kernel_headers: kernel headers library package

This change is foundational for converting many modules that
depend on kernel headers built via the platform build system.

Bug: 143567008
Change-Id: I5808a8464ed30287b75baac9a74285bff5825fe2
[rishabhb@codeaurora.org: add logic to iterate over mandatory headers
 and only generate these headers if not already present in
 usr/include/asm.]
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
[bharad@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Naitik Bharadiya <bharad@codeaurora.org>
[schikk@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>

1 files changed, 936 insertions, 0 deletions

diff --git a/kernel_headers.py b/kernel_headers.py
new file mode 100644
index 000000000000..5dfaadc0c955
--- /dev/null
+++ b/kernel_headers.py
@@ -0,0 +1,936 @@
+# Copyright 2019 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Generates gen_headers_<arch>.bp or generates/checks kernel headers."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import argparse
+import filecmp
+import os
+import re
+import subprocess
+import sys
+
+
+def gen_version_h(verbose, gen_dir, version_makefile):
+  """Generate linux/version.h
+
+  Scan the version_makefile for the version info, and then generate
+  linux/version.h in the gen_dir as done in kernel Makefile function
+  filechk_version.h
+
+  Args:
+    verbose: Set True to print progress messages.
+    gen_dir: Where to place the generated files.
+    version_makefile: The makefile that contains version info.
+  Return:
+    If version info not found, False. Otherwise, True.
+  """
+
+  version_re = re.compile(r'VERSION\s*=\s*(\d+)')
+  patchlevel_re = re.compile(r'PATCHLEVEL\s*=\s*(\d+)')
+  sublevel_re = re.compile(r'SUBLEVEL\s*=\s*(\d+)')
+
+  version_str = None
+  patchlevel_str = None
+  sublevel_str = None
+
+  if verbose:
+    print('gen_version_h: processing [%s]' % version_makefile)
+
+  with open(version_makefile, 'r') as f:
+    while not version_str or not patchlevel_str or not sublevel_str:
+      line = f.readline()
+
+      if not line:
+        print(
+            'error: gen_version_h: failed to parse kernel version from %s' %
+            version_makefile)
+        return False
+
+      line = line.rstrip()
+
+      if verbose:
+        print('gen_version_h: line is %s' % line)
+
+      if not version_str:
+        match = version_re.match(line)
+        if match:
+          if verbose:
+            print('gen_version_h: matched version [%s]' % line)
+          version_str = match.group(1)
+          continue
+
+      if not patchlevel_str:
+        match = patchlevel_re.match(line)
+        if match:
+          if verbose:
+            print('gen_version_h: matched patchlevel [%s]' % line)
+          patchlevel_str = match.group(1)
+          continue
+
+      if not sublevel_str:
+        match = sublevel_re.match(line)
+        if match:
+          if verbose:
+            print('gen_version_h: matched sublevel [%s]' % line)
+          sublevel_str = match.group(1)
+          continue
+
+  version = int(version_str)
+  patchlevel = int(patchlevel_str)
+  sublevel = int(sublevel_str)
+
+  if verbose:
+    print(
+        'gen_version_h: found kernel version %d.%d.%d' %
+        (version, patchlevel, sublevel))
+
+  version_h = os.path.join(gen_dir, 'linux', 'version.h')
+
+  with open(version_h, 'w') as f:
+    # This code must match the code in Makefile in the make function
+    # filechk_version.h
+    version_code = (version << 16) + (patchlevel << 8) + sublevel
+    f.write('#define LINUX_VERSION_CODE %d\n' % version_code)
+    f.write(
+        '#define KERNEL_VERSION(a,b,c) ' +
+        '(((a) << 16) + ((b) << 8) + (c))\n')
+
+  return True
+
+
+def scan_arch_kbuild(verbose, arch_asm_kbuild, asm_generic_kbuild, arch_include_uapi):
+  """Scan arch_asm_kbuild for generated headers.
+
+  This function processes the Kbuild file to scan for three types of files that
+  need to be generated. The first type are syscall generated headers, which are
+  identified by adding to the generated-y make variable. The second type are
+  generic headers, which are arch-specific headers that simply wrap the
+  asm-generic counterpart, and are identified by adding to the generic-y make
+  variable. The third type are mandatory headers that should be present in the
+  /usr/include/asm folder.
+
+  Args:
+    verbose: Set True to print progress messages.
+    arch_asm_kbuild: The Kbuild file containing lists of headers to generate.
+    asm_generic_kbuild: The Kbuild file containing lists of mandatory headers.
+    arch_include_uapi: Headers in /arch/<arch>/include/uapi directory
+  Return:
+    Two lists of discovered headers, one for generated and one for generic.
+  """
+
+  generated_y_re = re.compile(r'generated-y\s*\+=\s*(\S+)')
+  generic_y_re = re.compile(r'generic-y\s*\+=\s*(\S+)')
+  mandatory_y_re = re.compile(r'mandatory-y\s*\+=\s*(\S+)')
+
+  # This loop parses arch_asm_kbuild for various kinds of headers to generate.
+
+  if verbose:
+    print('scan_arch_kbuild: processing [%s]' % arch_asm_kbuild)
+
+  generated_list = []
+  generic_list = []
+  arch_include_uapi_list = [os.path.basename(x) for x in arch_include_uapi]
+  mandatory_pre_list = []
+  mandatory_list = []
+
+
+  with open(arch_asm_kbuild, 'r') as f:
+    while True:
+      line = f.readline()
+
+      if not line:
+        break
+
+      line = line.rstrip()
+
+      if verbose:
+        print('scan_arch_kbuild: line is %s' % line)
+
+      match = generated_y_re.match(line)
+
+      if match:
+        if verbose:
+          print('scan_arch_kbuild: matched [%s]' % line)
+        generated_list.append(match.group(1))
+        continue
+
+      match = generic_y_re.match(line)
+
+      if match:
+        if verbose:
+          print('scan_arch_kbuild: matched [%s]' % line)
+        generic_list.append(match.group(1))
+        continue
+
+  # This loop parses asm_generic_kbuild for various kinds of headers to generate.
+
+  if verbose:
+    print('scan_arch_kbuild: processing [%s]' % asm_generic_kbuild)
+
+  with open(asm_generic_kbuild, 'r') as f:
+    while True:
+      line = f.readline()
+
+      if not line:
+        break
+
+      line = line.rstrip()
+
+      if verbose:
+        print('scan_arch_kbuild: line is %s' % line)
+
+      match = mandatory_y_re.match(line)
+
+      if match:
+        if verbose:
+          print('scan_arch_kbuild: matched [%s]' % line)
+        mandatory_pre_list.append(match.group(1))
+        continue
+
+  # Mandatory headers need to be generated if they are not already generated.
+  comb_list = generic_list + generated_list + arch_include_uapi_list
+  mandatory_list = [x for x in mandatory_pre_list if x not in comb_list]
+  if verbose:
+    print("generic")
+    for x in generic_list:
+      print(x)
+    print("generated")
+    for x in generated_list:
+      print(x)
+    print("mandatory")
+    for x in mandatory_list:
+      print(x)
+    print("arch_include_uapi_list")
+    for x in arch_include_uapi_list:
+      print(x)
+
+  return (generated_list, generic_list, mandatory_list)
+
+
+def gen_arch_headers(
+    verbose, gen_dir, arch_asm_kbuild, asm_generic_kbuild, arch_syscall_tool, arch_syscall_tbl, arch_include_uapi):
+  """Process arch-specific and asm-generic uapi/asm/Kbuild to generate headers.
+
+  The function consists of a call to scan_arch_kbuild followed by three loops.
+  The first loop generates headers found and placed in the generated_list by
+  scan_arch_kbuild. The second loop generates headers found and placed in the
+  generic_list by the scan_arch_kbuild. The third loop generates headers found
+  in mandatory_list by scan_arch_kbuild.
+
+  The function does some parsing of file names and tool invocations. If that
+  parsing fails for some reason (e.g., we don't know how to generate the
+  header) or a tool invocation fails, then this function will count that as
+  an error but keep processing. In the end, the function returns the number of
+  errors encountered.
+
+  Args:
+    verbose: Set True to print progress messages.
+    gen_dir: Where to place the generated files.
+    arch_asm_kbuild: The Kbuild file containing lists of headers to generate.
+    asm_generic_kbuild: The Kbuild file containing lists of mandatory headers.
+    arch_syscall_tool: The arch script that generates syscall headers, or None.
+    arch_syscall_tbl: The arch script that defines syscall vectors, or None.
+    arch_include_uapi: Headers in arch/<arch>/include/uapi directory.
+  Return:
+    The number of parsing errors encountered.
+  """
+
+  error_count = 0
+
+  # First generate the lists
+
+  (generated_list, generic_list, mandatory_list) = scan_arch_kbuild(verbose, arch_asm_kbuild, asm_generic_kbuild ,arch_include_uapi)
+
+  # Now we're at the first loop, which is able to generate syscall headers
+  # found in the first loop, and placed in generated_list. It's okay for this
+  # list to be empty. In that case, of course, the loop does nothing.
+
+  abi_re = re.compile(r'unistd-(\S+)\.h')
+
+  for generated in generated_list:
+    gen_h = os.path.join(gen_dir, 'asm', generated)
+    match = abi_re.match(generated)
+
+    if match:
+      abi = match.group(1)
+
+      cmd = [
+          '/bin/bash',
+          arch_syscall_tool,
+          arch_syscall_tbl,
+          gen_h,
+          abi,
+          '',
+          '__NR_SYSCALL_BASE',
+      ]
+
+      if verbose:
+        print('gen_arch_headers: cmd is %s' % cmd)
+
+      result = subprocess.call(cmd)
+
+      if result != 0:
+        print('error: gen_arch_headers: cmd %s failed %d' % (cmd, result))
+        error_count += 1
+    else:
+      print('error: gen_arch_headers: syscall header has bad filename: %s' % generated)
+      error_count += 1
+
+  # Now we're at the second loop, which generates wrappers from arch-specific
+  # headers listed in generic_list to the corresponding asm-generic header.
+
+  for generic in generic_list:
+    wrap_h = os.path.join(gen_dir, 'asm', generic)
+    with open(wrap_h, 'w') as f:
+      f.write('#include <asm-generic/%s>\n' % generic)
+
+  # Now we're at the third loop, which generates wrappers from asm
+  # headers listed in mandatory_list to the corresponding asm-generic header.
+
+  for mandatory in mandatory_list:
+    wrap_h = os.path.join(gen_dir, 'asm', mandatory)
+    with open(wrap_h, 'w') as f:
+      f.write('#include <asm-generic/%s>\n' % mandatory)
+  return error_count
+
+
+def run_headers_install(verbose, gen_dir, headers_install, prefix, h):
+  """Process a header through the headers_install script.
+
+  The headers_install script does some processing of a header so that it is
+  appropriate for inclusion in a userland program. This function invokes that
+  script for one header file.
+
+  The input file is a header file found in the directory named by prefix. This
+  function stips the prefix from the header to generate the name of the
+  processed header.
+
+  Args:
+    verbose: Set True to print progress messages.
+    gen_dir: Where to place the generated files.
+    headers_install: The script that munges the header.
+    prefix: The prefix to strip from h to generate the output filename.
+    h: The input header to process.
+  Return:
+    If parsing or the tool fails, False. Otherwise, True
+  """
+
+  if not h.startswith(prefix):
+    print('error: expected prefix [%s] on header [%s]' % (prefix, h))
+    return False
+
+  out_h = os.path.join(gen_dir, h[len(prefix):])
+  (out_h_dirname, out_h_basename) = os.path.split(out_h)
+  h_dirname = os.path.dirname(h)
+
+  cmd = [headers_install, out_h_dirname, h_dirname, out_h_basename]
+
+  if verbose:
+    print('run_headers_install: cmd is %s' % cmd)
+
+  result = subprocess.call(cmd)
+
+  if result != 0:
+    print('error: run_headers_install: cmd %s failed %d' % (cmd, result))
+    return False
+
+  return True
+
+
+def glob_headers(prefix, rel_glob, excludes):
+  """Recursively scan the a directory for headers.
+
+  This function recursively scans the directory identified by prefix for
+  headers. We don't yet have a new enough version of python3 to use the
+  better glob function, so right now we assume the glob is '**/*.h'.
+
+  The function filters out any files that match the items in excludes.
+
+  Args:
+    prefix: The directory to recursively scan for headers.
+    rel_glob: The shell-style glob that identifies the header pattern.
+    excludes: A list of headers to exclude from the glob.
+  Return:
+    A list of headers discovered with excludes excluded.
+  """
+
+  # If we had python 3.5+, we could use the fancy new glob.glob.
+  # full_glob = os.path.join(prefix, rel_glob)
+  # full_srcs = glob.glob(full_glob, recursive=True)
+
+  full_dirs = [prefix]
+  full_srcs = []
+
+  while full_dirs:
+    full_dir = full_dirs.pop(0)
+    items = sorted(os.listdir(full_dir))
+
+    for item in items:
+      full_item = os.path.join(full_dir, item)
+
+      if os.path.isdir(full_item):
+        full_dirs.append(full_item)
+        continue
+
+      if full_item in excludes:
+        continue
+
+      if full_item.endswith('.h'):
+        full_srcs.append(full_item)
+
+  return full_srcs
+
+
+def find_out(verbose, module_dir, prefix, rel_glob, excludes, outs):
+  """Build a list of outputs for the genrule that creates kernel headers.
