loader: add a flattened device tree blob (dtb) object

this adds a dtb_object so the loader can load in the dtb
file for linux/android ARM kernels.

1 files changed, 169 insertions, 0 deletions

diff --git a/src/base/loader/dtb_object.cc b/src/base/loader/dtb_object.cc
new file mode 100644
index 000000000..f22cee1ed
--- /dev/null
+++ b/src/base/loader/dtb_object.cc
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2013 The Regents of The University of Michigan
+ * 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;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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.
+ *
+ * Authors: Anthony Gutierrez
+ */
+
+#include <sys/mman.h>
+#include <err.h>
+#include <unistd.h>
+
+#include <cassert>
+
+#include "base/loader/dtb_object.hh"
+#include "fdt.h"
+#include "libfdt.h"
+
+ObjectFile *
+DtbObject::tryFile(const std::string &fname, int fd, size_t len, uint8_t *data)
+{
+    // Check if this is a FDT file by looking for magic number
+    if (fdt_magic((void*)data) == FDT_MAGIC) {
+        return new DtbObject(fname, fd, len, data,
+                             ObjectFile::UnknownArch, ObjectFile::UnknownOpSys);
+    } else {
+        return NULL;
+    }
+}
+
+DtbObject::DtbObject(const std::string &_filename, int _fd,
+                     size_t _len, uint8_t *_data,
+                     Arch _arch, OpSys _opSys)
+    : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys)
+{
+    text.baseAddr = 0;
+    text.size = len;
+    text.fileImage = fileData;
+
+    data.baseAddr = 0;
+    data.size = 0;
+    data.fileImage = NULL;
+
+    bss.baseAddr = 0;
+    bss.size = 0;
+    bss.fileImage = NULL;
+
+    fileDataMmapped = true;
+}
+
+DtbObject::~DtbObject()
+{
+    if (descriptor >= 0) {
+        ::close(descriptor);
+        descriptor = -1;
+    }
+
+    // Make sure to clean up memory properly depending
+    // on how buffer was allocated.
+    if (fileData && !fileDataMmapped) {
+        delete [] fileData;
+        fileData = NULL;
+    } else if (fileData) {
+        munmap(fileData, len);
+        fileData = NULL;
+    }
+}
+
+bool
+DtbObject::addBootCmdLine(const char* _args, size_t len)
+{
+    const char* root_path = "/";
+    const char* node_name = "chosen";
+    const char* full_path_node_name = "/chosen";
+    const char* property_name = "bootargs";
+
+    // Make a new buffer that has extra space to add nodes/properties
+    int newLen = 2*this->len;
+    uint8_t* fdt_buf_w_space = new uint8_t[newLen];
+    // Copy and unpack flattened device tree into new buffer
+    int ret = fdt_open_into((void*)fileData, (void*)fdt_buf_w_space, (newLen));
+    if (ret < 0) {
+        warn("Error resizing buffer of flattened device tree, "
+             "errno: %d\n", ret);
+        delete [] fdt_buf_w_space;
+        return false;
+    }
+
+    // First try finding the /chosen node in the dtb
+    int offset = fdt_path_offset((void*)fdt_buf_w_space, full_path_node_name);
+    if (offset < 0) {
+        // try adding the node by walking dtb tree to proper insertion point
+        offset = fdt_path_offset((void*)fdt_buf_w_space, root_path);
+        offset = fdt_add_subnode((void*)fdt_buf_w_space, offset, node_name);
+        offset = fdt_path_offset((void*)fdt_buf_w_space, full_path_node_name);
+        if (offset < 0) {
+            warn("Error finding or adding \"chosen\" subnode to flattened "
+                 "device tree, errno: %d\n", offset);
+            delete [] fdt_buf_w_space;
+            return false;
+        }
+    }
+
+    // Set the bootargs property in the /chosen node
+    ret = fdt_setprop((void*)fdt_buf_w_space, offset, property_name,
+                      (const void*)_args, len+1);
+    if (ret < 0) {
+        warn("Error setting \"bootargs\" property to flattened device tree, "
+             "errno: %d\n", ret);
+        delete [] fdt_buf_w_space;
+        return false;
+    }
+
+    // Repack the dtb for kernel use
+    ret = fdt_pack((void*)fdt_buf_w_space);
+    if (ret < 0) {
+        warn("Error re-packing flattened device tree structure, "
+             "errno: %d\n", ret);
+        delete [] fdt_buf_w_space;
+        return false;
+    }
+
+    text.size = newLen;
+    text.fileImage = fdt_buf_w_space;
+
+    // clean up old buffer and set to new fdt blob
+    munmap(fileData, this->len);
+    fileData = fdt_buf_w_space;
+    fileDataMmapped = false;
+    this->len = newLen;
+
+    return true;
+}
+
+bool
+DtbObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask)
+{
+    // nothing to do here
+    return false;
+}
+
+bool
+DtbObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask)
+{
+    // nothing to do here
+    return false;
+}