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Kernel: Assert if rounding-up-to-page-size would wrap around to 0

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If we try to align a number above 0xfffff000 to the next multiple of
the page size (4 KiB), it would wrap around to 0. This is most likely
never what we want, so let's assert if that happens.
This commit is contained in:
Andreas Kling 2021-02-14 09:57:19 +01:00
parent 198d641808
commit 09b1b09c19
19 changed files with 67 additions and 40 deletions
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12
Kernel/VM/Region.cpp
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@ -154,8 +154,8 @@ bool Region::is_volatile(VirtualAddress vaddr, size_t size) const
return false;
auto offset_in_vmobject = vaddr.get() - (this->vaddr().get() - m_offset_in_vmobject);
size_t first_page_index = PAGE_ROUND_DOWN(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = PAGE_ROUND_UP(offset_in_vmobject + size) / PAGE_SIZE;
size_t first_page_index = page_round_down(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = page_round_up(offset_in_vmobject + size) / PAGE_SIZE;
return is_volatile_range({ first_page_index, last_page_index - first_page_index });
}
@ -171,16 +171,16 @@ auto Region::set_volatile(VirtualAddress vaddr, size_t size, bool is_volatile, b
// partial pages volatile to prevent potentially non-volatile
// data to be discarded. So rund up the first page and round
// down the last page.
size_t first_page_index = PAGE_ROUND_UP(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = PAGE_ROUND_DOWN(offset_in_vmobject + size) / PAGE_SIZE;
size_t first_page_index = page_round_up(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = page_round_down(offset_in_vmobject + size) / PAGE_SIZE;
if (first_page_index != last_page_index)
add_volatile_range({ first_page_index, last_page_index - first_page_index });
} else {
// If marking pages as non-volatile, round down the first page
// and round up the last page to make sure the beginning and
// end of the range doesn't inadvertedly get discarded.
size_t first_page_index = PAGE_ROUND_DOWN(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = PAGE_ROUND_UP(offset_in_vmobject + size) / PAGE_SIZE;
size_t first_page_index = page_round_down(offset_in_vmobject) / PAGE_SIZE;
size_t last_page_index = page_round_up(offset_in_vmobject + size) / PAGE_SIZE;
switch (remove_volatile_range({ first_page_index, last_page_index - first_page_index }, was_purged)) {
case PurgeablePageRanges::RemoveVolatileError::Success:
case PurgeablePageRanges::RemoveVolatileError::SuccessNoChange: