[PATCH 19/24] x86/mmiotrace: Lock down the testmmiotrace module

[David Howells]

The testmmiotrace module shouldn't be permitted when the kernel is locked
down as it can be used to arbitrarily read and write MMIO space.

Suggested-by: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: David Howells <dhowe...@redhat.com
cc: Thomas Gleixner <t...@linutronix.de>
cc: Steven Rostedt <rost...@goodmis.org>
cc: Ingo Molnar <mi...@kernel.org>
cc: "H. Peter Anvin" <h...@zytor.com>
cc: x...@kernel.org
---

 arch/x86/mm/testmmiotrace.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index f6ae6830b341..bbaad357f5d7 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -115,6 +115,9 @@ static int __init init(void)
 {
        unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
 
+       if (kernel_is_locked_down("MMIO trace testing"))
+               return -EPERM;
+
        if (mmio_address == 0) {
                pr_err("you have to use the module argument mmio_address.\n");
                pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU 
ARE DOING!\n");