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cheap and ugly first attempt
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@sparchatus
sparchatus committed Dec 2, 2024
1 parent 564bec9 commit e70022d
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Showing 4 changed files with 70 additions and 25 deletions.
62 changes: 39 additions & 23 deletions arch/x86/pagetables.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -196,11 +196,17 @@ static inline void clean_pagetable(void *tab) {
set_pgentry(e, MFN_INVALID, PT_NO_FLAGS);
}

static mfn_t get_cr3_mfn(cr3_t *cr3_entry) {
static mfn_t get_cr3_mfn(cr3_t *cr3_entry, bool special_path) {
void *cr3_mapped = NULL;

if (mfn_invalid(cr3_entry->mfn)) {
frame_t *frame = get_free_frame();
frame_t *frame;
if (special_path) {
frame = _get_backup_frame();
}
else {
frame = get_backup_frame();
}
BUG_ON(!frame);
frame->flags.pagetable = 1;

Expand Down Expand Up @@ -232,7 +238,8 @@ static inline void pgentry_fixup_flags(pgentry_t *entry, unsigned long flags) {
}
}

static mfn_t get_pgentry_mfn(mfn_t tab_mfn, pt_index_t index, unsigned long flags) {
static mfn_t get_pgentry_mfn(mfn_t tab_mfn, pt_index_t index, unsigned long flags,
bool special_path) {
pgentry_t *tab, *entry;
mfn_t mfn;

Expand All @@ -243,7 +250,13 @@ static mfn_t get_pgentry_mfn(mfn_t tab_mfn, pt_index_t index, unsigned long flag

mfn = mfn_from_pgentry(*entry);
if (mfn_invalid(mfn)) {
frame_t *frame = get_free_frame();
frame_t *frame;
if (special_path) {
frame = _get_backup_frame();
}
else {
frame = get_backup_frame();
}
BUG_ON(!frame);
frame->flags.pagetable = 1;

Expand All @@ -264,20 +277,21 @@ static mfn_t get_pgentry_mfn(mfn_t tab_mfn, pt_index_t index, unsigned long flag
* MAP_FAILED when failed to map a NULL (0x0) virtual address and otherwise
* it returns the same virtual address passed as argument.
*/
static void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
#if defined(__x86_64__)
unsigned long l4_flags,
unsigned long l4_flags,
#endif
unsigned long l3_flags, unsigned long l2_flags,
unsigned long l1_flags) {
unsigned long l3_flags, unsigned long l2_flags, unsigned long l1_flags,
bool special_path) {
mfn_t l1t_mfn, l2t_mfn, l3t_mfn;
pgentry_t *tab, *entry;

if ((_ul(va) & ~PAGE_ORDER_TO_MASK(order)) || !is_canon_va(va))
return va ? NULL : MAP_FAILED;

#if defined(__x86_64__)
l3t_mfn = get_pgentry_mfn(get_cr3_mfn(cr3_ptr), l4_table_index(va), l4_flags);
l3t_mfn = get_pgentry_mfn(get_cr3_mfn(cr3_ptr, special_path), l4_table_index(va),
l4_flags, special_path);
#else
l3t_mfn = get_cr3_mfn(cr3_ptr);
#endif
Expand All @@ -290,7 +304,7 @@ static void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
goto done;
}

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

if (order == PAGE_ORDER_2M) {
tab = tmp_map_mfn(l2t_mfn);
Expand All @@ -300,7 +314,7 @@ static void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
goto done;
}

