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]>
Signed-off-by: Vincenzo Frascino <[email protected]>
---
arch/arm64/include/asm/memory.h | 3 ++-
arch/arm64/include/asm/mte-kasan.h | 9 +++++++--
arch/arm64/kernel/mte.c | 16 ++++++++++++++--
3 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 18fce223b67b..233d9feec45c 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -231,7 +231,8 @@ 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_init_tags(max_tag) mte_init_tags(max_tag)
#define arch_get_random_tag() mte_get_random_tag()
#define arch_get_mem_tag(addr) mte_get_mem_tag(addr)
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 26349a4b5e2e..9a5e30dbe12a 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -29,7 +29,8 @@ u8 mte_get_mem_tag(void *addr);
u8 mte_get_random_tag(void);
void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag);
-void mte_enable_kernel(void);
+void mte_enable_kernel_sync(void);
+void mte_enable_kernel_async(void);
void mte_init_tags(u64 max_tag);
#else /* CONFIG_ARM64_MTE */
@@ -52,7 +53,11 @@ static inline void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
return addr;
}
-static inline void mte_enable_kernel(void)
+static inline void mte_enable_kernel_sync(void)
+{
+}
+
+static inline void mte_enable_kernel_sync(void)
{
}
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index dc9ada64feed..78fc079a3b1e 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -151,11 +151,23 @@ 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);
}
static void update_sctlr_el1_tcf0(u64 tcf0)
--
2.30.0
On Mon, Jan 18, 2021 at 06:30:29PM +0000, Vincenzo Frascino wrote:
> 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]>
> Signed-off-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
On Mon, Jan 18, 2021 at 7:30 PM Vincenzo Frascino
<[email protected]> wrote:
>
> 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]>
> Signed-off-by: Vincenzo Frascino <[email protected]>
> ---
> arch/arm64/include/asm/memory.h | 3 ++-
> arch/arm64/include/asm/mte-kasan.h | 9 +++++++--
> arch/arm64/kernel/mte.c | 16 ++++++++++++++--
> 3 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index 18fce223b67b..233d9feec45c 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -231,7 +231,8 @@ 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_init_tags(max_tag) mte_init_tags(max_tag)
> #define arch_get_random_tag() mte_get_random_tag()
> #define arch_get_mem_tag(addr) mte_get_mem_tag(addr)
> diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
> index 26349a4b5e2e..9a5e30dbe12a 100644
> --- a/arch/arm64/include/asm/mte-kasan.h
> +++ b/arch/arm64/include/asm/mte-kasan.h
> @@ -29,7 +29,8 @@ u8 mte_get_mem_tag(void *addr);
> u8 mte_get_random_tag(void);
> void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag);
>
> -void mte_enable_kernel(void);
> +void mte_enable_kernel_sync(void);
> +void mte_enable_kernel_async(void);
> void mte_init_tags(u64 max_tag);
>
> #else /* CONFIG_ARM64_MTE */
> @@ -52,7 +53,11 @@ static inline void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
> return addr;
> }
>
> -static inline void mte_enable_kernel(void)
> +static inline void mte_enable_kernel_sync(void)
> +{
> +}
> +
> +static inline void mte_enable_kernel_sync(void)
> {
> }
>
> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
> index dc9ada64feed..78fc079a3b1e 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -151,11 +151,23 @@ 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);
> }
>
> static void update_sctlr_el1_tcf0(u64 tcf0)
> --
> 2.30.0
>
Reviewed-by: Andrey Konovalov <[email protected]>