• Steven Rostedt (Red Hat)'s avatar
    ftrace/x86/extable: Add is_ftrace_trampoline() function · aec0be2d
    Steven Rostedt (Red Hat) authored
    Stack traces that happen from function tracing check if the address
    on the stack is a __kernel_text_address(). That is, is the address
    kernel code. This calls core_kernel_text() which returns true
    if the address is part of the builtin kernel code. It also calls
    is_module_text_address() which returns true if the address belongs
    to module code.
    But what is missing is ftrace dynamically allocated trampolines.
    These trampolines are allocated for individual ftrace_ops that
    call the ftrace_ops callback functions directly. But if they do a
    stack trace, the code checking the stack wont detect them as they
    are neither core kernel code nor module address space.
    Adding another field to ftrace_ops that also stores the size of
    the trampoline assigned to it we can create a new function called
    is_ftrace_trampoline() that returns true if the address is a
    dynamically allocate ftrace trampoline. Note, it ignores trampolines
    that are not dynamically allocated as they will return true with
    the core_kernel_text() function.
    Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
extable.c 4 KB