+
+  This function scans for headers in the source tree and produces a list of
+  output (generated) headers.
+
+  Args:
+    verbose: Set True to print progress messages.
+    module_dir: The root directory of the kernel source.
+    prefix: The prefix with in the kernel source tree to search for headers.
+    rel_glob: The pattern to use when matching headers under prefix.
+    excludes: A list of files to exclude from the glob.
+    outs: The list to populdate with the headers that will be generated.
+  Return:
+    The number of errors encountered.
+  """
+
+  # Turn prefix, which is relative to the soong module, to a full prefix that
+  # is relative to the Android source tree.
+
+  full_prefix = os.path.join(module_dir, prefix)
+
+  # Convert the list of excludes, which are relative to the soong module, to a
+  # set of excludes (for easy hashing), relative to the Android source tree.
+
+  full_excludes = set()
+
+  if excludes:
+    for exclude in excludes:
+      full_exclude = os.path.join(full_prefix, exclude)
+      full_excludes.add(full_exclude)
+
+  # Glob those headers.
+
+  full_srcs = glob_headers(full_prefix, rel_glob, full_excludes)
+
+  # Now convert the file names, which are relative to the Android source tree,
+  # to be relative to the gen dir. This means stripping off the module prefix
+  # and the directory within this module.
+
+  module_dir_sep = module_dir + os.sep
+  prefix_sep = prefix + os.sep
+
+  if verbose:
+    print('find_out: module_dir_sep [%s]' % module_dir_sep)
+    print('find_out: prefix_sep [%s]' % prefix_sep)
+
+  error_count = 0
+
+  for full_src in full_srcs:
+    if verbose:
+      print('find_out: full_src [%s]' % full_src)
+
+    if not full_src.startswith(module_dir_sep):
+      print('error: expected %s to start with %s' % (full_src, module_dir_sep))
+      error_count += 1
+      continue
+
+    local_src = full_src[len(module_dir_sep):]
+
+    if verbose:
+      print('find_out: local_src [%s]' % local_src)
+
+    if not local_src.startswith(prefix_sep):
+      print('error: expected %s to start with %s' % (local_src, prefix_sep))
+      error_count += 1
+      continue
+
+    # After stripping the module directory and the prefix, we're left with the
+    # name of a header that we'll generate, relative to the base of of a the
+    # the include path.
+
+    local_out = local_src[len(prefix_sep):]
+
+    if verbose:
+      print('find_out: local_out [%s]' % local_out)
+
+    outs.append(local_out)
+
+  return error_count
+
+
+def gen_blueprints(
+    verbose, header_arch, gen_dir, arch_asm_kbuild, asm_generic_kbuild, module_dir,
+    rel_arch_asm_kbuild, rel_asm_generic_kbuild, arch_include_uapi, techpack_include_uapi):
+  """Generate a blueprints file containing modules that invoke this script.
+
+  This function generates a blueprints file that contains modules that
+  invoke this script to generate kernel headers. We generate the blueprints
+  file as needed, but we don't actually use the generated file. The blueprints
+  file that we generate ends up in the out directory, and we can use it to
+  detect if the checked-in version of the file (in the source directory) is out
+  of date. This pattern occurs in the Android source tree in several places.
+
+  Args:
+    verbose: Set True to print progress messages.
+    header_arch: The arch for which to generate headers.
+    gen_dir: Where to place the generated files.
+    arch_asm_kbuild: The Kbuild file containing lists of headers to generate.
+    asm_generic_kbuild: The Kbuild file containing lists of mandatory headers.
+    module_dir: The root directory of the kernel source.
+    rel_arch_asm_kbuild: arch_asm_kbuild relative to module_dir.
+  Return:
+    The number of errors encountered.
+  """
+  error_count = 0
+
+  # The old and new blueprints files. We generate the new one, but we need to
+  # refer to the old one in the modules that we generate.
+  old_gen_headers_bp = 'gen_headers_%s.bp' % header_arch
+  new_gen_headers_bp = os.path.join(gen_dir, old_gen_headers_bp)
+
+  # Tools and tool files.
