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tracing/syscalls: Don't add events for unmapped syscalls

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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>
This commit is contained in:
Ian Munsie 2011-02-03 14:27:20 +11:00 committed by Steven Rostedt
parent 075de90c46
commit ba976970c7
2 changed files with 10 additions and 0 deletions
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2
include/linux/syscalls.h
View File

@ -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, \

8
kernel/trace/trace_syscalls.c
View File

@ -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;