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

tab = tmp_map_mfn(l1t_mfn);
entry = &tab[l1_table_index(va)];
Expand All @@ -314,19 +328,20 @@ static void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
static inline void *__vmap_1g(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned long l4_flags,
unsigned long l3_flags) {
return _vmap(cr3_ptr, va, mfn, PAGE_ORDER_1G, l4_flags, l3_flags | _PAGE_PSE,
PT_NO_FLAGS, PT_NO_FLAGS);
PT_NO_FLAGS, PT_NO_FLAGS, false);
}

static inline void *__vmap_2m(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned long l4_flags,
unsigned long l3_flags, unsigned long l2_flags) {
return _vmap(cr3_ptr, va, mfn, PAGE_ORDER_2M, l4_flags, l3_flags,
l2_flags | _PAGE_PSE, PT_NO_FLAGS);
l2_flags | _PAGE_PSE, PT_NO_FLAGS, false);
}

static inline void *__vmap_4k(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned long l4_flags,
unsigned long l3_flags, unsigned long l2_flags,
unsigned long l1_flags) {
return _vmap(cr3_ptr, va, mfn, PAGE_ORDER_4K, l4_flags, l3_flags, l2_flags, l1_flags);
return _vmap(cr3_ptr, va, mfn, PAGE_ORDER_4K, l4_flags, l3_flags, l2_flags, l1_flags,
false);
}

static inline void *_vmap_1g(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned long l3_flags,
Expand Down Expand Up @@ -375,7 +390,7 @@ void *vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
dprintk("%s: va: 0x%p mfn: 0x%lx (order: %u)\n", __func__, va, mfn, order);

spin_lock(&vmap_lock);
va = _vmap(cr3_ptr, va, mfn, order, l4_flags, l3_flags, l2_flags, l1_flags);
va = _vmap(cr3_ptr, va, mfn, order, l4_flags, l3_flags, l2_flags, l1_flags, false);
spin_unlock(&vmap_lock);

return va;
Expand Down Expand Up @@ -872,7 +887,8 @@ static void map_pagetable(cr3_t *cr3_ptr, mfn_t table, int level) {
void *va = mfn_to_virt_kern(table);
pte_t *pt;

pt = _vmap(cr3_ptr, va, table, PAGE_ORDER_4K, L4_PROT, L3_PROT, L2_PROT, L1_PROT);
pt = _vmap(cr3_ptr, va, table, PAGE_ORDER_4K, L4_PROT, L3_PROT, L2_PROT, L1_PROT,
false);
BUG_ON(!pt);

for (int i = 0; i < level_to_entries(level) && level > 1; i++) {
Expand Down Expand Up @@ -968,7 +984,7 @@ int map_pagetables_va(cr3_t *cr3_ptr, void *va) {
err = -EFAULT;
spin_lock(&vmap_lock);
tab = _vmap(cr3_ptr, mfn_to_virt_kern(cr3_ptr->mfn), cr3_ptr->mfn, PAGE_ORDER_4K,
L4_PROT, L3_PROT, L2_PROT, L1_PROT);
L4_PROT, L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto unlock;

Expand All @@ -980,7 +996,7 @@ int map_pagetables_va(cr3_t *cr3_ptr, void *va) {
}

tab = _vmap(cr3_ptr, mfn_to_virt_kern(l4e->mfn), l4e->mfn, PAGE_ORDER_4K, L4_PROT,
L3_PROT, L2_PROT, L1_PROT);
L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto unlock;
#endif
Expand All @@ -995,7 +1011,7 @@ int map_pagetables_va(cr3_t *cr3_ptr, void *va) {
goto done;

tab = _vmap(cr3_ptr, mfn_to_virt_kern(l3e->mfn), l3e->mfn, PAGE_ORDER_4K, L4_PROT,
L3_PROT, L2_PROT, L1_PROT);
L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto unlock;

Expand All @@ -1009,7 +1025,7 @@ int map_pagetables_va(cr3_t *cr3_ptr, void *va) {
goto done;

tab = _vmap(cr3_ptr, mfn_to_virt_kern(l2e->mfn), l2e->mfn, PAGE_ORDER_4K, L4_PROT,
L3_PROT, L2_PROT, L1_PROT);
L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto unlock;

