lkml.org 
[lkml]   [2010]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 01/40] ftrace syscalls: don't add events for unmapped syscalls
    Date
    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;
    + }

    if (set_syscall_print_fmt(call) < 0)
    return -ENOMEM;
    --
    1.7.1


    \
     
     \ /
      Last update: 2010-06-23 12:07    [W:0.021 / U:0.052 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site