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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2024-10-08 21:07:12 -0400
committerSteven Rostedt (Google) <rostedt@goodmis.org>2024-10-09 17:07:00 -0400
commit13d750c2c03e9861e15268574ed2c239cca9c9d5 (patch)
tree6154524b32659ef8255a95c2e2efe5e5521783f1 /kernel/trace
parent0e6caab8db8bc9359d1a8363e1ee9b2205ed704d (diff)
tracing/ftrace: disable preemption in syscall probe
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.com 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>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_syscalls.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 785733245ead..f9b21bac9d45 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;