Convert the definition of the system call enter/exit tracepoints to faultable tracepoints now that all upstream tracers handle it. This allows tracers to fault-in userspace system call arguments such as path strings within their probe callbacks. Link: https://lore.kernel.org/lkml/20231002202531.3160-1-mathieu.desnoyers@xxxxxxxxxxxx/ Co-developed-by: Michael Jeanson <mjeanson@xxxxxxxxxxxx> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Signed-off-by: Michael Jeanson <mjeanson@xxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> 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: bpf@xxxxxxxxxxxxxxx Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> --- Since v4: - Use 'guard(preempt_notrace)'. - Add brackets to multiline 'if' statements. --- include/trace/events/syscalls.h | 4 +-- kernel/trace/trace_syscalls.c | 52 ++++++++++++++++++++++++++++----- 2 files changed, 46 insertions(+), 10 deletions(-) diff --git a/include/trace/events/syscalls.h b/include/trace/events/syscalls.h index b6e0cbc2c71f..dc30e3004818 100644 --- a/include/trace/events/syscalls.h +++ b/include/trace/events/syscalls.h @@ -15,7 +15,7 @@ #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS -TRACE_EVENT_FN(sys_enter, +TRACE_EVENT_FN_MAY_FAULT(sys_enter, TP_PROTO(struct pt_regs *regs, long id), @@ -41,7 +41,7 @@ TRACE_EVENT_FN(sys_enter, TRACE_EVENT_FLAGS(sys_enter, TRACE_EVENT_FL_CAP_ANY) -TRACE_EVENT_FN(sys_exit, +TRACE_EVENT_FN_MAY_FAULT(sys_exit, TP_PROTO(struct pt_regs *regs, long ret), diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 9c581d6da843..314666d663b6 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; + /* + * Probe called with preemption enabled (may_fault), but 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; + /* + * Probe called with preemption enabled (may_fault), but 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; @@ -376,8 +388,11 @@ static int reg_event_syscall_enter(struct trace_event_file *file, if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return -ENOSYS; mutex_lock(&syscall_trace_lock); - if (!tr->sys_refcount_enter) - ret = register_trace_sys_enter(ftrace_syscall_enter, tr); + if (!tr->sys_refcount_enter) { + ret = register_trace_prio_flags_sys_enter(ftrace_syscall_enter, tr, + TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_FAULT); + } if (!ret) { rcu_assign_pointer(tr->enter_syscall_files[num], file); tr->sys_refcount_enter++; @@ -414,8 +429,11 @@ static int reg_event_syscall_exit(struct trace_event_file *file, if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return -ENOSYS; mutex_lock(&syscall_trace_lock); - if (!tr->sys_refcount_exit) - ret = register_trace_sys_exit(ftrace_syscall_exit, tr); + if (!tr->sys_refcount_exit) { + ret = register_trace_prio_flags_sys_exit(ftrace_syscall_exit, tr, + TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_FAULT); + } if (!ret) { rcu_assign_pointer(tr->exit_syscall_files[num], file); tr->sys_refcount_exit++; @@ -582,6 +600,12 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) int rctx; int size; + /* + * Probe called with preemption enabled (may_fault), but 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; @@ -630,8 +654,11 @@ static int perf_sysenter_enable(struct trace_event_call *call) num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); - if (!sys_perf_refcount_enter) - ret = register_trace_sys_enter(perf_syscall_enter, NULL); + if (!sys_perf_refcount_enter) { + ret = register_trace_prio_flags_sys_enter(perf_syscall_enter, NULL, + TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_FAULT); + } if (ret) { pr_info("event trace: Could not activate syscall entry trace point"); } else { @@ -682,6 +709,12 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret) int rctx; int size; + /* + * Probe called with preemption enabled (may_fault), but 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; @@ -727,8 +760,11 @@ static int perf_sysexit_enable(struct trace_event_call *call) num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); - if (!sys_perf_refcount_exit) - ret = register_trace_sys_exit(perf_syscall_exit, NULL); + if (!sys_perf_refcount_exit) { + ret = register_trace_prio_flags_sys_exit(perf_syscall_exit, NULL, + TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_FAULT); + } if (ret) { pr_info("event trace: Could not activate syscall exit trace point"); } else { -- 2.39.2
