linux-kernel - Re: [PATCH v16 08/11] x86, arm64: Add ARCH_WANT_RESERVE_CRASH

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Message-ID: <YbDmxIPdk7TKIKAU@arm.com>
Date:   Wed, 8 Dec 2021 17:09:24 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Zhen Lei <thunder.leizhen@...wei.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org, Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>
Subject: Re: [PATCH v16 08/11] x86, arm64: Add ARCH_WANT_RESERVE_CRASH_KERNEL
 config

On Tue, Nov 23, 2021 at 08:46:43PM +0800, Zhen Lei wrote:
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 26b8ed11639da46..19256aa924c3b2c 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -24,6 +24,9 @@ config KEXEC_ELF
>  config HAVE_IMA_KEXEC
>  	bool
>  
> +config ARCH_WANT_RESERVE_CRASH_KERNEL
> +	bool
> +
>  config SET_FS
>  	bool
>  
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index c4207cf9bb17ffb..4b99efa36da3793 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -95,6 +95,7 @@ config ARM64
>  	select ARCH_WANT_FRAME_POINTERS
>  	select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
>  	select ARCH_WANT_LD_ORPHAN_WARN
> +	select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>  	select ARCH_WANTS_NO_INSTR
>  	select ARCH_HAS_UBSAN_SANITIZE_ALL
>  	select ARM_AMBA
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 7399327d1eff79d..528034b4276ecf8 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -12,6 +12,7 @@ config X86_32
>  	depends on !64BIT
>  	# Options that are inherently 32-bit kernel only:
>  	select ARCH_WANT_IPC_PARSE_VERSION
> +	select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>  	select CLKSRC_I8253
>  	select CLONE_BACKWARDS
>  	select GENERIC_VDSO_32
> @@ -28,6 +29,7 @@ config X86_64
>  	select ARCH_HAS_GIGANTIC_PAGE
>  	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
>  	select ARCH_USE_CMPXCHG_LOCKREF
> +	select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>  	select HAVE_ARCH_SOFT_DIRTY
>  	select MODULES_USE_ELF_RELA
>  	select NEED_DMA_MAP_STATE
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 4dc2643fcbccf99..b23cfc0ca8905fd 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -321,9 +321,7 @@ int __init parse_crashkernel_low(char *cmdline,
>   * --------- Crashkernel reservation ------------------------------
>   */
>  
> -#ifdef CONFIG_KEXEC_CORE
> -
> -#if defined(CONFIG_X86) || defined(CONFIG_ARM64)
> +#ifdef CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL
>  static int __init reserve_crashkernel_low(void)
>  {
>  #ifdef CONFIG_64BIT
> @@ -451,8 +449,7 @@ void __init reserve_crashkernel(void)
>  	crashk_res.start = crash_base;
>  	crashk_res.end   = crash_base + crash_size - 1;
>  }
> -#endif
> -#endif /* CONFIG_KEXEC_CORE */
> +#endif /* CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL */

Nitpick mostly but it may simplify the patches if the x86, arch/Kconfig
and crash_core.c changes here could be moved to patch 5. The remaining
select for arm64 should be moved to patch 7 and drop the #if change in
that patch.

This way we can keep the x86 patches on a separate branch.

Thanks.

-- 
Catalin