Generate linkerconfig per mount namespaces

There are two namespaces from init - bootstrap and default - and those
will have different set of APEX modules. To support difference between
two namespaces, linker config should be generated per namespace and each
namespace should use its own linker configuration. As a first step of
the work, this change will create different mount point for each
namespace, and re-generate linker config after APEX mount from each
namespaces.

Bug: 144664390
Test: m -j passed & tested from cuttlefish
Change-Id: Iac2e222376ec4b0ced6c29eed18b21d39ff0b1ba
diff --git a/rootdir/init.rc b/rootdir/init.rc
index b89c45e..26b6877 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -38,9 +38,18 @@
     # Allow up to 32K FDs per process
     setrlimit nofile 32768 32768
 
+    # Set up linker config subdirectories based on mount namespaces
+    mkdir /linkerconfig/bootstrap 0755
+    mkdir /linkerconfig/default 0755
+
     # Generate ld.config.txt for early executed processes
-    exec -- /system/bin/linkerconfig --target /linkerconfig/ld.config.txt
-    chmod 444 /linkerconfig/ld.config.txt
+    exec -- /system/bin/linkerconfig --target /linkerconfig/bootstrap/ld.config.txt
+    chmod 644 /linkerconfig/bootstrap/ld.config.txt
+    copy /linkerconfig/bootstrap/ld.config.txt /linkerconfig/default/ld.config.txt
+    chmod 644 /linkerconfig/default/ld.config.txt
+
+    # Mount bootstrap linker configuration as current
+    mount none /linkerconfig/bootstrap /linkerconfig bind rec
 
     start ueventd
 
@@ -49,6 +58,9 @@
     # the libraries are available to the processes started after this statement.
     exec_start apexd-bootstrap
 
+    # Generate linker config based on apex mounted in bootstrap namespace
+    update_linker_config
+
     # These must already exist by the time boringssl_self_test32 / boringssl_self_test64 run.
     mkdir /dev/boringssl 0755 root root
     mkdir /dev/boringssl/selftest 0755 root root