From b62706c9f2ceed65394457ae9b131996a2b29463 Mon Sep 17 00:00:00 2001
From: Brett Weiland <brett_weiland@bpcspace.com>
Date: Fri, 24 Sep 2021 14:20:20 -0500
Subject: palloc/pfree found smp safe

---
 src/kernel/page.c | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

(limited to 'src/kernel/page.c')

diff --git a/src/kernel/page.c b/src/kernel/page.c
index 0b286a4..c79b1fa 100644
--- a/src/kernel/page.c
+++ b/src/kernel/page.c
@@ -100,7 +100,6 @@ void fix_stack() {
       :"r"(PA_OFFSET));
   
   while(frame->next != 0) {
-    printf("%p\n", frame->function_base);
     frame->next = PHYS_TO_VIRT((void *)frame->next);
     frame = frame->next;
   }
@@ -171,14 +170,13 @@ void debug_pmap() {
   }
 }
 
-//TODO I know you don't want to, but you need to thoroughly check this.
 void pfree(void *addr, size_t size) { 
   int blevel = 0;
   uint64_t *onbyte;         
   uint64_t page_bitloc; 
   int bbitlen;              
   int lshift;         
-  pmap_t *pmap = first_pmap;
+  pmap_t *pmap;
   
   /* note: there's no security check to see if the page is actually allocated,
    * or if we are freeing the table itself.
@@ -192,10 +190,13 @@ void pfree(void *addr, size_t size) {
     return; 
   }
   size /= 0x1000; 
-  for(; pmap != 0; pmap = pmap->next) {
+  for(pmap = first_pmap; pmap; pmap = pmap->next) {
     page_bitloc = (addr - (void *)pmap) / 0x1000;
     onbyte = pmap->buddy[0] + (page_bitloc / 64);
-    if((addr >= (void *)pmap) && onbyte < pmap->buddy[1]) break;
+    if((addr >= (void *)pmap) && onbyte < pmap->buddy[1]) {
+      lock(&pmap->mutex);
+      break;
+    }
   }
 
   while(blevel < MAX_BUDDY_ORDER) {
@@ -241,6 +242,7 @@ void pfree(void *addr, size_t size) {
       blevel++;
     }
   }
+  unlock(&pmap->mutex);
 }
 
 
@@ -276,13 +278,10 @@ void *palloc(size_t size) {
     self_alloc = false;
     min_blevel = 63 - __builtin_clzl(size);
     if(size & (size - 1)) min_blevel++;
-    if(min_blevel > MAX_BUDDY_ORDER - 1) return 0;
+    if(min_blevel > MAX_BUDDY_ORDER - 1) PANIC(KERNEL_PANIC_PALLOC_TOO_LARGE);
   }
 
   for(blevel = min_blevel; blevel < MAX_BUDDY_ORDER; blevel++) {
-    //for(pmap = first_pmap; pmap != 0; pmap = pmap->next) {
-    //while(!unlocked_pmaps_searched || 
-    //   is_empty(waiting_pmaps[core_id], sizeof(&pmap) * pmap_count)) {
     pmap = first_pmap;
     while(pmap) {
 
@@ -329,12 +328,13 @@ void *palloc(size_t size) {
           return ret;
         }
       }
-get_next_pmap:
       pmap->mutex = 0;
+get_next_pmap:
       if(unlocked_pmaps_searched) {
         pmap = 0;
         for(searchingp_i = waitingp_i + 1; searchingp_i < pmap_count; searchingp_i++) {
           if(waiting_pmaps[waitlist_i(searchingp_i)]) {
+            waitingp_i = searchingp_i;
             pmap = waiting_pmaps[waitlist_i(searchingp_i)];
             break;
           }
@@ -342,6 +342,7 @@ get_next_pmap:
         if(!pmap) {
           for(searchingp_i = 0; searchingp_i <= waitingp_i; searchingp_i++) {
             if(waiting_pmaps[waitlist_i(searchingp_i)]) {
+              waitingp_i = searchingp_i;
               pmap = waiting_pmaps[waitlist_i(searchingp_i)];
               break;
             }
@@ -350,6 +351,7 @@ get_next_pmap:
       }
       else {
         if(!pmap->next) {
+          waitingp_i = 0;
           pmap = waiting_pmaps ? waiting_pmaps[waitlist_i(0)] : 0;
           unlocked_pmaps_searched = true;
         }
@@ -515,3 +517,18 @@ void *init_pmap(size_t pagetable_size) {
   }
   return pmap;
 }
+
+void lock_all_maps() {
+  pmap_t *pmap;
+  for(pmap = first_pmap; pmap; pmap = pmap->next) pmap->mutex = 1;
+  pmap = first_pmap;
+  pmap_count++;
+  for(pmap = first_pmap;;pmap = pmap->next) {
+    if(!pmap->next) {
+      pmap->next = malloc(sizeof(pmap_t));
+      pmap->next->mutex = 1;
+      break;
+    }
+  }
+  first_pmap->mutex = 0;
+}
-- 
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