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Kernel: Add guard pages to kernel and userspace stacks

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Bananymous
2025-07-02 23:12:36 +03:00
parent e1319a06f2
commit 6084aae603
10 changed files with 47 additions and 35 deletions
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46
kernel/kernel/Memory/VirtualRange.cpp
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@@ -4,21 +4,30 @@
namespace Kernel
{
BAN::ErrorOr<BAN::UniqPtr<VirtualRange>> VirtualRange::create_to_vaddr(PageTable& page_table, vaddr_t vaddr, size_t size, PageTable::flags_t flags, bool preallocate_pages)
BAN::ErrorOr<BAN::UniqPtr<VirtualRange>> VirtualRange::create_to_vaddr(PageTable& page_table, vaddr_t vaddr, size_t size, PageTable::flags_t flags, bool preallocate_pages, bool add_guard_pages)
{
ASSERT(size % PAGE_SIZE == 0);
ASSERT(vaddr % PAGE_SIZE == 0);
ASSERT(vaddr > 0);
auto result = TRY(BAN::UniqPtr<VirtualRange>::create(page_table, preallocate_pages, vaddr, size, flags));
if (add_guard_pages)
{
vaddr -= PAGE_SIZE;
size += 2 * PAGE_SIZE;
}
auto result = TRY(BAN::UniqPtr<VirtualRange>::create(page_table, preallocate_pages, add_guard_pages, vaddr, size, flags));
ASSERT(page_table.reserve_range(vaddr, size));
TRY(result->initialize());
return result;
}
BAN::ErrorOr<BAN::UniqPtr<VirtualRange>> VirtualRange::create_to_vaddr_range(PageTable& page_table, vaddr_t vaddr_start, vaddr_t vaddr_end, size_t size, PageTable::flags_t flags, bool preallocate_pages)
BAN::ErrorOr<BAN::UniqPtr<VirtualRange>> VirtualRange::create_to_vaddr_range(PageTable& page_table, vaddr_t vaddr_start, vaddr_t vaddr_end, size_t size, PageTable::flags_t flags, bool preallocate_pages, bool add_guard_pages)
{
if (add_guard_pages)
size += 2 * PAGE_SIZE;
ASSERT(size % PAGE_SIZE == 0);
ASSERT(vaddr_start > 0);
ASSERT(vaddr_start + size <= vaddr_end);
@@ -31,13 +40,13 @@ namespace Kernel
ASSERT(vaddr_start < vaddr_end);
ASSERT(vaddr_end - vaddr_start + 1 >= size / PAGE_SIZE);
vaddr_t vaddr = page_table.reserve_free_contiguous_pages(size / PAGE_SIZE, vaddr_start, vaddr_end);
const vaddr_t vaddr = page_table.reserve_free_contiguous_pages(size / PAGE_SIZE, vaddr_start, vaddr_end);
if (vaddr == 0)
return BAN::Error::from_errno(ENOMEM);
ASSERT(vaddr >= vaddr_start);
ASSERT(vaddr + size <= vaddr_end);
auto result_or_error = BAN::UniqPtr<VirtualRange>::create(page_table, preallocate_pages, vaddr, size, flags);
auto result_or_error = BAN::UniqPtr<VirtualRange>::create(page_table, preallocate_pages, add_guard_pages, vaddr, size, flags);
if (result_or_error.is_error())
{
page_table.unmap_range(vaddr, size);
@@ -50,9 +59,10 @@ namespace Kernel
return result;
}
VirtualRange::VirtualRange(PageTable& page_table, bool preallocated, vaddr_t vaddr, size_t size, PageTable::flags_t flags)
VirtualRange::VirtualRange(PageTable& page_table, bool preallocated, bool has_guard_pages, vaddr_t vaddr, size_t size, PageTable::flags_t flags)
: m_page_table(page_table)
, m_preallocated(preallocated)
, m_has_guard_pages(has_guard_pages)
, m_vaddr(vaddr)
, m_size(size)
, m_flags(flags)
@@ -70,26 +80,26 @@ namespace Kernel
BAN::ErrorOr<void> VirtualRange::initialize()
{
TRY(m_paddrs.resize(m_size / PAGE_SIZE, 0));
TRY(m_paddrs.resize(size() / PAGE_SIZE, 0));
if (!m_preallocated)
return {};
const size_t page_count = m_size / PAGE_SIZE;
const size_t page_count = size() / PAGE_SIZE;
for (size_t i = 0; i < page_count; i++)
{
m_paddrs[i] = Heap::get().take_free_page();
if (m_paddrs[i] == 0)
return BAN::Error::from_errno(ENOMEM);
m_page_table.map_page_at(m_paddrs[i], m_vaddr + i * PAGE_SIZE, m_flags);
m_page_table.map_page_at(m_paddrs[i], vaddr() + i * PAGE_SIZE, m_flags);
}
if (&PageTable::current() == &m_page_table || &PageTable::kernel() == &m_page_table)
memset(reinterpret_cast<void*>(m_vaddr), 0, m_size);
memset(reinterpret_cast<void*>(vaddr()), 0, size());
else
{
const size_t page_count = m_size / PAGE_SIZE;
for (size_t i = 0; i < page_count; i++)
const size_t page_count = size() / PAGE_SIZE;
for (size_t i = m_has_guard_pages; i < page_count; i++)
{
PageTable::with_fast_page(m_paddrs[i], [&] {
memset(PageTable::fast_page_as_ptr(), 0, PAGE_SIZE);
@@ -107,10 +117,10 @@ namespace Kernel
SpinLockGuard _(m_lock);
auto result = TRY(create_to_vaddr(page_table, m_vaddr, m_size, m_flags, m_preallocated));
auto result = TRY(create_to_vaddr(page_table, vaddr(), size(), m_flags, m_preallocated, m_has_guard_pages));
const size_t page_count = m_size / PAGE_SIZE;
for (size_t i = 0; i < page_count; i++)
const size_t page_count = size() / PAGE_SIZE;
for (size_t i = m_has_guard_pages; i < page_count; i++)
{
if (m_paddrs[i] == 0)
continue;
@@ -119,11 +129,11 @@ namespace Kernel
result->m_paddrs[i] = Heap::get().take_free_page();
if (result->m_paddrs[i] == 0)
return BAN::Error::from_errno(ENOMEM);
result->m_page_table.map_page_at(result->m_paddrs[i], m_vaddr + i * PAGE_SIZE, m_flags);
result->m_page_table.map_page_at(result->m_paddrs[i], vaddr() + i * PAGE_SIZE, m_flags);
}
PageTable::with_fast_page(result->m_paddrs[i], [&] {
memcpy(PageTable::fast_page_as_ptr(), reinterpret_cast<void*>(m_vaddr + i * PAGE_SIZE), PAGE_SIZE);
memcpy(PageTable::fast_page_as_ptr(), reinterpret_cast<void*>(vaddr() + i * PAGE_SIZE), PAGE_SIZE);
});
}
@@ -137,7 +147,7 @@ namespace Kernel
ASSERT(contains(vaddr));
ASSERT(&PageTable::current() == &m_page_table);
const size_t index = (vaddr - m_vaddr) / PAGE_SIZE;
const size_t index = (vaddr - this->vaddr()) / PAGE_SIZE;
ASSERT(m_paddrs[index] == 0);
SpinLockGuard _(m_lock);