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[kernel] Remove 'allowed' page table flag

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The allowed flag was janky and easy to get lost when doing page table
manipulation. All allocation goes throug vm_area now, so 'allowed' can
be dropped.
This commit is contained in:
Justin C. Miller
2020-09-27 16:06:25 -07:00
parent f7f8bb3f45
commit 2d44e8112b
5 changed files with 8 additions and 83 deletions
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48
src/kernel/vm_space.cpp
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@@ -197,7 +197,6 @@ vm_space::clear(const vm_area &vma, uintptr_t offset, size_t count, bool free)
while (count--) {
uint64_t &e = it.entry(page_table::level::pt);
bool allowed = (e & page_table::flag::allowed);
uintptr_t phys = e & ~0xfffull;
if (e & page_table::flag::present) {
@@ -212,7 +211,7 @@ vm_space::clear(const vm_area &vma, uintptr_t offset, size_t count, bool free)
fa.free(e & ~0xfffull, 1);
}
e = 0 | (allowed ? page_table::flag::allowed : page_table::flag::none);
e = 0;
++it;
}
@@ -229,24 +228,6 @@ vm_space::lookup(const vm_area &vma, uintptr_t offset)
return base + offset;
}
void
vm_space::allow(uintptr_t start, size_t length, bool allow)
{
using level = page_table::level;
kassert((start & 0xfff) == 0, "non-page-aligned address");
kassert((length & 0xfff) == 0, "non-page-aligned length");
const uintptr_t end = start + length;
page_table::iterator it {start, m_pml4};
while (it.vaddress() < end) {
level d = it.align();
while (it.end(d) > end) ++d;
it.allow(d-1, allow);
it.next(d);
}
}
bool
vm_space::active() const
{
@@ -276,8 +257,6 @@ vm_space::handle_fault(uintptr_t addr, fault_type fault)
{
uintptr_t page = addr & ~0xfffull;
page_table::iterator it {addr, m_pml4};
// TODO: Handle more fult types
if (fault && fault_type::present)
return false;
@@ -285,33 +264,18 @@ vm_space::handle_fault(uintptr_t addr, fault_type fault)
uintptr_t base = 0;
vm_area *area = get(addr, &base);
if ((!area || !area->allowed(page-base)) && !it.allowed())
if (!area || !area->allowed(page-base))
return false;
uintptr_t phys = 0;
size_t n = frame_allocator::get().allocate(1, &phys);
kassert(n, "Failed to allocate a new page during page fault");
page_table::flag flags =
page_table::flag::present |
page_table::flag::write |
(area
? page_table::flag::none
: page_table::flag::allowed) |
(is_kernel()
? page_table::flag::global
: page_table::flag::user);
if (area->flags() && vm_flags::zero)
kutil::memset(memory::to_virtual<void>(phys), 0, memory::frame_size);
if (area) {
if (area->flags() && vm_flags::zero)
kutil::memset(memory::to_virtual<void>(phys), 0, memory::frame_size);
uintptr_t offset = page - base;
area->commit(phys, offset, 1);
return true;
}
it.entry(page_table::level::pt) = phys | flags;
uintptr_t offset = page - base;
area->commit(phys, offset, 1);
return true;
}