From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: Roland McGrath <roland@hack.frob.com>,
Renlin Li <renlin.li@foss.arm.com>
Cc: <nd@arm.com>, <libc-alpha@sourceware.org>,
Marcus Shawcroft <Marcus.Shawcroft@arm.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>
Subject: Re: [GLIBC][AARCH64]Rewrite elf_machine_load_address using _DYNAMIC symbol
Date: Mon, 07 Nov 2016 15:52:00 -0000 [thread overview]
Message-ID: <5820A31E.6030207@arm.com> (raw)
In-Reply-To: <58209C78.2010906@arm.com>
On 07/11/16 15:23, Szabolcs Nagy wrote:
> On 07/11/16 15:15, Szabolcs Nagy wrote:
>> On 04/11/16 21:24, Roland McGrath wrote:
>>> On many or perhaps all machines, elf_machine_load_address could now be
>>> implemented purely in C by using a link-time trick.
>>>
>>> In C, just:
>>>
>>> static inline ElfW(Addr) __attribute__ ((unused))
>>> elf_machine_load_address (void)
>>> {
>>> extern const char _BASE[] __attribute__ ((visibility ("hidden")));
>>> return (ElfW(Addr)) _BASE;
>>> }
>>>
>>> Then add a trivial input linker script to the ld.so link:
>>>
>>> PROVIDE_HIDDEN(_BASE = 0);
>
> on a second thought:
> why is it not ok to use _DYNAMIC instead of _BASE?
>
> then no linker script is needed (_DYNAMIC is in the elf spec).
>
hidden symbol is not accessed with direct pc relative addressing on mips
so this approach does not work in general.
next prev parent reply other threads:[~2016-11-07 15:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 9:42 Renlin Li
2016-11-04 21:24 ` Roland McGrath
2016-11-07 15:15 ` Szabolcs Nagy
2016-11-07 15:23 ` Szabolcs Nagy
2016-11-07 15:52 ` Szabolcs Nagy [this message]
2016-11-09 19:06 ` Maciej W. Rozycki
2016-11-08 21:28 ` Roland McGrath
2016-11-09 14:48 ` Szabolcs Nagy
2016-11-09 22:02 ` Roland McGrath
2017-10-17 15:41 ` Szabolcs Nagy
2017-10-17 16:28 ` Szabolcs Nagy
2017-10-18 10:32 ` Renlin Li
2017-10-18 16:12 ` Szabolcs Nagy
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