lkml.org 
[lkml]   [2010]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 01/40] ftrace syscalls: don't add events for unmapped syscalls
    From
    Date
    On Wed, 2010-06-23 at 20:02 +1000, Ian Munsie wrote:
    > From: Ian Munsie <imunsie@au1.ibm.com>
    >
    > 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>
    > ---
    > include/linux/syscalls.h | 2 ++
    > kernel/trace/trace_syscalls.c | 8 ++++++++
    > 2 files changed, 10 insertions(+), 0 deletions(-)
    >
    > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    > index 7f614ce..86f082b 100644
    > --- a/include/linux/syscalls.h
    > +++ b/include/linux/syscalls.h
    > @@ -159,6 +159,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
    > __attribute__((section("__syscalls_metadata"))) \
    > __syscall_meta_##sname = { \
    > .name = "sys"#sname, \
    > + .syscall_nr = -1, /* Filled in at boot */ \
    > .nb_args = nb, \
    > .types = types_##sname, \
    > .args = args_##sname, \
    > @@ -176,6 +177,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
    > __attribute__((section("__syscalls_metadata"))) \
    > __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, \
    > diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
    > index 34e3580..82246ce 100644
    > --- a/kernel/trace/trace_syscalls.c
    > +++ b/kernel/trace/trace_syscalls.c
    > @@ -431,6 +431,14 @@ 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;
    > + }

    Perhaps this should be:

    if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)
    return -ENOSYS;

    -- Steve

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




    \
     
     \ /
      Last update: 2010-06-23 17:05    [W:4.789 / U:0.268 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site