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Re: Difference in documentation vs implementation of R_X86_64_GOTPC32/64
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Siva Chandra <sivachandra at google dot com>
- Cc: binutils at sourceware dot org, Cary Coutant <ccoutant at gmail dot com>
- Date: Tue, 19 Mar 2019 05:05:17 +0800
- Subject: Re: Difference in documentation vs implementation of R_X86_64_GOTPC32/64
- References: <CAGyQ6gxo0fx-EuFJ6RXAS9XRP73_PnU7v3pVVyfds0qoT1BgUA@mail.gmail.com>
On 3/19/19, Siva Chandra via binutils <binutils@sourceware.org> wrote:
> Hello,
>
> The documentation I have at hand for the x86_64 ABI says the
> R_X86_64_GOTPC32/64 should be evaluated as:
>
> GOT + A - P
>
> where GOT is the address of the global offset table, A the addend, and
> P the program counter. But, I notice that, the implementations
> actually interpret GOT as the address of .got.plt.
>
> Also, it seems to me that a similar interpretation is also applied to
> R_X86_64_GOTOFF64, R_386_GOTPC and R_386_GOTOFF.
>
> Is there any reason why GOT is interpreted to be the address of
> .got.plt? Or, is it a defect in the documentation?
In 5.2 Dynamic Linking, there are
The symbol _GLOBAL_OFFSET_TABLE_ may reside in the middle of the .got section,
allowing both negative and non-negative offsets into the array of addresses.
--
H.J.