From dd95255d44c05c9977f962bf0f2afe5e11f8ab3e Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Fri, 5 Jan 2024 13:33:32 +0100 Subject: coresight: make coresight_bustype const Now that the driver core can properly handle constant struct bus_type, move the coresight_bustype variable to be a constant structure as well, placing it into read-only memory which can not be modified at runtime. Cc: Suzuki K Poulose Cc: Mike Leach Cc: James Clark Cc: Leo Yan Cc: Alexander Shishkin Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/2024010531-tinfoil-avert-4a57@gregkh --- include/linux/coresight.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index a4cb7dd6ca23..e8b6e388218c 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -35,7 +35,7 @@ #define CORESIGHT_UNLOCK 0xc5acce55 -extern struct bus_type coresight_bustype; +extern const struct bus_type coresight_bustype; enum coresight_dev_type { CORESIGHT_DEV_TYPE_SINK, -- cgit From a0fef3f05cf36338d471e8f35a9ced88a054d583 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:33 +0000 Subject: coresight: Make language around "activated" sinks consistent Activated has the specific meaning of a sink that's selected for use by the user via sysfs. But comments in some code that's shared by Perf use the same word, so in those cases change them to just say "selected" instead. With selected implying either via Perf or "activated" via sysfs. coresight_get_enabled_sink() doesn't actually get an enabled sink, it only gets an activated one, so change that too. And change the activated variable name to include "sysfs" so it can't be confused as a general status. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-3-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index e8b6e388218c..516ab45ff3c2 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -229,10 +229,12 @@ struct coresight_sysfs_link { * @refcnt: keep track of what is in use. * @orphan: true if the component has connections that haven't been linked. * @enable: 'true' if component is currently part of an active path. - * @activated: 'true' only if a _sink_ has been activated. A sink can be - * activated but not yet enabled. Enabling for a _sink_ - * happens when a source has been selected and a path is enabled - * from source to that sink. + * @sysfs_sink_activated: 'true' when a sink has been selected for use via sysfs + * by writing a 1 to the 'enable_sink' file. A sink can be + * activated but not yet enabled. Enabling for a _sink_ happens + * when a source has been selected and a path is enabled from + * source to that sink. A sink can also become enabled but not + * activated if it's used via Perf. * @ea: Device attribute for sink representation under PMU directory. * @def_sink: cached reference to default sink found for this device. * @nr_links: number of sysfs links created to other components from this @@ -252,9 +254,9 @@ struct coresight_device { struct device dev; atomic_t refcnt; bool orphan; - bool enable; /* true only if configured as part of a path */ + bool enable; /* sink specific fields */ - bool activated; /* true only if a sink is part of a path */ + bool sysfs_sink_activated; struct dev_ext_attribute *ea; struct coresight_device *def_sink; /* sysfs links between components */ -- cgit From 9cae77cf23e317f31de036ced7ad2c261317dc76 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:35 +0000 Subject: coresight: Move mode to struct coresight_device Most devices use mode, so move the mode definition out of the individual devices and up to the Coresight device. This will allow the core code to also know the mode which will be useful in a later commit. This also fixes the inconsistency of the documentation of the mode field on the individual device types. For example ETB10 had "this ETB is being used". Two devices didn't require an atomic mode type, so these usages have been converted to atomic_get() and atomic_set() only to make it compile, but the documentation of the field in struct coresight_device explains this type of usage. In the future, manipulation of the mode could be completely moved out of the individual devices and into the core code because it's almost all duplicate code, and this change is a step towards that. