From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH v5 4/7] csu: Avoid weak ref for __ehdr_start in static PIE
Date: Thu, 21 Jan 2021 11:01:45 -0300 [thread overview]
Message-ID: <a9ba8fbc-0e86-6378-2a29-2998474a8c7a@linaro.org> (raw)
In-Reply-To: <4da71cb981057048e8cf9dec8731ad936b433e38.1611155254.git.szabolcs.nagy@arm.com>
On 20/01/2021 12:31, Szabolcs Nagy via Libc-alpha wrote:
> All linkers support __ehdr_start that support static PIE linking,
> so there is no need to check for its presence via a weak reference.
>
> This avoids a RELATIVE relocation in static PIE startup code on some
> targets.
>
> With non-PIE static linking the weak ref check is kept in case the
> linker does not support __ehdr_start.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> csu/libc-start.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/csu/libc-start.c b/csu/libc-start.c
> index db859c3bed..5b9ce1d158 100644
> --- a/csu/libc-start.c
> +++ b/csu/libc-start.c
> @@ -175,8 +175,12 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
> information from auxv. */
>
> extern const ElfW(Ehdr) __ehdr_start
> +# if BUILD_PIE_DEFAULT
> + __attribute__ ((visibility ("hidden")));
> +# else
> __attribute__ ((weak, visibility ("hidden")));
> if (&__ehdr_start != NULL)
> +# endif
> {
> assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
> GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
>
next prev parent reply other threads:[~2021-01-21 14:01 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 15:29 [PATCH v5 0/7] fix ifunc with static pie [BZ #27072] Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 1/7] elf: Make the tunable struct definition internal only Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 2/7] elf: Avoid RELATIVE relocs in __tunables_init Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 3/7] configure: Check for static PIE support Szabolcs Nagy
2021-01-21 13:59 ` Adhemerval Zanella
2021-01-20 15:31 ` [PATCH v5 4/7] csu: Avoid weak ref for __ehdr_start in static PIE Szabolcs Nagy
2021-01-20 15:36 ` H.J. Lu
2021-01-21 14:01 ` Adhemerval Zanella [this message]
2021-01-20 15:31 ` [PATCH v5 5/7] Use hidden visibility for early static PIE code Szabolcs Nagy
2021-01-21 14:04 ` Adhemerval Zanella
2021-01-20 15:31 ` [PATCH v5 6/7] csu: Move static pie self relocation later [BZ #27072] Szabolcs Nagy
2021-01-21 14:07 ` Adhemerval Zanella
2021-01-21 15:38 ` Szabolcs Nagy
2021-01-20 15:31 ` [PATCH v5 7/7] Make libc symbols hidden in static PIE Szabolcs Nagy
2021-01-21 14:10 ` Adhemerval Zanella
2021-01-21 15:44 ` Szabolcs Nagy
2021-01-22 1:25 ` Tulio Magno Quites Machado Filho
2021-01-22 9:41 ` Szabolcs Nagy
2021-01-27 9:44 ` Andreas Schwab
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