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18ecff396c
- Fix thresh_return of function graph tracer The update to store data on the shadow stack removed the abuse of using the task recursion word as a way to keep track of what functions to ignore. The trace_graph_return() was updated to handle this, but when function_graph tracer is using a threshold (only trace functions that took longer than a specified time), it uses trace_graph_thresh_return() instead. This function was still incorrectly using the task struct recursion word causing the function graph tracer to permanently set all functions to "notrace" - Fix thresh_return nosleep accounting When the calltime was moved to the shadow stack storage instead of being on the fgraph descriptor, the calculations for the amount of sleep time was updated. The calculation was done in the trace_graph_thresh_return() function, which also called the trace_graph_return(), which did the calculation again, causing the time to be doubled. Remove the call to trace_graph_return() as what it needed to do wasn't that much, and just do the work in trace_graph_thresh_return(). - Fix syscall trace event activation on boot up The syscall trace events are pseudo events attached to the raw_syscall tracepoints. When the first syscall event is enabled, it enables the raw_syscall tracepoint and doesn't need to do anything when a second syscall event is also enabled. When events are enabled via the kernel command line, syscall events are partially enabled as the enabling is called before rcu_init. This is due to allow early events to be enabled immediately. Because kernel command line events do not distinguish between different types of events, the syscall events are enabled here but are not fully functioning. After rcu_init, they are disabled and re-enabled so that they can be fully enabled. The problem happened is that this "disable-enable" is done one at a time. If more than one syscall event is specified on the command line, by disabling them one at a time, the counter never gets to zero, and the raw_syscall is not disabled and enabled, keeping the syscall events in their non-fully functional state. Instead, disable all events and re-enabled them all, as that will ensure the raw_syscall event is also disabled and re-enabled. - Disable preemption in ftrace pid filtering The ftrace pid filtering attaches to the fork and exit tracepoints to add or remove pids that should be traced. They access variables protected by RCU (preemption disabled). Now that tracepoint callbacks are called with preemption enabled, this protection needs to be added explicitly, and not depend on the functions being called with preemption disabled. - Disable preemption in event pid filtering The event pid filtering needs the same preemption disabling guards as ftrace pid filtering. - Fix accounting of the memory mapped ring buffer on fork Memory mapping the ftrace ring buffer sets the vm_flags to DONTCOPY. But this does not prevent the application from calling madvise(MADVISE_DOFORK). This causes the mapping to be copied on fork. After the first tasks exits, the mapping is considered unmapped by everyone. But when he second task exits, the counter goes below zero and triggers a WARN_ON. Since nothing prevents two separate tasks from mmapping the ftrace ring buffer (although two mappings may mess each other up), there's no reason to stop the memory from being copied on fork. Update the vm_operations to have an ".open" handler to update the accounting and let the ring buffer know someone else has it mapped. - Add all ftrace headers in MAINTAINERS file The MAINTAINERS file only specifies include/linux/ftrace.h But misses ftrace_irq.h and ftrace_regs.h. Make the file use wildcards to get all *ftrace* files. -----BEGIN PGP SIGNATURE----- iIoEABYKADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCaamiIBQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qulnAP9ZO6iChQL0hX/Xuu2VyRhVz0Svf8Sg iq2IUHP48twOogEApR4zeelMORxdKqkLR+BajZUVFR1PukVbMaszPr9GoQw= =H9pj -----END PGP SIGNATURE----- Merge tag 'trace-v7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix thresh_return of function graph tracer The update to store data on the shadow stack removed the abuse of using the task recursion word as a way to keep track of what functions to ignore. The trace_graph_return() was updated to handle this, but when function_graph tracer is using a threshold (only trace functions that took longer than a specified time), it uses trace_graph_thresh_return() instead. This function was still incorrectly using the task struct recursion word causing the function graph tracer to permanently set all functions to "notrace" - Fix thresh_return nosleep accounting When the calltime was moved to the shadow stack storage instead of being on the fgraph descriptor, the calculations for the amount of sleep time was updated. The calculation was done in the trace_graph_thresh_return() function, which also called the trace_graph_return(), which did the calculation again, causing the time to be doubled. Remove the call to trace_graph_return() as what it needed to do wasn't that much, and just do the work in trace_graph_thresh_return(). - Fix syscall trace event activation on boot up The syscall trace events are pseudo events attached to the raw_syscall tracepoints. When the first syscall event is enabled, it enables the raw_syscall tracepoint and doesn't need to do anything when a second syscall event is also enabled. When events are enabled via the kernel command line, syscall events are partially enabled as the enabling is called before rcu_init. This is due to allow early events to be enabled immediately. Because kernel command line events do not distinguish between different types of events, the syscall events are enabled here but are not fully functioning. After rcu_init, they are disabled and re-enabled so that they can be fully enabled. The problem happened is that this "disable-enable" is done one at a time. If more than one syscall event is specified on the command line, by disabling them one at a time, the counter never gets to zero, and the raw_syscall is not disabled and enabled, keeping the syscall events in their non-fully functional state. Instead, disable all events and re-enabled them all, as that will ensure the raw_syscall event is also disabled and re-enabled. - Disable preemption in ftrace pid filtering The ftrace pid filtering attaches to the fork and exit tracepoints to add or remove pids that should be traced. They access variables protected by RCU (preemption disabled). Now that tracepoint callbacks are called with preemption enabled, this protection needs to be added explicitly, and not depend on the functions being called with preemption disabled. - Disable preemption in event pid filtering The event pid filtering needs the same preemption disabling guards as ftrace pid filtering. - Fix accounting of the memory mapped ring buffer on fork Memory mapping the ftrace ring buffer sets the vm_flags to DONTCOPY. But this does not prevent the application from calling madvise(MADVISE_DOFORK). This causes the mapping to be copied on fork. After the first tasks exits, the mapping is considered unmapped by everyone. But when he second task exits, the counter goes below zero and triggers a WARN_ON. Since nothing prevents two separate tasks from mmapping the ftrace ring buffer (although two mappings may mess each other up), there's no reason to stop the memory from being copied on fork. Update the vm_operations to have an ".open" handler to update the accounting and let the ring buffer know someone else has it mapped. - Add all ftrace headers in MAINTAINERS file The MAINTAINERS file only specifies include/linux/ftrace.h But misses ftrace_irq.h and ftrace_regs.h. Make the file use wildcards to get all *ftrace* files. * tag 'trace-v7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ftrace: Add MAINTAINERS entries for all ftrace headers tracing: Fix WARN_ON in tracing_buffers_mmap_close tracing: Disable preemption in the tracepoint callbacks handling filtered pids ftrace: Disable preemption in the tracepoint callbacks handling filtered pids tracing: Fix syscall events activation by ensuring refcount hits zero fgraph: Fix thresh_return nosleeptime double-adjust fgraph: Fix thresh_return clear per-task notrace |
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