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-5-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 516ab45ff3c2..01f67862ea2f 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -226,6 +226,11 @@ struct coresight_sysfs_link { * by @coresight_ops. * @access: Device i/o access abstraction for this device. * @dev: The device entity associated to this component. + * @mode: This tracer's mode, i.e sysFS, Perf or disabled. This is + * actually an 'enum cs_mode', but is stored in an atomic type. + * This is always accessed through local_read() and local_set(), + * but wherever it's done from within the Coresight device's lock, + * a non-atomic read would also work. * @refcnt: keep track of what is in use. * @orphan: true if the component has connections that haven't been linked. * @enable: 'true' if component is currently part of an active path. @@ -252,6 +257,7 @@ struct coresight_device { const struct coresight_ops *ops; struct csdev_access access; struct device dev; + local_t mode; atomic_t refcnt; bool orphan; bool enable; -- cgit From d5e83f97eb5669bfdd894ec980083f65517df2fb Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:36 +0000 Subject: coresight: Remove the 'enable' field. 'enable', which probably should have been 'enabled', is only ever read in the core code in relation to controlling sources, and specifically only sources in sysfs mode. Confusingly it's not labelled as such and relying on it can be a source of bugs like the one fixed by commit 078dbba3f0c9 ("coresight: Fix crash when Perf and sysfs modes are used concurrently"). Most importantly, it can only be used when the coresight_mutex is held which is only done when enabling and disabling paths in sysfs mode, and not Perf mode. So to prevent its usage spreading and leaking out to other devices, remove it. It's use is equivalent to checking if the mode is currently sysfs, as due to the coresight_mutex lock, mode == CS_MODE_SYSFS can only become true or untrue when that lock is held, and when mode == CS_MODE_SYSFS the device is both enabled and in sysfs mode. The one place it was used outside of the core code is in TPDA, but that pattern is more appropriately represented using refcounts inside the device's own spinlock. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-6-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 01f67862ea2f..d1fd7070099c 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -233,7 +233,6 @@ struct coresight_sysfs_link { * a non-atomic read would also work. * @refcnt: keep track of what is in use. * @orphan: true if the component has connections that haven't been linked. - * @enable: 'true' if component is currently part of an active path. * @sysfs_sink_activated: 'true' when a sink has been selected for use via sysfs * by writing a 1 to the 'enable_sink' file. A sink can be * activated but not yet enabled. Enabling for a _sink_ happens @@ -260,7 +259,6 @@ struct coresight_device { local_t mode; atomic_t refcnt; bool orphan; - bool enable; /* sink specific fields */ bool sysfs_sink_activated; struct dev_ext_attribute *ea; -- cgit From 1f5149c7751c50aba1a871143ffa6cb36af3fb49 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:37 +0000 Subject: coresight: Move all sysfs code to sysfs file At the moment the core file contains both sysfs functionality and core functionality, while the Perf mode is in a separate file in coresight-etm-perf.c Many of the functions have ambiguous names like coresight_enable_source() which actually only work in relation to the sysfs mode. To avoid further confusion, move everything that isn't core functionality into the sysfs file and append _sysfs to the ambiguous functions. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-7-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index d1fd7070099c..365b28022c5b 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -578,8 +578,8 @@ static inline bool coresight_is_percpu_sink(struct coresight_device *csdev) extern struct coresight_device * coresight_register(struct coresight_desc *desc); extern void coresight_unregister(struct coresight_device *csdev); -extern int coresight_enable(struct coresight_device *csdev); -extern void coresight_disable(struct coresight_device *csdev); +extern int coresight_enable_sysfs(struct coresight_device *csdev); +extern void coresight_disable_sysfs(struct coresight_device *csdev); extern int coresight_timeout(struct csdev_access *csa, u32 offset, int position, int value); @@ -609,8 +609,8 @@ static inline struct coresight_device * coresight_register(struct coresight_desc *desc) { return NULL; } static inline void coresight_unregister(struct coresight_device *csdev) {} static inline int -coresight_enable(struct coresight_device *csdev) { return -ENOSYS; } -static inline void coresight_disable(struct coresight_device *csdev) {} +coresight_enable_sysfs(struct coresight_device *csdev) { return -ENOSYS; } +static inline void coresight_disable_sysfs(struct coresight_device *csdev) {} static inline int coresight_timeout(struct csdev_access *csa, u32 offset, int position, int value) -- cgit From 4545b38ef004a586295750ea49a505b6396a7c90 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:38 +0000 Subject: coresight: Remove atomic type from refcnt Refcnt is only ever accessed from either inside the coresight_mutex, or the device's spinlock, making the atomic type and atomic_dec_return() calls confusing and unnecessary. The only point of synchronisation outside of these two types of locks is already done with a compare and swap on 'mode', which a comment has been added for. There was one instance of refcnt being used outside of a lock in TPIU, but that can easily be fixed by making it the same as all the other devices and adding a spinlock. Potentially in the future all the refcounting and locking can be moved up into the core code, and all the mostly duplicate code from the individual devices can be removed. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-8-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 365b28022c5b..74bcec526aa9 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -230,8 +230,15 @@ struct coresight_sysfs_link { * actually an 'enum cs_mode', but is stored in an atomic type. * This is always accessed through local_read() and local_set(), * but wherever it's done from within the Coresight device's lock, - * a non-atomic read would also work. - * @refcnt: keep track of what is in use. + * a non-atomic read would also work. This is the main point of + * synchronisation between code happening inside the sysfs mode's + * coresight_mutex and outside when running in Perf mode. A compare + * and exchange swap is done to atomically claim one mode or the + * other. + * @refcnt: keep track of what is in use. Only access this outside of the + * device's spinlock when the coresight_mutex held and mode == + * CS_MODE_SYSFS. Otherwise it must be accessed from inside the + * spinlock. * @orphan: true if the component has connections that haven't been linked. * @sysfs_sink_activated: 'true' when a sink has been selected for use via sysfs * by writing a 1 to the 'enable_sink' file. A sink can be @@ -257,7 +264,7 @@ struct coresight_device { struct csdev_access access; struct device dev; local_t mode; - atomic_t refcnt; + int refcnt; bool orphan; /* sink specific fields */ bool sysfs_sink_activated; -- cgit From 053ad9ad1d13f253605d7644de3aa20d958569ef Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:39 +0000 Subject: coresight: Remove unused stubs These are a bit annoying to keep up to date when the function signatures change. But if CONFIG_CORESIGHT isn't enabled, then they're not used anyway so just delete them. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-9-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 79 ----------------------------------------------- 1 file changed, 79 deletions(-) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 74bcec526aa9..ecf4b8aecca8 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -391,8 +391,6 @@ struct coresight_ops { const struct coresight_ops_helper *helper_ops; }; -#if IS_ENABLED(CONFIG_CORESIGHT) - static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa, u32 offset) { @@ -611,83 +609,6 @@ void coresight_relaxed_write64(struct coresight_device *csdev, u64 val, u32 offset); void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset); -#else -static inline struct coresight_device * -coresight_register(struct coresight_desc *desc) { return NULL; } -static inline void coresight_unregister(struct coresight_device *csdev) {} -static inline int -coresight_enable_sysfs(struct coresight_device *csdev) { return -ENOSYS; } -static inline void coresight_disable_sysfs(struct coresight_device *csdev) {} - -static inline int coresight_timeout(struct csdev_access *csa, u32 offset, - int position, int value) -{ - return 1; -} - -static inline int coresight_claim_device_unlocked(struct coresight_device *csdev) -{ - return -EINVAL; -} - -static inline int coresight_claim_device(struct coresight_device *csdev) -{ - return -EINVAL; -} - -static inline void coresight_disclaim_device(struct coresight_device *csdev) {} -static inline void coresight_disclaim_device_unlocked(struct coresight_device *csdev) {} - -static inline bool coresight_loses_context_with_cpu(struct device *dev) -{ - return false; -} - -static inline u32 coresight_relaxed_read32(struct coresight_device *csdev, u32 offset) -{ - WARN_ON_ONCE(1); - return 0; -} - -static inline u32 coresight_read32(struct coresight_device *csdev, u32 offset) -{ - WARN_ON_ONCE(1); - return 0; -} - -static inline void coresight_write32(struct coresight_device *csdev, u32 