From mboxrd@z Thu Jan  1 00:00:00 1970
From: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Date: Mon, 7 Sep 2020 11:52:35 +0200
Subject: [PATCH v2 2/3] arm64: Bail out PIE builds early if load address
 is not 4K aligned
In-Reply-To: <3196e201-a214-ebde-4ae4-35932d551ba0@wwwdotorg.org>
References: <20200904090749.4067768-1-edgar.iglesias@gmail.com>
 <20200904090749.4067768-3-edgar.iglesias@gmail.com>
 <3196e201-a214-ebde-4ae4-35932d551ba0@wwwdotorg.org>
Message-ID: <20200907095235.GA2954729@toto>
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On Fri, Sep 04, 2020 at 12:43:57PM -0600, Stephen Warren wrote:
> On 9/4/20 3:07 AM, Edgar E. Iglesias wrote:
> > From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
> > 
> > PIE requires a 4K aligned load address. If this is not met, trap
> > the startup sequence in a WFI loop rather than running into obscure
> > failures.
> 
> > diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
> >  #if CONFIG_POSITION_INDEPENDENT
> > +	/* Verify that we're 4K aligned.  */
> 
> Similar to the comment on the previous patch: I believe the code that
> implements this check should be outside the #if check, since it's always
> needed.

But a check for non-PIE would have to be stricter, wouldn't it?
I.e the load address needs to exactly match the link-time address.

Perhaps we should add the non-PIE check in a separate patch (if at all)?

Cheers,
Edgar