When the firmware supports it an otherwise useless combination of ORI
instruction arguments is interpreted as speculation barrier. Implement
barrier_nospec using this instruction.
Based on the out-of-tree gmb() implementation.
Signed-off-by: Michal Suchanek <msucha...@suse.de>
---
arch/powerpc/include/asm/barrier.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/include/asm/barrier.h
b/arch/powerpc/include/asm/barrier.h
index 10daa1d56e0a..8e47b3abe405 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -75,6 +75,15 @@ do {
\
___p1; \
})
+/* TODO: add patching so this can be disabled */
+/* Prevent speculative execution past this barrier. */
+#define barrier_nospec_asm ori 31,31,0
+#ifdef __ASSEMBLY__
+#define barrier_nospec barrier_nospec_asm
+#else
+#define barrier_nospec() __asm__ __volatile__
(stringify_in_c(barrier_nospec_asm) : : :)
+#endif
+
#include <asm-generic/barrier.h>
#endif /* _ASM_POWERPC_BARRIER_H */
--
2.13.6
