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

On 2014/1/22 20:56, Vaibhav Bedia wrote:

On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0 at huawei.com <mailto:wangnan0@huawei.com>> 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.