Revert "linker: get rid of the buddy allocator"

This reverts commit 7059b1f02e.
Bug: 5036610

linker/linker.c

@@ -51,6 +51,8 @@
 #include "linker_environ.h"
 #include "linker_format.h"
 
+#include "ba.h"
+
 #define ALLOW_SYMBOLS_FROM_MAIN 1
 #define SO_MAX 128
 
@@ -94,6 +96,17 @@ static soinfo *somain; /* main process, always the one after libdl_info */
 #endif
 
 
+/* Set up for the buddy allocator managing the non-prelinked libraries. */
+static struct ba_bits ba_nonprelink_bitmap[(LIBLAST - LIBBASE) / LIBINC];
+static struct ba ba_nonprelink = {
+    .base = LIBBASE,
+    .size = LIBLAST - LIBBASE,
+    .min_alloc = LIBINC,
+    /* max_order will be determined automatically */
+    .bitmap = ba_nonprelink_bitmap,
+    .num_entries = sizeof(ba_nonprelink_bitmap)/sizeof(ba_nonprelink_bitmap[0]),
+};
+
 static inline int validate_soinfo(soinfo *si)
 {
     return (si >= sopool && si < sopool + SO_MAX) ||
@@ -279,6 +292,7 @@ static soinfo *alloc_info(const char *name)
     memset(si, 0, sizeof(soinfo));
     strlcpy((char*) si->name, name, sizeof(si->name));
     sonext->next = si;
+    si->ba_index = -1; /* by default, prelinked */
     si->next = NULL;
     si->refcount = 0;
     sonext = si;
@@ -830,25 +844,28 @@ alloc_mem_region(soinfo *si)
 {
     if (si->base) {
         /* Attempt to mmap a prelinked library. */
+        si->ba_index = -1;
         return reserve_mem_region(si);
     }
 
-    /* This is not a prelinked library, so we use the kernel's default
-       allocator.
+    /* This is not a prelinked library, so we attempt to allocate space
+       for it from the buddy allocator, which manages the area between
+       LIBBASE and LIBLAST.
     */
-
-    void *base = mmap(NULL, si->size, PROT_READ | PROT_EXEC,
-                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-    if (base == MAP_FAILED) {
-        DL_ERR("%5d mmap of library '%s' failed: %d (%s)\n",
-              pid, si->name,
-              errno, strerror(errno));
-        goto err;
+    si->ba_index = ba_allocate(&ba_nonprelink, si->size);
+    if(si->ba_index >= 0) {
+        si->base = ba_start_addr(&ba_nonprelink, 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(&ba_nonprelink, si->ba_index);
+            si->ba_index = -1;
+            si->base = 0;
+            goto err;
+        }
+        return 0;
     }
-    si->base = (unsigned) base;
-    PRINT("%5d mapped library '%s' to %08x via kernel allocator.\n",
-          pid, si->name, si->base);
-    return 0;
 
 err:
     DL_ERR("OOPS: %5d cannot map library '%s'. no vspace available.",
@@ -1137,6 +1154,10 @@ 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(&ba_nonprelink, si->ba_index);
+            si->ba_index = -1;
+        }
         goto fail;
     }
 
@@ -1166,6 +1187,9 @@ init_library(soinfo *si)
     TRACE("[ %5d init_library base=0x%08x sz=0x%08x name='%s') ]\n",
           pid, si->base, si->size, si->name);
 
+    if (si->base < LIBBASE || si->base >= LIBLAST)
+        si->flags |= FLAG_PRELINKED;
+
     if(link_image(si, wr_offset)) {
             /* We failed to link.  However, we can only restore libbase
             ** if no additional libraries have moved it since we updated it.
@@ -1240,6 +1264,12 @@ unsigned unload_library(soinfo *si)
         }
 
         munmap((char *)si->base, si->size);
+        if (si->ba_index >= 0) {
+            PRINT("%5d releasing library '%s' address space at %08x "\
+                  "through buddy allocator.\n",
+                  pid, si->name, si->base);
+            ba_free(&ba_nonprelink, si->ba_index);
+        }
         notify_gdb_of_unload(si);
         free_info(si);
         si->refcount = 0;
@@ -2183,6 +2213,8 @@ unsigned __linker_init(unsigned **elfdata)
         vecs += 2;
     }
 
+    ba_init(&ba_nonprelink);
+
     si->base = 0;
     si->dynamic = (unsigned *)-1;
     si->wrprotect_start = 0xffffffff;