llext: add support for signing additional binaries

This allows the use of "west sign" command for signing of additional
binaries with rimage, specifically this is used to sign llext
extensions for SOF.
Example:

west sign -d build-mtl -t rimage -p build-rimage/rimage -- \
-k key.pem -c modules/audio/sof/src/samples/audio/smart_amp_test.toml \
-r build-mtl/zephyr/smart_amp_llext/libsmart_amp_test_out.so

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

scripts/west_commands/sign.py

@@ -440,6 +440,7 @@ def preprocess_toml(self, config_dir, toml_basename, subdir):
         compiler_path = self.cmake_cache.get("CMAKE_C_COMPILER")
         preproc_cmd = [compiler_path, '-P', '-E', str(config_dir / (toml_basename + '.h'))]
         preproc_cmd += ['-I', str(self.sof_src_dir / 'src')]
+        preproc_cmd += ['-I', str(self.sof_src_dir)]
         preproc_cmd += ['-imacros',
                         str(pathlib.Path('zephyr') / 'include' / 'generated' / 'autoconf.h')]
         preproc_cmd += ['-o', str(subdir / toml_basename)]
@@ -467,7 +468,14 @@ def sign(self, command, build_dir, build_conf, formats):
             else:
                 log.die(msg)
 
-        kernel_name = build_conf.get('CONFIG_KERNEL_BIN_NAME', 'zephyr')
+        sign_config_extra_args = config_get_words(command.config, 'rimage.extra-args', [])
+
+        is_llext = '-r' in sign_config_extra_args + args.tool_args
+
+        if is_llext:
+            kernel_name = 'llext'
+        else:
+            kernel_name = build_conf.get('CONFIG_KERNEL_BIN_NAME', 'zephyr')
 
         # TODO: make this a new sign.py --bootloader option.
         if target in ('imx8', 'imx8m', 'imx8ulp'):
@@ -552,10 +560,11 @@ def sign(self, command, build_dir, build_conf, formats):
         if not args.quiet and args.verbose:
             sign_base += ['-v'] * args.verbose
 
-        components = [ ] if bootloader is None else [ bootloader ]
-        components += [ kernel ]
-
-        sign_config_extra_args = config_get_words(command.config, 'rimage.extra-args', [])
+        components = [ ]
+        if not is_llext:
+            if bootloader is not None:
+                components += [ bootloader ]
+            components += [ kernel ]
 
         if '-k' not in sign_config_extra_args + args.tool_args:
             # rimage requires a key argument even when it does not sign
@@ -567,7 +576,10 @@ def sign(self, command, build_dir, build_conf, formats):
 
         if '-c' not in sign_config_extra_args + args.tool_args:
             conf_dir = self.rimage_config_dir()
-            toml_basename = target + '.toml'
+            if is_llext:
+                toml_basename = 'llext.toml'
+            else:
+                toml_basename = target + '.toml'
             if ((conf_dir / toml_basename).exists() and
                (conf_dir / (toml_basename + '.h')).exists()):
                 command.die(f"Cannot have both {toml_basename + '.h'} and {toml_basename} in {conf_dir}")