[kvm-unit-tests PATCH] arm/arm64: introduce is_aarch32

[Andrew Jones <drjones@redhat.com>]

ARMv7-A isn't exactly the same as ARMv8-A32 (AArch32). This
function allows unit tests to make the distinction.

Signed-off-by: Andrew Jones <drjones@redhat.com>

---
I'm actually unsure if there's a feature bit or not that I could
probe instead. It'd be nice if somebody can confirm. Thanks, drew

 lib/arm/asm/processor.h   | 20 ++++++++++++++++++++
 lib/arm64/asm/processor.h |  5 +++++
 2 files changed, 25 insertions(+)

diff --git a/lib/arm/asm/processor.h b/lib/arm/asm/processor.h
index f25e7eee3666..223e54beb72a 100644
--- a/lib/arm/asm/processor.h
+++ b/lib/arm/asm/processor.h
@@ -5,6 +5,7 @@
  *
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
+#include <bitops.h>
 #include <asm/ptrace.h>
 
 enum vector {
@@ -46,4 +47,23 @@ static inline unsigned int get_mpidr(void)
 extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
 extern bool is_user(void);
 
+/*
+ * ARMv7-A isn't exactly the same as ARMv8-A32 (AArch32). This
+ * function allows unit tests to make the distinction.
+ */
+static inline bool is_aarch32(void)
+{
+	/*
+	 * XXX: Unfortunately there's no feature bit we can probe for
+	 * this, so we do a hacky check for the processor type not being
+	 * a Cortex-A15, which is the only v7 type we currently use.
+	 */
+	unsigned long midr;
+
+	asm volatile("MRC p15, 0, %0, c0, c0, 0" : "=r" (midr));
+	midr &= GENMASK(31, 24) | GENMASK(15, 4);
+
+	return midr != ((0x41 << 24) | (0xc0f << 4));
+}
+
 #endif /* _ASMARM_PROCESSOR_H_ */
diff --git a/lib/arm64/asm/processor.h b/lib/arm64/asm/processor.h
index 84d5c7ce752b..b602e1fbbc2d 100644
--- a/lib/arm64/asm/processor.h
+++ b/lib/arm64/asm/processor.h
@@ -81,5 +81,10 @@ DEFINE_GET_SYSREG32(mpidr)
 extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
 extern bool is_user(void);
 
+static inline bool is_aarch32(void)
+{
+	return false;
+}
+
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASMARM64_PROCESSOR_H_ */
-- 
2.7.4