linux-kernel - Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated

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Date:   Mon, 1 Feb 2021 16:37:50 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Giancarlo Ferrari <giancarlo.ferrari89@...il.com>,
        linux-kernel@...r.kernel.org, penberg@...nel.org,
        geert@...ux-m68k.org, linux-arm-kernel@...ts.infradead.org,
        akpm@...ux-foundation.org, rppt@...nel.org,
        giancarlo.ferrari@...ia.com
Subject: Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated

On Mon, Feb 01, 2021 at 04:32:40PM +0000, Mark Rutland wrote:
> I reckon here we need:
> 
> 	__cpuc_flush_dcache_area(reboot_code_buffer,
> 				 relocate_new_kernel_size + sizeof(*data));
> 
> ... to make sure both the instructions and data are visible with the MMU
> off (since fncpy() only cleans to the PoU, not the PoC).

We don't. When soft_restart() turns the MMU off, and it calls
flush_cache_all() before and afterwards to ensure that all dirty lines
are pushed out.

The flushing to PoU in fncpy() is to cover other cases.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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