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Fix mis-flagged page table entries

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This commit is contained in:
Justin C. Miller
2019-07-04 17:43:08 -07:00
parent 3a68ec439d
commit c3dacb2906
2 changed files with 34 additions and 7 deletions
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28
src/kernel/memory_bootstrap.cpp
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@@ -186,9 +186,31 @@ memory_initialize(uint16_t scratch_pages, const void *memory_map, size_t map_len
page_table *id_pml4 = &tables[0];
page_table *id_pdp = &tables[1];
// Flags: 0 0 0 0 1 1 0 0 0 0 0 1 1 = 0x0183
// | IGN | | | | | | | | +- Present
// | | | | | | | | +--- Writeable
// | | | | | | | +----- Supervisor only
// | | | | | | +------- PWT (determining memory type for page)
// | | | | | +---------- PCD (determining memory type for page)
// | | | | +------------ Accessed flag (not accessed yet)
// | | | +-------------- Dirty (not dirtied yet)
// | | +---------------- Page size (1GiB page)
// | +------------------- Global
// +---------------------------- PAT (determining memory type for page)
for (int i=0; i<512; ++i)
id_pdp->entries[i] = (static_cast<uintptr_t>(i) << 30) | 0x18b;
id_pml4->entries[511] = reinterpret_cast<uintptr_t>(id_pdp) | 0x10b;
id_pdp->entries[i] = (static_cast<uintptr_t>(i) << 30) | 0x0183;
// Flags: 0 0 0 0 0 0 0 0 0 0 1 1 = 0x0003
// IGNORED | | | | | | | +- Present
// | | | | | | +--- Writeable
// | | | | | +----- Supervisor only
// | | | | +------- PWT (determining memory type for pdpt)
// | | | +---------- PCD (determining memory type for pdpt)
// | | +------------ Accessed flag (not accessed yet)
// | +-------------- Ignored
// +---------------- Reserved 0
id_pml4->entries[511] = reinterpret_cast<uintptr_t>(id_pdp) | 0x003;
// Make sure the page table is finished updating before we write to memory
__sync_synchronize();
@@ -218,7 +240,7 @@ memory_initialize(uint16_t scratch_pages, const void *memory_map, size_t map_len
pml4 = kutil::offset_pointer(pml4, page_offset);
kutil::memset(pml4, 0, sizeof(page_table));
pml4->entries[511] = reinterpret_cast<uintptr_t>(id_pdp) | 0x10b;
pml4->entries[511] = reinterpret_cast<uintptr_t>(id_pdp) | 0x003;
bootstrap.page_in_kernel(*pm, pml4);

13
src/kernel/page_manager.cpp
View File

@@ -17,6 +17,13 @@ using memory::page_mappable;
page_manager g_page_manager(g_frame_allocator);
extern kutil::vm_space g_kspace;
// NB: in 4KiB page table entries, bit 7 isn't pagesize but PAT. Currently this
// doesn't matter, becasue in the default PAT table, both 000 and 100 are WB.
constexpr uint64_t sys_page_flags = 0x183; // global, pagesize, write, present
constexpr uint64_t sys_table_flags = 0x003; // write, present
constexpr uint64_t user_page_flags = 0x087; // pagesize, user, write, present
constexpr uint64_t user_table_flags = 0x007; // user, write, present
static uintptr_t
pt_to_phys(page_table *pt)
{
@@ -335,7 +342,7 @@ page_manager::check_needs_page(page_table *table, unsigned index, bool user)
page_table *new_table = get_table_page();
for (int i=0; i<512; ++i) new_table->entries[i] = 0;
table->entries[index] = pt_to_phys(new_table) | (user ? 0xf : 0xb);
table->entries[index] = pt_to_phys(new_table) | (user ? user_table_flags : sys_table_flags);
}
void
@@ -349,9 +356,7 @@ page_manager::page_in(page_table *pml4, uintptr_t phys_addr, uintptr_t virt_addr
page_table_indices idx{virt_addr};
page_table *tables[4] = {pml4, nullptr, nullptr, nullptr};
uint64_t flags = user ?
0x00f: // writethru, user, write, present
0x10b; // global, writethru, write, present
uint64_t flags = user ? user_table_flags : sys_table_flags;
for (; idx[0] < 512; idx[0] += 1) {
check_needs_page(tables[0], idx[0], user);