On 2024-12-07 12:01, Mathieu Desnoyers wrote:
On 2024-12-07 11:55, Zi Yan wrote:
In commit eacd0e950dc2 ("ARC: [mm] Lazy D-cache flush (non aliasing
VIPT)"), arc adds the need to flush dcache to make icache see the code
page change. This also requires special handling for
clear_user_(high)page(). Introduce cpu_icache_is_aliasing() to make
MM code query special clear_user_(high)page() easier. This will be used
by the following commit.
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
We should probably use this new cpu_icache_is_aliasing() to gate
availability of DAX XIP, as described in the commit message here:
commit 8690bbcf3b ("Introduce cpu_dcache_is_aliasing() across all architectures)"
Note that this leaves "cpu_icache_is_aliasing()" to be implemented as future
work. This would be useful to gate features like XIP on architectures
which have aliasing CPU dcache-icache but not CPU dcache-dcache.
Thanks,
Mathieu
---
arch/arc/Kconfig | 1 +
arch/arc/include/asm/cachetype.h | 8 ++++++++
include/linux/cacheinfo.h | 6 ++++++
3 files changed, 15 insertions(+)
create mode 100644 arch/arc/include/asm/cachetype.h
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 5b2488142041..e96935373796 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -6,6 +6,7 @@
config ARC
def_bool y
select ARC_TIMERS
+ select ARCH_HAS_CPU_CACHE_ALIASING
select ARCH_HAS_CACHE_LINE_SIZE
select ARCH_HAS_DEBUG_VM_PGTABLE
select ARCH_HAS_DMA_PREP_COHERENT
diff --git a/arch/arc/include/asm/cachetype.h
b/arch/arc/include/asm/cachetype.h
new file mode 100644
index 000000000000..acd3b6cb4bf5
--- /dev/null
+++ b/arch/arc/include/asm/cachetype.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ARC_CACHETYPE_H
+#define __ASM_ARC_CACHETYPE_H
+
+#define cpu_dcache_is_aliasing() false
+#define cpu_icache_is_aliasing() true
+
+#endif
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 108060612bb8..7ad736538649 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -155,8 +155,14 @@ static inline int get_cpu_cacheinfo_id(int cpu,
int level)
#ifndef CONFIG_ARCH_HAS_CPU_CACHE_ALIASING
#define cpu_dcache_is_aliasing() false
+#define cpu_icache_is_aliasing() cpu_dcache_is_aliasing()
#else
#include <asm/cachetype.h>
+
+#ifndef cpu_icache_is_aliasing
+#define cpu_icache_is_aliasing() cpu_dcache_is_aliasing()
+#endif
+
#endif
#endif /* _LINUX_CACHEINFO_H */
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
