, ARCH_PAGE_SIZE);
_unmap_area(aspace, unmap_va);
MM_PGTBL_UNLOCK(aspace);
unmap_va += ARCH_PAGE_SIZE;
}
Expand Down Expand Up @@ -245,8 +245,8 @@ static void _unmap_pte(rt_ubase_t *pentry, rt_ubase_t *lvl_entry[], int level)
}
}

/* Unmaps a virtual address range from the page table. */
static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr, size_t size)
/* 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;
Expand All @@ -263,10 +263,23 @@ static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr, size_t size)
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];
Expand All @@ -278,6 +291,10 @@ static size_t _unmap_area(struct rt_aspace *aspace, void *v_addr, size_t size)
{
_unmap_pte(pentry, lvl_entry, i);
}
else
{
unmapped = 0; /* invalid pte, return 0. */
}

return unmapped;
}
Expand Down Expand Up @@ -315,7 +332,7 @@ void rt_hw_mmu_unmap(struct rt_aspace *aspace, void *v_addr, size_t size)
while (size > 0)
{
MM_PGTBL_LOCK(aspace);
unmapped = _unmap_area(aspace, v_addr, size);
unmapped = _unmap_area(aspace, v_addr);
MM_PGTBL_UNLOCK(aspace);

/* when unmapped == 0, region not exist in pgtbl */
Expand Down