linux-kernel - Re: [PATCH] arm64: Stop printing the virtual memory layout

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Message-ID: <CAGXu5jKH+XZLor5hApTpzbeq0SBz4Qo-AarAFjAfWXM5p3uSVA@mail.gmail.com>
Date:   Tue, 19 Dec 2017 13:04:55 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-arm-kernel@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH] arm64: Stop printing the virtual memory layout

On Tue, Dec 19, 2017 at 11:28 AM, Laura Abbott <labbott@...hat.com> wrote:
> Printing kernel addresses should be done in limited circumstances, mostly
> for debugging purposes. Printing out the virtual memory layout at every
> kernel bootup doesn't really fall into this category so delete the prints.
> There are other ways to get the same information.

In looking at this patch, I wonder: is there anything listed here that
is _missing_ from CONFIG_PTDUMP? I would expect all of these to
already be listed there, but I thought I'd ask...

Regardless:

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

>
> Signed-off-by: Laura Abbott <labbott@...hat.com>
> ---
> Follow up to my previous proposal to switch all these to %px
> ---
>  arch/arm64/mm/init.c | 43 -------------------------------------------
>  1 file changed, 43 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 5960bef0170d..672094ed7e07 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -599,49 +599,6 @@ void __init mem_init(void)
>
>         mem_init_print_info(NULL);
>
> -#define MLK(b, t) b, t, ((t) - (b)) >> 10
> -#define MLM(b, t) b, t, ((t) - (b)) >> 20
> -#define MLG(b, t) b, t, ((t) - (b)) >> 30
> -#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
> -
> -       pr_notice("Virtual kernel memory layout:\n");
> -#ifdef CONFIG_KASAN
> -       pr_notice("    kasan   : 0x%16lx - 0x%16lx   (%6ld GB)\n",
> -               MLG(KASAN_SHADOW_START, KASAN_SHADOW_END));
> -#endif
> -       pr_notice("    modules : 0x%16lx - 0x%16lx   (%6ld MB)\n",
> -               MLM(MODULES_VADDR, MODULES_END));
> -       pr_notice("    vmalloc : 0x%16lx - 0x%16lx   (%6ld GB)\n",
> -               MLG(VMALLOC_START, VMALLOC_END));
> -       pr_notice("      .text : 0x%p" " - 0x%p" "   (%6ld KB)\n",
> -               MLK_ROUNDUP(_text, _etext));
> -       pr_notice("    .rodata : 0x%p" " - 0x%p" "   (%6ld KB)\n",
> -               MLK_ROUNDUP(__start_rodata, __init_begin));
> -       pr_notice("      .init : 0x%p" " - 0x%p" "   (%6ld KB)\n",
> -               MLK_ROUNDUP(__init_begin, __init_end));
> -       pr_notice("      .data : 0x%p" " - 0x%p" "   (%6ld KB)\n",
> -               MLK_ROUNDUP(_sdata, _edata));
> -       pr_notice("       .bss : 0x%p" " - 0x%p" "   (%6ld KB)\n",
> -               MLK_ROUNDUP(__bss_start, __bss_stop));
> -       pr_notice("    fixed   : 0x%16lx - 0x%16lx   (%6ld KB)\n",
> -               MLK(FIXADDR_START, FIXADDR_TOP));
> -       pr_notice("    PCI I/O : 0x%16lx - 0x%16lx   (%6ld MB)\n",
> -               MLM(PCI_IO_START, PCI_IO_END));
> -#ifdef CONFIG_SPARSEMEM_VMEMMAP
> -       pr_notice("    vmemmap : 0x%16lx - 0x%16lx   (%6ld GB maximum)\n",
> -               MLG(VMEMMAP_START, VMEMMAP_START + VMEMMAP_SIZE));
> -       pr_notice("              0x%16lx - 0x%16lx   (%6ld MB actual)\n",
> -               MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()),
> -                   (unsigned long)virt_to_page(high_memory)));
> -#endif
> -       pr_notice("    memory  : 0x%16lx - 0x%16lx   (%6ld MB)\n",
> -               MLM(__phys_to_virt(memblock_start_of_DRAM()),
> -                   (unsigned long)high_memory));
> -
> -#undef MLK
> -#undef MLM
> -#undef MLK_ROUNDUP
> -
>         /*
>          * Check boundaries twice: Some fundamental inconsistencies can be
>          * detected at build time already.
> --
> 2.14.3
>



-- 
Kees Cook
Pixel Security