bionic/linker: change the buddy allocator to take a handle to the managed area

-- rename struct ba_info to struct ba
-- move the static ba descriptor from ba.c to linker.c and rename it ba_prelink
-- ba_init, ba_allocate, ba_free, ba_start_addr, and ba_len all take a pointer
   to struct ba

Signed-off-by: Iliyan Malchev <malchev@google.com>

3 files changed, 64 insertions, 62 deletions

diff --git a/linker/ba.c b/linker/ba.c
index bea6f84..8534919 100644
--- a/linker/ba.c
+++ b/linker/ba.c
@@ -30,65 +30,34 @@
 #include "linker_debug.h"
 #include "ba.h"
 
-struct ba_bits {
-    unsigned allocated:1;           /* 1 if allocated, 0 if free */
-    unsigned order:7;               /* size of the region in ba space */
-};
-
-struct ba_info {
-    /* start address of the ba space */
-    unsigned long base;
-    /* total size of the ba space */
-    unsigned long size;
-    /* number of entries in the ba space */
-    int num_entries;
-    /* the bitmap for the region indicating which entries are allocated
-     * and which are free */
-    struct ba_bits *bitmap;
-};
-
 #undef min
 #define min(a,b) ((a)<(b)?(a):(b))
 
-#define BA_MIN_ALLOC LIBINC
-#define BA_MAX_ORDER 128
-#define BA_START LIBBASE
-#define BA_SIZE (LIBLAST - LIBBASE)
-
-#define BA_IS_FREE(index) (!(ba.bitmap[index].allocated))
-#define BA_ORDER(index) ba.bitmap[index].order
+#define BA_IS_FREE(index) (!(ba->bitmap[index].allocated))
+#define BA_ORDER(index) ba->bitmap[index].order
 #define BA_BUDDY_INDEX(index) ((index) ^ (1 << BA_ORDER(index)))
 #define BA_NEXT_INDEX(index) ((index) + (1 << BA_ORDER(index)))
-#define BA_OFFSET(index) ((index) * BA_MIN_ALLOC)
-#define BA_START_ADDR(index) (BA_OFFSET(index) + ba.base)
-#define BA_LEN(index) ((1 << BA_ORDER(index)) * BA_MIN_ALLOC)
-
-static struct ba_bits ba_bitmap[BA_SIZE / BA_MIN_ALLOC];
-
-static struct ba_info ba = {
-    .base = BA_START,
-    .size = BA_SIZE,
-    .bitmap = ba_bitmap,
-    .num_entries = sizeof(ba_bitmap)/sizeof(ba_bitmap[0]),
-};
+#define BA_OFFSET(index) ((index) * ba->min_alloc)
+#define BA_START_ADDR(index) (BA_OFFSET(index) + ba->base)
+#define BA_LEN(index) ((1 << BA_ORDER(index)) * ba->min_alloc)
 
-void ba_init(void)
+void ba_init(struct ba *ba)
 {
     int i, index = 0;
-    for (i = sizeof(ba.num_entries) * 8 - 1; i >= 0; i--) {
-        if (ba.num_entries &  1<<i) {
+    for (i = sizeof(ba->num_entries) * 8 - 1; i >= 0; i--) {
+        if (ba->num_entries &  1<<i) {
             BA_ORDER(index) = i;
             index = BA_NEXT_INDEX(index);
         }
     }
 }
 
-int ba_free(int index)
+int ba_free(struct ba *ba, int index)
 {
     int buddy, curr = index;
 
     /* clean up the bitmap, merging any buddies */
-    ba.bitmap[curr].allocated = 0;
+    ba->bitmap[curr].allocated = 0;
     /* find a slots buddy Buddy# = Slot# ^ (1 << order)
      * if the buddy is also free merge them
      * repeat until the buddy is not free or end of the bitmap is reached
@@ -103,16 +72,16 @@ int ba_free(int index)
         } else {
             break;
         }
-    } while (curr < ba.num_entries);
+    } while (curr < ba->num_entries);
 
     return 0;
 }
 
-static unsigned long ba_order(unsigned long len)
+static unsigned long ba_order(struct ba *ba, unsigned long len)
 {
     unsigned long i;
 
-    len = (len + BA_MIN_ALLOC - 1) / BA_MIN_ALLOC;
+    len = (len + ba->min_alloc - 1) / ba->min_alloc;
     len--;
     for (i = 0; i < sizeof(len)*8; i++)
         if (len >> i == 0)
@@ -120,14 +89,14 @@ static unsigned long ba_order(unsigned long len)
     return i;
 }
 
-int ba_allocate(unsigned long len)
+int ba_allocate(struct ba *ba, unsigned long len)
 {
     int curr = 0;
-    int end = ba.num_entries;
+    int end = ba->num_entries;
     int best_fit = -1;
-    unsigned long order = ba_order(len);
+    unsigned long order = ba_order(ba, len);
 
-    if (order > BA_MAX_ORDER)
+    if (order > ba->max_order)
         return -1;
 
