[PATCH] selftests/resctrl: Implement cl_flush() and sb() on aarch64

[Richard Cheng]

cl_flush() and sb() only works for i386 and x86_64 in fill_buf.c, so on
aarch64 both compile to empty function. mem_flush() walks the buffer
calling no-op cl_flush() per cache line and finishes with a no-op sb(),
leaving any caller that expects a flushed buffer, e.g. CMT, L3_CAT
operating on unflushed state with no warning.

Add code block for aarch64 using the ARM equivalents
* "dc civac, %0" for cl_flush()
* "dsb sy" for sb()

Both are EL0-accessible on Linux aarch64.

Signed-off-by: Richard Cheng <icheng@xxxxxxxxxx>
---
 tools/testing/selftests/resctrl/fill_buf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
index 19a01a52dc1a..a41d21e5a64e 100644
--- a/tools/testing/selftests/resctrl/fill_buf.c
+++ b/tools/testing/selftests/resctrl/fill_buf.c
@@ -27,6 +27,9 @@ static void sb(void)
 #if defined(__i386) || defined(__x86_64)
 	asm volatile("sfence\n\t"
 		     : : : "memory");
+#elif defined(__aarch64__)
+	asm volatile("dsb sy\n\t"
+		     : : : "memory");
 #endif
 }
 
@@ -35,6 +38,9 @@ static void cl_flush(void *p)
 #if defined(__i386) || defined(__x86_64)
 	asm volatile("clflush (%0)\n\t"
 		     : : "r"(p) : "memory");
+#elif defined(__aarch64__)
+	asm volatile("dc civac, %0\n\t"
+		     : : "r"(p) : "memory");
 #endif
 }
 
-- 
2.43.0