Merge changes from topic "host_bionic"

* changes:
  Use an embedded linker for host bionic
  linker: Only link to debuggerd on Android

libc/Android.bp

@@ -2130,6 +2130,14 @@ cc_object {
         "crtbegin_dynamic1",
         "crtbrand",
     ],
+    target: {
+        linux_bionic: {
+            generated_sources: ["host_bionic_linker_asm"],
+            objs: [
+                "linker_wrapper",
+            ],
+        },
+    },
     defaults: ["crt_defaults"],
 }
 

linker/Android.bp

@@ -13,6 +13,48 @@ cc_library_static {
     static_libs: ["libasync_safe"],
 }
 
+// This is used for bionic on (host) Linux to bootstrap our linker embedded into
+// a binary.
+//
+// Host bionic binaries do not have a PT_INTERP section, instead this gets
+// embedded as the entry point, and the linker is embedded as ELF sections in
+// each binary. There's a linker script that sets all of that up (generated by
+// extract_linker), and defines the extern symbols used in this file.
+cc_object {
+    name: "linker_wrapper",
+    host_supported: true,
+    device_supported: false,
+    target: {
+        linux_bionic: { enabled: true },
+        linux: { enabled: false },
+        darwin: { enabled: false },
+    },
+
+    cflags: [
+        "-fno-stack-protector",
+        "-Wstrict-overflow=5",
+        "-fvisibility=hidden",
+        "-Wall",
+        "-Wextra",
+        "-Wno-unused",
+        "-Werror",
+    ],
+
+    srcs: [
+        "linker_wrapper.cpp",
+    ],
+    arch: {
+        x86_64: {
+            srcs: ["arch/x86_64/begin.S"],
+        },
+    },
+
+    prefix_symbols: "__dlwrap_",
+
+    // We need to access Bionic private headers in the linker.
+    include_dirs: ["bionic/libc"],
+}
+
 cc_binary {
     defaults: ["linux_bionic_supported"],
     srcs: [
@@ -136,7 +178,7 @@ cc_binary {
         "libbase",
         "libz",
 
-        "libdebuggerd_handler_fallback",
+        "libasync_safe",
 
         "liblog",
         "libc++_static",
@@ -156,7 +198,7 @@ cc_binary {
     },
     target: {
         android: {
-            static_libs: ["libdebuggerd_client"],
+            static_libs: ["libdebuggerd_handler_fallback"],
         },
         android64: {
             cflags: ["-DTARGET_IS_64_BIT"],

linker/linker.cpp

@@ -3474,7 +3474,7 @@ std::vector<android_namespace_t*> init_default_namespaces(const char* executable
 
   const char *interp = phdr_table_get_interpreter_name(somain->phdr, somain->phnum,
                                                        somain->load_bias);
-  const char* bname = basename(interp);
+  const char* bname = (interp != nullptr) ? basename(interp) : nullptr;
 
   g_is_asan = bname != nullptr &&
               (strcmp(bname, "linker_asan") == 0 ||

linker/linker_wrapper.cpp

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2017 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 "private/KernelArgumentBlock.h"
+
+extern const char linker_code_start;
+extern const char original_start;
+extern const char linker_entry;
+
+/*
+ * This is the entry point for the linker wrapper, which finds
+ * the real linker, then bootstraps into it.
+ */
+extern "C" ElfW(Addr) __linker_init(void* raw_args) {
+  KernelArgumentBlock args(raw_args);
+
+  static uintptr_t linker_offset = reinterpret_cast<uintptr_t>(&linker_code_start);
+  static uintptr_t linktime_addr = reinterpret_cast<uintptr_t>(&linktime_addr);
+  ElfW(Addr) my_addr = reinterpret_cast<uintptr_t>(&linktime_addr) - linktime_addr;
+
+  // Set AT_ENTRY to the proper entry point
+  for (ElfW(auxv_t)* v = args.auxv; v->a_type != AT_NULL; ++v) {
+    if (v->a_type == AT_BASE) {
+      v->a_un.a_val = my_addr + linker_offset;
+    }
+    if (v->a_type == AT_ENTRY) {
+      v->a_un.a_val = my_addr + reinterpret_cast<uintptr_t>(&original_start);
+    }
+  }
+
+  // Return address of linker entry point -- may need to ensure that raw_args
+  // was saved.
+  return my_addr + linker_offset + reinterpret_cast<uintptr_t>(&linker_entry);
+}