Expand Down Expand Up @@ -1040,7 +1056,7 @@ int unmap_pagetables_va(cr3_t *cr3_ptr, void *va) {
err = -EFAULT;
spin_lock(&vmap_lock);
tab = _vmap(cr3_ptr, mfn_to_virt_kern(cr3_ptr->mfn), cr3_ptr->mfn, PAGE_ORDER_4K,
L4_PROT, L3_PROT, L2_PROT, L1_PROT);
L4_PROT, L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto cleanup;
tables[level++] = tab;
Expand All @@ -1053,7 +1069,7 @@ int unmap_pagetables_va(cr3_t *cr3_ptr, void *va) {
}

tab = _vmap(cr3_ptr, mfn_to_virt_kern(l4e->mfn), l4e->mfn, PAGE_ORDER_4K, L4_PROT,
L3_PROT, L2_PROT, L1_PROT);
L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto cleanup;
tables[level++] = tab;
Expand All @@ -1069,7 +1085,7 @@ int unmap_pagetables_va(cr3_t *cr3_ptr, void *va) {
goto done;

tab = _vmap(cr3_ptr, mfn_to_virt_kern(l3e->mfn), l3e->mfn, PAGE_ORDER_4K, L4_PROT,
L3_PROT, L2_PROT, L1_PROT);
L3_PROT, L2_PROT, L1_PROT, false);
if (!tab)
goto cleanup;
tables[level++] = tab;
Expand Down
7 changes: 7 additions & 0 deletions include/arch/x86/pagetable.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -386,6 +386,13 @@ static inline void setup_tlb_global(void) {
write_cr4(opt_tlb_global ? (cr4 | X86_CR4_PGE) : (cr4 & ~X86_CR4_PGE));
}

void *_vmap(cr3_t *cr3_ptr, void *va, mfn_t mfn, unsigned int order,
#if defined(__x86_64__)
unsigned long l4_flags,
#endif
unsigned long l3_flags, unsigned long l2_flags, unsigned long l1_flags,
bool special_path);

#endif /* __ASSEMBLY__ */

#endif /* KTF_PAGETABLE_H */
3 changes: 3 additions & 0 deletions include/mm/pmm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -142,6 +142,9 @@ static inline bool is_frame_free(const frame_t *frame) {
return frame->flags.free;
}

frame_t *get_backup_frame(void);
frame_t *_get_backup_frame(void);

#endif /* __ASSEMBLY__ */

#endif /* KTF_PMM_H */
23 changes: 21 additions & 2 deletions mm/pmm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@ static frames_array_t early_frames;
static list_head_t free_frames[MAX_PAGE_ORDER + 1];
static list_head_t busy_frames[MAX_PAGE_ORDER + 1];

#define MIN_NUM_4K_FRAMES 2
#define MIN_NUM_4K_FRAMES 16
static size_t frames_count[MAX_PAGE_ORDER + 1];

static spinlock_t lock = SPINLOCK_INIT;
Expand Down Expand Up @@ -108,7 +108,10 @@ static frames_array_t *new_frames_array(void) {
if (!boot_flags.virt)
array = (frames_array_t *) mfn_to_virt_kern(frame->mfn);
else {
array = vmap_kern_4k(mfn_to_virt_map(frame->mfn), frame->mfn, L1_PROT);
array = _vmap(
&cr3,
_ptr(_ul(mfn_to_virt_map(frame->mfn)) & PAGE_ORDER_TO_MASK(PAGE_ORDER_4K)),
frame->mfn, PAGE_ORDER_4K, L4_PROT, L3_PROT, L2_PROT, L1_PROT, true);
if (!array)
goto error;
}
Expand Down Expand Up @@ -663,6 +666,22 @@ void put_free_frames(mfn_t mfn, unsigned int order) {
spin_unlock(&lock);
}

frame_t *get_backup_frame(void) {
// return get_free_frame();
frame_t *frame;

spin_lock(&lock);
frame = reserve_frame(get_first_frame(free_frames, PAGE_ORDER_4K));
spin_unlock(&lock);

return frame;
}

frame_t *_get_backup_frame(void) {
// return get_free_frame();
return reserve_frame(get_first_frame(free_frames, PAGE_ORDER_4K));
}

void map_frames_array(void) {
frames_array_t *array;

Expand Down

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