Re: [PATCH] perf: Get kernel start address by symbol name

[Jiri Olsa <jolsa@redhat.com>]

On Mon, Jun 16, 2014 at 10:06:49AM +0200, Jiri Olsa wrote:
> On Fri, Jun 13, 2014 at 11:45:21AM -0700, Simon Que wrote:
> > The function machine__get_kernel_start_addr() was taking the first symbol
> > of kallsyms as the start address. This is incorrect in certain cases
> > where the first symbol is something at 0, while the actual kernel
> > functions begin at a later point (e.g. 0x80200000).
> > 
> > This patch fixes machine__get_kernel_start_addr() to search for the
> > symbol "_text" or "_stext", which marks the beginning of kernel mapping.
> > This was already being done in machine__create_kernel_maps(). Thus, this
> > patch is just a refactor, to move that code into
> > machine__get_kernel_start_addr().
> > 
> > Change-Id: I0c38c36f5e8b0f4fb92a6f57211fa45aabe545a6
> > Signed-off-by: Simon Que <sque@chromium.org>
> 
> hi,
> looks good to me, adding Adrian to the loop

well, apart from this compile error ;-)

[jolsa@krava perf]$ make
  BUILD:   Doing 'make -j4' parallel build
  CC       util/machine.o
  SUBDIR   /home/jolsa/kernel.org/linux-perf/tools/lib/traceevent/
util/machine.c: In function ‘machine__get_kernel_start_addr’:
util/machine.c:520:6: error: ‘addr’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  u64 addr;
      ^
util/machine.c: In function ‘machine__process_kernel_mmap_event’:
util/machine.c:547:42: error: ‘addr’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   machine->vmlinux_maps[type] = map__new2(start, kernel, type);
                                          ^
util/machine.c:520:6: note: ‘addr’ was declared here
  u64 addr;
      ^
cc1: all warnings being treated as errors
make[1]: *** [util/machine.o] Error 1
make: *** [all] Error 2


jirka