[PATCH stable v4.9 27/35] powerpc/fsl: Add nospectre_v2 command line argument

Michael Ellerman
2019-04-11T11:47:16Z

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

commit f633a8ad636efb5d4bba1a047d4a0f1ef719aa06 upstream.

When the command line argument is present, the Spectre variant 2
mitigations are disabled.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/include/asm/setup.h | 5 +++++
arch/powerpc/kernel/security.c | 21 +++++++++++++++++++++
2 files changed, 26 insertions(+)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 23ee67e279ae..862ebce3ae54 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -65,6 +65,11 @@ void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
#endif

+#ifdef CONFIG_PPC_FSL_BOOK3E
+void setup_spectre_v2(void);
+#else
+static inline void setup_spectre_v2(void) {};
+#endif
void do_btb_flush_fixups(void);

#endif /* !__ASSEMBLY__ */
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index fc41bccd9ab6..6dc5cdc2b87c 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -27,6 +27,10 @@ static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NO

bool barrier_nospec_enabled;
static bool no_nospec;
+static bool btb_flush_enabled;
+#ifdef CONFIG_PPC_FSL_BOOK3E
+static bool no_spectrev2;
+#endif

static void enable_barrier_nospec(bool enable)
{
@@ -102,6 +106,23 @@ static __init int barrier_nospec_debugfs_init(void)
device_initcall(barrier_nospec_debugfs_init);
#endif /* CONFIG_DEBUG_FS */

+#ifdef CONFIG_PPC_FSL_BOOK3E
+static int __init handle_nospectre_v2(char *p)
+{
+ no_spectrev2 = true;
+
+ return 0;
+}
+early_param("nospectre_v2", handle_nospectre_v2);
+void setup_spectre_v2(void)
+{
+ if (no_spectrev2)
+ do_btb_flush_fixups();
+ else
+ btb_flush_enabled = true;
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
#ifdef CONFIG_PPC_BOOK3S_64
ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
{
--
2.20.1