perf annotate-data: Handle direct global variable access

Like per-cpu base offset array, sometimes it accesses the global
variable directly using the offset.  Allow this type of instructions as
long as it finds a global variable for the address.

  movslq  %edi, %rcx
  mov     -0x7dc94ae0(,%rcx,8), %rcx   <<<--- here

As %rcx has a valid type (i.e. array index) from the first instruction,
it will be checked by the first case in check_matching_type().  But as
it's not a pointer type, the match will fail.  But in this case, it
should check if it accesses the kernel global array variable.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240502060011.1838090-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 4dd0911904f21352ad1356f74d89a47dff15c6d2..f1e52a531563ad07f4f65f07798e1c0ff09ad63f 100644 (file)
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -1256,14 +1256,19 @@ static int check_matching_type(struct type_state *state,
        if (state->regs[reg].ok && state->regs[reg].kind == TSR_KIND_TYPE) {
                int tag = dwarf_tag(&state->regs[reg].type);
 
-               pr_debug_dtp("\n");
-
                /*
                 * Normal registers should hold a pointer (or array) to
                 * dereference a memory location.
                 */
-               if (tag != DW_TAG_pointer_type && tag != DW_TAG_array_type)
+               if (tag != DW_TAG_pointer_type && tag != DW_TAG_array_type) {
+                       if (dloc->op->offset < 0 && reg != state->stack_reg)
+                               goto check_kernel;
+
+                       pr_debug_dtp("\n");
                        return -1;
+               }
+
+               pr_debug_dtp("\n");
 
                /* Remove the pointer and get the target type */
                if (die_get_real_type(&state->regs[reg].type, type_die) == NULL)
@@ -1376,12 +1381,14 @@ static int check_matching_type(struct type_state *state,
                return -1;
        }
 
-       if (map__dso(dloc->ms->map)->kernel && arch__is(dloc->arch, "x86")) {
+check_kernel:
+       if (map__dso(dloc->ms->map)->kernel) {
                u64 addr;
                int offset;
 
                /* Direct this-cpu access like "%gs:0x34740" */
-               if (dloc->op->segment == INSN_SEG_X86_GS && dloc->op->imm) {
+               if (dloc->op->segment == INSN_SEG_X86_GS && dloc->op->imm &&
+                   arch__is(dloc->arch, "x86")) {
                        pr_debug_dtp(" this-cpu var\n");
 
                        addr = dloc->op->offset;
@@ -1394,17 +1401,13 @@ static int check_matching_type(struct type_state *state,
                        return -1;
                }
 
-               /* Access to per-cpu base like "-0x7dcf0500(,%rdx,8)" */
+               /* Access to global variable like "-0x7dcf0500(,%rdx,8)" */
                if (dloc->op->offset < 0 && reg != state->stack_reg) {
-                       const char *var_name = NULL;
-
                        addr = (s64) dloc->op->offset;
 
-                       if (get_global_var_info(dloc, addr, &var_name, &offset) &&
-                           !strcmp(var_name, "__per_cpu_offset") && offset == 0 &&
-                           get_global_var_type(cu_die, dloc, dloc->ip, addr,
+                       if (get_global_var_type(cu_die, dloc, dloc->ip, addr,
                                                &offset, type_die)) {
-                               pr_debug_dtp(" percpu base\n");
+                               pr_debug_dtp(" global var\n");
 
                                dloc->type_offset = offset;
                                return 1;