From: Florian Weimer via Libc-alpha <libc-alpha@sourceware.org>
To: Fangrui Song via Libc-alpha <libc-alpha@sourceware.org>
Cc: Fangrui Song <maskray@google.com>
Subject: Re: [PATCH 0/3] Allow LLD 13.0.0 and improve compatibility with gold and clang
Date: Fri, 30 Jul 2021 09:57:10 +0200 [thread overview]
Message-ID: <87o8akz12h.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20210726035802.275992-1-maskray@google.com> (Fangrui Song via Libc-alpha's message of "Sun, 25 Jul 2021 20:57:59 -0700")
* Fangrui Song via Libc-alpha:
> For malloc/tst-compathooks-on,
>
> malloc/tst-compathooks-on: Symbol `__free_hook' has different size in shared object, consider re-linking
>
> the root cause is that lld's symbol versioning is different from GNU ld in an unusal case:
>
> __asm__ (".symver " "__free_hook" "," "__free_hook" "@" "GLIBC_2.2.5");
>
> This leaves two symbols __free_hook and __free_hook@GLIBC_2.2.5.
> __free_hook is then attached a default version GLIBC_2.2.5.
> I think malloc/malloc-debug.c uses a fragile versioned symbol here.
> If the inline asm uses @@ the failure should go away.
But we want to produce a compat symbol here. With the current version
scripts, BFD ld will not export a symbol unless it is listed in the
version script. That is, if I remove __free_hook from libc_malloc_debug
in malloc/Versions, I get an ABI check failure:
--- ../sysdeps/unix/sysv/linux/x86_64/64/libc_malloc_debug.abilist 2021-07-27 16:14:51.516781791 +0200
+++ …/malloc/libc_malloc_debug.symlist 2021-07-30 09:55:09.818875449 +0200
@@ -3 +2,0 @@ GLIBC_2.16 aligned_alloc F
-GLIBC_2.2.5 __free_hook D 0x8
If this works with a linker, it appears to ignore “local: *;” in version
nodes for versioned symbols. That looks like a linker bug.
Thanks,
Florian
next prev parent reply other threads:[~2021-07-30 7:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 3:57 [PATCH 0/3] Allow LLD 13.0.0 and improve compatibility with gold and clang Fangrui Song via Libc-alpha
2021-07-26 3:58 ` [PATCH 1/3] elf: Replace .tls_common with .tbss definition Fangrui Song via Libc-alpha
2021-07-29 14:26 ` H.J. Lu via Libc-alpha
2021-07-29 16:21 ` Fangrui Song via Libc-alpha
2021-07-26 3:58 ` [PATCH 2/3] elf: Skip tst-auditlogmod-* if the linker doesn't support --depaudit Fangrui Song via Libc-alpha
2021-07-29 14:23 ` H.J. Lu via Libc-alpha
2021-07-29 16:28 ` Fangrui Song via Libc-alpha
2021-07-26 3:58 ` [PATCH 3/3] configure: Allow LD to be LLD 13.0.0 or above Fangrui Song via Libc-alpha
2021-07-28 18:02 ` [PATCH 0/3] Allow LLD 13.0.0 and improve compatibility with gold and clang H.J. Lu via Libc-alpha
2021-07-28 21:52 ` Fangrui Song via Libc-alpha
2021-07-29 14:45 ` H.J. Lu via Libc-alpha
2021-07-30 7:57 ` Florian Weimer via Libc-alpha [this message]
2021-07-31 6:34 ` Fāng-ruì Sòng via Libc-alpha
2021-07-31 6:41 ` Florian Weimer via Libc-alpha
2021-08-02 20:55 ` Fāng-ruì Sòng via Libc-alpha
2021-08-02 4:02 ` Siddhesh Poyarekar
2021-08-02 4:23 ` Siddhesh Poyarekar
2021-08-08 16:50 ` Fāng-ruì Sòng via Libc-alpha
2021-08-08 2:54 ` Fāng-ruì Sòng via Libc-alpha
2021-08-08 16:45 ` Siddhesh Poyarekar
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