nvgpu: gpu: Add speculation barrier macro

Provide a macro for preventing CPU speculation.

bug 2039126
CVE-2017-5753

Change-Id: Ifa936c079d9f2a0231d0cf35c4d8bdd18d54b238
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1640497
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

3 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/Makefile b/drivers/gpu/nvgpu/Makefile
index 680a9f4f..d70c44e8 100644
--- a/drivers/gpu/nvgpu/Makefile
+++ b/drivers/gpu/nvgpu/Makefile
@@ -14,6 +14,9 @@ ifeq ($(VERSION),4)
 ccflags-y += -Wextra -Wno-unused-parameter -Wno-missing-field-initializers
 endif
 
+# Turn off when this is fixed upstream, if ever.
+ccflags-y += -D__NVGPU_PREVENT_UNTRUSTED_SPECULATION
+
 obj-$(CONFIG_GK20A) := nvgpu.o
 
 nvgpu-y := \
diff --git a/drivers/gpu/nvgpu/include/nvgpu/barrier.h b/drivers/gpu/nvgpu/include/nvgpu/barrier.h
index 01bd3023..03a14a99 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/barrier.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/barrier.h
@@ -47,4 +47,13 @@
 
 #define NV_ACCESS_ONCE(x)       __NV_ACCESS_ONCE(x)
 
+/*
+ * Sometimes we want to prevent speculation.
+ */
+#ifdef __NVGPU_PREVENT_UNTRUSTED_SPECULATION
+#define nvgpu_speculation_barrier()     __nvgpu_speculation_barrier()
+#else
+#define nvgpu_speculation_barrier()
+#endif
+
 #endif /* __NVGPU_BARRIER_H__ */
diff --git a/drivers/gpu/nvgpu/include/nvgpu/linux/barrier.h b/drivers/gpu/nvgpu/include/nvgpu/linux/barrier.h
index b20f9462..ef867c44 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/linux/barrier.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/linux/barrier.h
@@ -32,4 +32,6 @@
 
 #define __NV_ACCESS_ONCE(x)     ACCESS_ONCE(x)
 
+#define __nvgpu_speculation_barrier() speculation_barrier()
+
 #endif /* __NVGPU_BARRIER_LINUX_H__ */