[RFC 11/31] objtool: Add section/symbol type helpers

Josh Poimboeuf
2024-09-03T04:00:34Z

Add some helper macros to improve readability.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/arch/x86/special.c | 2 +-
tools/objtool/check.c | 66 +++++++++++++-------------
tools/objtool/elf.c | 24 +++++-----
tools/objtool/include/objtool/elf.h | 73 ++++++++++++++++++++++++++++-
tools/objtool/special.c | 4 +-
5 files changed, 120 insertions(+), 49 deletions(-)

diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 4134d27c696b..b0e21b2e9f53 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -95,7 +95,7 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
/* look for a relocation which references .rodata */
text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
insn->offset, insn->len);
- if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
+ if (!text_reloc || !is_section_symbol(text_reloc->sym) ||
!text_reloc->sym->sec->rodata)
return NULL;

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 06e7b3f5481d..95f5de0c293d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -202,12 +202,12 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
if (!func)
return false;

- if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
+ if (!is_local_symbol(func))
for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
if (!strcmp(func->name, global_noreturns[i]))
return true;

- if (func->bind == STB_WEAK)
+ if (is_weak_symbol(func))
return false;

if (!func->len)
@@ -379,7 +379,7 @@ static int decode_instructions(struct objtool_file *file)
u8 prev_len = 0;
u8 idx = 0;

- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_section(sec))
continue;

if (strcmp(sec->name, ".altinstr_replacement") &&
@@ -402,7 +402,7 @@ static int decode_instructions(struct objtool_file *file)
if (!strcmp(sec->name, ".init.text") && !opts.module)
sec->init = true;

- for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
+ for (offset = 0; offset < sec_size(sec); offset += insn->len) {
if (!insns || idx == INSN_CHUNK_MAX) {
insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
if (!insns) {
@@ -422,7 +422,7 @@ static int decode_instructions(struct objtool_file *file)
insn->prev_len = prev_len;

ret = arch_decode_instruction(file, sec, offset,
- sec->sh.sh_size - offset,
+ sec_size(sec) - offset,
insn);
if (ret)
return ret;
@@ -444,12 +444,12 @@ static int decode_instructions(struct objtool_file *file)
// printf("%s: last chunk used: %d\n", sec->name, (int)idx);

sec_for_each_sym(sec, func) {
- if (func->type != STT_NOTYPE && func->type != STT_FUNC)
+ if (!is_notype_symbol(func) && !is_function_symbol(func))
continue;

- if (func->offset == sec->sh.sh_size) {
+ if (func->offset == sec_size(sec)) {
/* Heuristic: likely an "end" symbol */
- if (func->type == STT_NOTYPE)
+ if (is_notype_symbol(func))
continue;
WARN("%s(): STT_FUNC at end of section",
func->name);
@@ -467,7 +467,7 @@ static int decode_instructions(struct objtool_file *file)

sym_for_each_insn(file, func, insn) {
insn->sym = func;
- if (func->type == STT_FUNC &&
+ if (is_function_symbol(func) &&
insn->type == INSN_ENDBR &&
list_empty(&insn->call_node)) {
if (insn->offset == func->offset) {
@@ -509,7 +509,7 @@ static int add_pv_ops(struct objtool_file *file, const char *symname)
break;

func = reloc->sym;
- if (func->type == STT_SECTION)
+ if (is_section_symbol(func))
func = find_symbol_by_offset(reloc->sym->sec,
reloc_addend(reloc));

@@ -569,9 +569,9 @@ static struct instruction *find_last_insn(struct objtool_file *file,
{
struct instruction *insn = NULL;
unsigned int offset;
- unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
+ unsigned int end = (sec_size(sec) > 10) ? sec_size(sec) - 10 : 0;

