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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2024-10-09 04:07:15 +0300 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-10-10 00:08:03 +0300 |
| commit | a363d27cdbc2bc2d1899b5a1520b64e3590fcd9a (patch) | |
| tree | 0d3f6f2713f92210b7b861cf9fe45b025fc7b46d | |
| parent | 4aadde89d81fbf4cf3105a61dbc48888b819ecfb (diff) | |
| download | linux-a363d27cdbc2bc2d1899b5a1520b64e3590fcd9a.tar.xz | |
tracing: Allow system call tracepoints to handle page faults
Use Tasks Trace RCU to protect iteration of system call enter/exit
tracepoint probes to allow those probes to handle page faults.
In preparation for this change, all tracers registering to system call
enter/exit tracepoints should expect those to be called with preemption
enabled.
This allows tracers to fault-in userspace system call arguments such as
path strings within their probe callbacks.
Cc: Michael Jeanson <mjeanson@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: https://lore.kernel.org/20241009010718.2050182-6-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | include/linux/tracepoint.h | 18 | ||||
| -rw-r--r-- | init/Kconfig | 1 |
2 files changed, 17 insertions, 2 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 76e441b39a96..0dc67fad706c 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -17,6 +17,7 @@ #include <linux/errno.h> #include <linux/types.h> #include <linux/rcupdate.h> +#include <linux/rcupdate_trace.h> #include <linux/tracepoint-defs.h> #include <linux/static_call.h> @@ -107,6 +108,7 @@ void for_each_tracepoint_in_module(struct module *mod, #ifdef CONFIG_TRACEPOINTS static inline void tracepoint_synchronize_unregister(void) { + synchronize_rcu_tasks_trace(); synchronize_rcu(); } #else @@ -196,6 +198,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) /* * it_func[0] is never NULL because there is at least one element in the array * when the array itself is non NULL. + * + * With @syscall=0, the tracepoint callback array dereference is + * protected by disabling preemption. + * With @syscall=1, the tracepoint callback array dereference is + * protected by Tasks Trace RCU, which allows probes to handle page + * faults. */ #define __DO_TRACE(name, args, cond, syscall) \ do { \ @@ -204,11 +212,17 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) if (!(cond)) \ return; \ \ - preempt_disable_notrace(); \ + if (syscall) \ + rcu_read_lock_trace(); \ + else \ + preempt_disable_notrace(); \ \ __DO_TRACE_CALL(name, TP_ARGS(args)); \ \ - preempt_enable_notrace(); \ + if (syscall) \ + rcu_read_unlock_trace(); \ + else \ + preempt_enable_notrace(); \ } while (0) /* diff --git a/init/Kconfig b/init/Kconfig index 530a382ee0fe..4ac3d1b48278 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1985,6 +1985,7 @@ config BINDGEN_VERSION_TEXT # config TRACEPOINTS bool + select TASKS_TRACE_RCU source "kernel/Kconfig.kexec" |