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Message-ID: <6dbcae4a-93f4-f01e-dcde-34b926c4c635@ispras.ru>
Date: Sat, 23 Nov 2024 15:36:06 +0300 (MSK)
From: Alexander Monakov <amonakov@...ras.ru>
To: Alex Rønne Petersen <alex@...xrp.com>
cc: musl@...ts.openwall.com
Subject: Re: [PATCH] s390x: Mark __tls_get_addr hidden before invoking
it.
On Sat, 23 Nov 2024, Alex Rønne Petersen wrote:
> On Sat, Nov 23, 2024 at 9:30 AM Alexander Monakov <amonakov@...ras.ru> wrote:
> >
> > On Sat, 23 Nov 2024, Alex Rønne Petersen wrote:
> >
> > > Similar to what's done for __syscall_ret, __sigsetjmp_tail, etc. This fixes a
> > > linker error when building musl libc.so with zig cc.
> >
> > Hm, on s390 __tls_get_addr is not used for TLS ABI, so it's fine that it ends up
> > hidden in libc.so. Unusual.
> >
> > (linkers must take the most restrictive visibility from all mentions of a symbol)
> >
> > I'm curious, what kind of error with zig cc were you seeing?
>
> This:
>
> ld.lld: error: relocation R_390_PC32DBL cannot be used against symbol
> '__tls_get_addr'; recompile with -fPIC
> >>> defined in obj/src/thread/__tls_get_addr.lo
> >>> referenced by __tls_get_offset.s:8 (src/thread/s390x/__tls_get_offset.s:8)
> >>> obj/src/thread/s390x/__tls_get_offset.lo:(.text+0x10)
>
> (-fPIC is actually in use.)
>
> Presumably this could be fixed in lld, considering GNU ld seems fine
> with it. But I figured that, since glibc also marks __tls_get_addr
> hidden for s390x, musl should probably just do the same anyway.
I see, thanks. Your commit message was confusing to me, because unlike
__syscall_ret and the like, __tls_get_addr is not an internal helper,
it may not have hidden visibility anywhere except s390. So it felt like
the commit message was drawing a false parallel.
I would love this to land with a clearer commit message, but that's up
to Rich and yourself to sort out.
Alexander
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