+  headers_install_sh = 'headers_install.sh'
+  kernel_headers_py = 'kernel_headers.py'
+  arm_syscall_tool = 'arch/arm/tools/syscallhdr.sh'
+
+  # Sources
+  makefile = 'Makefile'
+  arm_syscall_tbl = 'arch/arm/tools/syscall.tbl'
+  rel_glob = '**/*.h'
+  generic_prefix = 'include/uapi'
+  arch_prefix = os.path.join('arch', header_arch, generic_prefix)
+  generic_src = os.path.join(generic_prefix, rel_glob)
+  arch_src = os.path.join(arch_prefix, rel_glob)
+  techpack_src = 'techpack/*'
+
+  # Excluded sources, architecture specific.
+  exclude_srcs = []
+
+  if header_arch == "arm":
+    exclude_srcs = ['linux/a.out.h']
+
+  if header_arch == "arm64":
+    exclude_srcs = ['linux/a.out.h', 'linux/kvm_para.h']
+
+  # Scan the arch_asm_kbuild file for files that need to be generated and those
+  # that are generic (i.e., need to be wrapped).
+
+  (generated_list, generic_list, mandatory_list) = scan_arch_kbuild(verbose,
+					arch_asm_kbuild, asm_generic_kbuild, arch_include_uapi)
+
+  generic_out = []
+  error_count += find_out(
+      verbose, module_dir, generic_prefix, rel_glob, exclude_srcs, generic_out)
+
+  arch_out = []
+  error_count += find_out(
+      verbose, module_dir, arch_prefix, rel_glob, None, arch_out)
+
+  techpack_out = [x.split('include/uapi/')[1] for x in techpack_include_uapi]
+
+  if error_count != 0:
+    return error_count
+
+  # Generate the blueprints file.
+
+  if verbose:
+    print('gen_blueprints: generating %s' % new_gen_headers_bp)
+
+  with open(new_gen_headers_bp, 'w') as f:
+    f.write('// ***** DO NOT EDIT *****\n')
+    f.write('// This file is generated by %s\n' % kernel_headers_py)
+    f.write('\n')
+    f.write('gen_headers_%s = [\n' % header_arch)
+
+    if generated_list:
+      f.write('\n')
+      f.write('    // Matching generated-y:\n')
+      f.write('\n')
+      for h in generated_list:
+        f.write('    "asm/%s",\n' % h)
+
+    if generic_list:
+      f.write('\n')
+      f.write('    // Matching generic-y:\n')
+      f.write('\n')
+      for h in generic_list:
+        f.write('    "asm/%s",\n' % h)
+
+    if mandatory_list:
+      f.write('\n')
+      f.write('    // Matching mandatory-y:\n')
+      f.write('\n')
+      for h in mandatory_list:
+        f.write('    "asm/%s",\n' % h)
+
+    if generic_out:
+      f.write('\n')
+      f.write('    // From %s\n' % generic_src)
+      f.write('\n')
+      for h in generic_out:
+        f.write('    "%s",\n' % h)
+
+    if arch_out:
+      f.write('\n')
+      f.write('    // From %s\n' % arch_src)
+      f.write('\n')
+      for h in arch_out:
+        f.write('    "%s",\n' % h)
+
+    if techpack_out:
+      f.write('\n')
+      f.write('    // From %s\n' % techpack_src)
+      f.write('\n')
+      for h in techpack_out:
+        f.write('    "%s",\n' % h)
+
+    f.write(']\n')
+    f.write('\n')
+
+    gen_blueprints_module_name = 'qti_generate_gen_headers_%s' % header_arch
+
+    f.write('genrule {\n')
+    f.write('    // This module generates the gen_headers_<arch>.bp file\n')
+    f.write('    // (i.e., a new version of this file) so that it can be\n')
+    f.write('    // checked later to ensure that it matches the checked-\n')
+    f.write('    // in version (this file).\n')
+    f.write('    name: "%s",\n' % gen_blueprints_module_name)
+    f.write('    srcs: ["%s", "%s", "%s"],\n' % (rel_arch_asm_kbuild, rel_asm_generic_kbuild, arch_src))
+    f.write('    tool_files: ["kernel_headers.py"],\n')
+    f.write('    cmd: "python3 $(location kernel_headers.py) " +\n')
+    f.write('        kernel_headers_verbose +\n')
+    f.write('        "--header_arch %s " +\n' % header_arch)
+    f.write('        "--gen_dir $(genDir) " +\n')
+    f.write('        "--arch_asm_kbuild $(location %s) " +\n' % rel_arch_asm_kbuild)
