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Merged
wipawel merged 11 commits into from
Oct 27, 2023
Merged

General improvements and cleanup to page tables handling #309

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1644643
arch,pmm: Explicitly map PMM frame arrays
wipawel Oct 22, 2023
b687f75
arch,pt: map all levels of PT for temporary mapping location
wipawel Oct 23, 2023
10f589d
arch,pt: map multiboot areas already during pagetables init
wipawel Oct 23, 2023
970b963
setup: map BIOS areas after switching to virtual mode
wipawel Oct 23, 2023
c2a6ad4
arch,pt: switch page tables already in init_pagetables()
wipawel Oct 23, 2023
8a46eb2
arch,pt: do not map all used memory
wipawel Oct 23, 2023
91a4d75
arch,pt: refactor init_map_mfn()
wipawel Oct 23, 2023
dbb6f42
arch,pt: minor refactoring of get_pgentry_mfn()
wipawel Oct 25, 2023
a48d24f
arch,pt: optimize temporary mapping handling
wipawel Oct 23, 2023
7d6e25f
lib: add invlpg() helper function
wipawel Oct 23, 2023
9f7ae9c
arch,pt: do not flush entire TLB upon PT change
wipawel Oct 25, 2023
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64 changes: 45 additions & 19 deletions arch/x86/pagetables.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,12 +24,16 @@
*/
#include <console.h>
#include <ktf.h>
#include <multiboot2.h>
#include <page.h>
#include <pagetable.h>
#include <setup.h>
#include <spinlock.h>
#include <string.h>

static uint8_t _tmp_mapping[PAGE_SIZE] __aligned(PAGE_SIZE);
static pgentry_t *_tmp_mapping_entry;

cr3_t __aligned(PAGE_SIZE) cr3;
cr3_t user_cr3;

Expand Down Expand Up @@ -100,17 +104,11 @@ void dump_pagetables(cr3_t cr3) {
dump_page_table(paddr_to_virt_kern(cr3.paddr), 4);
}

static void *init_map_mfn(mfn_t mfn) {
static uint8_t _tmp[PAGE_SIZE] __aligned(PAGE_SIZE);
pgentry_t *e;

static inline void *tmp_map_mfn(mfn_t mfn) {
BUG_ON(mfn_invalid(mfn));

e = (pgentry_t *) l1_table_entry(get_l1_table(_tmp), _tmp);
BUG_ON(!e);
set_pgentry(e, mfn, L1_PROT);

return _tmp;
set_pgentry(_tmp_mapping_entry, mfn, L1_PROT);
invlpg(_tmp_mapping);
return _tmp_mapping;
}

static mfn_t get_cr3_mfn(cr3_t *cr3_entry) {
Expand All @@ -121,7 +119,7 @@ static mfn_t get_cr3_mfn(cr3_t *cr3_entry) {
BUG_ON(!frame);

cr3_entry->mfn = frame->mfn;
cr3_mapped = init_map_mfn(cr3_entry->mfn);
cr3_mapped = tmp_map_mfn(cr3_entry->mfn);
memset(cr3_mapped, 0, PAGE_SIZE);
}

Expand Down Expand Up @@ -154,17 +152,17 @@ static mfn_t get_pgentry_mfn(mfn_t tab_mfn, pt_index_t index, unsigned long flag

BUG_ON(mfn_invalid(tab_mfn));

tab = init_map_mfn(tab_mfn);
tab = tmp_map_mfn(tab_mfn);
entry = &tab[index];

mfn = mfn_from_pgentry(*entry);
if (mfn_invalid(mfn)) {
frame_t *frame = get_free_frame();
BUG_ON(!frame);

set_pgentry(entry, frame->mfn, flags);
mfn = mfn_from_pgentry(*entry);
tab = init_map_mfn(mfn);
mfn = frame->mfn;
set_pgentry(entry, mfn, flags);
tab = tmp_map_mfn(mfn);
memset(tab, 0, PAGE_SIZE);
}
else {
Expand Down Expand Up @@ -199,26 +197,29 @@ static void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
#endif

if (order == PAGE_ORDER_1G) {
tab = init_map_mfn(l3t_mfn);
tab = tmp_map_mfn(l3t_mfn);
entry = &tab[l3_table_index(va)];
set_pgentry(entry, mfn, l3_flags | _PAGE_PSE);
invlpg(va);
goto done;
}

