[PULL v2 7/8] util/cacheflush: fix cache on windows-arm64

[Richard Henderson]

From: Pierrick Bouvier <pierrick.bouvier@linaro.org>

ctr_el0 access is privileged on this platform and fails as an illegal
instruction.

Windows does not offer a way to flush data cache from userspace, and
only FlushInstructionCache is available in Windows API.

The generic implementation of flush_idcache_range uses,
__builtin___clear_cache, which already use the FlushInstructionCache
function. So we rely on that.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230221153006.20300-2-pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 util/cacheflush.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/util/cacheflush.c b/util/cacheflush.c
index 2c2c73e085..06c2333a60 100644
--- a/util/cacheflush.c
+++ b/util/cacheflush.c
@@ -121,8 +121,12 @@ static void sys_cache_info(int *isize, int *dsize)
 static bool have_coherent_icache;
 #endif
 
-#if defined(__aarch64__) && !defined(CONFIG_DARWIN)
-/* Apple does not expose CTR_EL0, so we must use system interfaces. */
+#if defined(__aarch64__) && !defined(CONFIG_DARWIN) && !defined(CONFIG_WIN32)
+/*
+ * Apple does not expose CTR_EL0, so we must use system interfaces.
+ * Windows neither, but we use a generic implementation of flush_idcache_range
+ * in this case.
+ */
 static uint64_t save_ctr_el0;
 static void arch_cache_info(int *isize, int *dsize)
 {
@@ -225,7 +229,11 @@ static void __attribute__((constructor)) 
init_cache_info(void)
 
 /* Caches are coherent and do not require flushing; symbol inline. */
 
-#elif defined(__aarch64__)
+#elif defined(__aarch64__) && !defined(CONFIG_WIN32)
+/*
+ * For Windows, we use generic implementation of flush_idcache_range, that
+ * performs a call to FlushInstructionCache, through __builtin___clear_cache.
+ */
 
 #ifdef CONFIG_DARWIN
 /* Apple does not expose CTR_EL0, so we must use system interfaces. */
-- 
2.34.1