lkml.org 
[lkml]   [2019]   [Aug]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [patch 2/2] x86/mm/pti: Do not invoke PTI functions when PTI is disabled
Date


> On Aug 28, 2019, at 7:24 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> When PTI is disabled at boot time either because the CPU is not affected or
> PTI has been disabled on the command line, the boot code still calls into
> pti_finalize() which then unconditionally invokes:
>
> pti_clone_entry_text()
> pti_clone_kernel_text()
>
> pti_clone_kernel_text() was called unconditionally before the 32bit support
> was added and 32bit added the call to pti_clone_entry_text().
>
> The call has no side effects as cloning the page tables into the available
> second one, which was allocated for PTI does not create damage. But it does
> not make sense either and in case that this functionality would be extended
> later this might actually lead to hard to diagnose issue.
>
> Neither function should be called when PTI is runtime disabled. Make the
> invocation conditional.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Song Liu <songliubraving@fb.com>

\
 
 \ /
  Last update: 2019-08-28 19:51    [W:0.222 / U:1.932 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site