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 <[email protected]>
Cc: Will Deacon <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Signed-off-by: Vincenzo Frascino <[email protected]>
---
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 --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)
}
#ifdef CONFIG_KASAN_HW_TAGS
-#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);
isb();
+
+ 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)
--
2.30.0