x86, prctl: Hook L1D flushing in via prctl

[linux-2.6-microblaze.git] / arch / x86 / kernel / cpu / bugs.c

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1a5a1b0..ecfca3b 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1252,6 +1252,24 @@ static void task_update_spec_tif(struct task_struct *tsk)
                speculation_ctrl_update_current();
 }
 
+static int l1d_flush_prctl_set(struct task_struct *task, unsigned long ctrl)
+{
+
+       if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
+               return -EPERM;
+
+       switch (ctrl) {
+       case PR_SPEC_ENABLE:
+               set_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
+               return 0;
+       case PR_SPEC_DISABLE:
+               clear_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
+               return 0;
+       default:
+               return -ERANGE;
+       }
+}
+
 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
 {
        if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
@@ -1361,6 +1379,8 @@ int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
                return ssb_prctl_set(task, ctrl);
        case PR_SPEC_INDIRECT_BRANCH:
                return ib_prctl_set(task, ctrl);
+       case PR_SPEC_L1D_FLUSH:
+               return l1d_flush_prctl_set(task, ctrl);
        default:
                return -ENODEV;
        }
@@ -1377,6 +1397,17 @@ void arch_seccomp_spec_mitigate(struct task_struct *task)
 }
 #endif
 
+static int l1d_flush_prctl_get(struct task_struct *task)
+{
+       if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
+               return PR_SPEC_FORCE_DISABLE;
+
+       if (test_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH))
+               return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
+       else
+               return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
+}
+
 static int ssb_prctl_get(struct task_struct *task)
 {
        switch (ssb_mode) {
@@ -1427,6 +1458,8 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
                return ssb_prctl_get(task);
        case PR_SPEC_INDIRECT_BRANCH:
                return ib_prctl_get(task);
+       case PR_SPEC_L1D_FLUSH:
+               return l1d_flush_prctl_get(task);
        default:
                return -ENODEV;
        }