| Message ID | 20210121163943.9889-3-vincenzo.frascino@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: ARMv8.5-A: MTE: Add async mode support | expand |
On Thu, Jan 21, 2021 at 5:39 PM Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > Architectures supported by KASAN_HW_TAGS can provide a sync or async mode > of execution. On an MTE enabled arm64 hw for example this can be identified > with the synchronous or asynchronous tagging mode of execution. > In synchronous mode, an exception is triggered if a tag check fault occurs. > In asynchronous mode, if a tag check fault occurs, the TFSR_EL1 register is > updated asynchronously. The kernel checks the corresponding bits > periodically. > > KASAN requires a specific kernel command line parameter to make use of this > hw features. > > Add KASAN HW execution mode kernel command line parameter. > > Note: This patch adds the kasan.mode kernel parameter and the > sync/async kernel command line options to enable the described features. > > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > Documentation/dev-tools/kasan.rst | 7 +++++++ > lib/test_kasan.c | 2 +- > mm/kasan/hw_tags.c | 27 ++++++++++++++++++++++++++- > mm/kasan/kasan.h | 6 ++++-- > 4 files changed, 38 insertions(+), 4 deletions(-) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index e022b7506e37..7e4a6e0c9f57 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/Documentation/dev-tools/kasan.rst > @@ -161,6 +161,13 @@ particular KASAN features. > > - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). > > +- ``kasan.mode=sync`` or ``=async`` controls whether KASAN is configured in > + synchronous or asynchronous mode of execution (default: ``sync``). > + ``synchronous mode``: an exception is triggered if a tag check fault occurs. Synchronous mode: a bad access is detected immediately when a tag check fault occurs. (No need for `` here, "synchronous mode" is not an inline snippet.) > + ``asynchronous mode``: if a tag check fault occurs, the information is stored > + asynchronously in hardware (e.g. in the TFSR_EL1 register for arm64). The kernel > + checks the hardware location and reports an error if the fault is detected. Asynchronous mode: a bad access detection is delayed. When a tag check fault occurs, the information is stored in hardware (in the TFSR_EL1 register for arm64). The kernel periodically checks the hardware and only reports tag faults during these checks. > + > - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack > traces collection (default: ``on`` for ``CONFIG_DEBUG_KERNEL=y``, otherwise > ``off``). > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index d16ec9e66806..7285dcf9fcc1 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -97,7 +97,7 @@ static void kasan_test_exit(struct kunit *test) > READ_ONCE(fail_data.report_found)); \ > if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ > if (READ_ONCE(fail_data.report_found)) \ > - hw_enable_tagging(); \ > + hw_enable_tagging_sync(); \ > migrate_enable(); \ > } \ > } while (0) > diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c > index e529428e7a11..224a2187839c 100644 > --- a/mm/kasan/hw_tags.c > +++ b/mm/kasan/hw_tags.c > @@ -25,6 +25,11 @@ enum kasan_arg { > KASAN_ARG_ON, > }; > > +enum kasan_arg_mode { > + KASAN_ARG_MODE_SYNC, > + KASAN_ARG_MODE_ASYNC, For other modes I explicitly added a _DEFAULT option first. It makes sense to do this here as well for consistency. > +}; > + > enum kasan_arg_stacktrace { > KASAN_ARG_STACKTRACE_DEFAULT, > KASAN_ARG_STACKTRACE_OFF, > @@ -38,6 +43,7 @@ enum kasan_arg_fault { > }; > > static enum kasan_arg kasan_arg __ro_after_init; > +static enum kasan_arg_mode kasan_arg_mode __ro_after_init; > static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init; > static enum kasan_arg_fault kasan_arg_fault __ro_after_init; > > @@ -68,6 +74,21 @@ static int __init early_kasan_flag(char *arg) > } > early_param("kasan", early_kasan_flag); > > +/* kasan.mode=sync/async */ > +static int __init early_kasan_mode(char *arg) > +{ > + /* If arg is not set the default mode is sync */ > + if ((!arg) || !strcmp(arg, "sync")) > + kasan_arg_mode = KASAN_ARG_MODE_SYNC; > + else if (!strcmp(arg, "async")) > + kasan_arg_mode = KASAN_ARG_MODE_ASYNC; > + else > + return -EINVAL; > + > + return 0; > +} > +early_param("kasan.mode", early_kasan_mode); > + > /* kasan.stacktrace=off/on */ > static int __init early_kasan_flag_stacktrace(char *arg) > { > @@ -115,7 +136,11 @@ void kasan_init_hw_tags_cpu(void) > return; > > hw_init_tags(KASAN_TAG_MAX); > - hw_enable_tagging(); > + Let's add