[PATCH 04/15] gendwarfksyms: Expand base_type

[Sami Tolvanen <samitolvanen@google.com>]

Add support for expanding basic DWARF attributes and DW_TAG_base_type
types.

Example usage:

  $ nm -p --defined-only vmlinux.o | \
      awk '/ (T|R|D) / {printf "%s %s\n",$1, $3}' | \
      grep loops_per_jiffy | \
      ./tools/gendwarfksyms/gendwarfksyms --debug vmlinux.o

Output:

  gendwarfksyms: symbol_read_list: adding { 4b0, "loops_per_jiffy" }
  gendwarfksyms: process_modules: vmlinux.o
  gendwarfksyms: process_exported_symbols: loops_per_jiffy (@ 4b0)
  variable base_type unsigned long byte_size(8);
  #SYMVER loops_per_jiffy 0xc694aefc

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 tools/gendwarfksyms/types.c | 109 +++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/tools/gendwarfksyms/types.c b/tools/gendwarfksyms/types.c
index 47ae967d42ee..7508d0fb8b80 100644
--- a/tools/gendwarfksyms/types.c
+++ b/tools/gendwarfksyms/types.c
@@ -16,6 +16,7 @@
 	}
 
 DEFINE_GET_ATTR(addr, Dwarf_Addr)
+DEFINE_GET_ATTR(udata, Dwarf_Word)
 
 static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
 {
@@ -82,6 +83,73 @@ static int process(struct state *state, const char *s)
 	return 0;
 }
 
+#define MAX_FMT_BUFFER_SIZE 128
+
+static int process_fmt(struct state *state, const char *fmt, ...)
+{
+	char buf[MAX_FMT_BUFFER_SIZE];
+	va_list args;
+	int res;
+
+	va_start(args, fmt);
+
+	res = check(vsnprintf(buf, sizeof(buf), fmt, args));
+	if (res >= MAX_FMT_BUFFER_SIZE - 1) {
+		error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE");
+		res = -1;
+	} else {
+		check(process(state, buf));
+	}
+
+	va_end(args);
+	return res;
+}
+
+/* Process a fully qualified name from DWARF scopes */
+static int process_fqn(struct state *state, Dwarf_Die *die)
+{
+	Dwarf_Die *scopes = NULL;
+	const char *name;
+	int res;
+	int i;
+
+	res = check(dwarf_getscopes_die(die, &scopes));
+	if (!res) {
+		name = get_name(die);
+		name = name ?: "<unnamed>";
+		return check(process(state, name));
+	}
+
+	for (i = res - 1; i >= 0; i--) {
+		if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit)
+			continue;
+
+		name = get_name(&scopes[i]);
+		name = name ?: "<unnamed>";
+		check(process(state, name));
+		if (i > 0)
+			check(process(state, "::"));
+	}
+
+	free(scopes);
+	return 0;
+}
+
+#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute)                         \
+	static int process_##attribute##_attr(struct state *state,        \
+					      Dwarf_Die *die)             \
+	{                                                                 \
+		Dwarf_Word value;                                         \
+		if (get_udata_attr(die, DW_AT_##attribute, &value))       \
+			check(process_fmt(state,                          \
+					  " " #attribute "(%" PRIu64 ")", \
+					  value));                        \
+		return 0;                                                 \
+	}
+
+DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
+
 bool match_all(Dwarf_Die *die)
 {
 	return true;
@@ -103,11 +171,48 @@ int process_die_container(struct state *state, Dwarf_Die *die,
 	return 0;
 }
 
+static int process_type(struct state *state, Dwarf_Die *die);
+
+static int process_type_attr(struct state *state, Dwarf_Die *die)
+{
+	Dwarf_Die type;
+
+	if (get_ref_die_attr(die, DW_AT_type, &type))
+		return check(process_type(state, &type));
+
+	/* Compilers can omit DW_AT_type -- print out 'void' to clarify */
+	return check(process(state, "base_type void"));
+}
+
+static int process_base_type(struct state *state, Dwarf_Die *die)
+{
+	check(process(state, "base_type "));
+	check(process_fqn(state, die));
+	check(process_byte_size_attr(state, die));
+	return check(process_alignment_attr(state, die));
+}
+
 static void state_init(struct state *state)
 {
 	state->crc = 0xffffffff;
 }
 
+static int process_type(struct state *state, Dwarf_Die *die)
+{
+	int tag = dwarf_tag(die);
+
+	switch (tag) {
+	case DW_TAG_base_type:
+		check(process_base_type(state, die));
+		break;
+	default:
+		debug("unimplemented type: %x", tag);
+		break;
+	}
+
+	return 0;
+}
+
 /*
  * Exported symbol processing
  */
@@ -118,7 +223,9 @@ static int process_subprogram(struct state *state, Dwarf_Die *die)
 
 static int process_variable(struct state *state, Dwarf_Die *die)
 {
-	return check(process(state, "variable;\n"));
+	check(process(state, "variable "));
+	check(process_type_attr(state, die));
+	return check(process(state, ";\n"));
 }
 
 static int process_exported_symbols(struct state *state, Dwarf_Die *die)
-- 
2.45.2.627.g7a2c4fd464-goog