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

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Message-ID: <CAGXu5jKQbgFNEYsd3dB0bjkzAhWfFzK3XaOSNKirZdpTdSBz4A@mail.gmail.com>
Date:   Tue, 28 Aug 2018 07:31:13 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Russell King <linux@...linux.org.uk>,
        Laura Abbott <labbott@...hat.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: mm: Stop printing the virtual memory layout

On Tue, Aug 28, 2018 at 7:22 AM, Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
> Since commit ad67b74d2469d9b8 ("printk: hash addresses printed with
> %p"), the virtual memory layout printed during boot up contains "ptrval"
> instead of actual addresses:
>
>     Memory: 501296K/524288K available (6144K kernel code, 528K rwdata, 1944K rodata, 1024K init, 7584K bss, 22992K reserved, 0K cma-reserved)
>     Virtual kernel memory layout:
>         vector  : 0xffff0000 - 0xffff1000   (   4 kB)
>         fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
>         vmalloc : 0xe0800000 - 0xff800000   ( 496 MB)
>         lowmem  : 0xc0000000 - 0xe0000000   ( 512 MB)
>         modules : 0xbf000000 - 0xc0000000   (  16 MB)
>           .text : 0x(ptrval) - 0x(ptrval)   (7136 kB)
>           .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
>           .data : 0x(ptrval) - 0x(ptrval)   ( 529 kB)
>            .bss : 0x(ptrval) - 0x(ptrval)   (7585 kB)
>
> Instead of changing the printing to "%px", and leaking virtual memory
> layout information again, just remove the printing completely, cfr. e.g.
> commits 071929dbdd865f77 ("arm64: Stop printing the virtual memory
> layout") and  31833332f7987636 ("m68k/mm: Stop printing the virtual
> memory layout").
>
> All interesting information (actual section sizes) is already printed by
> mem_init_print_info() just above anyway.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

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

-Kees

> ---
>  arch/arm/mm/init.c | 49 ----------------------------------------------
>  1 file changed, 49 deletions(-)
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 0cc8e04295a40dc1..e90422ae8adfa511 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -519,55 +519,6 @@ 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 MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
> -
> -       pr_notice("Virtual kernel memory layout:\n"
> -                       "    vector  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
> -#ifdef CONFIG_HAVE_TCM
> -                       "    DTCM    : 0x%08lx - 0x%08lx   (%4ld kB)\n"
> -                       "    ITCM    : 0x%08lx - 0x%08lx   (%4ld kB)\n"
> -#endif
> -                       "    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
> -                       "    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> -                       "    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> -#ifdef CONFIG_HIGHMEM
> -                       "    pkmap   : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> -#endif
> -#ifdef CONFIG_MODULES
> -                       "    modules : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> -#endif
> -                       "      .text : 0x%p" " - 0x%p" "   (%4td kB)\n"
> -                       "      .init : 0x%p" " - 0x%p" "   (%4td kB)\n"
> -                       "      .data : 0x%p" " - 0x%p" "   (%4td kB)\n"
> -                       "       .bss : 0x%p" " - 0x%p" "   (%4td kB)\n",
> -
> -                       MLK(VECTORS_BASE, VECTORS_BASE + PAGE_SIZE),
> -#ifdef CONFIG_HAVE_TCM
> -                       MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
> -                       MLK(ITCM_OFFSET, (unsigned long) itcm_end),
> -#endif
> -                       MLK(FIXADDR_START, FIXADDR_END),
> -                       MLM(VMALLOC_START, VMALLOC_END),
> -                       MLM(PAGE_OFFSET, (unsigned long)high_memory),
> -#ifdef CONFIG_HIGHMEM
> -                       MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP) *
> -                               (PAGE_SIZE)),
> -#endif
> -#ifdef CONFIG_MODULES
> -                       MLM(MODULES_VADDR, MODULES_END),
> -#endif
> -
> -                       MLK_ROUNDUP(_text, _etext),
> -                       MLK_ROUNDUP(__init_begin, __init_end),
> -                       MLK_ROUNDUP(_sdata, _edata),
> -                       MLK_ROUNDUP(__bss_start, __bss_stop));
> -
> -#undef MLK
> -#undef MLM
> -#undef MLK_ROUNDUP
> -
>         /*
>          * Check boundaries twice: Some fundamental inconsistencies can
>          * be detected at build time already.
> --
> 2.17.1
>



-- 
Kees Cook
Pixel Security