Re: [musl] `musl-gcc -static` and lld/mold

[Fangrui Song <i@maskray.me>]

On 2022-11-13, Rui Ueyama wrote:
>The below patch should fix the issue.
>
>diff --git a/tools/musl-gcc.specs.sh b/tools/musl-gcc.specs.sh
>index 30492574..ffb46d70 100644
>--- a/tools/musl-gcc.specs.sh
>+++ b/tools/musl-gcc.specs.sh
>@@ -23,7 +23,7 @@ libgcc.a%s %:if-exists(libgcc_eh.a%s)
> crtendS.o%s $libdir/crtn.o
>
> *link:
>--dynamic-linker $ldso -nostdlib %{shared:-shared} %{static:-static}
>%{rdynamic:-export-dynamic}
>+%{!static:-dynamic-linker $ldso} -nostdlib %{shared:-shared}
>%{static:-static} %{rdynamic:-export-dynamic}
>
> *esp_link:

I use this patch which handles -static-pie as well: https://github.com/MaskRay/musl/tree/musl-gcc

In addition, I use `*libdir: $libdir` to avoid absolute path references
so that the spec file can be easily fixed after moving the build directory.

>On Sun, Nov 13, 2022 at 8:46 AM Rui Ueyama <rui314@gmail.com> wrote:
>
>> Let me try to create a patch.
>>
>> On Sun, Nov 13, 2022 at 8:38 AM Rich Felker <dalias@libc.org> wrote:
>>
>>> On Sun, Nov 13, 2022 at 08:11:29AM +0800, Rui Ueyama wrote:
>>> > Hi,
>>> >
>>> > I think I found a musl-gcc issue. It looks like musl-gcc always appends
>>> > `-dynamic-linker /lib/ld-musl-x86_64.so.1` even if `-static` is given.
>>> That
>>> > causes a created program to immediately crash on startup as you can see
>>> > below:
>>> >
>>> > $ cat hello.c
>>> > #include <stdio.h>
>>> > int main() { printf("Hello\n"); }
>>> >
>>> > $ musl-gcc -static -fuse-ld=lld hello.c -o hello
>>> >
>>> > $ ./hello
>>> > Segmentation fault (core dumped)
>>> >
>>> > $ musl-gcc -static -fuse-ld=lld hello.c -o hello -Wl,-no-dynamic-linker
>>> > $ ./hello
>>> > Hello
>>> >
>>> > This also happens to my new linker, mold, as well. `-dynamic-linker`
>>> option
>>> > is passed to the linker, and lld and mold do what it is told to do, so I
>>> > don't think it is a linker's bug. Rather, it's a compiler front end's
>>> bug
>>> > that passes the unnecessary command line option. Can you not to append
>>> > `-dynamic-linker` if `-static`?
>>>
>>> Yes, I think this should be fixed. It only works with bfd ld without
>>> static pie (which we're also missing support for) because it just
>>> ignores -dynamic-linker in the ET_EXEC case.
>>>
>>> Would you be willing to propose a candidate patch? I believe this has
>>> been raised before in the context of static pie not working with
>>> musl-gcc (it didn't exist when the wrapper was added) so ideally that
>>> will get fixed too.
>>>
>>> Rich
>>>
>>