• Josh Poimboeuf's avatar
    ftrace: Add return address pointer to ftrace_ret_stack · 9a7c348b
    Josh Poimboeuf authored
    Storing this value will help prevent unwinders from getting out of sync
    with the function graph tracer ret_stack.  Now instead of needing a
    stateful iterator, they can compare the return address pointer to find
    the right ret_stack entry.
    
    Note that an array of 50 ftrace_ret_stack structs is allocated for every
    task.  So when an arch implements this, it will add either 200 or 400
    bytes of memory usage per task (depending on whether it's a 32-bit or
    64-bit platform).
    Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
    Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Byungchul Park <byungchul.park@lge.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Nilay Vaish <nilayvaish@gmail.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    9a7c348b
trace_functions_graph.c 36.4 KB