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objtool: Mark .cold subfunctions

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Introduce a flag to identify .cold subfunctions so they can be detected
easier and faster.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf
2025-09-17 09:03:37 -07:00
parent 25eac74b6b
commit 4ea029389b
3 changed files with 17 additions and 17 deletions
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14
tools/objtool/check.c
View File

@@ -1575,7 +1575,9 @@ static int add_jump_destinations(struct objtool_file *file)
/*
* Cross-function jump.
*/
if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {
if (func && insn_func(jump_dest) && !func->cold &&
insn_func(jump_dest)->cold) {
/*
* For GCC 8+, create parent/child links for any cold
@@ -1592,11 +1594,8 @@ static int add_jump_destinations(struct objtool_file *file)
* case where the parent function's only reference to a
* subfunction is through a jump table.
*/
if (!strstr(func->name, ".cold") &&
strstr(insn_func(jump_dest)->name, ".cold")) {
func->cfunc = insn_func(jump_dest);
insn_func(jump_dest)->pfunc = func;
}
func->cfunc = insn_func(jump_dest);
insn_func(jump_dest)->pfunc = func;
}
if (jump_is_sibling_call(file, insn, jump_dest)) {
@@ -4066,9 +4065,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
* If this hole jumps to a .cold function, mark it ignore too.
*/
if (insn->jump_dest && insn_func(insn->jump_dest) &&
strstr(insn_func(insn->jump_dest)->name, ".cold")) {
insn_func(insn->jump_dest)->cold)
insn_func(insn->jump_dest)->ignore = true;
}
}
return false;

19
tools/objtool/elf.c
View File

@@ -441,6 +441,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
list_add(&sym->list, entry);
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
if (is_func_sym(sym) && strstr(sym->name, ".cold"))
sym->cold = 1;
sym->pfunc = sym->cfunc = sym;
}
static int read_symbols(struct elf *elf)
@@ -527,18 +531,15 @@ static int read_symbols(struct elf *elf)
sec_for_each_sym(sec, sym) {
char *pname;
size_t pnamelen;
if (!is_func_sym(sym))
if (!sym->cold)
continue;
if (sym->pfunc == NULL)
sym->pfunc = sym;
if (sym->cfunc == NULL)
sym->cfunc = sym;
coldstr = strstr(sym->name, ".cold");
if (!coldstr)
continue;
if (!coldstr) {
ERROR("%s(): cold subfunction without \".cold\"?", sym->name);
return -1;
}
pnamelen = coldstr - sym->name;
pname = strndup(sym->name, pnamelen);

1
tools/objtool/include/objtool/elf.h
View File

@@ -72,6 +72,7 @@ struct symbol {
u8 frame_pointer : 1;
u8 ignore : 1;
u8 nocfi : 1;
u8 cold : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;