scons: build arm sel_ldr and nacl_helper_bootstrap with 64K page size

Build arm sel_ldr and nacl_helper_bootstrap with 64K page size alignment.
Makes it compatible with 16k page size kernels.
SCons plumbing.

Author: illwieckz

SConstruct

@@ -2683,6 +2683,8 @@ def MakeGenericLinuxEnv(platform=None):
       LINK = '$CXX',
   )
 
+  linux_env.SetDefault(MAX_PAGE_SIZE='0x1000')
+
   # Prepend so we can disable warnings via Append
   linux_env.Prepend(
       CPPDEFINES = [['_POSIX_C_SOURCE', '199506'],
@@ -2705,6 +2707,7 @@ def MakeGenericLinuxEnv(platform=None):
         LINKFLAGS = ['-m64'] + sysroot_flags,
         )
   elif linux_env.Bit('build_arm'):
+    linux_env.Replace(MAX_PAGE_SIZE='0x10000')
     SetUpLinuxEnvArm(linux_env)
   elif linux_env.Bit('build_mips32'):
     SetUpLinuxEnvMips(linux_env)
@@ -2730,7 +2733,8 @@ def MakeGenericLinuxEnv(platform=None):
   linux_env.Prepend(SHLINKFLAGS=['$COMMON_LINKFLAGS'])
   linux_env.Prepend(COMMON_LINKFLAGS=['-Wl,-z,relro',
                                       '-Wl,-z,now',
-                                      '-Wl,-z,noexecstack'])
+                                      '-Wl,-z,noexecstack',
+                                      '-Wl,-z,max-page-size=${MAX_PAGE_SIZE}'])
   linux_env.Prepend(LINKFLAGS=['-pie'])
   # The ARM toolchain has a linker that doesn't handle the code its
   # compiler generates under -fPIE.

src/trusted/service_runtime/build.scons

@@ -427,7 +427,7 @@ if (env.Bit('linux') and not env.Bit('built_elsewhere')):
       'nacl_bootstrap_raw',
       [bootstrap_obj],
       ("env CXX='${CXX}' ${PYTHON} %s %s " +
-       '-m %s --build-id -static -z max-page-size=0x1000 ' +
+       '-m %s --build-id -static -z max-page-size=${MAX_PAGE_SIZE} ' +
        '--orphan-handling=discard ' +
        '--defsym RESERVE_TOP=%s --script %s -o ${TARGET} ${SOURCES}') %
       (bootstrap_env.File('linux/ld_bfd.py'), compiler_override, ld_emul,