pmm: get_free_frames() returns frame_t pointer instead of mfn

Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>

Author: wipawel

arch/x86/pagetables.c

@@ -118,7 +118,10 @@ static mfn_t get_cr3_mfn(cr3_t *cr3_entry) {
     void *cr3_mapped = NULL;
 
     if (mfn_invalid(cr3_entry->mfn)) {
-        cr3_entry->mfn = get_free_frame();
+        frame_t *frame = get_free_frame();
+        BUG_ON(!frame);
+
+        cr3_entry->mfn = frame->mfn;
         cr3_mapped = init_map_mfn(cr3_entry->mfn);
         memset(cr3_mapped, 0, PAGE_SIZE);
     }
@@ -137,7 +140,10 @@ 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)) {
-        set_pgentry(entry, get_free_frame(), flags);
+        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);
         memset(tab, 0, PAGE_SIZE);

include/mm/pmm.h

@@ -48,7 +48,7 @@ extern void display_frames_count(void);
 extern void init_pmm(void);
 
 extern frame_t *get_free_frames_cond(free_frames_cond_t cb);
-extern mfn_t get_free_frames(unsigned int order);
+extern frame_t *get_free_frames(unsigned int order);
 extern void put_frame(mfn_t mfn, unsigned int order);
 extern void reclaim_frame(mfn_t mfn, unsigned int order);
 
@@ -62,7 +62,7 @@ static inline bool paddr_invalid(paddr_t pa) {
 
 static inline bool mfn_invalid(mfn_t mfn) { return paddr_invalid(mfn_to_paddr(mfn)); }
 
-static inline mfn_t get_free_frame(void) { return get_free_frames(PAGE_ORDER_4K); }
+static inline frame_t *get_free_frame(void) { return get_free_frames(PAGE_ORDER_4K); }
 
 #endif /* __ASSEMBLY__ */
 

mm/pmm.c

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2020 Amazon.com, Inc. or its affiliates.
+ * Copyright © 2021 Amazon.com, Inc. or its affiliates.
  * All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -188,22 +188,22 @@ frame_t *get_free_frames_cond(free_frames_cond_t cb) {
     return NULL;
 }
 
-mfn_t get_free_frames(unsigned int order) {
+frame_t *get_free_frames(unsigned int order) {
     frame_t *frame;
 
     if (order > MAX_PAGE_ORDER)
-        return MFN_INVALID;
+        return NULL;
 
     if (list_is_empty(&free_frames[order])) {
         /* FIXME: Add page split */
-        return MFN_INVALID;
+        return NULL;
     }
 
     frame = list_first_entry(&free_frames[order], frame_t, list);
 
     frame = reserve_frame(frame, order);
 
-    return frame->mfn;
+    return frame;
 }
 
 void put_frame(mfn_t mfn, unsigned int order) {

mm/vmm.c

@@ -30,12 +30,15 @@
 #include <mm/vmm.h>
 
 void *get_free_pages(unsigned int order, uint32_t flags) {
-    mfn_t mfn = get_free_frames(order);
+    frame_t *frame = get_free_frames(order);
     void *va = NULL;
+    mfn_t mfn;
 
-    if (mfn_invalid(mfn))
+    if (!frame)
         return NULL;
 
+    mfn = frame->mfn;
+
     if (flags & GFP_IDENT)
         va = vmap(mfn_to_virt(mfn), mfn, order, L4_PROT, L3_PROT, L2_PROT, L1_PROT);
     if (flags & GFP_USER)