The -nostdlib option requests the compiler to not use the standard
system startup files or libraries when linking. It is effective only
when $(CC) is used as a linker driver.
$(LD) is directly used for linking purgatory.{ro,chk} here, hence
-nostdlib is unneeded.
Signed-off-by: Masahiro Yamada <[email protected]>
---
arch/x86/purgatory/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 95ea17a9d20c..ae53d54d7959 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
# When linking purgatory.ro with -r unresolved symbols are not checked,
# also link a purgatory.chk binary without -r to check for unresolved symbols.
-PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
+PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
targets += purgatory.ro purgatory.chk
--
2.30.2
On Sun, Nov 7, 2021 at 8:27 AM Masahiro Yamada <[email protected]> wrote:
>
> The -nostdlib option requests the compiler to not use the standard
> system startup files or libraries when linking. It is effective only
> when $(CC) is used as a linker driver.
Is that right? ld.lld recognizes --nostdlib and has --help text for it.
>
> $(LD) is directly used for linking purgatory.{ro,chk} here, hence
> -nostdlib is unneeded.
>
> Signed-off-by: Masahiro Yamada <[email protected]>
> ---
>
> arch/x86/purgatory/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> index 95ea17a9d20c..ae53d54d7959 100644
> --- a/arch/x86/purgatory/Makefile
> +++ b/arch/x86/purgatory/Makefile
> @@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
>
> # When linking purgatory.ro with -r unresolved symbols are not checked,
> # also link a purgatory.chk binary without -r to check for unresolved symbols.
> -PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
> +PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
> LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
> LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
> targets += purgatory.ro purgatory.chk
> --
> 2.30.2
--
Thanks,
~Nick Desaulniers
On 2021-11-08, Nick Desaulniers wrote:
>On Sun, Nov 7, 2021 at 8:27 AM Masahiro Yamada <[email protected]> wrote:
>>
>> The -nostdlib option requests the compiler to not use the standard
>> system startup files or libraries when linking. It is effective only
>> when $(CC) is used as a linker driver.
>
>Is that right? ld.lld recognizes --nostdlib and has --help text for it.
GCC/Clang driver -nostdlib != ld.bfd/ld.lld -nostdlib.
ld.lld -nostdlib just ignores SEARCH_DIR in a linker script.
I think ld.bfd's -nostdlib is more complex than that which also has
something to do with its internal linker script location.
Anyway, getting of the obscure ld -nostdlib is a good idea.
>>
>> $(LD) is directly used for linking purgatory.{ro,chk} here, hence
>> -nostdlib is unneeded.
>>
>> Signed-off-by: Masahiro Yamada <[email protected]>
>> ---
>>
>> arch/x86/purgatory/Makefile | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
>> index 95ea17a9d20c..ae53d54d7959 100644
>> --- a/arch/x86/purgatory/Makefile
>> +++ b/arch/x86/purgatory/Makefile
>> @@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
>>
>> # When linking purgatory.ro with -r unresolved symbols are not checked,
>> # also link a purgatory.chk binary without -r to check for unresolved symbols.
>> -PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
>> +PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
>> LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
>> LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
>> targets += purgatory.ro purgatory.chk
>> --
>> 2.30.2
>
>--
>Thanks,
>~Nick Desaulniers
On Mon, Nov 8, 2021 at 4:05 PM 'Fangrui Song' via Clang Built Linux
<[email protected]> wrote:
>
> On 2021-11-08, Nick Desaulniers wrote:
> >On Sun, Nov 7, 2021 at 8:27 AM Masahiro Yamada <[email protected]> wrote:
> >>
> >> The -nostdlib option requests the compiler to not use the standard
> >> system startup files or libraries when linking. It is effective only
> >> when $(CC) is used as a linker driver.
> >
> >Is that right? ld.lld recognizes --nostdlib and has --help text for it.
>
> GCC/Clang driver -nostdlib != ld.bfd/ld.lld -nostdlib.
>
> ld.lld -nostdlib just ignores SEARCH_DIR in a linker script.
> I think ld.bfd's -nostdlib is more complex than that which also has
> something to do with its internal linker script location.
> Anyway, getting of the obscure ld -nostdlib is a good idea.
Ok, I verified that the size of arch/x86/purgatory/purgatory.ro,
arch/x86/entry/vdso/vdso64.so, and arch/x86/entry/vdso/vdso32.so don't
change with this series. (ldd is not happy with the .so's regardless).
I also suspect that the linker when invoked directly can't assuming
it's linking object files created from C sources (ie. could have been
assembler sources), so there's no reason to assume that the libc, C
runtime, or compiler runtime would need to be linked against.
Reviewed-by: Nick Desaulniers <[email protected]>
>
> >>
> >> $(LD) is directly used for linking purgatory.{ro,chk} here, hence
> >> -nostdlib is unneeded.
> >>
> >> Signed-off-by: Masahiro Yamada <[email protected]>
> >> ---
> >>
> >> arch/x86/purgatory/Makefile | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> >> index 95ea17a9d20c..ae53d54d7959 100644
> >> --- a/arch/x86/purgatory/Makefile
> >> +++ b/arch/x86/purgatory/Makefile
> >> @@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
> >>
> >> # When linking purgatory.ro with -r unresolved symbols are not checked,
> >> # also link a purgatory.chk binary without -r to check for unresolved symbols.
> >> -PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
> >> +PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
> >> LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
> >> LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
> >> targets += purgatory.ro purgatory.chk
> >> --
> >> 2.30.2
> >
> >--
> >Thanks,
> >~Nick Desaulniers
>
> --
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--
Thanks,
~Nick Desaulniers
The following commit has been merged into the x86/vdso branch of tip:
Commit-ID: 9102fa34604159642625f42d7f801f1e04d9ca12
Gitweb: https://git.kernel.org/tip/9102fa34604159642625f42d7f801f1e04d9ca12
Author: Masahiro Yamada <[email protected]>
AuthorDate: Mon, 08 Nov 2021 01:26:41 +09:00
Committer: Borislav Petkov <[email protected]>
CommitterDate: Thu, 30 Dec 2021 14:13:06 +01:00
x86/purgatory: Remove -nostdlib compiler flag
The -nostdlib option requests the compiler to not use the standard
system startup files or libraries when linking. It is effective only
when $(CC) is used as a linker driver.
$(LD) is directly used for linking purgatory.{ro,chk} here, hence
-nostdlib is unneeded.
Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/purgatory/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 95ea17a..ae53d54 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
# When linking purgatory.ro with -r unresolved symbols are not checked,
# also link a purgatory.chk binary without -r to check for unresolved symbols.
-PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
+PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
targets += purgatory.ro purgatory.chk