linux-kernel - Re: [PATCH] arm64: crash_core: Export MODULES, VMALLOC, and VMEMMAP ranges

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Message-ID: <YgMyIOZ+USwLKCQI@MiWiFi-R3L-srv>
Date:   Wed, 9 Feb 2022 11:16:48 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Huang Shijie <shijie@...amperecomputing.com>,
        Kazuhito Hagio <k-hagio-ab@....com>,
        Lianbo Jiang <lijiang@...hat.com>
Cc:     catalin.marinas@....com, will@...nel.org, vgoyal@...hat.com,
        dyoung@...hat.com, corbet@....net, kexec@...ts.infradead.org,
        linux-doc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, zwang@...erecomputing.com,
        patches@...erecomputing.com, darren@...amperecomputing.com
Subject: Re: [PATCH] arm64: crash_core: Export MODULES, VMALLOC, and VMEMMAP
 ranges

On 02/09/22 at 09:26am, Huang Shijie wrote:
> The following interrelated ranges are needed by the kdump crash tool:
> 	MODULES_VADDR ~ MODULES_END,
> 	VMALLOC_START ~ VMALLOC_END,
> 	VMEMMAP_START ~ VMEMMAP_END
> 
> Since these values change from time to time, it is preferable to export
> them via vmcoreinfo than to change the crash's code frequently.

Add Kazu and Lianbo to CC since they take care of Crash utility now,
please check if this is necessary for Crash.

> 
> Signed-off-by: Huang Shijie <shijie@...amperecomputing.com>
> ---
>  Documentation/admin-guide/kdump/vmcoreinfo.rst | 8 ++++++++
>  arch/arm64/kernel/crash_core.c                 | 6 ++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
> index 3861a25faae1..a339af45a22e 100644
> --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
> +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
> @@ -494,6 +494,14 @@ architecture which is used to lookup the page-tables for the Virtual
>  addresses in the higher VA range (refer to ARMv8 ARM document for
>  more details).
>  
> +MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END
> +-------------
> +
> +Used to get the correct ranges:
> +	MODULES_VADDR ~ MODULES_END-1 : Kernel module space.
> +	VMALLOC_START ~ VMALLOC_END-1 : vmalloc() / ioremap() space.
> +	VMEMMAP_START ~ VMEMMAP_END-1 : vmemmap region, used for struct page array.
> +
>  arm
>  ===
>  
> diff --git a/arch/arm64/kernel/crash_core.c b/arch/arm64/kernel/crash_core.c
> index 314391a156ee..2b65aae332ce 100644
> --- a/arch/arm64/kernel/crash_core.c
> +++ b/arch/arm64/kernel/crash_core.c
> @@ -20,6 +20,12 @@ void arch_crash_save_vmcoreinfo(void)
>  {
>  	VMCOREINFO_NUMBER(VA_BITS);
>  	/* Please note VMCOREINFO_NUMBER() uses "%d", not "%x" */
> +	vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
> +	vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
> +	vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
> +	vmcoreinfo_append_str("NUMBER(VMALLOC_END)=0x%lx\n", VMALLOC_END);
> +	vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", VMEMMAP_START);
> +	vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END);
>  	vmcoreinfo_append_str("NUMBER(kimage_voffset)=0x%llx\n",
>  						kimage_voffset);
>  	vmcoreinfo_append_str("NUMBER(PHYS_OFFSET)=0x%llx\n",
> -- 
> 2.30.2
>