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From: Andrey Smirnov <andrew.smirnov@gmail.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Barebox List <barebox@lists.infradead.org>
Subject: Re: [PATCH 2/8] ARM: aarch64: Fix get_runtime_offset after relocation
Date: Thu, 22 Aug 2019 13:14:23 -0700	[thread overview]
Message-ID: <CAHQ1cqHb2EtQ_CCFW7PYOyR-yZ86Fx0605gSwsx_fxUojYffKw@mail.gmail.com> (raw)
In-Reply-To: <20190822125158.10296-3-s.hauer@pengutronix.de>

On Thu, Aug 22, 2019 at 5:52 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
>
> get_runtime_offset shall return the offset between the address we are
> running at and the address we are linked at. This value obviously
> changes when we relocate the binary. cf3b09737b tried to avoid using
> R_AARCH64_RELATIVE relocations, but in fact this is exactly what the
> function needs to work. Consider barebox starting at 0x10000000
> when we are linked at 0x0 then get_runtime_offset() should return
> 0x10000000 before relocate_to_current_adr(), but afterwards it should
> return 0x0.
>
> This patch brings back the previously removed "a" flag. Since gcc5
> doesn't put the values of R_AARCH64_RELATIVE fixup'd relocations
> into the binary but zeroes instead, we help ourselves by basing
> get_runtime_offset on an address which actually is zero. With
> CONFIG_RELOCATABLE=y the binary is always linked to 0x0, so _text
> is initially zero.
>

This paragraph might be worth putting in the comment as well to
document some cleverness that is still required to deal with GCC5.

Thanks,
Andrey Smirnov

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  parent reply	other threads:[~2019-08-22 20:14 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22 12:51 [PATCH 0/8] i.MX8 EVK patches Sascha Hauer
2019-08-22 12:51 ` [PATCH 1/8] ARM: aarch64: Fixup relocation table for the second relocation Sascha Hauer
2019-08-22 13:09   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 2/8] ARM: aarch64: Fix get_runtime_offset after relocation Sascha Hauer
2019-08-22 13:08   ` Rouven Czerwinski
2019-08-22 20:14   ` Andrey Smirnov [this message]
2019-08-23  8:11     ` Sascha Hauer
2019-08-22 12:51 ` [PATCH 3/8] pbl: Move piggy verification into pbl_barebox_uncompress() Sascha Hauer
2019-08-22 13:07   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 4/8] ARM: i.MX: imx8-ddrc: Remove debug code Sascha Hauer
2019-08-22 13:04   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 5/8] ARM: nxp-imx8mq-evk: Remove duplicate call to imx8mq_cpu_lowlevel_init() Sascha Hauer
2019-08-22 13:03   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 6/8] ARM: nxp-imx8mq-evk: Replace trampoline Sascha Hauer
2019-08-22 13:03   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 7/8] ARM: i.MX8: Fix piggydata loading Sascha Hauer
2019-08-22 13:02   ` Rouven Czerwinski
2019-08-22 12:51 ` [PATCH 8/8] ARM: nxp-imx8mq-evk: Update comments Sascha Hauer
2019-08-22 12:59   ` Rouven Czerwinski
2019-08-22 13:19 ` [PATCH 0/8] i.MX8 EVK patches Rouven Czerwinski

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