Re: [added to the 4.1 stable tree] ARM: OMAP2+: Fix l2_inv_api_params for rodata

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On Thu, Feb 11, 2016 at 07:48:10AM -0800, Tony Lindgren wrote:
> Hi,
> 
> * Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> [160211 02:43]:
> > Yes, this isn't going to work if it is copied out of the DDR, because
> > moving the data to the .data section and introducing a PC relative
> > access to it will make the code expect to access data at a relative
> > offset from the SRAM.
> > 
> > Sascha, please drop this for now.
> 
> Hmm did I miss something? Since commit 46e130d298a3 ("ARM: pm: omap3:
> run the ASM sleep code from DDR") we only run minimal parts of the
> code in SRAM. Naturally if any SRAM code uses PC relative access things
> won't work.
> 
> Here are the only pieces running in SRAM:
> 
> - omap3_do_wfi running in SRAM only for retention idle as off
>   idle restores DDR for us
> 
> - For HS omaps, save_secure_ram_context is already in .data as it's
>   only run in SRAM
> 
> - For some revisions, we have es3_sdrc_fix dynamically copied to
>   SRAM
> 
> If there are other places that I've missed, please let me know and
> I'll take a look ASAP!

Hmm, ok, I missed that.  It looks fine, but now that I'm looking deeper,
I'm wondering what the point of this particular change is.

>From what I can see, you're moving both l2dis_3630 and l2_inv_api_params
into the .data section, and adding extra complication to access those in
a position-relative manner.  However, I'm unable to locate anything which
writes to either of these: they're only read from - nothing can, they're
not even global symbols, so aren't referencable outside of sleep34xx.S.

So I don't see why this should be Cc'd for stable kernels, since as far
as I can see, it's not fixing any bug.

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