perf machine: Refine the function for LBR call stack reconstruction

LBR only collect the user call stack. To reconstruct a call stack, both
kernel call stack and user call stack are required. The function
resolve_lbr_callchain_sample() mix the kernel call stack and user call
stack.

Now, with the help of HW idx, perf tool can reconstruct a more complete
call stack by adding some user call stack from previous sample. However,
current implementation is hard to be extended to support it.

Current code path for resolve_lbr_callchain_sample()

  for (j = 0; j < mix_chain_nr; j++) {
       if (ORDER_CALLEE) {
             if (kernel callchain)
                  Fill callchain info
             else if (LBR callchain)
                  Fill callchain info
       } else {
             if (LBR callchain)
                  Fill callchain info
             else if (kernel callchain)
                  Fill callchain info
       }
       add_callchain_ip();
  }

With the patch,

  if (ORDER_CALLEE) {
       for (j = 0; j < NUM of kernel callchain) {
             Fill callchain info
             add_callchain_ip();
       }
       for (; j < mix_chain_nr) {
             Fill callchain info
             add_callchain_ip();
       }
  } else {
       for (; j < NUM of LBR callchain) {
             Fill callchain info
             add_callchain_ip();
       }
       for (j = 0; j < mix_chain_nr) {
             Fill callchain info
             add_callchain_ip();
       }
  }

No functional changes.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-7-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index be1bd92..0da540e 100644 (file)
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2214,6 +2214,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
        bool branch;
        struct branch_flags *flags;
        int mix_chain_nr;
+       int err;
 
        for (i = 0; i < chain_nr; i++) {
                if (chain->ips[i] == PERF_CONTEXT_USER)
@@ -2239,50 +2240,90 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
         */
        mix_chain_nr = i + 1 + lbr_nr + 1;
 
-       for (j = 0; j < mix_chain_nr; j++) {
-               int err;
-
-               branch = false;
-               flags = NULL;
-
-               if (callchain_param.order == ORDER_CALLEE) {
-                       if (j < i + 1)
-                               ip = chain->ips[j];
-                       else if (j > i + 1) {
-                               k = j - i - 2;
-                               ip = entries[k].from;
-                               branch = true;
-                               flags = &entries[k].flags;
-                       } else {
-                               ip = entries[0].to;
-                               branch = true;
-                               flags = &entries[0].flags;
-                               branch_from = entries[0].from;
-                       }
-               } else {
-                       if (j < lbr_nr) {
-                               k = lbr_nr - j - 1;
-                               ip = entries[k].from;
-                               branch = true;
-                               flags = &entries[k].flags;
-                       } else if (j > lbr_nr)
-                               ip = chain->ips[i + 1 - (j - lbr_nr)];
-                       else {
-                               ip = entries[0].to;
-                               branch = true;
-                               flags = &entries[0].flags;
-                               branch_from = entries[0].from;
-                       }
+       if (callchain_param.order == ORDER_CALLEE) {
+               /* Add kernel ip */
+               for (j = 0; j < i + 1; j++) {
+                       ip = chain->ips[j];
+                       branch = false;
+                       flags = NULL;
+                       err = add_callchain_ip(thread, cursor, parent,
+                                              root_al, &cpumode, ip,
+                                              branch, flags, NULL,
+                                              branch_from);
+                       if (err)
+                               goto error;
                }
+               /* Add LBR ip from first entries.to */
+               ip = entries[0].to;
+               branch = true;
+               flags = &entries[0].flags;
+               branch_from = entries[0].from;
+               err = add_callchain_ip(thread, cursor, parent,
+                                      root_al, &cpumode, ip,
+                                      branch, flags, NULL,
+                                      branch_from);
+               if (err)
+                       goto error;
 
+               /* Add LBR ip from entries.from one by one. */
+               for (j = i + 2; j < mix_chain_nr; j++) {
+                       k = j - i - 2;
+                       ip = entries[k].from;
+                       branch = true;
+                       flags = &entries[k].flags;
+
+                       err = add_callchain_ip(thread, cursor, parent,
+                                              root_al, &cpumode, ip,
+                                              branch, flags, NULL,
+                                              branch_from);
+                       if (err)
+                               goto error;
+               }
+       } else {
+               /* Add LBR ip from entries.from one by one. */
+               for (j = 0; j < lbr_nr; j++) {
+                       k = lbr_nr - j - 1;
+                       ip = entries[k].from;
+                       branch = true;
+                       flags = &entries[k].flags;
+
+                       err = add_callchain_ip(thread, cursor, parent,
+                                              root_al, &cpumode, ip,
+                                              branch, flags, NULL,
+                                              branch_from);
+                       if (err)
+                               goto error;
+               }
+
+               /* Add LBR ip from first entries.to */
+               ip = entries[0].to;
+               branch = true;
+               flags = &entries[0].flags;
+               branch_from = entries[0].from;
                err = add_callchain_ip(thread, cursor, parent,
                                       root_al, &cpumode, ip,
                                       branch, flags, NULL,
                                       branch_from);
                if (err)
-                       return (err < 0) ? err : 0;
+                       goto error;
+
+               /* Add kernel ip */
+               for (j = lbr_nr + 1; j < mix_chain_nr; j++) {
+                       ip = chain->ips[i + 1 - (j - lbr_nr)];
+                       branch = false;
+                       flags = NULL;
+                       err = add_callchain_ip(thread, cursor, parent,
+                                              root_al, &cpumode, ip,
+                                              branch, flags, NULL,
+                                              branch_from);
+                       if (err)
+                               goto error;
+               }
        }
        return 1;
+
+error:
+       return (err < 0) ? err : 0;
 }
 
 static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,