+    f.write('        "--arch_include_uapi $(locations %s) " +\n' % arch_src)
+    f.write('        "--asm_generic_kbuild $(location %s) " +\n' % rel_asm_generic_kbuild)
+    f.write('        "blueprints",\n')
+    f.write('    out: ["gen_headers_%s.bp"],\n' % header_arch)
+    f.write('}\n')
+    f.write('\n')
+
+    f.write('genrule {\n')
+    f.write('    name: "qti_generate_kernel_headers_%s",\n' % header_arch)
+    f.write('    tools: ["%s"],\n' % headers_install_sh)
+    f.write('    tool_files: [\n')
+    f.write('        "%s",\n' % kernel_headers_py)
+
+    if header_arch == "arm":
+      f.write('        "%s",\n' % arm_syscall_tool)
+
+    f.write('    ],\n')
+    f.write('    srcs: [\n')
+    f.write('        "%s",\n' % rel_arch_asm_kbuild)
+    f.write('        "%s",\n' % rel_asm_generic_kbuild)
+    f.write('        "%s",\n' % old_gen_headers_bp)
+    f.write('        ":%s",\n' % gen_blueprints_module_name)
+    f.write('        "%s",\n' % makefile)
+
+    if header_arch == "arm":
+      f.write('        "%s",\n' % arm_syscall_tbl)
+
+    f.write('        "%s",\n' % generic_src)
+    f.write('        "%s",\n' % arch_src)
+    f.write('    ],\n')
+
+    if exclude_srcs:
+      f.write('    exclude_srcs: [\n')
+      for h in exclude_srcs:
+        f.write('        "%s",\n' % os.path.join(generic_prefix, h))
+      f.write('    ],\n')
+
+    f.write('    cmd: "python3 $(location %s) " +\n' % kernel_headers_py)
+    f.write('        kernel_headers_verbose +\n')
+    f.write('        "--header_arch %s " +\n' % header_arch)
+    f.write('        "--gen_dir $(genDir) " +\n')
+    f.write('        "--arch_asm_kbuild $(location %s) " +\n' % rel_arch_asm_kbuild)
+    f.write('        "--arch_include_uapi $(locations %s) " +\n' % arch_src)
+    f.write('        "--asm_generic_kbuild $(location %s) " +\n' % rel_asm_generic_kbuild)
+    f.write('        "headers " +\n')
+    f.write('        "--old_gen_headers_bp $(location %s) " +\n' % old_gen_headers_bp)
+    f.write('        "--new_gen_headers_bp $(location :%s) " +\n' % gen_blueprints_module_name)
+    f.write('        "--version_makefile $(location %s) " +\n' % makefile)
+
+    if header_arch == "arm":
+      f.write('        "--arch_syscall_tool $(location %s) " +\n' % arm_syscall_tool)
+      f.write('        "--arch_syscall_tbl $(location %s) " +\n' % arm_syscall_tbl)
+
+    f.write('        "--headers_install $(location %s) " +\n' % headers_install_sh)
+    f.write('        "--include_uapi $(locations %s)",\n' % generic_src)
+    f.write('    out: ["linux/version.h"] + gen_headers_%s,\n' % header_arch)
+    f.write('}\n')
+
+    return 0
+
+
+def gen_headers(
+    verbose, header_arch, gen_dir, arch_asm_kbuild, asm_generic_kbuild, module_dir,
+    old_gen_headers_bp, new_gen_headers_bp, version_makefile,
+    arch_syscall_tool, arch_syscall_tbl, headers_install, include_uapi,
+    arch_include_uapi, techpack_include_uapi):
+  """Generate the kernel headers.
+
+  This script generates the version.h file, the arch-specific headers including
+  syscall-related generated files and wrappers around generic files, and uses
+  the headers_install tool to process other generic uapi and arch-specific uapi
+  files.
+
+  Args:
+    verbose: Set True to print progress messages.
+    header_arch: The arch for which to generate headers.
+    gen_dir: Where to place the generated files.
+    arch_asm_kbuild: The Kbuild file containing lists of headers to generate.
+    asm_generic_kbuild: The Kbuild file containing mandatory headers.
+    module_dir: The root directory of the kernel source.
+    old_gen_headers_bp: The old gen_headers_<arch>.bp file to check.
+    new_gen_headers_bp: The new gen_headers_<arch>.bp file to check.
