When invoked from system call enter/exit instrumentation, accessing user-space data is a common use-case for tracers. However, tracepoints currently disable preemption around iteration on the registered tracepoint probes and invocation of the probe callbacks, which prevents tracers from handling page faults. Extend the tracepoint and trace event APIs to allow specific tracer probes to take page faults. Adapt ftrace, perf, and ebpf to allow being called from sleepable context, and convert the system call enter/exit instrumentation to sleepable tracepoints. This series only implements the tracepoint infrastructure required to allow tracers to handle page faults. Modifying each tracer to handle those page faults would be a next step after we all agree on this piece of instrumentation infrastructure. This patchset is base on v5.9.1. Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Yonghong Song <yhs@xxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> Cc: bpf@xxxxxxxxxxxxxxx Mathieu Desnoyers (1): tracing: use sched-RCU instead of SRCU for rcuidle tracepoints Michael Jeanson (5): tracing: introduce sleepable tracepoints tracing: ftrace: add support for sleepable tracepoints tracing: bpf-trace: add support for sleepable tracepoints tracing: perf: add support for sleepable tracepoints tracing: convert sys_enter/exit to sleepable tracepoints include/linux/tracepoint-defs.h | 11 ++++ include/linux/tracepoint.h | 104 +++++++++++++++++++++----------- include/trace/bpf_probe.h | 23 ++++++- include/trace/define_trace.h | 7 +++ include/trace/events/syscalls.h | 4 +- include/trace/perf.h | 26 ++++++-- include/trace/trace_events.h | 79 ++++++++++++++++++++++-- init/Kconfig | 1 + kernel/trace/bpf_trace.c | 5 +- kernel/trace/trace_events.c | 15 ++++- kernel/trace/trace_syscalls.c | 68 +++++++++++++-------- kernel/tracepoint.c | 104 +++++++++++++++++++++++++------- 12 files changed, 351 insertions(+), 96 deletions(-) -- 2.25.1
