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Implement API to find the frame for a given virtual address #313

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merged 3 commits into from
Nov 21, 2023
Merged

Implement API to find the frame for a given virtual address #313

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4882428
arch,pt: add get_va_mfn_order() functionality
wipawel Nov 14, 2023
7cbcafe
mm/pmm: add frame finder functions for MFN and paddr
wipawel Oct 31, 2023
e794cc9
arch,pt: add frame finder for virtual address functionality
wipawel Nov 2, 2023
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100 changes: 100 additions & 0 deletions arch/x86/pagetables.c
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Original file line number Diff line number Diff line change
Expand Up @@ -446,6 +446,106 @@ int vunmap_user(void *va, mfn_t *mfn, unsigned int *order) {
return err;
}

static int get_va_mfn_order(const cr3_t *cr3_ptr, const void *va, mfn_t *mfn,
unsigned int *order) {
unsigned int _order;
mfn_t _mfn;
pgentry_t *tab;

ASSERT(mfn || order);
if (mfn_invalid(cr3_ptr->mfn))
return -EINVAL;

tab = tmp_map_mfn(cr3_ptr->mfn);
#if defined(__x86_64__)
pml4_t *l4e = l4_table_entry((pml4_t *) tab, va);
if (mfn_invalid(l4e->mfn) || !l4e->P)
return -ENOENT;

tab = tmp_map_mfn(l4e->mfn);
#endif
pdpe_t *l3e = l3_table_entry((pdpe_t *) tab, va);
if (mfn_invalid(l3e->mfn) || !l3e->P)
return -ENOENT;

if (l3e->PS) {
_mfn = l3e->mfn;
_order = PAGE_ORDER_1G;
goto done;
}

tab = tmp_map_mfn(l3e->mfn);
pde_t *l2e = l2_table_entry((pde_t *) tab, va);
if (mfn_invalid(l2e->mfn) || !l2e->P)
return -ENOENT;

if (l2e->PS) {
_mfn = l2e->mfn;
_order = PAGE_ORDER_2M;
goto done;
}

tab = tmp_map_mfn(l2e->mfn);
pte_t *l1e = l1_table_entry((pte_t *) tab, va);
if (mfn_invalid(l1e->mfn) || !l1e->P)
return -ENOENT;

_mfn = l1e->mfn;
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_order = PAGE_ORDER_4K;

done:
if (mfn)
*mfn = _mfn;
if (order)
*order = _order;
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return 0;
}

int get_kern_va_mfn_order(void *va, mfn_t *mfn, unsigned int *order) {
int err;

dprintk("%s: va: 0x%p (cr3: 0x%p)\n", __func__, va, &cr3);

spin_lock(&vmap_lock);
err = get_va_mfn_order(&cr3, va, mfn, order);
spin_unlock(&vmap_lock);

return err;
}

int get_user_va_mfn_order(void *va, mfn_t *mfn, unsigned int *order) {
int err;

dprintk("%s: va: 0x%p (cr3: 0x%p)\n", __func__, va, &user_cr3);

spin_lock(&vmap_lock);
err = get_va_mfn_order(&user_cr3, va, mfn, order);
spin_unlock(&vmap_lock);

return err;
}

static frame_t *find_va_frame(const cr3_t *cr3_ptr, const void *va) {
unsigned int order;
mfn_t mfn;
int err;

spin_lock(&vmap_lock);
err = get_va_mfn_order(cr3_ptr, va, &mfn, &order);
spin_unlock(&vmap_lock);

return err ? NULL : find_mfn_frame(mfn, order);
}

frame_t *find_kern_va_frame(const void *va) {
return find_va_frame(&cr3, va);
}

frame_t *find_user_va_frame(const void *va) {
return find_va_frame(&user_cr3, va);
}

static inline void init_cr3(cr3_t *cr3_ptr) {
memset(cr3_ptr, 0, sizeof(*cr3_ptr));
cr3_ptr->mfn = MFN_INVALID;
Expand Down
6 changes: 6 additions & 0 deletions include/arch/x86/pagetable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -301,6 +301,12 @@ extern void dump_pagetables(cr3_t *cr3_ptr);
extern void dump_kern_pagetable_va(void *va);
extern void dump_user_pagetable_va(void *va);

extern int get_kern_va_mfn_order(void *va, mfn_t *mfn, unsigned int *order);
extern int get_user_va_mfn_order(void *va, mfn_t *mfn, unsigned int *order);

extern frame_t *find_kern_va_frame(const void *va);
extern frame_t *find_user_va_frame(const void *va);

#endif /* __ASSEMBLY__ */

#endif /* KTF_PAGETABLE_H */
17 changes: 17 additions & 0 deletions include/mm/pmm.h
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Expand Up @@ -76,6 +76,13 @@ extern frame_t *get_free_frames(unsigned int order);
extern void put_free_frames(mfn_t mfn, unsigned int order);
extern void reclaim_frame(mfn_t mfn, unsigned int order);

extern frame_t *find_free_mfn_frame(mfn_t mfn, unsigned int order);
extern frame_t *find_busy_mfn_frame(mfn_t mfn, unsigned int order);
extern frame_t *find_mfn_frame(mfn_t mfn, unsigned int order);
extern frame_t *find_free_paddr_frame(paddr_t paddr);
extern frame_t *find_busy_paddr_frame(paddr_t paddr);
extern frame_t *find_paddr_frame(paddr_t paddr);
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extern void map_used_memory(void);
extern void map_frames_array(void);

