Revert "linker: get rid of the buddy allocator"

This reverts commit 7059b1f02ea9197728c851edd9ae0dd7688fa700.
Bug: 5036610

5 files changed, 277 insertions, 15 deletions

diff --git a/linker/Android.mk b/linker/Android.mk
index 60f291c..abe5995 100644
--- a/linker/Android.mk
+++ b/linker/Android.mk
@@ -8,7 +8,8 @@ LOCAL_SRC_FILES:= \
 	linker_format.c \
 	rt.c \
 	dlfcn.c \
-	debugger.c
+	debugger.c \
+	ba.c
 
 ifeq ($(TARGET_ARCH),sh)
 # SH-4A series virtual address range from 0x00000000 to 0x7FFFFFFF.
diff --git a/linker/ba.c b/linker/ba.c
new file mode 100644
index 0000000..db49c4b
--- /dev/null
+++ b/linker/ba.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "linker.h"
+#include "linker_debug.h"
+#include "ba.h"
+
+#undef min
+#define min(a,b) ((a)<(b)?(a):(b))
+
+#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 unsigned long ba_order(struct ba *ba, unsigned long len);
+
+void ba_init(struct ba *ba)
+{
+    int i, index = 0;
+
+    unsigned long max_order = ba_order(ba, ba->size);
+    if (ba->max_order == 0 || ba->max_order > max_order)
+        ba->max_order = max_order;
+
+    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(struct ba *ba, int index)
+{
+    int buddy, curr = index;
+
+    /* clean up the bitmap, merging any buddies */
+    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
+     */
+    do {
+        buddy = BA_BUDDY_INDEX(curr);
+        if (BA_IS_FREE(buddy) &&
+                BA_ORDER(buddy) == BA_ORDER(curr)) {
+            BA_ORDER(buddy)++;
+            BA_ORDER(curr)++;
+            curr = min(buddy, curr);
+        } else {
+            break;
+        }
+    } while (curr < ba->num_entries);
+
+    return 0;
+}
+
+static unsigned long ba_order(struct ba *ba, unsigned long len)
+{
+    unsigned long i;
+
+    len = (len + ba->min_alloc - 1) / ba->min_alloc;
+    len--;
+    for (i = 0; i < sizeof(len)*8; i++)
+        if (len >> i == 0)
+            break;
+    return i;
+}
+
+int ba_allocate(struct ba *ba, unsigned long len)
+{
+    int curr = 0;
+    int end = ba->num_entries;
+    int best_fit = -1;
+    unsigned long order = ba_order(ba, len);
+
+    if (order > ba->max_order)
+        return -1;
+
+    /* look through the bitmap:
+     *  if you find a free slot of the correct order use it
+     *  otherwise, use the best fit (smallest with size > order) slot
+     */
+    while (curr < end) {
+        if (BA_IS_FREE(curr)) {
+            if (BA_ORDER(curr) == (unsigned char)order) {
+                /* set the not free bit and clear others */
+                best_fit = curr;
+                break;
+            }
+            if (BA_ORDER(curr) > (unsigned char)order &&
+                (best_fit < 0 ||
+                 BA_ORDER(curr) < BA_ORDER(best_fit)))
+                best_fit = curr;
+        }
+        curr = BA_NEXT_INDEX(curr);
+    }
+
+    /* if best_fit < 0, there are no suitable slots,
+     * return an error
+     */
+    if (best_fit < 0)
+        return -1;
+
+    /* now partition the best fit:
+     *  split the slot into 2 buddies of order - 1
+     *  repeat until the slot is of the correct order
+     */
+    while (BA_ORDER(best_fit) > (unsigned char)order) {
+        int buddy;
+        BA_ORDER(best_fit) -= 1;
+        buddy = BA_BUDDY_INDEX(best_fit);
+        BA_ORDER(buddy) = BA_ORDER(best_fit);
+    }
+    ba->bitmap[best_fit].allocated = 1;
+    return best_fit;
+}
+
+unsigned long ba_start_addr(struct ba *ba, int index)
+{
+    return BA_START_ADDR(index);
+}
+
+unsigned long ba_len(struct ba *ba, int index)
+{
+    return BA_LEN(index);
+}
diff --git a/linker/ba.h b/linker/ba.h
new file mode 100644
index 0000000..c11017b
--- /dev/null
+++ b/linker/ba.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef __LINKER_BA_H
+#define __LINKER_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 {
+    /* 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 4d85064..e350d89 100644
--- a/linker/linker.c
+++ b/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;
diff --git a/linker/linker.h b/linker/linker.h
index 301d268..68ac275 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -83,6 +83,7 @@ typedef struct soinfo soinfo;
 #define FLAG_LINKED     0x00000001
 #define FLAG_ERROR      0x00000002
 #define FLAG_EXE        0x00000004 // The main executable
+#define FLAG_PRELINKED  0x00000008 // This is a pre-linked lib
 
 #define SOINFO_NAME_LEN 128
 
@@ -94,6 +95,8 @@ struct soinfo
     unsigned entry;
     unsigned base;
     unsigned size;
+    // buddy-allocator index, negative for prelinked libraries
+    int ba_index;
 
     unsigned *dynamic;
 
@@ -151,6 +154,17 @@ struct soinfo
 
 extern soinfo libdl_info;
 
+/* these must all be powers of two */
+#ifdef ARCH_SH
+#define LIBBASE 0x60000000
+#define LIBLAST 0x70000000
+#define LIBINC  0x00100000
+#else
+#define LIBBASE 0x80000000
+#define LIBLAST 0x90000000
+#define LIBINC  0x00100000
+#endif
+
 #ifdef ANDROID_ARM_LINKER
 
 #define R_ARM_COPY       20