perf dwarf-aux: Add die_collect_vars()

The die_collect_vars() is to find all variable information in the scope
including function parameters.  The struct die_var_type is to save the
type of the variable with the location (reg and offset) as well as where
it's defined in the code (addr).

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index e84d0d6a7750030a3951eb3e9e5fca159cbeb49a..785aa7a3d7254124b4fd65892ee9732fb032a714 100644 (file)
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1136,6 +1136,40 @@ int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
        return ret < 0 ? ret : strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
 }
 
+#if defined(HAVE_DWARF_GETLOCATIONS_SUPPORT) || defined(HAVE_DWARF_CFI_SUPPORT)
+static int reg_from_dwarf_op(Dwarf_Op *op)
+{
+       switch (op->atom) {
+       case DW_OP_reg0 ... DW_OP_reg31:
+               return op->atom - DW_OP_reg0;
+       case DW_OP_breg0 ... DW_OP_breg31:
+               return op->atom - DW_OP_breg0;
+       case DW_OP_regx:
+       case DW_OP_bregx:
+               return op->number;
+       default:
+               break;
+       }
+       return -1;
+}
+
+static int offset_from_dwarf_op(Dwarf_Op *op)
+{
+       switch (op->atom) {
+       case DW_OP_reg0 ... DW_OP_reg31:
+       case DW_OP_regx:
+               return 0;
+       case DW_OP_breg0 ... DW_OP_breg31:
+               return op->number;
+       case DW_OP_bregx:
+               return op->number2;
+       default:
+               break;
+       }
+       return -1;
+}
+#endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT || HAVE_DWARF_CFI_SUPPORT */
+
 #ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
 /**
  * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
@@ -1476,41 +1510,69 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr,
                *offset = data.offset;
        return result;
 }
-#endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
-#ifdef HAVE_DWARF_CFI_SUPPORT
-static int reg_from_dwarf_op(Dwarf_Op *op)
+static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg)
 {
-       switch (op->atom) {
-       case DW_OP_reg0 ... DW_OP_reg31:
-               return op->atom - DW_OP_reg0;
-       case DW_OP_breg0 ... DW_OP_breg31:
-               return op->atom - DW_OP_breg0;
-       case DW_OP_regx:
-       case DW_OP_bregx:
-               return op->number;
-       default:
-               break;
-       }
-       return -1;
+       struct die_var_type **var_types = arg;
+       Dwarf_Die type_die;
+       int tag = dwarf_tag(die_mem);
+       Dwarf_Attribute attr;
+       Dwarf_Addr base, start, end;
+       Dwarf_Op *ops;
+       size_t nops;
+       struct die_var_type *vt;
+
+       if (tag != DW_TAG_variable && tag != DW_TAG_formal_parameter)
+               return DIE_FIND_CB_SIBLING;
+
+       if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
+               return DIE_FIND_CB_SIBLING;
+
+       /*
+        * Only collect the first location as it can reconstruct the
+        * remaining state by following the instructions.
+        * start = 0 means it covers the whole range.
+        */
+       if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
+               return DIE_FIND_CB_SIBLING;
+
+       if (die_get_real_type(die_mem, &type_die) == NULL)
+               return DIE_FIND_CB_SIBLING;
+
+       vt = malloc(sizeof(*vt));
+       if (vt == NULL)
+               return DIE_FIND_CB_END;
+
+       vt->die_off = dwarf_dieoffset(&type_die);
+       vt->addr = start;
+       vt->reg = reg_from_dwarf_op(ops);
+       vt->offset = offset_from_dwarf_op(ops);
+       vt->next = *var_types;
+       *var_types = vt;
+
+       return DIE_FIND_CB_SIBLING;
 }
 
-static int offset_from_dwarf_op(Dwarf_Op *op)
+/**
+ * die_collect_vars - Save all variables and parameters
+ * @sc_die: a scope DIE
+ * @var_types: a pointer to save the resulting list
+ *
+ * Save all variables and parameters in the @sc_die and save them to @var_types.
+ * The @var_types is a singly-linked list containing type and location info.
+ * Actual type can be retrieved using dwarf_offdie() with 'die_off' later.
+ *
+ * Callers should free @var_types.
+ */
+void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types)
 {
-       switch (op->atom) {
-       case DW_OP_reg0 ... DW_OP_reg31:
-       case DW_OP_regx:
-               return 0;
-       case DW_OP_breg0 ... DW_OP_breg31:
-               return op->number;
-       case DW_OP_bregx:
-               return op->number2;
-       default:
-               break;
-       }
-       return -1;
+       Dwarf_Die die_mem;
+
+       die_find_child(sc_die, __die_collect_vars_cb, (void *)var_types, &die_mem);
 }
+#endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
+#ifdef HAVE_DWARF_CFI_SUPPORT
 /**
  * die_get_cfa - Get frame base information
  * @dwarf: a Dwarf info

diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index 9973801a20c1752905d164f5ee84f4daaee8dcbe..cd171b06fd4c660143eee90e3d6f96dd6d1227ce 100644 (file)
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -135,6 +135,15 @@ void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
 /* Get the list of including scopes */
 int die_get_scopes(Dwarf_Die *cu_die, Dwarf_Addr pc, Dwarf_Die **scopes);
 
+/* Variable type information */
+struct die_var_type {
+       struct die_var_type *next;
+       u64 die_off;
+       u64 addr;
+       int reg;
+       int offset;
+};
+
 #ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
 
 /* Get byte offset range of given variable DIE */
@@ -149,6 +158,9 @@ Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die, Dwarf_Addr pc, int reg,
 Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr,
                                     Dwarf_Die *die_mem, int *offset);
 
+/* Save all variables and parameters in this scope */
+void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types);
+
 #else /*  HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
 static inline int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
@@ -176,6 +188,11 @@ static inline Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die __maybe_unu
        return NULL;
 }
 
+static inline void die_collect_vars(Dwarf_Die *sc_die __maybe_unused,
+                                   struct die_var_type **var_types __maybe_unused)
+{
+}
+
 #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
 #ifdef HAVE_DWARF_CFI_SUPPORT