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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-30 09:22:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-30 09:22:00 -0700
commit034dd340b08be1f2f0477ad16131d609f9dbd53c (patch)
tree2536f4b2d7893ccd916b5abdf3c454ad6edc03c2 /Documentation/ABI/testing/amdpmf-interface
downloadlinux-stable-034dd340b08be1f2f0477ad16131d609f9dbd53c.tar.gz
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Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted
Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure
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+What: /dev/amdpmf_interface
+Date: June 2026
+KernelVersion: 7.2
+Contact: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
+Description:
+ The AMD Platform Management Framework (PMF) util layer exposes a
+ minimal user-space interface via a character device for feature
+ discovery and metrics monitoring.
+
+ When CONFIG_AMD_PMF_UTIL_SUPPORT is enabled, the driver creates
+ a character device:
+
+ ======================
+ /dev/amdpmf_interface
+ ======================
+
+ The interface supports a single ioctl:
+
+ ============================ =======================================
+ IOCTL Usage
+ IOCTL_AMD_PMF_POPULATE_DATA User passes a struct amd_pmf_info with
+ the size field set to sizeof(struct
+ amd_pmf_info). The driver returns all
+ available metrics and feature status
+ in the structure.
+ ============================ =======================================
+
+ struct amd_pmf_info layout:
+
+ ======================= ========== ================================
+ Field Type Description
+ size __u64 Structure size for versioning
+ features_supported __u32 Bitmask of supported features
+ platform_type __u32 Platform form factor orientation
+ power_source __u32 AC/DC power source
+ laptop_placement __u32 Device placement state
+ lid_state __u32 Lid open/closed status
+ user_presence __u32 User presence detection
+ slider_position __u32 Current power slider position
+ skin_temp __s32 Skin temperature (centidegrees)
+ gfx_busy __u32 Graphics workload percentage
+ ambient_light __s32 Ambient light sensor reading
+ avg_c0_residency __u32 Average C0 state residency
+ max_c0_residency __u32 Maximum C0 state residency
+ socket_power __u32 Socket power consumption
+ bios_input[10] __u32 Custom BIOS input parameters
+ bios_output[10] __u32 Custom BIOS output parameters
+ ======================= ========== ================================
+
+ Feature Support Flags (features_supported bitmask):
+
+ ===================================== ==== =============================
+ Flag Bit Description
+ AMD_PMF_FEAT_AUTO_MODE 0 Auto Mode feature support
+ AMD_PMF_FEAT_STATIC_POWER_SLIDER 1 Static Power Slider support
+ AMD_PMF_FEAT_POLICY_BUILDER 2 Policy Builder (Smart PC)
+ AMD_PMF_FEAT_DYNAMIC_POWER_SLIDER_AC 3 Dynamic slider on AC
+ AMD_PMF_FEAT_DYNAMIC_POWER_SLIDER_DC 4 Dynamic slider on DC
+ ===================================== ==== =============================
+
+ Return codes:
+
+ ============= ============================================================
+ Return code Description
+ 0 Success
+ EINVAL Invalid size or parameter
+ EFAULT copy_to_user/copy_from_user failures
+ ENODEV PMF device not available
+ ENOTTY Unknown ioctl command
+ ============= ============================================================
+
+ User-space tools integrating with AMD PMF to discover capabilities and
+ monitor real-time metrics for thermal and power management validation.