- for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
+ for (offset = sec_size(sec) - 1; offset >= end && !insn; offset--)
insn = find_insn(file, sec, offset);

return insn;
@@ -607,7 +607,7 @@ static int add_dead_ends(struct objtool_file *file)
insn = find_insn(file, reloc->sym->sec, offset);
if (insn)
insn = prev_insn_same_sec(file, insn);
- else if (offset == reloc->sym->sec->sh.sh_size) {
+ else if (offset == sec_size(reloc->sym->sec)) {
insn = find_last_insn(file, reloc->sym->sec);
if (!insn) {
WARN("can't find unreachable insn at %s+0x%" PRIx64,
@@ -647,7 +647,7 @@ static int add_dead_ends(struct objtool_file *file)
insn = find_insn(file, reloc->sym->sec, offset);
if (insn)
insn = prev_insn_same_sec(file, insn);
- else if (offset == reloc->sym->sec->sh.sh_size) {
+ else if (offset == sec_size(reloc->sym->sec)) {
insn = find_last_insn(file, reloc->sym->sec);
if (!insn) {
WARN("can't find reachable insn at %s+0x%" PRIx64,
@@ -868,7 +868,7 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
struct symbol *sym = insn->sym;
*site = 0;

- if (opts.module && sym && sym->type == STT_FUNC &&
+ if (opts.module && sym && is_function_symbol(sym) &&
insn->offset == sym->offset &&
(!strcmp(sym->name, "init_module") ||
!strcmp(sym->name, "cleanup_module")))
@@ -900,7 +900,7 @@ static int create_cfi_sections(struct objtool_file *file)

idx = 0;
for_each_sym(file->elf, sym) {
- if (sym->type != STT_FUNC)
+ if (!is_function_symbol(sym))
continue;

if (strncmp(sym->name, "__cfi_", 6))
@@ -916,7 +916,7 @@ static int create_cfi_sections(struct objtool_file *file)

idx = 0;
for_each_sym(file->elf, sym) {
- if (sym->type != STT_FUNC)
+ if (!is_function_symbol(sym))
continue;

if (strncmp(sym->name, "__cfi_", 6))
@@ -1534,7 +1534,7 @@ static bool jump_is_sibling_call(struct objtool_file *file,
return false;

/* Disallow sibling calls into STT_NOTYPE */
- if (ts->type == STT_NOTYPE)
+ if (is_notype_symbol(ts))
return false;

/* Must not be self to be a sibling */
@@ -1566,7 +1566,7 @@ static int add_jump_destinations(struct objtool_file *file)
if (!reloc) {
dest_sec = insn->sec;
dest_off = arch_jump_destination(insn);
- } else if (reloc->sym->type == STT_SECTION) {
+ } else if (is_section_symbol(reloc->sym)) {
dest_sec = reloc->sym->sec;
dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
} else if (reloc->sym->retpoline_thunk) {
@@ -1712,12 +1712,12 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}

- if (insn_func(insn) && insn_call_dest(insn)->type != STT_FUNC) {
+ if (insn_func(insn) && !is_function_symbol(insn_call_dest(insn))) {
WARN_INSN(insn, "unsupported call to non-function");
return -1;
}

- } else if (reloc->sym->type == STT_SECTION) {
+ } else if (is_section_symbol(reloc->sym)) {
dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
dest = find_call_destination(reloc->sym->sec, dest_off);
if (!dest) {
@@ -2199,7 +2199,7 @@ static int add_jump_table_alts(struct objtool_file *file)
return 0;

for_each_sym(file->elf, func) {
- if (func->type != STT_FUNC)
+ if (!is_function_symbol(func))
continue;

mark_func_jump_tables(file, func);
@@ -2239,14 +2239,14 @@ static int read_unwind_hints(struct objtool_file *file)
return -1;
}

- if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
+ if (sec_size(sec) % sizeof(struct unwind_hint)) {
WARN("struct unwind_hint size mismatch");
return -1;
}

file->hints = true;

- for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
+ for (i = 0; i < sec_size(sec) / sizeof(struct unwind_hint); i++) {
hint = (struct unwind_hint *)sec->data->d_buf + i;

reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
@@ -2291,7 +2291,7 @@ static int read_unwind_hints(struct objtool_file *file)
if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);

- if (sym && sym->bind == STB_GLOBAL) {
+ if (sym && is_global_symbol(sym)) {
if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
WARN_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
}
@@ -2469,7 +2469,7 @@ static int read_intra_function_calls(struct objtool_file *file)
for_each_reloc(rsec, reloc) {
unsigned long dest_off;