a comment: /* Enable async mode only when explicitly requested through the command line. */ > + if (kasan_arg_mode == KASAN_ARG_MODE_ASYNC) > + hw_enable_tagging_async(); > + else > + hw_enable_tagging_sync(); > } > > /* kasan_init_hw_tags() is called once on boot CPU. */ > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 07ef7fc742ad..3923d9744105 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -294,7 +294,8 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) > #define arch_set_mem_tag_range(addr, size, tag) ((void *)(addr)) > #endif > > -#define hw_enable_tagging() arch_enable_tagging() > +#define hw_enable_tagging_sync() arch_enable_tagging_sync() > +#define hw_enable_tagging_async() arch_enable_tagging_async() > #define hw_init_tags(max_tag) arch_init_tags(max_tag) > #define hw_set_tagging_report_once(state) arch_set_tagging_report_once(state) > #define hw_get_random_tag() arch_get_random_tag() > @@ -303,7 +304,8 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) > > #else /* CONFIG_KASAN_HW_TAGS */ > > -#define hw_enable_tagging() > +#define hw_enable_tagging_sync() > +#define hw_enable_tagging_async() > #define hw_set_tagging_report_once(state) > > #endif /* CONFIG_KASAN_HW_TAGS */ > -- > 2.30.0 >
On 1/21/21 5:34 PM, Andrey Konovalov wrote: >> +- ``kasan.mode=sync`` or ``=async`` controls whether KASAN is configured in >> + synchronous or asynchronous mode of execution (default: ``sync``). >> + ``synchronous mode``: an exception is triggered if a tag check fault occurs. > Synchronous mode: a bad access is detected immediately when a tag > check fault occurs. > > (No need for `` here, "synchronous mode" is not an inline snippet.) > Ok will do in v5. >> + ``asynchronous mode``: if a tag check fault occurs, the information is stored >> + asynchronously in hardware (e.g. in the TFSR_EL1 register for arm64). The kernel >> + checks the hardware location and reports an error if the fault is detected. > Asynchronous mode: a bad access detection is delayed. When a tag check > fault occurs, the information is stored in hardware (in the TFSR_EL1 > register for arm64). The kernel periodically checks the hardware and > only reports tag faults during these checks. > Will do in v5. >> + >> - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack >> traces collection (default: ``on`` for ``CONFIG_DEBUG_KERNEL=y``, otherwise >> ``off``). >> diff --git a/lib/test_kasan.c b/lib/test_kasan.c >> index d16ec9e66806..7285dcf9fcc1 100644 >> --- a/lib/test_kasan.c >> +++ b/lib/test_kasan.c >> @@ -97,7 +97,7 @@ static void kasan_test_exit(struct kunit *test) >> READ_ONCE(fail_data.report_found)); \ >> if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ >> if (READ_ONCE(fail_data.report_found)) \ >> - hw_enable_tagging(); \ >> + hw_enable_tagging_sync(); \ >> migrate_enable(); \ >> } \ >> } while (0) >> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c >> index e529428e7a11..224a2187839c 100644 >> --- a/mm/kasan/hw_tags.c >> +++ b/mm/kasan/hw_tags.c >> @@ -25,6 +25,11 @@ enum kasan_arg { >> KASAN_ARG_ON, >> }; >> >> +enum kasan_arg_mode { >> + KASAN_ARG_MODE_SYNC, >> + KASAN_ARG_MODE_ASYNC, > For other modes I explicitly added a _DEFAULT option first. It makes > sense to do this here as well for consistency. > Will do in v5. >> +}; >> + >> enum kasan_arg_stacktrace { >> KASAN_ARG_STACKTRACE_DEFAULT, >> KASAN_ARG_STACKTRACE_OFF, >> @@ -38,6 +43,7 @@ enum kasan_arg_fault { >> }; >> >> static enum kasan_arg kasan_arg __ro_after_init; >> +static enum kasan_arg_mode kasan_arg_mode __ro_after_init; >> static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init; >> static enum kasan_arg_fault kasan_arg_fault __ro_after_init; >> >> @@ -68,6 +74,21 @@ static int __init early_kasan_flag(char *arg) >> } >> early_param("kasan", early_kasan_flag); >> >> +/* kasan.mode=sync/async */ >> +static int __init early_kasan_mode(char *arg) >> +{ >> + /* If arg is not set the default mode is sync */ >> + if ((!arg) || !strcmp(arg, "sync")) >> + kasan_arg_mode = KASAN_ARG_MODE_SYNC; >> + else if (!strcmp(arg, "async")) >> + kasan_arg_mode = KASAN_ARG_MODE_ASYNC; >> + else >> + return -EINVAL; >> + >> + return 0; >> +} >> +early_param("kasan.mode", early_kasan_mode); >> + >> /* kasan.stacktrace=off/on */ >> static int __init early_kasan_flag_stacktrace(char *arg) >> { >> @@ -115,7 +136,11 @@ void kasan_init_hw_tags_cpu(void) >> return; >> >> hw_init_tags(KASAN_TAG_MAX); >> - hw_enable_tagging(); >> + > Let's add a comment: > > /* Enable async mode only when explicitly requested through the command line. */ > Will do in v5.
