Re: [PATCH 2/3] ARM: kexec: copying code to ioremapped area

From: Wang Nan
Date: Wed Jan 22 2014 - 08:05:09 EST

On 2014/1/22 20:56, Vaibhav Bedia wrote:
> On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0@xxxxxxxxxx <mailto:wangnan0@xxxxxxxxxx>> wrote:
> ARM's kdump is actually corrupted (at least for omap4460), mainly because of
> cache problem: flush_icache_range can't reliably ensure the copied data
> correctly goes into RAM. After mmu turned off and jump to the trampoline, kexec
> always failed due to random undef instructions.
> This patch use ioremap to make sure the destnation of all memcpy() is
> uncachable memory, including copying of target kernel and trampoline.
> AFAIK ioremap on RAM in forbidden in ARM and device memory that ioremap()
> ends up creating is not meant for executable code.
> Doesn't this trigger the WARN_ON() in _arm_ioremap_pfn_caller)?

This patch is depend on the previous one:

ARM: Premit ioremap() to map reserved pages

However, Russell is opposed to it.

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