[v14,1/8] arm64: mte: Add asynchronous mode support
diff mbox series

Message ID 20210308161434.33424-2-vincenzo.frascino@arm.com
State New, archived
Headers show
  • arm64: ARMv8.5-A: MTE: Add async mode support
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Commit Message

Vincenzo Frascino March 8, 2021, 4:14 p.m. UTC
MTE provides an asynchronous mode for detecting tag exceptions. In
particular instead of triggering a fault the arm64 core updates a
register which is checked by the kernel after the asynchronous tag
check fault has occurred.

Add support for MTE asynchronous mode.

The exception handling mechanism will be added with a future patch.

Note: KASAN HW activates async mode via kasan.mode kernel parameter.
The default mode is set to synchronous.
The code that verifies the status of TFSR_EL1 will be added with a
future patch.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
 arch/arm64/include/asm/memory.h    |  4 +++-
 arch/arm64/include/asm/mte-kasan.h |  9 +++++++--
 arch/arm64/kernel/mte.c            | 16 ++++++++++++++--
 3 files changed, 24 insertions(+), 5 deletions(-)

diff mbox series

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index c759faf7a1ff..076b913caa65 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -243,7 +243,9 @@  static inline const void *__tag_set(const void *addr, u8 tag)
-#define arch_enable_tagging()			mte_enable_kernel()
+#define arch_enable_tagging_sync()		mte_enable_kernel_sync()
+#define arch_enable_tagging_async()		mte_enable_kernel_async()
+#define arch_enable_tagging()			arch_enable_tagging_sync()
 #define arch_set_tagging_report_once(state)	mte_set_report_once(state)
 #define arch_init_tags(max_tag)			mte_init_tags(max_tag)
 #define arch_get_random_tag()			mte_get_random_tag()
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 7ab500e2ad17..4acf8bf41cad 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -77,7 +77,8 @@  static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
 	} while (curr != end);
-void mte_enable_kernel(void);
+void mte_enable_kernel_sync(void);
+void mte_enable_kernel_async(void);
 void mte_init_tags(u64 max_tag);
 void mte_set_report_once(bool state);
@@ -104,7 +105,11 @@  static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
-static inline void mte_enable_kernel(void)
+static inline void mte_enable_kernel_sync(void)
+static inline void mte_enable_kernel_async(void)
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index b3c70a612c7a..fa755cf94e01 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -107,11 +107,23 @@  void mte_init_tags(u64 max_tag)
 	write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1);
-void mte_enable_kernel(void)
+static inline void __mte_enable_kernel(const char *mode, unsigned long tcf)
 	/* Enable MTE Sync Mode for EL1. */
-	sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, SCTLR_ELx_TCF_SYNC);
+	sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, tcf);
+	pr_info_once("MTE: enabled in %s mode at EL1\n", mode);
+void mte_enable_kernel_sync(void)
+	__mte_enable_kernel("synchronous", SCTLR_ELx_TCF_SYNC);
+void mte_enable_kernel_async(void)
+	__mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC);
 void mte_set_report_once(bool state)