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[kernel] Add VMA interface

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Finished the VMA kobject and added the related syscalls. Processes can
now allocate memory! Other changes in this commit:

- stop using g_frame_allocator and add frame_allocator::get()
- make sure to release all handles in the process dtor
- fix kutil::map::iterator never comparing to end()
This commit is contained in:
Justin C. Miller
2020-09-23 00:29:05 -07:00
parent d4283731e4
commit 0e0975e5f6
13 changed files with 245 additions and 173 deletions
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63
src/kernel/vm_space.cpp
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@@ -5,8 +5,6 @@
#include "objects/vm_area.h"
#include "vm_space.h"
extern frame_allocator &g_frame_allocator;
int
vm_space::area::compare(const vm_space::area &o) const
{
@@ -91,6 +89,21 @@ vm_space::get(uintptr_t addr, uintptr_t *base)
return nullptr;
}
void
vm_space::copy_from(const vm_space &source, uintptr_t from, uintptr_t to, size_t count)
{
page_table::iterator sit {from, source.m_pml4};
page_table::iterator dit {to, m_pml4};
while (count--) {
uint64_t &e = dit.entry(page_table::level::pt);
if (e & page_table::flag::present) {
// TODO: handle clobbering mapping
}
e = sit.entry(page_table::level::pt);
}
}
void
vm_space::page_in(uintptr_t virt, uintptr_t phys, size_t count)
{
@@ -107,17 +120,37 @@ vm_space::page_in(uintptr_t virt, uintptr_t phys, size_t count)
void
vm_space::clear(uintptr_t addr, size_t count)
{
using memory::frame_size;
uintptr_t free_start = 0;
size_t free_count = 0;
frame_allocator &fa = frame_allocator::get();
page_table::iterator it {addr, m_pml4};
while (count--) {
uint64_t &e = it.entry(page_table::level::pt);
if (e & page_table::flag::present) {
g_frame_allocator.free(e & ~0xfffull, 1);
}
bool allowed = (e & page_table::flag::allowed);
e = 0;
if (allowed) e |= page_table::flag::allowed;
uintptr_t phys = e & ~0xfffull;
if (e & page_table::flag::present) {
if (free_count && phys == free_start + (free_count * frame_size)) {
++free_count;
} else {
if (free_count)
fa.free(free_start, free_count);
free_start = phys;
free_count = 1;
}
fa.free(e & ~0xfffull, 1);
}
e = 0 | (allowed ? page_table::flag::allowed : page_table::flag::none);
++it;
}
if (free_count)
fa.free(free_start, free_count);
}
void
@@ -173,22 +206,32 @@ vm_space::handle_fault(uintptr_t addr, fault_type fault)
if (fault && fault_type::present)
return false;
if (!it.allowed())
uintptr_t base = 0;
vm_area *area = get(addr, &base);
if (!area && !it.allowed())
return false;
uintptr_t phys = 0;
size_t n = g_frame_allocator.allocate(1, &phys);
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 |
page_table::flag::allowed |
(area
? page_table::flag::none
: page_table::flag::allowed) |
(is_kernel()
? page_table::flag::global
: page_table::flag::user);
it.entry(page_table::level::pt) = phys | flags;
if (area) {
uintptr_t offset = page - base;
area->commit(phys, offset, 1);
}
return true;
}