lkml.org 
[lkml]   [2016]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/9] mm: implement new pkey_mprotect() system call
On Wed, 8 Jun 2016, Dave Hansen wrote:
> Proposed semantics:
> 1. protection key 0 is special and represents the default,
> unassigned protection key. It is always allocated.
> 2. mprotect() never affects a mapping's pkey_mprotect()-assigned
> protection key. A protection key of 0 (even if set explicitly)
> represents an unassigned protection key.
> 2a. mprotect(PROT_EXEC) on a mapping with an assigned protection
> key may or may not result in a mapping with execute-only
> properties. pkey_mprotect() plus pkey_set() on all threads
> should be used to _guarantee_ execute-only semantics.
> 3. mprotect(PROT_EXEC) may result in an "execute-only" mapping. The
> kernel will internally attempt to allocate and dedicate a
> protection key for the purpose of execute-only mappings. This
> may not be possible in cases where there are no free protection
> keys available.

Shouldn't we just reserve a protection key for PROT_EXEC unconditionally?

Thanks,

tglx

\
 
 \ /
  Last update: 2016-06-11 12:21    [W:0.107 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site