tracing/syscalls: Don't add events for unmapped syscalls (ba976970) · Commits · 戴 / test

FTRACE_SYSCALLS would create events for each and every system call, even if it had failed to map the system call's name with it's number. This resulted in a number of events being created that would not behave as expected. This could happen, for example, on architectures who's symbol names are unusual and will not match the system call name. It could also happen with system calls which were mapped to sys_ni_syscall. This patch changes the default system call number in the metadata to -1. If the system call name from the metadata is not successfully mapped to a system call number during boot, than the event initialisation routine will now return an error, preventing the event from being created. Signed-off-by:

Ian Munsie <imunsie@au1.ibm.com> LKML-Reference: <1296703645-18718-2-git-send-email-imunsie@au1.ibm.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

include/linux/syscalls.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -158,6 +158,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
		static struct syscall_metadata __used \
		__syscall_meta_##sname = { \
		.name = "sys"#sname, \
		.syscall_nr = -1, /* Filled in at boot */ \
		.nb_args = nb, \
		.types = types_##sname, \
		.args = args_##sname, \
		@@ -175,6 +176,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
		static struct syscall_metadata __used \
		__syscall_meta__##sname = { \
		.name = "sys_"#sname, \
		.syscall_nr = -1, /* Filled in at boot */ \
		.nb_args = 0, \
		.enter_event = &event_enter__##sname, \
		.exit_event = &event_exit__##sname, \

kernel/trace/trace_syscalls.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -424,6 +424,14 @@ void unreg_event_syscall_exit(struct ftrace_event_call *call)
		int init_syscall_trace(struct ftrace_event_call *call)
		{
		int id;
		int num;

		num = ((struct syscall_metadata *)call->data)->syscall_nr;
		if (num < 0 \|\| num >= NR_syscalls) {
		pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
		((struct syscall_metadata *)call->data)->name);
		return -ENOSYS;
		}

		if (set_syscall_print_fmt(call) < 0)
		return -ENOMEM;

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