On 07/01/2015 12:07 PM, Ingo Molnar wrote:
> 
> * Andrey Ryabinin <a.ryabi...@samsung.com> wrote:
> 
>> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
>> index 5a46681..f129a9a 100644
>> --- a/arch/x86/kernel/head64.c
>> +++ b/arch/x86/kernel/head64.c
>> @@ -161,11 +161,12 @@ asmlinkage __visible void __init 
>> x86_64_start_kernel(char * real_mode_data)
>>      /* Kill off the identity-map trampoline */
>>      reset_early_page_tables();
>>  
>> -    kasan_map_early_shadow(early_level4_pgt);
>> -
>> -    /* clear bss before set_intr_gate with early_idt_handler */
>>      clear_bss();
>>  
>> +    clear_page(init_level4_pgt);
>> +
>> +    kasan_early_init();
>> +
>>      for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
>>              set_intr_gate(i, early_idt_handler_array[i]);
>>      load_idt((const struct desc_ptr *)&idt_descr);
>> @@ -177,12 +178,9 @@ asmlinkage __visible void __init 
>> x86_64_start_kernel(char * real_mode_data)
>>       */
>>      load_ucode_bsp();
>>  
>> -    clear_page(init_level4_pgt);
>>      /* set init_level4_pgt kernel high mapping*/
>>      init_level4_pgt[511] = early_level4_pgt[511];
>>  
>> -    kasan_map_early_shadow(init_level4_pgt);
>> -
>>      x86_64_start_reservations(real_mode_data);
>>  }
>>  
> 
> So this changes generic code (moves the clear_page(init_level4_pgt) call), 
> but the 
> changelog claims it's a KASAN-specific change.
> 
> Please split this into two patches: the first one does the generic change, 
> the 
> second one the KASAN specific one.
> 

Hm...  We will need to backport that generic change to stable, because second 
change depends on it.
So, maybe split this on three changes:

        #1 fix kasan page tables (without touching clear_page() or 
kasan_map_early_shadow(init_level4_pgt))
        #2 generic move clear_page()
        #3 clean up kasan initialization (move 
kasan_map_early_shadow(init_level4_pgt)).

Only #1 will have stable tag. Does that makes sense?


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