- if (reloc->sym->type != STT_SECTION) {
+ if (!is_section_symbol(reloc->sym)) {
WARN("unexpected relocation symbol type in %s",
rsec->name);
return -1;
@@ -2535,10 +2535,10 @@ static int classify_symbols(struct objtool_file *file)
struct symbol *func;

for_each_sym(file->elf, func) {
- if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
+ if (is_notype_symbol(func) && strstarts(func->name, ".L"))
func->local_label = true;

- if (func->bind != STB_GLOBAL)
+ if (!is_global_symbol(func))
continue;

if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
@@ -4199,11 +4199,11 @@ static int add_prefix_symbols(struct objtool_file *file)
struct symbol *func;

for_each_sec(file->elf, sec) {
- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_section(sec))
continue;

sec_for_each_sym(sec, func) {
- if (func->type != STT_FUNC)
+ if (!is_function_symbol(func))
continue;

add_prefix_symbol(file, func);
@@ -4246,7 +4246,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
int warnings = 0;

sec_for_each_sym(sec, func) {
- if (func->type != STT_FUNC)
+ if (!is_function_symbol(func))
continue;

init_insn_state(file, &state, sec);
@@ -4290,7 +4290,7 @@ static int validate_functions(struct objtool_file *file)
int warnings = 0;

for_each_sec(file->elf, sec) {
- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_section(sec))
continue;

warnings += validate_section(file, sec);
@@ -4461,7 +4461,7 @@ static int validate_ibt(struct objtool_file *file)
for_each_sec(file->elf, sec) {

/* Already done by validate_ibt_insn() */
- if (sec->sh.sh_flags & SHF_EXECINSTR)
+ if (is_text_section(sec))
continue;

if (!sec->rsec)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index b42ee4ef7015..5301fff87bea 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -170,7 +170,7 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
struct symbol *iter;

__sym_for_each(iter, tree, offset, offset) {
- if (iter->offset == offset && iter->type != STT_SECTION)
+ if (iter->offset == offset && !is_section_symbol(iter))
return iter;
}

@@ -183,7 +183,7 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
struct symbol *iter;

__sym_for_each(iter, tree, offset, offset) {
- if (iter->offset == offset && iter->type == STT_FUNC)
+ if (iter->offset == offset && is_function_symbol(iter))
return iter;
}

@@ -244,7 +244,7 @@ struct symbol *find_func_containing(struct section *sec, unsigned long offset)
struct symbol *iter;

__sym_for_each(iter, tree, offset, offset) {
- if (iter->type == STT_FUNC)
+ if (is_function_symbol(iter))
return iter;
}

@@ -353,14 +353,14 @@ static int read_sections(struct elf *elf)
return -1;
}

- if (sec->sh.sh_size != 0 && !is_dwarf_section(sec)) {
+ if (sec_size(sec) != 0 && !is_dwarf_section(sec)) {
sec->data = elf_getdata(s, NULL);
if (!sec->data) {
WARN_ELF("elf_getdata");
return -1;
}
if (sec->data->d_off != 0 ||
- sec->data->d_size != sec->sh.sh_size) {
+ sec->data->d_size != sec_size(sec)) {
WARN("unexpected data attributes for %s",
sec->name);
return -1;
@@ -371,7 +371,7 @@ static int read_sections(struct elf *elf)
elf_hash_add(section, &sec->hash, sec->idx);
elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));

- if (is_reloc_sec(sec))
+ if (is_reloc_section(sec))
elf->num_relocs += sec_num_entries(sec);
}

@@ -401,7 +401,7 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->type = GELF_ST_TYPE(sym->sym.st_info);
sym->bind = GELF_ST_BIND(sym->sym.st_info);

- if (sym->type == STT_FILE)
+ if (is_file_symbol(sym))
elf->num_files++;

sym->offset = sym->sym.st_value;
@@ -515,7 +515,7 @@ static int read_symbols(struct elf *elf)
sec_for_each_sym(sec, sym) {
char *pname;
size_t pnamelen;
- if (sym->type != STT_FUNC)
+ if (!is_function_symbol(sym))
continue;

if (sym->pfunc == NULL)
@@ -890,7 +890,7 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
struct symbol *sym = insn_sec->sym;
int addend = insn_off;

