[PATCH stable v4.4 33/52] powerpc/64: Disable the speculation barrier from the command line

[Michael Ellerman]

From: Diana Craciun <diana.craciun at nxp.com>

commit cf175dc315f90185128fb061dc05b6fbb211aa2f upstream.

The speculation barrier can be disabled from the command line
with the parameter: "nospectre_v1".

Signed-off-by: Diana Craciun <diana.craciun at nxp.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
---
 arch/powerpc/kernel/security.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index e74057ba2e36..acfb11853d29 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -17,6 +17,7 @@
 unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
 
 bool barrier_nospec_enabled;
+static bool no_nospec;
 
 static void enable_barrier_nospec(bool enable)
 {
@@ -43,9 +44,18 @@ void setup_barrier_nospec(void)
 	enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
 		 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
 
-	enable_barrier_nospec(enable);
+	if (!no_nospec)
+		enable_barrier_nospec(enable);
 }
 
+static int __init handle_nospectre_v1(char *p)
+{
+	no_nospec = true;
+
+	return 0;
+}
+early_param("nospectre_v1", handle_nospectre_v1);
+
 #ifdef CONFIG_DEBUG_FS
 static int barrier_nospec_set(void *data, u64 val)
 {
-- 
2.20.1