linux-kernel - [PATCH 1/6] perf dwarf-aux: Add die_collect_global

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Date: Wed,  1 May 2024 23:00:06 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Masami Hiramatsu <mhiramat@...nel.org>
Subject: [PATCH 1/6] perf dwarf-aux: Add die_collect_global_vars()

This function is to search all global variables in the CU.  We want to
have the list of global variables at once and match them later.

Cc: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/dwarf-aux.c | 62 +++++++++++++++++++++++++++++++++++++
 tools/perf/util/dwarf-aux.h |  8 +++++
 2 files changed, 70 insertions(+)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 40cfbdfe2d75..c0a492e65388 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1630,6 +1630,68 @@ void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types)
 
 	die_find_child(sc_die, __die_collect_vars_cb, (void *)var_types, &die_mem);
 }
+
+static int __die_collect_global_vars_cb(Dwarf_Die *die_mem, void *arg)
+{
+	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)
+		return DIE_FIND_CB_SIBLING;
+
+	if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
+		return DIE_FIND_CB_SIBLING;
+
+	/* Only collect the location with an absolute address. */
+	if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
+		return DIE_FIND_CB_SIBLING;
+
+	if (ops->atom != DW_OP_addr)
+		return DIE_FIND_CB_SIBLING;
+
+	if (!check_allowed_ops(ops, nops))
+		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 = ops->number;
+	vt->reg = -1;
+	vt->offset = 0;
+	vt->next = *var_types;
+	*var_types = vt;
+
+	return DIE_FIND_CB_SIBLING;
+}
+
+/**
+ * die_collect_global_vars - Save all global variables
+ * @cu_die: a CU DIE
+ * @var_types: a pointer to save the resulting list
+ *
+ * Save all global variables in the @cu_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_global_vars(Dwarf_Die *cu_die, struct die_var_type **var_types)
+{
+	Dwarf_Die die_mem;
+
+	die_find_child(cu_die, __die_collect_global_vars_cb, (void *)var_types, &die_mem);
+}
 #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
 #ifdef HAVE_DWARF_CFI_SUPPORT
diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index b0f25fbf9668..24446412b869 100644
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -171,6 +171,9 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr,
 /* Save all variables and parameters in this scope */
 void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types);
 
+/* Save all global variables in this CU */
+void die_collect_global_vars(Dwarf_Die *cu_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,
@@ -203,6 +206,11 @@ static inline void die_collect_vars(Dwarf_Die *sc_die __maybe_unused,
 {
 }
 
+static inline void die_collect_global_vars(Dwarf_Die *cu_die __maybe_unused,
+					   struct die_var_type **var_types __maybe_unused)
+{
+}
+
 #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
 
 #ifdef HAVE_DWARF_CFI_SUPPORT
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog