lkml.org 
[lkml]   [2016]   [Jun]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2 03/13] x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately
On Fri, Jun 17, 2016 at 1:30 PM, Borislav Petkov <bp@alien8.de> wrote:
> On Fri, Jun 17, 2016 at 01:00:39PM -0700, Andy Lutomirski wrote:
>> It's currently only used in the EFI code, which is safe AFAICT.
>
> "It is basically useful for a pagetable hierarchy which is not init_mm."
>
>> Warn if anyone tries to use it on the normal kernel pgd.
>>
>> Signed-off-by: Andy Lutomirski <luto@kernel.org>
>> ---
>> arch/x86/mm/pageattr.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
>> index 6a8026918bf6..e9b9c5cedbb8 100644
>> --- a/arch/x86/mm/pageattr.c
>> +++ b/arch/x86/mm/pageattr.c
>> @@ -1996,6 +1996,9 @@ out:
>> void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address,
>> unsigned numpages)
>> {
>> + /* Unmapping kernel entries from init_mm's pgd is not allowed. */
>> + WARN_ON(root == init_mm.pgd);
>
> We can also return and not do the unmapping:
>
> if (WARN_ON(root == init_mm.pgd))
> return;

I'll do one better: the only function that calls this function is
unused. I'll just delete it.

--Andy

\
 
 \ /
  Last update: 2016-06-18 13:21    [W:0.059 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site