Changes in kernel/meson.build [d231a54:c21d4d6] in mainline

File:

• kernel/meson.build (modified) (5 diffs)

kernel/meson.build

@@ -42 +42 @@
 subdir('test')
 
+## Cross-platform assembly to start a symtab.data section
+#
+symtab_section = '.section symtab.data, "a", ' + atsign + 'progbits;'
+
 kernel_include_dirs = include_directories(
         'generic/include',
@@ -48 +52 @@
         '..' / 'abi' / 'arch' / KARCH / 'include',
         '..' / 'abi' / 'include',
-        '..' / 'common' / 'include',
         'test',
 )
@@ -86 +89 @@
         '-T', meson.current_build_dir() / '_link.ld',
 ]
-# The kernel is built as ELF but then copied as a blob of bytes and
-# the permissions are not relevant anyway (needed for binutils 2.39+).
-kernel_link_args += ldflags_ignore_rwx_segments
 
 if CONFIG_LTO
@@ -94 +94 @@
 endif
 
+if CONFIG_STRIP_BINARIES
+        # TODO: do this after disassembling
+        kernel_link_args += [ '-s' ]
+endif
+
 kernel_c_args = arch_kernel_c_args + kernel_defs + [
         '-ffreestanding',
-        '-fdebug-prefix-map=../../kernel/=',
-        '-fdebug-prefix-map=../../../kernel/=',
-
-        cc.get_supported_arguments([
-                # TODO: remove this flag
-                '-Wno-cast-function-type',
-
-                # When accessing specific memory addresses that are below
-                # normal page size, the compiler may assume that we actually
-                # dereferenced NULL pointer and warns us about that.
-                # But in kernel we often need to access these addresses
-                # directly hence we need to ignore these warnings.
-                #
-                # TODO: might make more sense to disable this selectively
-                # in specific files (or better yet, for specific lines).
-                '--param=min-pagesize=0',
-        ]),
+        # TODO: remove this flag
+        cc.get_supported_arguments([ '-Wno-cast-function-type' ]),
 ]
-
-if not CONFIG_LINE_DEBUG
-        # Keep the debug info needed to get file names for kernel stack traces.
-        kernel_c_args += cc.get_supported_arguments([ '-gdwarf-5', '-g1', '-gno-statement-frontiers' ])
-endif
 
 if CONFIG_LTO
@@ -148 +133 @@
 all_kernel_objects = [ instrumentables, noninstrumentables ]
 
-kernel_name = 'kernel.elf'
-kernel_map_name = kernel_name + '.map'
-kernel_map_path = meson.current_build_dir() / kernel_map_name
-
-kernel_elf = executable(kernel_name,
-        include_directories: kernel_include_dirs,
-        implicit_include_directories: false,
-        c_args: kernel_c_args,
-        link_args: kernel_c_args + kernel_link_args + [
-                '-Wl,-Map,' + kernel_map_path,
-        ],
-        link_depends: kernel_ldscript,
-        link_whole: all_kernel_objects,
-        pie: false,
-)
-
-kernel_dbg = custom_target('kernel.dbg',
-        output: 'kernel.dbg',
-        input: kernel_elf,
-        command: [
-                objcopy,
-                '--only-keep-debug',
-                '@INPUT@',
-                '@OUTPUT@',
-        ],
-)
-
-kernel_elf_stripped = custom_target(kernel_name + '.stripped',
-        output: kernel_name + '.stripped',
-        input: kernel_elf,
-        command: [
-                objcopy,
-                '--strip-unneeded',
-                '@INPUT@',
-                '@OUTPUT@',
-        ],
-)
-
-rd_init_binaries += [[ kernel_elf_stripped, 'boot/kernel.elf' ]]
-install_files += [[ 'boot', kernel_elf_stripped.full_path(), 'kernel.elf' ]]
-install_deps += [ kernel_elf_stripped ]
+# We iterate the build several times to get symbol table right.
+# Three times is sufficient to get correct even symbols after symtab.
 
 if CONFIG_SYMTAB
-        rd_init_binaries += [[ kernel_dbg, 'kernel.dbg' ]]
-        install_files += [[ 'boot', kernel_dbg.full_path(), 'kernel.dbg' ]]
-        install_deps += [ kernel_dbg ]
-endif
+        # Iterate build three times.
+        iterations = [ 1, 2, 3 ]
+
+        # Generates symbol table information as an object file.
+        genmap = find_program('tools/genmap.py')
+
+        # Symbol table dump needed for genmap.
+        kernel_syms = custom_target('kernel_syms.txt',
+                input: all_kernel_objects,
+                output: 'kernel_syms.txt',
+                command: [ objdump, '-t', '@INPUT@' ],
+                capture: true,
+        )
+else
+        # Build just once.
+        iterations = [ 1 ]
+endif
+
+# Empty symbol map for first iteration.
+kernel_map_S = custom_target('empty_map.S',
+        output: 'empty_map.S',
+        capture: true,
+        command: [ 'echo', kernel_as_prolog + symtab_section ],
+)
+
+foreach iter : iterations
+        is_last = (iter == iterations.length())
+        kernel_name = 'kernel.@0@.elf'.format(iter)
+        kernel_map_name = kernel_name + '.map'
+        kernel_map_path = meson.current_build_dir() / kernel_map_name
+
+        kernel_elf = executable(kernel_name, kernel_map_S,
+                include_directories: kernel_include_dirs,
+                implicit_include_directories: false,
+                c_args: kernel_c_args,
+                link_args: kernel_c_args + kernel_link_args + [
+                        '-Wl,-Map,' + kernel_map_path,
+                ],
+                link_depends: kernel_ldscript,
+                link_whole: all_kernel_objects,
+                pie: false,
+        )
+
+        # Generate symbol table if this is not the final iteration.
+        if not is_last
+
+                # TODO: Teach kernel to read its own ELF symbol table and get rid of this nonsense.
+                # Need to first make sure all architectures (even future ones with dumb bootloaders) can use ELF formatted kernel.
+
+                kernel_map_bin = custom_target(kernel_map_name + '.bin',
+                        output: kernel_map_name + '.bin',
+                        input: [ kernel_elf, kernel_syms ],
+                        command: [ genmap, kernel_map_path, '@INPUT1@', '@OUTPUT@' ],
+                )
+
+                kernel_map_S_name = kernel_name + '.map.S'
+
+                kernel_map_S = custom_target(kernel_map_S_name,
+                        input: kernel_map_bin,
+                        output: kernel_map_S_name,
+                        capture: true,
+                        command: [ 'echo', kernel_as_prolog + symtab_section + ' .incbin "@INPUT@"' ],
+                )
+        endif
+endforeach
+
+rd_init_binaries += [[ kernel_elf, 'boot/kernel.elf' ]]
+
+install_files += [[ 'boot', kernel_elf.full_path(), 'kernel.elf' ]]
+install_deps += [ kernel_elf ]
 
 kernel_disasm = custom_target('kernel.elf.disasm',