[PATCH v4 09/19] gendwarfksyms: Expand structure types

Sami Tolvanen
2024-10-08T18:38:53Z

Recursively expand DWARF structure types, i.e. structs, unions, and
enums. Also include relevant DWARF attributes in type strings to
encode structure layout, for example.

Example output with --dump-dies:

subprogram (
formal_parameter structure_type &str {
member pointer_type {
base_type u8 byte_size(1) encoding(7)
} data_ptr data_member_location(0) ,
member base_type usize byte_size(8) encoding(7) length data_member_location(8)
} byte_size(16) alignment(8) msg
)
-> base_type void

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/dwarf.c | 138 +++++++++++++++++++++++++-
scripts/gendwarfksyms/gendwarfksyms.h | 5 +
2 files changed, 141 insertions(+), 2 deletions(-)

diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index ade9b3b7b119..f5cebbdcc212 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -207,9 +207,14 @@ static void process_fqn(struct die *cache, Dwarf_Die *die)
value); \
}

+DEFINE_PROCESS_UDATA_ATTRIBUTE(accessibility)
DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(bit_size)
DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(data_bit_offset)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(data_member_location)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(discr_value)

/* Match functions -- die_match_callback_t */
#define DEFINE_MATCH(type) \
@@ -218,7 +223,9 @@ DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
return dwarf_tag(die) == DW_TAG_##type##_type; \
}

+DEFINE_MATCH(enumerator)
DEFINE_MATCH(formal_parameter)
+DEFINE_MATCH(member)
DEFINE_MATCH(subrange)

bool match_all(Dwarf_Die *die)
@@ -297,6 +304,10 @@ static void __process_list_type(struct state *state, struct die *cache,
process(cache, " ");
process(cache, name);
}
+ process_accessibility_attr(cache, die);
+ process_bit_size_attr(cache, die);
+ process_data_bit_offset_attr(cache, die);
+ process_data_member_location_attr(cache, die);
}

#define DEFINE_PROCESS_LIST_TYPE(type) \
@@ -307,6 +318,7 @@ static void __process_list_type(struct state *state, struct die *cache,
}

DEFINE_PROCESS_LIST_TYPE(formal_parameter)
+DEFINE_PROCESS_LIST_TYPE(member)

/* Container types with DW_AT_type */
static void __process_type(struct state *state, struct die *cache,
@@ -339,6 +351,7 @@ DEFINE_PROCESS_TYPE(reference)
DEFINE_PROCESS_TYPE(restrict)
DEFINE_PROCESS_TYPE(rvalue_reference)
DEFINE_PROCESS_TYPE(shared)
+DEFINE_PROCESS_TYPE(template_type_parameter)
DEFINE_PROCESS_TYPE(volatile)
DEFINE_PROCESS_TYPE(typedef)

@@ -392,6 +405,107 @@ static void process_subroutine_type(struct state *state, struct die *cache,
__process_subroutine_type(state, cache, die, "subroutine_type");
}

