Re: [PATCH v2 01/15] x86, kaslr: Use init_size instead of run_size

[Yinghai Lu]

On Fri, Mar 6, 2015 at 11:56 AM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> On Fri, Mar 6, 2015 at 11:28 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> Okay, I've proven this to myself now. :) I think it would be valuable
> to call out that brk and bss are included in the _end calculation. For
> others:
...
> So, _end - _text does equal _text + bss offset + bss size + brk size
>
> Thanks! It'll be nice to lose the run_size hack. Adding some
> documentation to the code here would help others in the future trying
> to find this value, I think. :)

in arch/x86/kernel/vmlinux.lds.S, we have

        /* BSS */
        . = ALIGN(PAGE_SIZE);
        .bss : AT(ADDR(.bss) - LOAD_OFFSET) {
                __bss_start = .;
                *(.bss..page_aligned)
                *(.bss)
                . = ALIGN(PAGE_SIZE);
                __bss_stop = .;
        }

        . = ALIGN(PAGE_SIZE);
        .brk : AT(ADDR(.brk) - LOAD_OFFSET) {
                __brk_base = .;
                . += 64 * 1024;         /* 64k alignment slop space */
                *(.brk_reservation)     /* areas brk users have reserved */
                __brk_limit = .;
        }

        _end = .;

so _end already cover bss and brk.
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