Expand All @@ -100,6 +107,16 @@ static inline frame_t *get_first_frame(list_head_t *frames, unsigned int order)
return list_first_entry(&frames[order], frame_t, list);
}

static inline bool frame_has_paddr(const frame_t *frame, paddr_t pa) {
if (!frame)
return false;

paddr_t start_pa = mfn_to_paddr(frame->mfn);
paddr_t end_pa = start_pa + ORDER_TO_SIZE(frame->order) - 1;

return pa >= start_pa && pa <= end_pa;
}

static inline frame_t *get_free_frame(void) {
return get_free_frames(PAGE_ORDER_4K);
}
Expand Down
85 changes: 81 additions & 4 deletions mm/pmm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -407,7 +407,7 @@ static inline bool return_frame(frame_t *frame) {
return false;
}

static frame_t *find_mfn_frame(list_head_t *list, mfn_t mfn, unsigned int order) {
static frame_t *_find_mfn_frame(list_head_t *list, mfn_t mfn, unsigned int order) {
frame_t *frame;

if (!has_frames(list, order))
Expand All @@ -421,6 +421,83 @@ static frame_t *find_mfn_frame(list_head_t *list, mfn_t mfn, unsigned int order)
return NULL;
}

frame_t *find_free_mfn_frame(mfn_t mfn, unsigned int order) {
frame_t *frame;

spin_lock(&lock);
frame = _find_mfn_frame(free_frames, mfn, order);
spin_unlock(&lock);

return frame;
}

frame_t *find_busy_mfn_frame(mfn_t mfn, unsigned int order) {
frame_t *frame;

spin_lock(&lock);
frame = _find_mfn_frame(busy_frames, mfn, order);
spin_unlock(&lock);

return frame;
}

frame_t *find_mfn_frame(mfn_t mfn, unsigned int order) {
frame_t *frame;

spin_lock(&lock);
frame = _find_mfn_frame(busy_frames, mfn, order);
if (!frame)
frame = _find_mfn_frame(free_frames, mfn, order);
spin_unlock(&lock);
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return frame;
}

static frame_t *_find_paddr_frame(list_head_t *list, paddr_t paddr) {
frame_t *frame;

for_each_order (order) {
list_for_each_entry (frame, &list[order], list) {
if (frame_has_paddr(frame, paddr))
return frame;
}
}

return NULL;
}

frame_t *find_free_paddr_frame(paddr_t paddr) {
frame_t *frame;

spin_lock(&lock);
frame = _find_paddr_frame(free_frames, paddr);
spin_unlock(&lock);

return frame;
}

frame_t *find_busy_paddr_frame(paddr_t paddr) {
frame_t *frame;

spin_lock(&lock);
frame = _find_paddr_frame(busy_frames, paddr);
spin_unlock(&lock);

return frame;
}

frame_t *find_paddr_frame(paddr_t paddr) {
frame_t *frame;

spin_lock(&lock);
frame = _find_paddr_frame(busy_frames, paddr);
if (!frame)
frame = _find_paddr_frame(free_frames, paddr);
spin_unlock(&lock);
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return frame;
}

static frame_t *find_larger_frame(list_head_t *list, unsigned int order) {
while (++order <= MAX_PAGE_ORDER) {
frame_t *frame = get_first_frame(list, order);
Expand Down Expand Up @@ -491,13 +568,13 @@ static void merge_frames(frame_t *first) {

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if (FIRST_FRAME_SIBLING(first->mfn, first->order + 1)) {
mfn_t next_mfn = NEXT_MFN(first->mfn, first->order);
second = find_mfn_frame(free_frames, next_mfn, first->order);
second = _find_mfn_frame(free_frames, next_mfn, first->order);
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}
else {
/* Second frame sibling */
mfn_t prev_mfn = PREV_MFN(first->mfn, first->order);
second = first;
first = find_mfn_frame(free_frames, prev_mfn, first->order);
first = _find_mfn_frame(free_frames, prev_mfn, first->order);
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}

if (!first || !second)
Expand Down Expand Up @@ -547,7 +624,7 @@ void put_free_frames(mfn_t mfn, unsigned int order) {
ASSERT(order <= MAX_PAGE_ORDER);

spin_lock(&lock);
frame = find_mfn_frame(busy_frames, mfn, order);
frame = _find_mfn_frame(busy_frames, mfn, order);
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if (!frame) {
warning("PMM: unable to find frame: %lx, order: %u among busy frames", mfn,
order);
Expand Down
8 changes: 6 additions & 2 deletions tests/unittests.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include <console.h>
#include <cpuid.h>
#include <ktf.h>
#include <pagetable.h>
#include <real_mode.h>
#include <sched.h>
#include <string.h>
Expand Down Expand Up @@ -203,13 +204,16 @@ int unit_tests(void *_unused) {
task_user3 = new_user_task("test3 user", test_user_task_func3, NULL);
task_user4 = new_user_task("test4 user", test_user_task_func4, NULL);

vmap_4k(HIGH_USER_PTR + 0x1000, get_free_frame()->mfn, L1_PROT);
frame_t *frame = get_free_frame();
vmap_4k(HIGH_USER_PTR + 0x1000, frame->mfn, L1_PROT);
memset(HIGH_USER_PTR + 0x1000, 0, 0x1000);
vmap_user_4k(HIGH_USER_PTR, get_free_frame()->mfn, L1_PROT_USER);
vmap_user_4k(HIGH_USER_PTR, frame->mfn, L1_PROT_USER);

/* Be sure that we can still touch this vmap despite the user vmap. */
BUG_ON(*(unsigned long *) (HIGH_USER_PTR + 0x1000) != 0);

BUG_ON(frame != find_kern_va_frame(HIGH_USER_PTR + 0x1000));

set_task_repeat(task1, 10);
schedule_task(task1, get_bsp_cpu());
schedule_task(task2, get_cpu(1));
Expand Down
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