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medhefgomedhefgo
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sd-boot: Let the compiler invoke the linker for us
For LTO to work, the linker has to be called with some magic sauce arguments. And the easiest way to get those is to just let the compiler to the job for us.
1 parent 8fb4440 commit fe330f0

2 files changed

Lines changed: 42 additions & 22 deletions

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‎meson_options.txt‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -411,7 +411,9 @@ option('gnu-efi', type : 'combo', choices : ['auto', 'true', 'false'],
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description : 'gnu-efi support for sd-boot')
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option('efi-cc', type : 'array',
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description : 'the compiler to use for EFI modules')
414-
option('efi-ld', type : 'string', value : 'ld',
414+
# Note that LLD does not support PE/COFF relocations
415+
# https://lists.llvm.org/pipermail/llvm-dev/2021-March/149234.html
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option('efi-ld', type : 'combo', choices : ['bfd', 'gold'],
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description : 'the linker to use for EFI modules')
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option('efi-libdir', type : 'string',
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description : 'path to the EFI lib directory')

‎src/boot/efi/meson.build‎

Lines changed: 39 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -48,14 +48,6 @@ if efi_cc.length() == 0
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efi_cc = cc.cmd_array()
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endif
5050

51-
efi_ld = find_program(get_option('efi-ld'))
52-
efi_ld_name = efi_ld.path().split('/')[-1]
53-
if efi_ld_name == 'lld' or efi_ld_name == 'ld.lld'
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# LLVM/LLD does not support PE/COFF relocations
55-
# https://lists.llvm.org/pipermail/llvm-dev/2021-March/149234.html
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error('LLVM/lld does not support PE/COFF relocations. Use different linker for EFI image.')
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endif
58-
5951
efi_libdir = ''
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foreach dir : [get_option('efi-libdir'),
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'/usr/lib/gnuefi' / efi_arch[0],
@@ -260,26 +252,52 @@ foreach arg : get_option('c_args')
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endif
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endforeach
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263-
efi_ldflags = ['-T', efi_lds,
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'-shared',
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'-Bsymbolic',
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'-nostdlib',
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'--no-undefined',
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'--warn-common',
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'--fatal-warnings',
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'-znocombreloc',
271-
'--build-id=sha1',
272-
'-L', efi_libdir,
273-
efi_crt0]
255+
efi_ldflags = [
256+
'-fuse-ld=' + get_option('efi-ld'),
257+
'-L', efi_libdir,
258+
'-nostdlib',
259+
'-shared',
260+
'-T', efi_lds,
261+
'-Wl,--build-id=sha1',
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'-Wl,--fatal-warnings',
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'-Wl,--no-undefined',
264+
'-Wl,--warn-common',
265+
'-Wl,-Bsymbolic',
266+
'-z', 'nocombreloc',
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efi_crt0,
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]
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if efi_arch[1] in ['aarch64', 'arm', 'riscv64']
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# Aarch64, ARM32 and 64bit RISC-V don't have an EFI capable objcopy.
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# Use 'binary' instead, and add required symbols manually.
277-
efi_ldflags += ['--defsym=EFI_SUBSYSTEM=0xa']
272+
efi_ldflags += ['-Wl,--defsym=EFI_SUBSYSTEM=0xa']
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efi_format = ['-O', 'binary']
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else
280275
efi_format = ['--target=efi-app-@0@'.format(efi_arch[1])]
281276
endif
282277

278+
if run_command('grep', '-q', '__CTOR_LIST__', efi_lds).returncode() == 0
279+
# fedora has a patched gnu-efi that adds support for ELF constructors.
280+
# If ld is called by gcc something about these symbols breaks, resulting
281+
# in sd-boot freezing when gnu-efi runs the constructors. Force defining
282+
# them seems to work around this.
283+
efi_ldflags += [
284+
'-Wl,--defsym=_init_array=0',
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'-Wl,--defsym=_init_array_end=0',
286+
'-Wl,--defsym=_fini_array=0',
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'-Wl,--defsym=_fini_array_end=0',
288+
'-Wl,--defsym=__CTOR_LIST__=0',
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'-Wl,--defsym=__CTOR_END__=0',
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'-Wl,--defsym=__DTOR_LIST__=0',
291+
'-Wl,--defsym=__DTOR_END__=0',
292+
]
293+
endif
294+
295+
efi_cc_version = run_command(efi_cc, '--version').stdout().split('\n')[0]
296+
if efi_cc_version.contains('clang') and efi_cc_version.split('.')[0].split(' ')[-1].to_int() <= 10
297+
# clang <= 10 doesn't pass -T to the linker and then even complains about it being unused
298+
efi_ldflags += ['-Wl,-T,' + efi_lds, '-Wno-unused-command-line-argument']
299+
endif
300+
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systemd_boot_objects = []
284302
stub_objects = []
285303
foreach file : fundamental_source_paths + common_sources + systemd_boot_sources + stub_sources
@@ -308,7 +326,7 @@ foreach tuple : [['systemd_boot.so', systemd_boot_efi_name, systemd_boot_objects
308326
tuple[0],
309327
input : tuple[2],
310328
output : tuple[0],
311-
command : [efi_ld, '-o', '@OUTPUT@', efi_ldflags, tuple[2], '-lefi', '-lgnuefi', libgcc_file_name],
329+
command : [efi_cc, '-o', '@OUTPUT@', efi_ldflags, tuple[2], '-lefi', '-lgnuefi', libgcc_file_name],
312330
install : tuple[3],
313331
install_dir : bootlibdir)
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