- if (!(insn_sec->sh.sh_flags & SHF_EXECINSTR)) {
+ if (!is_text_section(insn_sec)) {
WARN("bad call to %s() for data symbol %s",
__func__, sym->name);
return NULL;
@@ -920,7 +920,7 @@ struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
struct symbol *sym,
s64 addend)
{
- if (sym->sec && (sec->sh.sh_flags & SHF_EXECINSTR)) {
+ if (is_text_section(sec)) {
WARN("bad call to %s() for text symbol %s",
__func__, sym->name);
return NULL;
@@ -943,7 +943,7 @@ static int read_relocs(struct elf *elf)
return -1;

list_for_each_entry(rsec, &elf->sections, list) {
- if (!is_reloc_sec(rsec))
+ if (!is_reloc_section(rsec))
continue;

rsec->base = find_section_by_index(elf, rsec->sh.sh_info);
@@ -1249,7 +1249,7 @@ int elf_write_insn(struct elf *elf, struct section *sec,
*/
static int elf_truncate_section(struct elf *elf, struct section *sec)
{
- u64 size = sec->sh.sh_size;
+ u64 size = sec_size(sec);
bool truncated = false;
Elf_Data *data = NULL;
Elf_Scn *s;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 7524510b5565..0c2af699b1bf 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -8,6 +8,7 @@

#include <stdio.h>
#include <gelf.h>
+#include <linux/string.h>
#include <linux/list.h>
#include <linux/hashtable.h>
#include <linux/rbtree.h>
@@ -174,11 +175,76 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
}

-static inline bool is_reloc_sec(struct section *sec)
+static inline bool sym_has_section(struct symbol *sym)
+{
+ return sym->sec->idx;
+}
+
+static inline bool is_null_symbol(struct symbol *sym)
+{
+ return !sym->idx;
+}
+
+static inline bool is_section_symbol(struct symbol *sym)
+{
+ return sym->type == STT_SECTION;
+}
+
+static inline bool is_object_symbol(struct symbol *sym)
+{
+ return sym->type == STT_OBJECT;
+}
+
+static inline bool is_function_symbol(struct symbol *sym)
+{
+ return sym->type == STT_FUNC;
+}
+
+static inline bool is_file_symbol(struct symbol *sym)
+{
+ return sym->type == STT_FILE;
+}
+
+static inline bool is_notype_symbol(struct symbol *sym)
+{
+ return sym->type == STT_NOTYPE;
+}
+
+static inline bool is_prefix_symbol(struct symbol *sym)
+{
+ return is_function_symbol(sym) && strstarts(sym->name, "__pfx_");
+}
+
+static inline bool is_global_symbol(struct symbol *sym)
+{
+ return sym->bind == STB_GLOBAL;
+}
+
+static inline bool is_weak_symbol(struct symbol *sym)
+{
+ return sym->bind == STB_WEAK;
+}
+
+static inline bool is_local_symbol(struct symbol *sym)
+{
+ return sym->bind == STB_LOCAL;
+}
+
+static inline bool is_reloc_section(struct section *sec)
{
return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
}

+static inline bool is_string_section(struct section *sec)
+{
+ return sec->sh.sh_flags & SHF_STRINGS;
+}
+
+static inline bool is_text_section(struct section *sec)
+{
+ return sec->sh.sh_flags & SHF_EXECINSTR;
+}
+
static inline bool sec_changed(struct section *sec)
{
return sec->_changed;
@@ -219,6 +285,11 @@ static inline bool is_32bit_reloc(struct reloc *reloc)
return reloc->sec->sh.sh_entsize < 16;
}

+static inline unsigned long sec_size(struct section *sec)
+{
+ return sec->sh.sh_size;
+}
+
#define __get_reloc_field(reloc, field) \
({ \
is_32bit_reloc(reloc) ? \
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 91b1950f5bd8..312d01684e21 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -152,13 +152,13 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
if (!sec)
continue;

- if (sec->sh.sh_size % entry->size != 0) {
+ if (sec_size(sec) % entry->size != 0) {
WARN("%s size not a multiple of %d",
sec->name, entry->size);
return -1;
}

- nr_entries = sec->sh.sh_size / entry->size;
+ nr_entries = sec_size(sec) / entry->size;

for (idx = 0; idx < nr_entries; idx++) {
alt = malloc(sizeof(*alt));
--
2.45.2