On Fri, Nov 14, 2014 at 6:46 PM, Kees Cook <keesc...@chromium.org> wrote:
> On Fri, Nov 14, 2014 at 6:29 PM, Yinghai Lu <ying...@kernel.org> wrote:
>> should use attached one instead.
>>
>> 1. should use _brk_end instead of &end, as we only use partial of
>> brk.
>> 2. [_brk_end, pm_end) page range is already converted. aka
>> is not wasted.
>
> Are you sure? For me, _brk_end isn't far enough:
>
> [ 1.475572] all_end: 0xffffffff82df5000
> [ 1.476736] _brk_end: 0xffffffff82dd6000
Yes. _brk_end should be small then &_end.
>
>>
>> ---
>> arch/x86/mm/init_64.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> Index: linux-2.6/arch/x86/mm/init_64.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/mm/init_64.c
>> +++ linux-2.6/arch/x86/mm/init_64.c
>> @@ -1124,7 +1124,8 @@ void mark_rodata_ro(void)
>> unsigned long end = (unsigned long) &__end_rodata_hpage_align;
>> unsigned long text_end = PFN_ALIGN(&__stop___ex_table);
>> unsigned long rodata_end = PFN_ALIGN(&__end_rodata);
>> - unsigned long all_end = PFN_ALIGN(&_end);
>> + unsigned long all_end = PFN_ALIGN(_brk_end);
>> + unsigned long pmd_end = roundup(all_end, PMD_SIZE);
>>
>> printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
>> (end - start) >> 10);
>> @@ -1136,7 +1137,7 @@ void mark_rodata_ro(void)
>> * The rodata/data/bss/brk section (but not the kernel text!)
>> * should also be not-executable.
>> */
>> - set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);
>> + set_memory_nx(rodata_start, (pmd_end - rodata_start) >> PAGE_SHIFT);
>>
>> rodata_test();
>>
>> @@ -1148,6 +1149,7 @@ void mark_rodata_ro(void)
>> set_memory_ro(start, (end-start) >> PAGE_SHIFT);
>> #endif
>>
>> + /* all_end to pmd_end is handled via free_all_bootmem() */
>> free_init_pages("unused kernel",
>> (unsigned long) __va(__pa_symbol(text_end)),
>> (unsigned long) __va(__pa_symbol(rodata_start)));
>
> This patch produces the same results as my v1 patch:
>
> 0xffffffff8202d000-0xffffffff82200000 1868K RW GLB NX pte
> 0xffffffff82200000-0xffffffff82e00000 12M RW PSE GLB NX pmd
> 0xffffffff82e00000-0xffffffffc0000000 978M pmd
>
> Is this correct? It sounded like tglx wanted the pmd split, like this:
>
> 0xffffffff82200000-0xffffffff82c00000 10M RW PSE GLB NX pmd
> 0xffffffff82c00000-0xffffffff82df5000 2004K RW GLB NX pte
> 0xffffffff82df5000-0xffffffff82e00000 44K RW NX pte
> 0xffffffff82e00000-0xffffffffc0000000 978M pmd
Need to remove GLB ?
Yinghai
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
