perf report: Use properly build_id kernel binaries

If we bring the recorded perf data together with kernel binary from another
machine using:

	on server A:
	perf archive

	on server B:
	tar xjvf perf.data.tar.bz2 -C ~/.debug

the build_id kernel dso is not properly recognized during the "perf report"
command on server B.

The reason is, that build_id dsos are added during the session initialization,
while the kernel maps are created during the sample event processing.

The machine__create_kernel_maps functions ends up creating new dso object for
kernel, but it does not check if we already have one added by build_id
processing.

Also the build_id reading ABI quirk added in commit:

 - commit b25114817a73bbd2b84ce9dba02ee1ef8989a947
   perf build-id: Add quirk to deal with perf.data file format breakage

populates the "struct build_id_event::pid" with 0, which
is later interpreted as DEFAULT_GUEST_KERNEL_ID.

This is not always correct, so it's better to guess the pid
value based on the "struct build_id_event::header::misc" value.

- Tested with data generated on x86 kernel version v2.6.34
  and reported back on x86_64 current kernel.
- Not tested for guest kernel case.

Note the problem stays for PERF_RECORD_MMAP events recorded by perf that
does not use proper pid (HOST_KERNEL_ID/DEFAULT_GUEST_KERNEL_ID). They are
misinterpreted within the current perf code. Probably there's not much we
can do about that.

Cc: Avi Kivity <avi@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Link: http://lkml.kernel.org/r/20110601194346.GB1934@jolsa.brq.redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 32 insertions, 25 deletions

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a8b53714542a..e142c21ae9a5 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2181,27 +2181,22 @@ size_t machines__fprintf_dsos_buildid(struct rb_root *machines,
         return ret;
 }
 
-struct dso *dso__new_kernel(const char *name)
+static struct dso*
+dso__kernel_findnew(struct machine *machine, const char *name,
+                    const char *short_name, int dso_type)
 {
-        struct dso *dso = dso__new(name ?: "[kernel.kallsyms]");
-
-        if (dso != NULL) {
-                dso__set_short_name(dso, "[kernel]");
-                dso->kernel = DSO_TYPE_KERNEL;
-        }
-
-        return dso;
-}
+        /*
+         * The kernel dso could be created by build_id processing.
+         */
+        struct dso *dso = __dsos__findnew(&machine->kernel_dsos, name);
 
-static struct dso *dso__new_guest_kernel(struct machine *machine,
-                                        const char *name)
-{
-        char bf[PATH_MAX];
-        struct dso *dso = dso__new(name ?: machine__mmap_name(machine, bf,
-                                                              sizeof(bf)));
+        /*
+         * We need to run this in all cases, since during the build_id
+         * processing we had no idea this was the kernel dso.
+         */
         if (dso != NULL) {
-                dso__set_short_name(dso, "[guest.kernel]");
-                dso->kernel = DSO_TYPE_GUEST_KERNEL;
+                dso__set_short_name(dso, short_name);
+                dso->kernel = dso_type;
         }
 
         return dso;
@@ -2219,24 +2214,36 @@ void dso__read_running_kernel_build_id(struct dso *dso, struct machine *machine)
                 dso->has_build_id = true;
 }
 
-static struct dso *machine__create_kernel(struct machine *machine)
+static struct dso *machine__get_kernel(struct machine *machine)
 {
         const char *vmlinux_name = NULL;
         struct dso *kernel;
 
         if (machine__is_host(machine)) {
                 vmlinux_name = symbol_conf.vmlinux_name;
-                kernel = dso__new_kernel(vmlinux_name);
+                if (!vmlinux_name)
+                        vmlinux_name = "[kernel.kallsyms]";
+
+                kernel = dso__kernel_findnew(machine, vmlinux_name,
+                                             "[kernel]",
+                                             DSO_TYPE_KERNEL);
         } else {
+                char bf[PATH_MAX];
+
                 if (machine__is_default_guest(machine))
                         vmlinux_name = symbol_conf.default_guest_vmlinux_name;
-                kernel = dso__new_guest_kernel(machine, vmlinux_name);
+                if (!vmlinux_name)
+                        vmlinux_name = machine__mmap_name(machine, bf,
+                                                          sizeof(bf));
+
+                kernel = dso__kernel_findnew(machine, vmlinux_name,
+                                             "[guest.kernel]",
+                                             DSO_TYPE_GUEST_KERNEL);
         }
 
-        if (kernel != NULL) {
+        if (kernel != NULL && (!kernel->has_build_id))
                 dso__read_running_kernel_build_id(kernel, machine);
-                dsos__add(&machine->kernel_dsos, kernel);
-        }
+
         return kernel;
 }
 
@@ -2340,7 +2347,7 @@ void machine__destroy_kernel_maps(struct machine *machine)
 
 int machine__create_kernel_maps(struct machine *machine)
 {
-        struct dso *kernel = machine__create_kernel(machine);
+        struct dso *kernel = machine__get_kernel(machine);
 
         if (kernel == NULL ||
             __machine__create_kernel_maps(machine, kernel) < 0)