[PATCH 6.9 102/374] perf dwarf-aux: Add die_collect_vars()

Greg Kroah-Hartman
2024-06-06T14:09:30Z

From: Namhyung Kim <namhyung@kernel.org>

[ Upstream commit 932dcc2c39aedf54ef291bc0b4129a54f5fe1e84 ]

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>
Stable-dep-of: c9d492378fae ("perf dwarf-aux: Fix build with HAVE_DWARF_CFI_SUPPORT")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/dwarf-aux.c | 118 +++++++++++++++++++++++++++---------
tools/perf/util/dwarf-aux.h | 17 ++++++
2 files changed, 107 insertions(+), 28 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index f7f7171539d3c..ff1874ae0832e 100644
--- 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
@@ -1493,41 +1527,69 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr pc,
*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 85dd527ae1f70..efafd3a1f5b6f 100644
--- 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 */
@@ -150,6 +159,9 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr pc,
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,
@@ -178,6 +190,11 @@ 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
--
2.43.0