val, u32 offset) -{ -} - -static inline void coresight_relaxed_write32(struct coresight_device *csdev, - u32 val, u32 offset) -{ -} - -static inline u64 coresight_relaxed_read64(struct coresight_device *csdev, - u32 offset) -{ - WARN_ON_ONCE(1); - return 0; -} - -static inline u64 coresight_read64(struct coresight_device *csdev, u32 offset) -{ - WARN_ON_ONCE(1); - return 0; -} - -static inline void coresight_relaxed_write64(struct coresight_device *csdev, - u64 val, u32 offset) -{ -} - -static inline void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset) -{ -} - -#endif /* IS_ENABLED(CONFIG_CORESIGHT) */ - extern int coresight_get_cpu(struct device *dev); struct coresight_platform_data *coresight_get_platform_data(struct device *dev); -- cgit From d724f65218b994da234081df5dfe417c23802a65 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:41 +0000 Subject: coresight: Add helper for atomically taking the device Now that mode is in struct coresight_device, this pattern can be wrapped in a helper. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-11-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index ecf4b8aecca8..414bcbbdaf62 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -580,6 +580,17 @@ static inline bool coresight_is_percpu_sink(struct coresight_device *csdev) (csdev->subtype.sink_subtype == CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM); } +/* + * Atomically try to take the device and set a new mode. Returns true on + * success, false if the device is already taken by someone else. + */ +static inline bool coresight_take_mode(struct coresight_device *csdev, + enum cs_mode new_mode) +{ + return local_cmpxchg(&csdev->mode, CS_MODE_DISABLED, new_mode) == + CS_MODE_DISABLED; +} + extern struct coresight_device * coresight_register(struct coresight_desc *desc); extern void coresight_unregister(struct coresight_device *csdev); -- cgit From c95c2733e5feb1f6848923f166849b2d1c7bf682 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:42 +0000 Subject: coresight: Add a helper for getting csdev->mode Now that mode is in struct coresight_device accesses can be wrapped. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-12-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 414bcbbdaf62..a49e4e20e899 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -591,6 +591,11 @@ static inline bool coresight_take_mode(struct coresight_device *csdev, CS_MODE_DISABLED; } +static inline enum cs_mode coresight_get_mode(struct coresight_device *csdev) +{ + return local_read(&csdev->mode); +} + extern struct coresight_device * coresight_register(struct coresight_desc *desc); extern void coresight_unregister(struct coresight_device *csdev); -- cgit From bcaabb95f0c9883fb8e1112bd13eaba9cfd62c15 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:43 +0000 Subject: coresight: Add helper for setting csdev->mode Now that mode is in struct coresight_device, sets can be wrapped. This also allows us to add a sanity check that there have been no concurrent modifications of mode. Currently all usages of local_set() were inside the device's spin locks so this new warning shouldn't be triggered. coresight_take_mode() could maybe have been used in place of adding the warning, but there may be use cases which set the mode to the same mode which are valid but would fail in coresight_take_mode() because it requires the device to only be in the disabled state. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-13-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- include/linux/coresight.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include/linux/coresight.h') diff --git a/include/linux/coresight.h b/include/linux/coresight.h index a49e4e20e899..5f288d475490 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -596,6 +596,22 @@ static inline enum cs_mode coresight_get_mode(struct coresight_device *csdev) return local_read(&csdev->mode); } +static inline void coresight_set_mode(struct coresight_device *csdev, + enum cs_mode new_mode) +{ + enum cs_mode current_mode = coresight_get_mode(csdev); + + /* + * Changing to a new mode must be done from an already disabled state + * unless it's synchronized with coresight_take_mode(). Otherwise the + * device is already in use and signifies a locking issue. + */ + WARN(new_mode != CS_MODE_DISABLED && current_mode != CS_MODE_DISABLED && + current_mode != new_mode, "Device already in use\n"); + + local_set(&csdev->mode, new_mode); +} + extern struct coresight_device * coresight_register(struct coresight_desc *desc); extern void coresight_unregister(struct coresight_device *csdev); -- cgit