Re: [PATCH v2 1/4] util/cacheflush: fix cache on windows-arm64

[Richard Henderson]

On 2/16/23 03:49, Pierrick Bouvier wrote:
> 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>

This is reasonable for now.  I'll note that gcc does not yet support windows for aarch64, 
and I would guess this would be fixed for libgcc at such time as.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~


> ---
>   util/cacheflush.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/util/cacheflush.c b/util/cacheflush.c
> index 2c2c73e085..0a0acd70fa 100644
> --- a/util/cacheflush.c
> +++ b/util/cacheflush.c
> @@ -121,8 +121,10 @@ 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 +227,9 @@ 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. */