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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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13
src/kernel/page_manager.cpp
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@@ -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);