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

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Message-ID: <8b6ff575-9ac3-6d43-2da8-e3c4c69baea1@redhat.com>
Date:   Tue, 19 Dec 2017 14:18:04 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Kees Cook <keescook@...omium.org>
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 12/19/2017 01:04 PM, Kees Cook wrote:
> 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...
> 

It doesn't print the .text etc. but those can be calculated other ways.

> 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
>>
> 
> 
>