linux-kernel - Re: [PATCH 0/2 v8] x86/kdump: Fix 'kmem -s' reported an invalid freepointer when SME was active

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Date:   Thu, 31 Oct 2019 09:26:56 +0800
From:   lijiang <lijiang@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        x86@...nel.org, bhe@...hat.com, dyoung@...hat.com, jgross@...e.com,
        dhowells@...hat.com, Thomas.Lendacky@....com,
        ebiederm@...ssion.com, vgoyal@...hat.com, d.hatayama@...itsu.com,
        horms@...ge.net.au, kexec@...ts.infradead.org
Subject: Re: [PATCH 0/2 v8] x86/kdump: Fix 'kmem -s' reported an invalid
 freepointer when SME was active

Hi, 

Please ignore this patch series because the compile warnings are reported by kduild.

I will resend v8 later after the warnings are fixed.

Sorry for this.

Thanks.
Lianbo

在 2019年10月30日 11:54, Lianbo Jiang 写道:
> In purgatory(), the main things are as below:
> 
> [1] verify sha256 hashes for various segments.
>     Lets keep these codes, and do not touch the logic.
> 
> [2] copy the first 640k content to a backup region.
>     Lets safely remove it and clean all code related to backup region.
> 
> This patch series will remove the backup region, because the current
> handling of copying the first 640k runs into problems when SME is
> active(https://bugzilla.kernel.org/show_bug.cgi?id=204793).
> 
> The low 1M region will always be reserved when the crashkernel kernel
> command line option is specified. And this way makes it unnecessary to
> do anything with the low 1M region, because the memory allocated later
> won't fall into the low 1M area.
> 
> This series includes two patches:
> [1] x86/kdump: always reserve the low 1M when the crashkernel option
>     is specified
>     The low 1M region will always be reserved when the crashkernel
>     kernel command line option is specified, which ensures that the
>     memory allocated later won't fall into the low 1M area.
> 
> [2] x86/kdump: clean up all the code related to the backup region
>     Remove the backup region and clean up.
> 
> Changes since v1:
> [1] Add extra checking condition: when the crashkernel option is
>     specified, reserve the low 640k area.
> 
> Changes since v2:
> [1] Reserve the low 1M region when the crashkernel option is only
>     specified.(Suggested by Eric)
> 
> [2] Remove the unused crash_copy_backup_region()
> 
> [3] Remove the backup region and clean up
> 
> [4] Split them into three patches
> 
> Changes since v3:
> [1] Improve the first patch's log
> 
> [2] Improve the third patch based on Eric's suggestions
> 
> Changes since v4:
> [1] Correct some typos, and also improve the first patch's log
> 
> [2] Add a new function kexec_reserve_low_1MiB() in kernel/kexec_core.c
>     and which is called by reserve_real_mode(). (Suggested by Boris)
> 
> Changes since v5:
> [1] Call the cmdline_find_option() instead of strstr() to check the
>     crashkernel option. (Suggested by Hatayama)
> 
> [2] Add a weak function kexec_reserve_low_1MiB() in kernel/kexec_core.c,
>     and implement the kexec_reserve_low_1MiB() in arch/x86/kernel/
>     machine_kexec_64.c so that it does not cause the compile error
>     on non-x86 kernel, and also ensures that it can work well on x86
>     kernel.
> 
> Changes since v6:
> [1] Move the kexec_reserve_low_1MiB() to arch/x86/kernel/crash.c and
>     also move its declaration function to arch/x86/include/asm/crash.h
>     (Suggested by Dave Young)
> 
> [2] Adjust the corresponding header files.
> 
> Changes since v7:
> [1] Change the function name from kexec_reserve_low_1MiB() to
>     crash_reserve_low_1M().
> 
> Lianbo Jiang (2):
>   x86/kdump: always reserve the low 1M when the crashkernel option is
>     specified
>   x86/kdump: clean up all the code related to the backup region
> 
>  arch/x86/include/asm/crash.h       |   6 ++
>  arch/x86/include/asm/kexec.h       |  10 ---
>  arch/x86/include/asm/purgatory.h   |  10 ---
>  arch/x86/kernel/crash.c            | 102 ++++++++---------------------
>  arch/x86/kernel/machine_kexec_64.c |  47 -------------
>  arch/x86/purgatory/purgatory.c     |  19 ------
>  arch/x86/realmode/init.c           |   2 +
>  7 files changed, 34 insertions(+), 162 deletions(-)
>