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index e022b7506e37..7e4a6e0c9f57 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -161,6 +161,13 @@ particular KASAN features. - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). +- ``kasan.mode=sync`` or ``=async`` controls whether KASAN is configured in + synchronous or asynchronous mode of execution (default: ``sync``). + ``synchronous mode``: an exception is triggered if a tag check fault occurs. + ``asynchronous mode``: if a tag check fault occurs, the information is stored + asynchronously in hardware (e.g. in the TFSR_EL1 register for arm64). The kernel + checks the hardware location and reports an error if the fault is detected. + - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack traces collection (default: ``on`` for ``CONFIG_DEBUG_KERNEL=y``, otherwise ``off``). diff --git a/lib/test_kasan.c b/lib/test_kasan.c index d16ec9e66806..7285dcf9fcc1 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -97,7 +97,7 @@ static void kasan_test_exit(struct kunit *test) READ_ONCE(fail_data.report_found)); \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ if (READ_ONCE(fail_data.report_found)) \ - hw_enable_tagging(); \ + hw_enable_tagging_sync(); \ migrate_enable(); \ } \ } while (0) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index e529428e7a11..224a2187839c 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -25,6 +25,11 @@ enum kasan_arg { KASAN_ARG_ON, }; +enum kasan_arg_mode { + KASAN_ARG_MODE_SYNC, + KASAN_ARG_MODE_ASYNC, +}; + enum kasan_arg_stacktrace { KASAN_ARG_STACKTRACE_DEFAULT, KASAN_ARG_STACKTRACE_OFF, @@ -38,6 +43,7 @@ enum kasan_arg_fault { }; static enum kasan_arg kasan_arg __ro_after_init; +static enum kasan_arg_mode kasan_arg_mode __ro_after_init; static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init; static enum kasan_arg_fault kasan_arg_fault __ro_after_init; @@ -68,6 +74,21 @@ static int __init early_kasan_flag(char *arg) } early_param("kasan", early_kasan_flag); +/* kasan.mode=sync/async */ +static int __init early_kasan_mode(char *arg) +{ + /* If arg is not set the default mode is sync */ + if ((!arg) || !strcmp(arg, "sync")) + kasan_arg_mode = KASAN_ARG_MODE_SYNC; + else if (!strcmp(arg, "async")) + kasan_arg_mode = KASAN_ARG_MODE_ASYNC; + else + return -EINVAL; + + return 0; +} +early_param("kasan.mode", early_kasan_mode); + /* kasan.stacktrace=off/on */ static int __init early_kasan_flag_stacktrace(char *arg) { @@ -115,7 +136,11 @@ void kasan_init_hw_tags_cpu(void) return; hw_init_tags(KASAN_TAG_MAX); - hw_enable_tagging(); + + if (kasan_arg_mode == KASAN_ARG_MODE_ASYNC) + hw_enable_tagging_async(); + else + hw_enable_tagging_sync(); } /* kasan_init_hw_tags() is called once on boot CPU. */ diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 07ef7fc742ad..3923d9744105 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -294,7 +294,8 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #define arch_set_mem_tag_range(addr, size, tag) ((void *)(addr)) #endif -#define hw_enable_tagging() arch_enable_tagging() +#define hw_enable_tagging_sync() arch_enable_tagging_sync() +#define hw_enable_tagging_async() arch_enable_tagging_async() #define hw_init_tags(max_tag) arch_init_tags(max_tag) #define hw_set_tagging_report_once(state) arch_set_tagging_report_once(state) #define hw_get_random_tag() arch_get_random_tag() @@ -303,7 +304,8 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #else /* CONFIG_KASAN_HW_TAGS */ -#define hw_enable_tagging() +#define hw_enable_tagging_sync() +#define hw_enable_tagging_async() #define hw_set_tagging_report_once(state) #endif /* CONFIG_KASAN_HW_TAGS */
Architectures supported by KASAN_HW_TAGS can provide a sync or async mode of execution. On an MTE enabled arm64 hw for example this can be identified with the synchronous or asynchronous tagging mode of execution. In synchronous mode, an exception is triggered if a tag check fault occurs. In asynchronous mode, if a tag check fault occurs, the TFSR_EL1 register is updated asynchronously. The kernel checks the corresponding bits periodically. KASAN requires a specific kernel command line parameter to make use of this hw features. Add KASAN HW execution mode kernel command line parameter. Note: This patch adds the kasan.mode kernel parameter and the sync/async kernel command line options to enable the described features. Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- Documentation/dev-tools/kasan.rst | 7 +++++++ lib/test_kasan.c | 2 +- mm/kasan/hw_tags.c | 27 ++++++++++++++++++++++++++- mm/kasan/kasan.h | 6 ++++-- 4 files changed, 38 insertions(+), 4 deletions(-)