linux-kernel - Re: [PATCH v3 06/60] arm64: ptdump: Allow VMALLOC

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Message-ID: <448139c7-bef0-3ddc-388c-db793a37d55e@arm.com>
Date:   Tue, 7 Mar 2023 16:58:48 +0000
From:   Ryan Roberts <ryan.roberts@....com>
To:     Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v3 06/60] arm64: ptdump: Allow VMALLOC_END to be defined
 at boot

On 07/03/2023 14:04, Ard Biesheuvel wrote:
> Extend the existing pattern for populating ptdump marker entries at
> boot, and add handling of VMALLOC_END, which will cease to be a compile
> time constant for configurations that support 52-bit virtual addressing.
> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>  arch/arm64/mm/ptdump.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
> index 76d28056bd14920a..910b35f02280cbdb 100644
> --- a/arch/arm64/mm/ptdump.c
> +++ b/arch/arm64/mm/ptdump.c
> @@ -31,7 +31,12 @@ enum address_markers_idx {
>  	PAGE_END_NR,
>  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>  	KASAN_START_NR,
> +	KASAN_END_NR,
>  #endif
> +	MODULES_NR,
> +	MODULES_END_NR,
> +	VMALLOC_START_NR,
> +	VMALLOC_END_NR,
>  };
>  
>  static struct addr_marker address_markers[] = {
> @@ -44,7 +49,7 @@ static struct addr_marker address_markers[] = {
>  	{ MODULES_VADDR,		"Modules start" },
>  	{ MODULES_END,			"Modules end" },
>  	{ VMALLOC_START,		"vmalloc() area" },
> -	{ VMALLOC_END,			"vmalloc() end" },
> +	{ 0,				"vmalloc() end" },
>  	{ VMEMMAP_START,		"vmemmap start" },
>  	{ VMEMMAP_START + VMEMMAP_SIZE,	"vmemmap end" },
>  	{ PCI_IO_START,			"PCI I/O start" },

With all the VA layout changes, and the addition of 52-bit PA/VA for 4KB and
16KB pages, Documentation/arm64/memory.rst now looks very wrong. Suggest
updating it to reflect reality?



> @@ -379,6 +384,7 @@ static int __init ptdump_init(void)
>  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>  	address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
>  #endif
> +	address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
>  	ptdump_initialize();
>  	ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
>  	return 0;