From: Peter Feiner <pfeiner@xxxxxxxxxx>
Convenience functions for manipulating and querying page tables.
Signed-off-by: Peter Feiner <pfeiner@xxxxxxxxxx>
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
lib/x86/vm.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
lib/x86/vm.h | 27 +++++++++++++++++
2 files changed, 108 insertions(+), 18 deletions(-)
diff --git a/lib/x86/vm.c b/lib/x86/vm.c
index 438ab9c70ffa..d52bb53fcf5e 100644
--- a/lib/x86/vm.c
+++ b/lib/x86/vm.c
@@ -139,23 +139,62 @@ unsigned long *install_pte(unsigned long *cr3,
return &pt[offset];
}
+/*
+ * Finds last PTE in the mapping of @virt that's at or above @lowest_level. The
+ * returned PTE isn't necessarily present, but its parent is.
+ */
+struct pte_search find_pte_level(unsigned long *cr3, void *virt,
+ int lowest_level)
+{
+ unsigned long *pt = cr3, pte;
+ unsigned offset;
+ unsigned long shift;
+ struct pte_search r;
+
+ assert(lowest_level >= 1 && lowest_level <= PAGE_LEVEL);
+
+ for (r.level = PAGE_LEVEL;; --r.level) {
+ shift = (r.level - 1) * PGDIR_WIDTH + 12;
+ offset = ((unsigned long)virt >> shift) & PGDIR_MASK;
+ r.pte = &pt[offset];
+ pte = *r.pte;
+
+ if (!(pte & PT_PRESENT_MASK))
+ return r;
+
+ if ((r.level == 2 || r.level == 3) && (pte & PT_PAGE_SIZE_MASK))
+ return r;
+
+ if (r.level == lowest_level)
+ return r;
+
+ pt = phys_to_virt(pte & 0xffffffffff000ull);
+ }
+}
+
+/*
+ * Returns the leaf PTE in the mapping of @virt (i.e., 4K PTE or a present huge
+ * PTE). Returns NULL if no leaf PTE exists.
+ */
unsigned long *get_pte(unsigned long *cr3, void *virt)
{
- int level;
- unsigned long *pt = cr3, pte;
- unsigned offset;
+ struct pte_search search;
- for (level = PAGE_LEVEL; level > 1; --level) {
- offset = ((unsigned long)virt >> (((level-1) * PGDIR_WIDTH) + 12)) & PGDIR_MASK;
- pte = pt[offset];
- if (!(pte & PT_PRESENT_MASK))
- return NULL;
- if (level == 2 && (pte & PT_PAGE_SIZE_MASK))
- return &pt[offset];
- pt = phys_to_virt(pte & PT_ADDR_MASK);
- }
- offset = ((unsigned long)virt >> (((level-1) * PGDIR_WIDTH) + 12)) & PGDIR_MASK;
- return &pt[offset];
+ search = find_pte_level(cr3, virt, 1);
+ return found_leaf_pte(search) ? search.pte : NULL;
+}
+
+/*
+ * Returns the PTE in the mapping of @virt at the given level @pte_level.
+ * Returns NULL if the PT at @pte_level isn't present (i.e., the mapping at
+ * @pte_level - 1 isn't present).
+ */
+unsigned long *get_pte_level(unsigned long *cr3, void *virt, int pte_level)
+{
+ struct pte_search search;
+
+ search = find_pte_level(cr3, virt, pte_level);
+ return search.level == pte_level ? search.pte : NULL;
}
unsigned long *install_large_page(unsigned long *cr3,
@@ -173,6 +212,33 @@ unsigned long *install_page(unsigned long *cr3,
return install_pte(cr3, 1, virt, phys | PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK, 0);
}
+void install_pages(unsigned long *cr3, unsigned long phys, unsigned long len,
+ void *virt)
+{
+ unsigned long max = (u64)len + (u64)phys;
+ assert(phys % PAGE_SIZE == 0);
+ assert((unsigned long) virt % PAGE_SIZE == 0);
+ assert(len % PAGE_SIZE == 0);
+
+ while (phys + PAGE_SIZE <= max) {
+ install_page(cr3, phys, virt);
+ phys += PAGE_SIZE;
+ virt = (char *) virt + PAGE_SIZE;
+ }
+}
+
+bool any_present_pages(unsigned long *cr3, void *virt, unsigned long len)
+{
+ unsigned long max = (unsigned long) virt + len;
+ unsigned long curr;
+
+ for (curr = (unsigned long) virt; curr < max; curr += PAGE_SIZE) {
+ unsigned long *ptep = get_pte(cr3, (void *) curr);
+ if (ptep && (*ptep & PT_PRESENT_MASK))
+ return true;
+ }
+ return false;
+}
static void setup_mmu_range(unsigned long *cr3, unsigned long start,
unsigned long len)
@@ -184,10 +250,7 @@ static void setup_mmu_range(unsigned long *cr3, unsigned long start,
install_large_page(cr3, phys, (void *)(ulong)phys);
phys += LARGE_PAGE_SIZE;
}
- while (phys + PAGE_SIZE <= max) {
- install_page(cr3, phys, (void *)(ulong)phys);
- phys += PAGE_SIZE;
- }
+ install_pages(cr3, phys, max - phys, (void *)(ulong)phys);
}
static void setup_mmu(unsigned long len)
diff --git a/lib/x86/vm.h b/lib/x86/vm.h
index 64e4b566333f..3522ba8b99b0 100644
--- a/lib/x86/vm.h
+++ b/lib/x86/vm.h
@@ -14,7 +14,27 @@ void *alloc_vpage(void);
void *alloc_vpages(ulong nr);
uint64_t virt_to_phys_cr3(void *mem);
+struct pte_search {
+ int level;
+ unsigned long *pte;
+};
+
+static inline bool found_huge_pte(struct pte_search search)
+{
+ return (search.level == 2 || search.level == 3) &&
+ (*search.pte & PT_PRESENT_MASK) &&
+ (*search.pte & PT_PAGE_SIZE_MASK);
+}
+
+static inline bool found_leaf_pte(struct pte_search search)
+{
+ return search.level == 1 || found_huge_pte(search);
+}
+
+struct pte_search find_pte_level(unsigned long *cr3, void *virt,
+ int lowest_level);
unsigned long *get_pte(unsigned long *cr3, void *virt);
+unsigned long *get_pte_level(unsigned long *cr3, void *virt, int pte_level);
unsigned long *install_pte(unsigned long *cr3,
int pte_level,
void *virt,
@@ -28,5 +48,12 @@ void free_page(void *page);
unsigned long *install_large_page(unsigned long *cr3,unsigned long phys,
void *virt);
unsigned long *install_page(unsigned long *cr3, unsigned long phys, void *virt);
+void install_pages(unsigned long *cr3, unsigned long phys, unsigned long len,
+ void *virt);
+bool any_present_pages(unsigned long *cr3, void *virt, unsigned long len);
+static inline void *current_page_table(void)
+{
+ return phys_to_virt(read_cr3());
+}
#endif
--
2.12.2.816.g2cccc81164-goog