+    version_makefile: The kernel Makefile that contains version info.
+    arch_syscall_tool: The arch script that generates syscall headers.
+    arch_syscall_tbl: The arch script that defines syscall vectors.
+    headers_install: The headers_install tool to process input headers.
+    include_uapi: The list of include/uapi header files.
+    arch_include_uapi: The list of arch/<arch>/include/uapi header files.
+  Return:
+    The number of errors encountered.
+  """
+
+  if not filecmp.cmp(old_gen_headers_bp, new_gen_headers_bp):
+    print('error: gen_headers blueprints file is out of date, suggested fix:')
+    print('cp %s %s' % (new_gen_headers_bp, old_gen_headers_bp))
+    print('then re-run the build')
+    return 1
+
+  error_count = 0
+
+  if not gen_version_h(verbose, gen_dir, version_makefile):
+    error_count += 1
+
+  error_count += gen_arch_headers(
+      verbose, gen_dir, arch_asm_kbuild, asm_generic_kbuild, arch_syscall_tool, arch_syscall_tbl ,arch_include_uapi)
+
+  uapi_include_prefix = os.path.join(module_dir, 'include', 'uapi') + os.sep
+
+  arch_uapi_include_prefix = os.path.join(
+      module_dir, 'arch', header_arch, 'include', 'uapi') + os.sep
+
+  for h in include_uapi:
+    if not run_headers_install(
+        verbose, gen_dir, headers_install,
+        uapi_include_prefix, h):
+      error_count += 1
+
+  for h in arch_include_uapi:
+    if not run_headers_install(
+        verbose, gen_dir, headers_install,
+        arch_uapi_include_prefix, h):
+      error_count += 1
+
+  for h in techpack_include_uapi:
+    techpack_uapi_include_prefix = os.path.join(h.split('/include/uapi')[0], 'include', 'uapi') + os.sep
+    if not run_headers_install(
+        verbose, gen_dir, headers_install,
+        techpack_uapi_include_prefix, h):
+      error_count += 1
+
+  return error_count
+
+def extract_techpack_uapi_headers(verbose, module_dir):
+
+  """EXtract list of uapi headers from techpack/* directories. We need to export
+     these headers to userspace.
+
+  Args:
+      verbose: Verbose option is provided to script
+      module_dir: Base directory
+  Returs:
+      List of uapi headers
+  """
+
+  techpack_subdir = []
+  techpack_dir = os.path.join(module_dir,'techpack')
+  techpack_uapi = []
+  techpack_uapi_sub = []
+
+  #get list of techpack directories under techpack/
+  if os.path.isdir(techpack_dir):
+    items = sorted(os.listdir(techpack_dir))
+    for x in items:
+      p = os.path.join(techpack_dir, x)
+      if os.path.isdir(p):
+        techpack_subdir.append(p)
+
+  #Print list of subdirs obtained
+  if (verbose):
+    for x in techpack_subdir:
+      print(x)
+
+  #For every subdirectory get list of .h files under include/uapi and append to techpack_uapi list
+  for x in techpack_subdir:
+    techpack_uapi_path = os.path.join(x, 'include/uapi')
+    if (os.path.isdir(techpack_uapi_path)):
+      techpack_uapi_sub = []
+      find_out(verbose, x, 'include/uapi', '**/*.h', None, techpack_uapi_sub)
+      tmp = [os.path.join(techpack_uapi_path, y) for y in techpack_uapi_sub]
+      techpack_uapi = techpack_uapi + tmp
+
+  if (verbose):
+    for x in techpack_uapi:
+      print(x)
+
+  return techpack_uapi
+
+def main():
+  """Parse command line arguments and perform top level control."""
+
+  parser = argparse.ArgumentParser(
+      description=__doc__,
+      formatter_class=argparse.RawDescriptionHelpFormatter)
+
+  # Arguments that apply to every invocation of this script.
+
+  parser.add_argument(
+      '--verbose',
+      action='store_true',
+      help='Print output that describes the workings of this script.')
+  parser.add_argument(
+      '--header_arch',
+      required=True,
+      help='The arch for which to generate headers.')
+  parser.add_argument(
+      '--gen_dir',
+      required=True,
+      help='Where to place the generated files.')
+  parser.add_argument(
+      '--arch_asm_kbuild',
+      required=True,
+      help='The Kbuild file containing lists of headers to generate.')
+  parser.add_argument(
+      '--asm_generic_kbuild',
+      required=True,
+      help='The Kbuild file containing lists of mandatory headers.')