+static void process_variant_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process_list_comma(state, cache);
+ process(cache, "variant {");
+ process_linebreak(cache, 1);
+ check(process_die_container(state, cache, die, process_type,
+ match_member_type));
+ process_linebreak(cache, -1);
+ process(cache, "}");
+ process_discr_value_attr(cache, die);
+}
+
+static void process_variant_part_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process_list_comma(state, cache);
+ process(cache, "variant_part {");
+ process_linebreak(cache, 1);
+ check(process_die_container(state, cache, die, process_type,
+ match_all));
+ process_linebreak(cache, -1);
+ process(cache, "}");
+}
+
+static int ___process_structure_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ switch (dwarf_tag(die)) {
+ case DW_TAG_member:
+ case DW_TAG_variant_part:
+ return check(process_type(state, cache, die));
+ case DW_TAG_class_type:
+ case DW_TAG_enumeration_type:
+ case DW_TAG_structure_type:
+ case DW_TAG_template_type_parameter:
+ case DW_TAG_union_type:
+ case DW_TAG_subprogram:
+ /* Skip non-member types, including member functions */
+ return 0;
+ default:
+ error("unexpected structure_type child: %x", dwarf_tag(die));
+ }
+}
+
+static void __process_structure_type(struct state *state, struct die *cache,
+ Dwarf_Die *die, const char *type,
+ die_callback_t process_func,
+ die_match_callback_t match_func)
+{
+ process(cache, type);
+ process_fqn(cache, die);
+ process(cache, " {");
+ process_linebreak(cache, 1);
+
+ check(process_die_container(state, cache, die, process_func,
+ match_func));
+
+ process_linebreak(cache, -1);
+ process(cache, "}");
+
+ process_byte_size_attr(cache, die);
+ process_alignment_attr(cache, die);
+}
+
+#define DEFINE_PROCESS_STRUCTURE_TYPE(structure) \
+ static void process_##structure##_type( \
+ struct state *state, struct die *cache, Dwarf_Die *die) \
+ { \
+ __process_structure_type(state, cache, die, \
+ #structure "_type", \
+ ___process_structure_type, \
+ match_all); \
+ }
+
+DEFINE_PROCESS_STRUCTURE_TYPE(class)
+DEFINE_PROCESS_STRUCTURE_TYPE(structure)
+DEFINE_PROCESS_STRUCTURE_TYPE(union)
+
+static void process_enumerator_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ Dwarf_Word value;
+
+ process_list_comma(state, cache);
+ process(cache, "enumerator");
+ process_fqn(cache, die);
+
+ if (get_udata_attr(die, DW_AT_const_value, &value)) {
+ process(cache, " = ");
+ process_fmt(cache, "%" PRIu64, value);
+ }
+}
+
+static void process_enumeration_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ __process_structure_type(state, cache, die, "enumeration_type",
+ process_type, match_enumerator_type);
+}
+
static void process_base_type(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -402,6 +516,16 @@ static void process_base_type(struct state *state, struct die *cache,
process_alignment_attr(cache, die);
}

+static void process_unspecified_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ /*
+ * These can be emitted for stand-elone assembly code, which means we
+ * might run into them in vmlinux.o.
+ */
+ process(cache, "unspecified_type");
+}
+
static void process_cached(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -462,17 +586,27 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
PROCESS_TYPE(rvalue_reference)
PROCESS_TYPE(shared)
PROCESS_TYPE(volatile)
+ /* Container types */
+ PROCESS_TYPE(class)
+ PROCESS_TYPE(structure)
+ PROCESS_TYPE(union)
+ PROCESS_TYPE(enumeration)
/* Subtypes */
+ PROCESS_TYPE(enumerator)
PROCESS_TYPE(formal_parameter)
+ PROCESS_TYPE(member)
PROCESS_TYPE(subrange)
+ PROCESS_TYPE(template_type_parameter)
+ PROCESS_TYPE(variant)
+ PROCESS_TYPE(variant_part)
/* Other types */
PROCESS_TYPE(array)
PROCESS_TYPE(base)
PROCESS_TYPE(subroutine)
PROCESS_TYPE(typedef)
+ PROCESS_TYPE(unspecified)
default:
- debug("unimplemented type: %x", tag);
- break;
+ error("unexpected type: %x", tag);
}

/* Update cache state and append to the parent (if any) */
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index f31bfcb0dfe7..f317de5b0653 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -63,8 +63,13 @@ extern int dump_dies;
#define checkp(expr) __check(expr, __res < 0)

/* Consistent aliases (DW_TAG_<type>_type) for DWARF tags */
+#define DW_TAG_enumerator_type DW_TAG_enumerator
#define DW_TAG_formal_parameter_type DW_TAG_formal_parameter
+#define DW_TAG_member_type DW_TAG_member
+#define DW_TAG_template_type_parameter_type DW_TAG_template_type_parameter
#define DW_TAG_typedef_type DW_TAG_typedef
+#define DW_TAG_variant_part_type DW_TAG_variant_part
+#define DW_TAG_variant_type DW_TAG_variant

/*
* symbols.c