path: root/scripts/gendwarfksyms/dwarf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2024 Google LLC
 */

#define _GNU_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <stdarg.h>
#include "gendwarfksyms.h"

/* See get_union_kabi_status */
#define KABI_PREFIX "__kabi_"
#define KABI_PREFIX_LEN (sizeof(KABI_PREFIX) - 1)
#define KABI_RESERVED_PREFIX "reserved"
#define KABI_RESERVED_PREFIX_LEN (sizeof(KABI_RESERVED_PREFIX) - 1)
#define KABI_RENAMED_PREFIX "renamed"
#define KABI_RENAMED_PREFIX_LEN (sizeof(KABI_RENAMED_PREFIX) - 1)
#define KABI_IGNORED_PREFIX "ignored"
#define KABI_IGNORED_PREFIX_LEN (sizeof(KABI_IGNORED_PREFIX) - 1)

static inline bool is_kabi_prefix(const char *name)
{
	return name && !strncmp(name, KABI_PREFIX, KABI_PREFIX_LEN);
}

enum kabi_status {
	/* >0 to stop DIE processing */
	KABI_NORMAL = 1,
	KABI_RESERVED,
	KABI_IGNORED,
};

static bool do_linebreak;
static int indentation_level;

/* Line breaks and indentation for pretty-printing */
static void process_linebreak(struct die *cache, int n)
{
	indentation_level += n;
	do_linebreak = true;
	die_map_add_linebreak(cache, n);
}

#define DEFINE_GET_ATTR(attr, type)                                    \
	static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \
				      type *value)                     \
	{                                                              \
		Dwarf_Attribute da;                                    \
		return dwarf_attr(die, id, &da) &&                     \
		       !dwarf_form##attr(&da, value);                  \
	}

DEFINE_GET_ATTR(flag, bool)
DEFINE_GET_ATTR(udata, Dwarf_Word)

static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
{
	Dwarf_Attribute da;

	/* dwarf_formref_die returns a pointer instead of an error value. */
	return dwarf_attr(die, id, &da) && dwarf_formref_die(&da, value);
}

#define DEFINE_GET_STRING_ATTR(attr)                         \
	static const char *get_##attr##_attr(Dwarf_Die *die) \
	{                                                    \
		Dwarf_Attribute da;                          \
		if (dwarf_attr(die, DW_AT_##attr, &da))      \
			return dwarf_formstring(&da);        \
		return NULL;                                 \
	}

DEFINE_GET_STRING_ATTR(name)
DEFINE_GET_STRING_ATTR(linkage_name)

static const char *get_symbol_name(Dwarf_Die *die)
{
	const char *name;

	/* rustc uses DW_AT_linkage_name for exported symbols */
	name = get_linkage_name_attr(die);
	if (!name)
		name = get_name_attr(die);

	return name;
}

static bool match_export_symbol(struct state *state, Dwarf_Die *die)
{
	Dwarf_Die *source = die;
	Dwarf_Die origin;

	/* If the DIE has an abstract origin, use it for type information. */
	if (get_ref_die_attr(die, DW_AT_abstract_origin, &origin))
		source = &origin;

	state->sym = symbol_get(get_symbol_name(die));

	/* Look up using the origin name if there are no matches. */
	if (!state->sym && source != die)
		state->sym = symbol_get(get_symbol_name(source));

	state->die = *source;
	return !!state->sym;
}

/* DW_AT_decl_file -> struct srcfile */
static struct cache srcfile_cache;

static bool is_definition_private(Dwarf_Die *die)
{
	Dwarf_Word filenum;
	Dwarf_Files *files;
	Dwarf_Die cudie;
	const char *s;
	int res;

	/*
	 * Definitions in .c files cannot change the public ABI,
	 * so consider them private.
	 */
	if (!get_udata_attr(die, DW_AT_decl_file, &filenum))
		return false;

	res = cache_get(&srcfile_cache, filenum);
	if (res >= 0)
		return !!res