From: Mathieu Desnoyers mathieu.desnoyers@efficios.com
[ Upstream commit 13d750c2c03e9861e15268574ed2c239cca9c9d5 ]
In preparation for allowing system call enter/exit instrumentation to handle page faults, make sure that ftrace can handle this change by explicitly disabling preemption within the ftrace system call tracepoint probes to respect the current expectations within ftrace ring buffer code.
This change does not yet allow ftrace to take page faults per se within its probe, but allows its existing probes to adapt to the upcoming change.
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/20241009010718.2050182-3-mathieu.desnoyers@efficios.... Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/trace/trace_events.h | 36 +++++++++++++++++++++++++++++++---- kernel/trace/trace_syscalls.c | 12 ++++++++++++ 2 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h index c2f9cabf154d1..fa0d51cad57a8 100644 --- a/include/trace/trace_events.h +++ b/include/trace/trace_events.h @@ -244,6 +244,9 @@ static struct trace_event_fields trace_event_fields_##call[] = { \ tstruct \ {} };
+#undef DECLARE_EVENT_SYSCALL_CLASS +#define DECLARE_EVENT_SYSCALL_CLASS DECLARE_EVENT_CLASS + #undef DEFINE_EVENT_PRINT #define DEFINE_EVENT_PRINT(template, name, proto, args, print)
@@ -374,11 +377,11 @@ static inline notrace int trace_event_get_offsets_##call( \
#include "stages/stage6_event_callback.h"
-#undef DECLARE_EVENT_CLASS -#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ - \ + +#undef __DECLARE_EVENT_CLASS +#define __DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ static notrace void \ -trace_event_raw_event_##call(void *__data, proto) \ +do_trace_event_raw_event_##call(void *__data, proto) \ { \ struct trace_event_file *trace_file = __data; \ struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\ @@ -403,6 +406,29 @@ trace_event_raw_event_##call(void *__data, proto) \ \ trace_event_buffer_commit(&fbuffer); \ } + +#undef DECLARE_EVENT_CLASS +#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ +__DECLARE_EVENT_CLASS(call, PARAMS(proto), PARAMS(args), PARAMS(tstruct), \ + PARAMS(assign), PARAMS(print)) \ +static notrace void \ +trace_event_raw_event_##call(void *__data, proto) \ +{ \ + do_trace_event_raw_event_##call(__data, args); \ +} + +#undef DECLARE_EVENT_SYSCALL_CLASS +#define DECLARE_EVENT_SYSCALL_CLASS(call, proto, args, tstruct, assign, print) \ +__DECLARE_EVENT_CLASS(call, PARAMS(proto), PARAMS(args), PARAMS(tstruct), \ + PARAMS(assign), PARAMS(print)) \ +static notrace void \ +trace_event_raw_event_##call(void *__data, proto) \ +{ \ + preempt_disable_notrace(); \ + do_trace_event_raw_event_##call(__data, args); \ + preempt_enable_notrace(); \ +} + /* * The ftrace_test_probe is compiled out, it is only here as a build time check * to make sure that if the tracepoint handling changes, the ftrace probe will @@ -418,6 +444,8 @@ static inline void ftrace_test_probe_##call(void) \
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+#undef __DECLARE_EVENT_CLASS + #include "stages/stage7_class_define.h"
#undef DECLARE_EVENT_CLASS diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 9c581d6da843a..f76efcb6336aa 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -299,6 +299,12 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) int syscall_nr; int size;
+ /* + * Syscall probe called with preemption enabled, but the ring + * buffer and per-cpu data require preemption to be disabled. + */ + guard(preempt_notrace)(); + syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return; @@ -338,6 +344,12 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret) struct trace_event_buffer fbuffer; int syscall_nr;
+ /* + * Syscall probe called with preemption enabled, but the ring + * buffer and per-cpu data require preemption to be disabled. + */ + guard(preempt_notrace)(); + syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return;