From: Jan Janssen <medhefgo@web.de>
Date: Fri, 22 Sep 2023 12:41:47 +0000 (+0200)
Subject: boot: Lift linker requirements
X-Git-Tag: v255-rc1~379^2~2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0b042d3de8e88effcd48255e4f17fa72ac2816bd;p=thirdparty%2Fsystemd.git

boot: Lift linker requirements

The biggest reason for forcing bfd was the use of linker scrips. Since
we don't rely on those anymore we can lift the requirement.

The biggest issue is gold as it does not understand -static-pie. Given
that it's pretty much on life support it's safe to just declare it not
supported anymore.

Don't link addons with libefi as clang/lld is sometimes very eager to
include memset etc., causing needless binary bloat and link errors with
LTO.

Fixes: #29165
---

diff --git a/src/boot/efi/meson.build b/src/boot/efi/meson.build
index 1591ff7f096..dfb8700547d 100644
--- a/src/boot/efi/meson.build
+++ b/src/boot/efi/meson.build
@@ -147,10 +147,6 @@ if get_option('mode') == 'developer' and get_option('debug')
 endif
 
 efi_c_ld_args = [
-        # We only support bfd. gold is going away, lld has issues with LTO on x86
-        # and mold does not support linker scripts.
-        '-fuse-ld=bfd',
-
         '-lgcc',
         '-nostdlib',
         '-static-pie',
@@ -170,9 +166,10 @@ efi_c_ld_args = [
         '-z', 'separate-code',
 ]
 
-# On CentOS 8 the nopack-relative-relocs linker flag is not supported, and we get:
-#   /usr/bin/ld.bfd: warning: -z nopack-relative-relocs ignored
-efi_c_ld_args += cc.get_supported_link_arguments('-Wl,-z,nopack-relative-relocs')
+efi_c_ld_args += cc.get_supported_link_arguments(
+        # binutils >= 2.38
+        '-Wl,-z,nopack-relative-relocs',
+)
 
 # efi_c_args is explicitly passed to targets so that they can override distro-provided flags
 # that should not be used for EFI binaries.
@@ -213,11 +210,35 @@ efi_arch_c_args = {
 efi_arch_c_ld_args = {
         # libgcc is not compiled with -fshort-wchar, but it does not use it anyways,
         # so it's fine to link against it.
-        'arm'    : ['-Wl,--no-wchar-size-warning'],
+        'arm'    : cc.get_supported_link_arguments('-Wl,--no-wchar-size-warning'),
         'x86_64' : ['-m64'],
         'x86'    : ['-m32'],
 }
 
+linker_sanity_code = 'void a(void) {}; void _start(void) { a(); }'
+linker_sanity_args = ['-nostdlib', '-Wl,--fatal-warnings']
+if not cc.links(linker_sanity_code,
+                name : 'linker supports -static-pie',
+                args : [linker_sanity_args, '-static-pie'])
+        error('Linker does not support -static-pie.')
+endif
+
+# https://github.com/llvm/llvm-project/issues/67152
+if not cc.links(linker_sanity_code,
+                name : 'linker supports LTO with -nostdlib',
+                args : [linker_sanity_args, '-flto'])
+        efi_c_args += '-fno-lto'
+        efi_c_ld_args += '-fno-lto'
+endif
+
+# https://github.com/llvm/llvm-project/issues/61101
+if efi_cpu_family_alt == 'x86' and not cc.links(linker_sanity_code,
+                name : 'linker supports LTO with -nostdlib (x86)',
+                args : [linker_sanity_args, '-flto', '-m32'])
+        efi_arch_c_args += { 'x86' : efi_arch_c_args['x86'] + '-fno-lto' }
+        efi_arch_c_ld_args += { 'x86' : efi_arch_c_ld_args['x86'] + '-fno-lto' }
+endif
+
 ############################################################
 
 libefi_sources = files(
@@ -315,7 +336,6 @@ foreach archspec : efi_archspecs
                 'include_directories' : efi_includes,
                 'c_args' : archspec['c_args'],
                 'link_args' : archspec['link_args'],
-                'link_with' : libefi,
                 'gnu_symbol_visibility' : 'hidden',
                 'override_options' : efi_override_options,
                 'pie' : true,
@@ -324,12 +344,14 @@ foreach archspec : efi_archspecs
         efi_elf_binaries += executable(
                 'systemd-boot' + archspec['arch'],
                 sources : [systemd_boot_sources, version_h],
+                link_with : libefi,
                 name_suffix : 'elf',
                 kwargs : kwargs)
 
         efi_elf_binaries += executable(
                 'linux' + archspec['arch'],
                 sources : [stub_sources, version_h],
+                link_with : libefi,
                 name_suffix : 'elf.stub',
                 kwargs : kwargs)