l2t_mfn = get_pgentry_mfn(l3t_mfn, l3_table_index(va), l3_flags);

if (order == PAGE_ORDER_2M) {
tab = init_map_mfn(l2t_mfn);
tab = tmp_map_mfn(l2t_mfn);
entry = &tab[l2_table_index(va)];
set_pgentry(entry, mfn, l2_flags | _PAGE_PSE);
invlpg(va);
goto done;
}

l1t_mfn = get_pgentry_mfn(l2t_mfn, l2_table_index(va), l2_flags);

tab = init_map_mfn(l1t_mfn);
tab = tmp_map_mfn(l1t_mfn);
entry = &tab[l1_table_index(va)];
set_pgentry(entry, mfn, l1_flags);
invlpg(va);

done:
spin_unlock(&lock);
Expand Down Expand Up @@ -246,7 +247,28 @@ void *vmap_user(void *va, mfn_t mfn, unsigned int order,
l1_flags);
}

static inline void init_tmp_mapping(void) {
pte_t *tab = get_l1_table(_tmp_mapping);
_tmp_mapping_entry = (pgentry_t *) l1_table_entry(tab, _tmp_mapping);
BUG_ON(!_tmp_mapping_entry);
}

static void map_tmp_mapping_entry(void) {
pml4_t *l3e = l4_table_entry(mfn_to_virt(cr3.mfn), _tmp_mapping);
pdpe_t *l2e = l3_table_entry(mfn_to_virt(l3e->mfn), _tmp_mapping);
pde_t *l1e = l2_table_entry(mfn_to_virt(l2e->mfn), _tmp_mapping);
pte_t *entry = l1_table_entry(mfn_to_virt(l1e->mfn), _tmp_mapping);

/* Map _tmp_mapping_entry PTE of new page tables */
kmap_4k(l1e->mfn, L1_PROT);

/* Point _tmp_mapping_entry at new page tables location */
_tmp_mapping_entry = paddr_to_virt_kern(_paddr(entry));
}

void init_pagetables(void) {
init_tmp_mapping();

for_each_memory_range (r) {
switch (r->base) {
case VIRT_IDENT_BASE:
Expand All @@ -270,5 +292,9 @@ void init_pagetables(void) {
}
}

map_used_memory();
map_frames_array();
map_multiboot_areas();
map_tmp_mapping_entry();

write_cr3(cr3.paddr);
}
8 changes: 3 additions & 5 deletions common/setup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -222,17 +222,15 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic, unsigned long

/* Setup final pagetables */
init_pagetables();

map_multiboot_areas();
map_bios_area();

write_cr3(cr3.paddr);
boot_flags.virt = true;

WRITE_SP(get_free_pages_top(PAGE_ORDER_2M, GFP_KERNEL_MAP));

if (opt_debug)
dump_pagetables(cr3);

map_bios_area();

if (setup_framebuffer())
display_banner();
else
Expand Down
1 change: 0 additions & 1 deletion include/arch/x86/pagetable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -272,7 +272,6 @@ static inline pdpe_t *get_pdpe(const void *va) {
static inline void set_pgentry(pgentry_t *e, mfn_t mfn, unsigned long flags) {
*e = pgentry_from_mfn(mfn, flags);
barrier();
flush_tlb();
}

/* External declarations */
Expand Down
4 changes: 4 additions & 0 deletions include/lib.h
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Original file line number Diff line number Diff line change
Expand Up @@ -324,6 +324,10 @@ static inline void str(unsigned int *selector) {
asm volatile("str %0" : "=m"(*selector));
}

static inline void invlpg(void *addr) {
asm volatile("invlpg (%0)" ::"r"(addr) : "memory");
}

static inline void flush_tlb(void) {
write_cr3(read_cr3());
}
Expand Down
1 change: 1 addition & 0 deletions include/mm/pmm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ extern void put_free_frames(mfn_t mfn, unsigned int order);
extern void reclaim_frame(mfn_t mfn, unsigned int order);

extern void map_used_memory(void);
extern void map_frames_array(void);

/* Static definitions */

Expand Down
6 changes: 6 additions & 0 deletions mm/pmm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -570,3 +570,9 @@ void map_used_memory(void) {
}
}
}

void map_frames_array(void) {
frames_array_t *array;

list_for_each_entry (array, &frames, list) { kmap_4k(virt_to_mfn(array), L1_PROT); }
}