From: Sascha Hauer <s.hauer@pengutronix.de>
To: Carlo Caione <carlo.caione@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: SVC32 and SP
Date: Fri, 18 May 2012 11:41:11 +0200 [thread overview]
Message-ID: <20120518094110.GS30400@pengutronix.de> (raw)
In-Reply-To: <CAOQ7t2aPsARo+NTNDobCAUVjhRR4TE9X7-L5m8xqMo4+R6oNOA@mail.gmail.com>
On Fri, May 18, 2012 at 12:06:00AM +0200, Carlo Caione wrote:
> Hi,
> I was debugging the problem with barebox and qemu-linaro as I
> described in a previous post.
> This is what I have discovered.
>
> The problem is in the strlen function that seems to get corrupted
> runtime during barebox initialization. The problem seems related to
> the switch to SVC32 mode together with the __mmu_cache_flush
> implementation.
> Before setting the cpu to SVC32 mode, the Stack Pointer is correctly
> set to 0x4020fcb0, but, immediately after the writing in the cpsr
> register (__asm__ __volatile__("msr cpsr, %0" : : "r"(r));) the Stack
> Pointer (now R13_SVC) is in 0x40205cb0 that is in the middle of the
> .text section (and precisely in the middle of the strlen routine).
> The problem is that in the __mmu_cache_flush disassembly I have a huge
> push {r0, r1, r2, r3, r4, r5, r6, r7, r9, r10, r11} that overwrites
> the strlen function and corrupts the code.
Can you try and remove the call to __mmu_cache_flush in start.c?
I think this call shouldn't be there at all. A (pre-) bootloader should
always manage to call the next image with the caches properly flushed,
otherwise we are doomed in barebox anyway.
The problem with the armv7 __mmu_cache_flush implementation is that
it uses the stack which we haven't configured at that time.
I thought I had already wired up a patch for this, but it seems I
haven't.
Sascha
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next prev parent reply other threads:[~2012-05-18 9:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-17 22:06 Carlo Caione
2012-05-18 9:41 ` Sascha Hauer [this message]
2012-05-21 19:31 ` Carlo Caione
2012-05-21 19:37 ` Sascha Hauer
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