+  parser.add_argument(
+      '--arch_include_uapi',
+      required=True,
+      nargs='*',
+      help='The list of arch/<arch>/include/uapi header files.')
+
+  # The modes.
+
+  subparsers = parser.add_subparsers(
+      dest='mode',
+      help='Select mode')
+  parser_blueprints = subparsers.add_parser(
+      'blueprints',
+      help='Generate the gen_headers_<arch>.bp file.')
+  parser_headers = subparsers.add_parser(
+      'headers',
+      help='Check blueprints, then generate kernel headers.')
+
+  # Arguments that apply to headers mode.
+
+  parser_headers.add_argument(
+      '--old_gen_headers_bp',
+      required=True,
+      help='The old gen_headers_<arch>.bp file to check.')
+  parser_headers.add_argument(
+      '--new_gen_headers_bp',
+      required=True,
+      help='The new gen_headers_<arch>.bp file to check.')
+  parser_headers.add_argument(
+      '--version_makefile',
+      required=True,
+      help='The kernel Makefile that contains version info.')
+  parser_headers.add_argument(
+      '--arch_syscall_tool',
+      help='The arch script that generates syscall headers, if applicable.')
+  parser_headers.add_argument(
+      '--arch_syscall_tbl',
+      help='The arch script that defines syscall vectors, if applicable.')
+  parser_headers.add_argument(
+      '--headers_install',
+      required=True,
+      help='The headers_install tool to process input headers.')
+  parser_headers.add_argument(
+      '--include_uapi',
+      required=True,
+      nargs='*',
+      help='The list of include/uapi header files.')
+
+  args = parser.parse_args()
+
+  if args.verbose:
+    print('mode [%s]' % args.mode)
+    print('header_arch [%s]' % args.header_arch)
+    print('gen_dir [%s]' % args.gen_dir)
+    print('arch_asm_kbuild [%s]' % args.arch_asm_kbuild)
+    print('asm_generic_kbuild [%s]' % args.asm_generic_kbuild)
+
+  # Extract the module_dir from args.arch_asm_kbuild and rel_arch_asm_kbuild.
+
+  rel_arch_asm_kbuild = os.path.join(
+      'arch', args.header_arch, 'include/uapi/asm/Kbuild')
+
+  suffix = os.sep + rel_arch_asm_kbuild
+
+  if not args.arch_asm_kbuild.endswith(suffix):
+    print('error: expected %s to end with %s' % (args.arch_asm_kbuild, suffix))
+    return 1
+
+  module_dir = args.arch_asm_kbuild[:-len(suffix)]
+
+  rel_asm_generic_kbuild = os.path.join('include/uapi/asm-generic', os.path.basename(args.asm_generic_kbuild))
+
+
+  if args.verbose:
+    print('module_dir [%s]' % module_dir)
+
+  # Get list of techpack uapi headers to be exported from techpack/* directories.
+  techpack_uapi = extract_techpack_uapi_headers(args.verbose, module_dir)
+
+  if args.mode == 'blueprints':
+    return gen_blueprints(
+        args.verbose, args.header_arch, args.gen_dir, args.arch_asm_kbuild,
+        args.asm_generic_kbuild, module_dir, rel_arch_asm_kbuild, rel_asm_generic_kbuild, args.arch_include_uapi, techpack_uapi)
+
+  if args.mode == 'headers':
+    if args.verbose:
+      print('old_gen_headers_bp [%s]' % args.old_gen_headers_bp)
+      print('new_gen_headers_bp [%s]' % args.new_gen_headers_bp)
+      print('version_makefile [%s]' % args.version_makefile)
+      print('arch_syscall_tool [%s]' % args.arch_syscall_tool)
+      print('arch_syscall_tbl [%s]' % args.arch_syscall_tbl)
+      print('headers_install [%s]' % args.headers_install)
+
+    return gen_headers(
+        args.verbose, args.header_arch, args.gen_dir, args.arch_asm_kbuild,
+        args.asm_generic_kbuild, module_dir, args.old_gen_headers_bp, args.new_gen_headers_bp,
+        args.version_makefile, args.arch_syscall_tool, args.arch_syscall_tbl,
+        args.headers_install, args.include_uapi, args.arch_include_uapi, techpack_uapi)
+
+  print('error: unknown mode: %s' % args.mode)
+  return 1
+
+
+if __name__ == '__main__':
+  sys.exit(main())