Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/pti update from Thomas Gleixner:
 "Just a single change from the anti-performance departement:

   - Add a new PR_SPEC_DISABLE_NOEXEC option which allows to apply the
     speculation protections on a process without inheriting the state
     on exec.

     This remedies a situation where a Java-launcher has speculation
     protections enabled because that's the default for JVMs which
     causes the launched regular harmless processes to inherit the
     protection state which results in unintended performance
     degradation"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Add PR_SPEC_DISABLE_NOEXEC

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 01874d54f4fd..2da82eff0eb4 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -798,15 +798,25 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
                 if (task_spec_ssb_force_disable(task))
                         return -EPERM;
                 task_clear_spec_ssb_disable(task);
+                task_clear_spec_ssb_noexec(task);
                 task_update_spec_tif(task);
                 break;
         case PR_SPEC_DISABLE:
                 task_set_spec_ssb_disable(task);
+                task_clear_spec_ssb_noexec(task);
                 task_update_spec_tif(task);
                 break;
         case PR_SPEC_FORCE_DISABLE:
                 task_set_spec_ssb_disable(task);
                 task_set_spec_ssb_force_disable(task);
+                task_clear_spec_ssb_noexec(task);
+                task_update_spec_tif(task);
+                break;
+        case PR_SPEC_DISABLE_NOEXEC:
+                if (task_spec_ssb_force_disable(task))
+                        return -EPERM;
+                task_set_spec_ssb_disable(task);
+                task_set_spec_ssb_noexec(task);
                 task_update_spec_tif(task);
                 break;
         default:
@@ -885,6 +895,8 @@ static int ssb_prctl_get(struct task_struct *task)
         case SPEC_STORE_BYPASS_PRCTL:
                 if (task_spec_ssb_force_disable(task))
                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
+                if (task_spec_ssb_noexec(task))
+                        return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
                 if (task_spec_ssb_disable(task))
                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;