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objtool/klp: Use sym->demangled_name for symbol_name hash

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For klp-build with LTO, it is necessary to correlate demangled symbols,
e.g., correlate foo.llvm.<num 1> and foo.llvm.<num 2>. However, these two
symbols do not have the same str_hash(name). To be able to correlate the
two symbols, calculate hash based on demanged_name, so that these two
symbols have the same hash.

No functional changes intended.

Signed-off-by: Song Liu <song@kernel.org>
Link: https://patch.msgid.link/20260305231531.3847295-4-song@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Song Liu
2026-03-05 15:15:27 -08:00
committed by Josh Poimboeuf
parent a3f28d2072
commit 0b8fc6adc3
1 changed files with 40 additions and 18 deletions
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tools/objtool/elf.c
+40 -18
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@@ -26,11 +26,18 @@
#include <objtool/elf.h>
#include <objtool/warn.h>
static ssize_t demangled_name_len(const char *name);
static inline u32 str_hash(const char *str)
{
return jhash(str, strlen(str), 0);
}
static inline u32 str_hash_demangled(const char *str)
{
return jhash(str, demangled_name_len(str), 0);
}
#define __elf_table(name) (elf->name##_hash)
#define __elf_bits(name) (elf->name##_bits)
@@ -294,7 +301,7 @@ static struct symbol *find_local_symbol_by_file_and_name(const struct elf *elf,
{
struct symbol *sym;
elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash_demangled(name)) {
if (sym->bind == STB_LOCAL && sym->file == file &&
!strcmp(sym->name, name)) {
return sym;
@@ -308,7 +315,7 @@ struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *nam
{
struct symbol *sym;
elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash_demangled(name)) {
if (!strcmp(sym->name, name) && !is_local_sym(sym))
return sym;
}
@@ -441,6 +448,28 @@ static int read_sections(struct elf *elf)
return 0;
}
/*
* Returns desired length of the demangled name.
* If name doesn't need demangling, return strlen(name).
*/
static ssize_t demangled_name_len(const char *name)
{
ssize_t idx;
if (!strstarts(name, "__UNIQUE_ID_") && !strchr(name, '.'))
return strlen(name);
for (idx = strlen(name) - 1; idx >= 0; idx--) {
char c = name[idx];
if (!isdigit(c) && c != '.' && c != '_')
break;
}
if (idx <= 0)
return strlen(name);
return idx + 1;
}
/*
* Remove number suffix of a symbol.
*
@@ -457,6 +486,7 @@ static int read_sections(struct elf *elf)
static const char *demangle_name(struct symbol *sym)
{
char *str;
ssize_t len;
if (!is_local_sym(sym))
return sym->name;
@@ -464,24 +494,16 @@ static const char *demangle_name(struct symbol *sym)
if (!is_func_sym(sym) && !is_object_sym(sym))
return sym->name;
if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
len = demangled_name_len(sym->name);
if (len == strlen(sym->name))
return sym->name;
str = strdup(sym->name);
str = strndup(sym->name, len);
if (!str) {
ERROR_GLIBC("strdup");
return NULL;
}
for (int i = strlen(str) - 1; i >= 0; i--) {
char c = str[i];
if (!isdigit(c) && c != '.' && c != '_') {
str[i + 1] = '\0';
break;
}
}
return str;
}
@@ -517,9 +539,13 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
entry = &sym->sec->symbol_list;
list_add(&sym->list, entry);
sym->demangled_name = demangle_name(sym);
if (!sym->demangled_name)
return -1;
list_add_tail(&sym->global_list, &elf->symbols);
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->demangled_name));
if (is_func_sym(sym) &&
(strstarts(sym->name, "__pfx_") ||
@@ -543,10 +569,6 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->pfunc = sym->cfunc = sym;
sym->demangled_name = demangle_name(sym);
if (!sym->demangled_name)
return -1;
return 0;
}