On Thu, 15 Oct 2020 23:54:58 +0900 Masami Hiramatsu <[email protected]> wrote:
> Hi, > > Here is the 3rd version of the series for real address printing in trace log. > > Here is the previous version, I've fixed [1/3] to use krealloc(), fix memory > allocation error check and add __printf() attribute, according to Steve's > comment. > > https://lore.kernel.org/lkml/160275239876.115066.10891356497426857018.stgit@devnote2/ > > > Since trace_seq_printf() use in-kernel vsprintf() at last, the %p is always > converted to the hash value instead of real address. > > For the dmesg it maybe secure, but for the ftrace, I think it is > meaningless because > > - tracefs is used by root user, so no need to hide it. > - tracefs user can access percpu/cpu*/trace_pipe_raw which stores real > address on the trace buffer. > - external commands like perf doesn't convert to the hash value. > > And when debugging kernel, we would like to know real address which tells > us the address is in which area in the kernel by comparing with kernel > memory mapping. > > However, to compare the trace log with dmesg, we also need a bridging > information. So 3/3 gives the options/hash-ptr knob which switches > the output format. > Thanks Masami, I'm going to hold off on adding this for this merge window, and look at applying it for the next window. -- Steve
