[v13,1/7] arm64: mte: Add asynchronous mode support
diff mbox series

Message ID 20210211153353.29094-2-vincenzo.frascino@arm.com
State New, archived
Headers show
Series
  • arm64: ARMv8.5-A: MTE: Add async mode support
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Commit Message

Vincenzo Frascino Feb. 11, 2021, 3:33 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    |  3 ++-
 arch/arm64/include/asm/mte-kasan.h |  9 +++++++--
 arch/arm64/kernel/mte.c            | 19 ++++++++++++++++---
 3 files changed, 25 insertions(+), 6 deletions(-)

Comments

Andrey Konovalov Feb. 12, 2021, 9:21 p.m. UTC | #1
On Thu, Feb 11, 2021 at 4:34 PM Vincenzo Frascino
<vincenzo.frascino@arm.com> 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 <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    |  3 ++-
>  arch/arm64/include/asm/mte-kasan.h |  9 +++++++--
>  arch/arm64/kernel/mte.c            | 19 ++++++++++++++++---
>  3 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index c759faf7a1ff..91515383d763 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -243,7 +243,8 @@ 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()

We need to update KASAN usage of arch_enable_tagging() to
arch_enable_tagging_sync() in this patch as well. Otherwise, this
leaves KASAN broken between this patch and the next one.


>  #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 a66c2806fc4d..706b7ab75f31 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -107,13 +107,26 @@ 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);
> +}
> +EXPORT_SYMBOL_GPL(mte_enable_kernel_sync);
> +
> +void mte_enable_kernel_async(void)
> +{
> +       __mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC);
>  }
> -EXPORT_SYMBOL_GPL(mte_enable_kernel);
> +EXPORT_SYMBOL_GPL(mte_enable_kernel_async);
>
>  void mte_set_report_once(bool state)
>  {
> --
> 2.30.0
>
Vincenzo Frascino Feb. 22, 2021, 11:14 a.m. UTC | #2
On 2/12/21 9:21 PM, Andrey Konovalov wrote:
> On Thu, Feb 11, 2021 at 4:34 PM Vincenzo Frascino
> <vincenzo.frascino@arm.com> 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 <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    |  3 ++-
>>  arch/arm64/include/asm/mte-kasan.h |  9 +++++++--
>>  arch/arm64/kernel/mte.c            | 19 ++++++++++++++++---
>>  3 files changed, 25 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
>> index c759faf7a1ff..91515383d763 100644
>> --- a/arch/arm64/include/asm/memory.h
>> +++ b/arch/arm64/include/asm/memory.h
>> @@ -243,7 +243,8 @@ 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()
> 
> We need to update KASAN usage of arch_enable_tagging() to
> arch_enable_tagging_sync() in this patch as well. Otherwise, this
> leaves KASAN broken between this patch and the next one.
>

Yes you are right, still can't explain why it did bysect cleanly though.
I will introduce temporarily here:

#define arch_enable_tagging() arch_enable_tagging_sync()

and remove it again in the respective kasan patch.

> 
>>  #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 a66c2806fc4d..706b7ab75f31 100644
>> --- a/arch/arm64/kernel/mte.c
>> +++ b/arch/arm64/kernel/mte.c
>> @@ -107,13 +107,26 @@ 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);
>> +}
>> +EXPORT_SYMBOL_GPL(mte_enable_kernel_sync);
>> +
>> +void mte_enable_kernel_async(void)
>> +{
>> +       __mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC);
>>  }
>> -EXPORT_SYMBOL_GPL(mte_enable_kernel);
>> +EXPORT_SYMBOL_GPL(mte_enable_kernel_async);
>>
>>  void mte_set_report_once(bool state)
>>  {
>> --
>> 2.30.0
>>

Patch
diff mbox series

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index c759faf7a1ff..91515383d763 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -243,7 +243,8 @@  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_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 a66c2806fc4d..706b7ab75f31 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -107,13 +107,26 @@  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);
+}
+EXPORT_SYMBOL_GPL(mte_enable_kernel_sync);
+
+void mte_enable_kernel_async(void)
+{
+	__mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC);
 }
-EXPORT_SYMBOL_GPL(mte_enable_kernel);
+EXPORT_SYMBOL_GPL(mte_enable_kernel_async);
 
 void mte_set_report_once(bool state)
 {