     /* look through the bitmap:
@@ -165,16 +134,16 @@ int ba_allocate(unsigned long len)
         buddy = BA_BUDDY_INDEX(best_fit);
         BA_ORDER(buddy) = BA_ORDER(best_fit);
     }
-    ba.bitmap[best_fit].allocated = 1;
+    ba->bitmap[best_fit].allocated = 1;
     return best_fit;
 }
 
-unsigned long ba_start_addr(int index)
+unsigned long ba_start_addr(struct ba *ba, int index)
 {
     return BA_START_ADDR(index);
 }
 
-unsigned long ba_len(int index)
+unsigned long ba_len(struct ba *ba, int index)
 {
     return BA_LEN(index);
 }
diff --git a/linker/ba.h b/linker/ba.h
index 78f4626..c11017b 100644
--- a/linker/ba.h
+++ b/linker/ba.h
@@ -29,10 +29,31 @@
 #ifndef __LINKER_BA_H
 #define __LINKER_BA_H
 
-extern void ba_init(void);
-extern int ba_allocate(unsigned long len);
-extern int ba_free(int index);
-extern unsigned long ba_start_addr(int index);
-extern unsigned long ba_len(int index);
+struct ba_bits {
+    unsigned allocated:1;           /* 1 if allocated, 0 if free */
+    unsigned order:7;               /* size of the region in ba space */
+};
+
+struct ba {
+    /* start address of the ba space */
+    unsigned long base;
+    /* total size of the ba space */
+    unsigned long size;
+    /* the smaller allocation that can be made */
+    unsigned long min_alloc;
+    /* the order of the largest allocation that can be made */
+    unsigned long max_order;
+    /* number of entries in the ba space */
+    int num_entries;
+    /* the bitmap for the region indicating which entries are allocated
+     * and which are free */
+    struct ba_bits *bitmap;
+};
+
+extern void ba_init(struct ba *ba);
+extern int ba_allocate(struct ba *ba, unsigned long len);
+extern int ba_free(struct ba *ba, int index);
+extern unsigned long ba_start_addr(struct ba *ba, int index);
+extern unsigned long ba_len(struct ba *ba, int index);
 
 #endif
diff --git a/linker/linker.c b/linker/linker.c
index a6ecd1a..07c7d78 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -91,6 +91,18 @@ static soinfo *sonext = &libdl_info;
 static soinfo *somain; /* main process, always the one after libdl_info */
 #endif
 
+
+/* Set up for the buddy allocator managing the prelinked libraries. */
+static struct ba_bits ba_prelink_bitmap[(LIBLAST - LIBBASE) / LIBINC];
+static struct ba ba_prelink = {
+    .base = LIBBASE,
+    .size = LIBLAST - LIBBASE,
+    .min_alloc = LIBINC,
+    .max_order = 128,
+    .bitmap = ba_prelink_bitmap,
+    .num_entries = sizeof(ba_prelink_bitmap)/sizeof(ba_prelink_bitmap[0]),
+};
+
 static inline int validate_soinfo(soinfo *si)
 {
     return (si >= sopool && si < sopool + SO_MAX) ||
@@ -783,14 +795,14 @@ alloc_mem_region(soinfo *si)
        for it from the buddy allocator, which manages the area between
        LIBBASE and LIBLAST.
     */
-    si->ba_index = ba_allocate(si->size);
+    si->ba_index = ba_allocate(&ba_prelink, si->size);
     if(si->ba_index >= 0) {
-        si->base = ba_start_addr(si->ba_index);
+        si->base = ba_start_addr(&ba_prelink, si->ba_index);
         PRINT("%5d mapping library '%s' at %08x (index %d) " \
               "through buddy allocator.\n",
               pid, si->name, si->base, si->ba_index);
         if (reserve_mem_region(si) < 0) {
-            ba_free(si->ba_index);
+            ba_free(&ba_prelink, si->ba_index);
             si->ba_index = -1;
             si->base = 0;
             goto err;
@@ -1086,7 +1098,7 @@ load_library(const char *name)
     /* Now actually load the library's segments into right places in memory */
     if (load_segments(fd, &__header[0], si) < 0) {
         if (si->ba_index >= 0) {
-            ba_free(si->ba_index);
+            ba_free(&ba_prelink, si->ba_index);
             si->ba_index = -1;
         }
         goto fail;
@@ -1189,7 +1201,7 @@ unsigned unload_library(soinfo *si)
             PRINT("%5d releasing library '%s' address space at %08x "\
                   "through buddy allocator.\n",
                   pid, si->name, si->base);
-            ba_free(si->ba_index);
+            ba_free(&ba_prelink, si->ba_index);
         }
         notify_gdb_of_unload(si);
         free_info(si);
@@ -1897,7 +1909,7 @@ unsigned __linker_init(unsigned **elfdata)
         vecs += 2;
     }
 
-    ba_init();
+    ba_init(&ba_prelink);
 
     si->base = 0;
     si->dynamic = (unsigned *)-1;