Add support for passing a list of exported symbols to gendwarfksyms via stdin and filter out non-exported symbols from the output.
Signed-off-by: Sami Tolvanen <[email protected]> --- scripts/gendwarfksyms/Makefile | 1 + scripts/gendwarfksyms/dwarf.c | 53 ++++++++++++++- scripts/gendwarfksyms/gendwarfksyms.c | 4 +- scripts/gendwarfksyms/gendwarfksyms.h | 21 ++++++ scripts/gendwarfksyms/symbols.c | 96 +++++++++++++++++++++++++++ 5 files changed, 171 insertions(+), 4 deletions(-) create mode 100644 scripts/gendwarfksyms/symbols.c diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile index c1389c161f9c..623f8fc975ea 100644 --- a/scripts/gendwarfksyms/Makefile +++ b/scripts/gendwarfksyms/Makefile @@ -2,6 +2,7 @@ hostprogs-always-y += gendwarfksyms gendwarfksyms-objs += gendwarfksyms.o gendwarfksyms-objs += dwarf.o +gendwarfksyms-objs += symbols.o HOST_EXTRACFLAGS := -I $(srctree)/tools/include HOSTLDLIBS_gendwarfksyms := -ldw -lelf diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c index 65a29d0bd8f4..71cfab0553da 100644 --- a/scripts/gendwarfksyms/dwarf.c +++ b/scripts/gendwarfksyms/dwarf.c @@ -5,6 +5,48 @@ #include "gendwarfksyms.h" +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); +} + +static const char *get_name(Dwarf_Die *die) +{ + Dwarf_Attribute attr; + + /* rustc uses DW_AT_linkage_name for exported symbols */ + if (dwarf_attr(die, DW_AT_linkage_name, &attr) || + dwarf_attr(die, DW_AT_name, &attr)) { + return dwarf_formstring(&attr); + } + + return NULL; +} + +static bool is_export_symbol(struct state *state, Dwarf_Die *die) +{ + Dwarf_Die *source = die; + Dwarf_Die origin; + + state->sym = NULL; + + /* 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_name(die)); + + /* Look up using the origin name if there are no matches. */ + if (!state->sym && source != die) + state->sym = symbol_get(get_name(source)); + + state->die = *source; + return !!state->sym; +} + /* * Type string processing */ @@ -40,7 +82,7 @@ int process_die_container(struct state *state, Dwarf_Die *die, } /* - * Symbol processing + * Exported symbol processing */ static int process_subprogram(struct state *state, Dwarf_Die *die) { @@ -67,10 +109,15 @@ static int process_exported_symbols(struct state *state, Dwarf_Die *die) /* Possible exported symbols */ case DW_TAG_subprogram: case DW_TAG_variable: + if (!is_export_symbol(state, die)) + return 0; + + debug("%s", state->sym->name); + if (tag == DW_TAG_subprogram) - check(process_subprogram(state, die)); + check(process_subprogram(state, &state->die)); else - check(process_variable(state, die)); + check(process_variable(state, &state->die)); return 0; default: diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c index 27f2d6423c45..d209b237766b 100644 --- a/scripts/gendwarfksyms/gendwarfksyms.c +++ b/scripts/gendwarfksyms/gendwarfksyms.c @@ -27,7 +27,7 @@ static const struct { static int usage(void) { - error("usage: gendwarfksyms [options] elf-object-file ..."); + error("usage: gendwarfksyms [options] elf-object-file ... < symbol-list"); return -1; } @@ -105,6 +105,8 @@ int main(int argc, const char **argv) if (parse_options(argc, argv) < 0) return usage(); + check(symbol_read_exports(stdin)); + for (n = 0; n < object_count; n++) { Dwfl *dwfl; int fd; diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h index 5ab7ce7d4efb..03f3e408a839 100644 --- a/scripts/gendwarfksyms/gendwarfksyms.h +++ b/scripts/gendwarfksyms/gendwarfksyms.h @@ -7,9 +7,11 @@ #include <elfutils/libdw.h> #include <elfutils/libdwfl.h> #include <linux/hashtable.h> +#include <linux/jhash.h> #include <inttypes.h> #include <stdlib.h> #include <stdio.h> +#include <string.h> #ifndef __GENDWARFKSYMS_H #define __GENDWARFKSYMS_H @@ -56,6 +58,23 @@ extern bool debug; /* Error == negative values */ #define checkp(expr) __check(expr, __res < 0, __res) +/* + * symbols.c + */ + +static inline u32 name_hash(const char *name) +{ + return jhash(name, strlen(name), 0); +} + +struct symbol { + const char *name; + struct hlist_node name_hash; +}; + +extern int symbol_read_exports(FILE *file); +extern struct symbol *symbol_get(const char *name); + /* * dwarf.c */ @@ -63,6 +82,8 @@ extern bool debug; struct state { Dwfl_Module *mod; Dwarf *dbg; + struct symbol *sym; + Dwarf_Die die; }; typedef int (*die_callback_t)(struct state *state, Dwarf_Die *die); diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c new file mode 100644 index 000000000000..673ad9cf9e77 --- /dev/null +++ b/scripts/gendwarfksyms/symbols.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2024 Google LLC + */ + +#include "gendwarfksyms.h" + +#define SYMBOL_HASH_BITS 15 +static DEFINE_HASHTABLE(symbol_names, SYMBOL_HASH_BITS); + +typedef int (*symbol_callback_t)(struct symbol *, void *arg); + +static int for_each(const char *name, symbol_callback_t func, void *data) +{ + struct hlist_node *tmp; + struct symbol *match; + + if (!name || !*name) + return 0; + + hash_for_each_possible_safe(symbol_names, match, tmp, name_hash, + name_hash(name)) { + if (strcmp(match->name, name)) + continue; + + if (func) + check(func(match, data)); + + return 1; + } + + return 0; +} + +static bool is_exported(const char *name) +{ + return checkp(for_each(name, NULL, NULL)) > 0; +} + +int symbol_read_exports(FILE *file) +{ + struct symbol *sym; + char *line = NULL; + char *name = NULL; + size_t size = 0; + int nsym = 0; + + while (getline(&line, &size, file) > 0) { + if (sscanf(line, "%ms\n", &name) != 1) { + error("malformed input line: %s", line); + return -1; + } + + free(line); + line = NULL; + + if (is_exported(name)) + continue; /* Ignore duplicates */ + + sym = malloc(sizeof(struct symbol)); + if (!sym) { + error("malloc failed"); + return -1; + } + + sym->name = name; + name = NULL; + + hash_add(symbol_names, &sym->name_hash, name_hash(sym->name)); + ++nsym; + + debug("%s", sym->name); + } + + if (line) + free(line); + + debug("%d exported symbols", nsym); + return 0; +} + +static int get_symbol(struct symbol *sym, void *arg) +{ + struct symbol **res = arg; + + *res = sym; + return 0; +} + +struct symbol *symbol_get(const char *name) +{ + struct symbol *sym = NULL; + + for_each(name, get_symbol, &sym); + return sym; +} -- 2.46.0.184.g6999bdac58-goog
