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objtool/klp: Calculate object checksums

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Start checksumming data objects in preparation for revamping the
correlation algorithm.

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2026-04-15 22:49:53 -07:00
parent 225d16dd51
commit 873a2208ea
4 changed files with 117 additions and 47 deletions
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44
tools/objtool/include/objtool/checksum.h
View File

@ -6,28 +6,44 @@
#ifdef BUILD_KLP
static inline void checksum_init(struct symbol *func)
static inline void checksum_init(struct symbol *sym)
{
if (func && !func->csum.state) {
func->csum.state = XXH3_createState();
XXH3_64bits_reset(func->csum.state);
if (sym && !sym->csum.state) {
sym->csum.state = XXH3_createState();
XXH3_64bits_reset(sym->csum.state);
}
}
static inline void checksum_update(struct symbol *func,
struct instruction *insn,
const void *data, size_t size)
static inline void __checksum_update(struct symbol *sym, const void *data,
size_t size)
{
XXH3_64bits_update(func->csum.state, data, size);
dbg_checksum(func, insn, XXH3_64bits_digest(func->csum.state));
XXH3_64bits_update(sym->csum.state, data, size);
}
static inline void checksum_finish(struct symbol *func)
static inline void __checksum_update_insn(struct symbol *sym,
struct instruction *insn,
const void *data, size_t size)
{
if (func && func->csum.state) {
func->csum.checksum = XXH3_64bits_digest(func->csum.state);
XXH3_freeState(func->csum.state);
func->csum.state = NULL;
__checksum_update(sym, data, size);
dbg_checksum_insn(sym, insn, XXH3_64bits_digest(sym->csum.state));
}
static inline void __checksum_update_object(struct symbol *sym,
unsigned long offset,
const char *what, const void *data,
size_t size)
{
__checksum_update(sym, &offset, sizeof(offset));
__checksum_update(sym, data, size);
dbg_checksum_object(sym, offset, what, XXH3_64bits_digest(sym->csum.state));
}
static inline void checksum_finish(struct symbol *sym)
{
if (sym && sym->csum.state) {
sym->csum.checksum = XXH3_64bits_digest(sym->csum.state);
XXH3_freeState(sym->csum.state);
sym->csum.state = NULL;
}
}

29
tools/objtool/include/objtool/warn.h
View File

@ -130,10 +130,22 @@ static inline void unindent(int *unused) { indent--; }
objname ? ": " : "", \
##__VA_ARGS__)
#define dbg(args...) \
#define dbg_checksum_insn(func, insn, checksum) \
({ \
if (unlikely(debug)) \
__dbg(args); \
if (unlikely(func->debug_checksum)) { \
char *insn_off = offstr(insn->sec, insn->offset); \
__dbg("checksum: %s(): %s %016llx", \
func->name, insn_off, (unsigned long long)checksum);\
free(insn_off); \
} \
})
#define dbg_checksum_object(sym, offset, what, checksum) \
({ \
if (unlikely(sym->debug_checksum)) \
__dbg("checksum: %s+0x%lx: %s %016llx", \
sym->name, offset, what, \
(unsigned long long)checksum); \
})
#define __dbg_indent(format, ...) \
@ -147,15 +159,4 @@ static inline void unindent(int *unused) { indent--; }
__dbg_indent(args); \
indent++
#define dbg_checksum(func, insn, checksum) \
({ \
if (unlikely(insn->sym && insn->sym->pfunc && \
insn->sym->pfunc->debug_checksum)) { \
char *insn_off = offstr(insn->sec, insn->offset); \
__dbg("checksum: %s %s %016llx", \
func->name, insn_off, (unsigned long long)checksum);\
free(insn_off); \
} \
})
#endif /* _WARN_H */

89
tools/objtool/klp-checksum.c
View File

@ -35,7 +35,7 @@ static int checksum_debug_init(struct objtool_file *file)
*comma = '\0';
for_each_sym_by_name(file->elf, s, sym) {
if (!is_func_sym(sym))
if (!is_func_sym(sym) && !is_object_sym(sym))
continue;
sym->debug_checksum = 1;
found = true;
@ -66,14 +66,14 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
if (insn->fake)
return;
checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
__checksum_update_insn(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
if (!reloc) {
struct symbol *call_dest = insn_call_dest(insn);
if (call_dest)
checksum_update(func, insn, call_dest->demangled_name,
strlen(call_dest->demangled_name));
__checksum_update_insn(func, insn, call_dest->demangled_name,
strlen(call_dest->demangled_name));
goto alts;
}
@ -84,7 +84,7 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
char *str;
str = sym->sec->data->d_buf + sym->offset + offset;
checksum_update(func, insn, str, strlen(str));
__checksum_update_insn(func, insn, str, strlen(str));
goto alts;
}
@ -96,8 +96,9 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
offset -= sym->offset;
}
checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
checksum_update(func, insn, &offset, sizeof(offset));
__checksum_update_insn(func, insn, sym->demangled_name,
strlen(sym->demangled_name));
__checksum_update_insn(func, insn, &offset, sizeof(offset));
alts:
for (alt = insn->alts; alt; alt = alt->next) {
@ -108,12 +109,13 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
break;
in_alt = true;
checksum_update(func, insn, &alt->type, sizeof(alt->type));
__checksum_update_insn(func, insn, &alt->type,
sizeof(alt->type));
if (alt_group && alt_group->orig_group) {
struct instruction *alt_insn;
checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
__checksum_update_insn(func, insn, &alt_group->feature,sizeof(alt_group->feature));
for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
checksum_update_insn(file, func, alt_insn);
@ -128,31 +130,82 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
}
}
static void checksum_update_object(struct objtool_file *file, struct symbol *sym)
{
struct reloc *reloc;
__checksum_update_object(sym, 0, "len", &sym->len, sizeof(sym->len));
if (sym->sec->data->d_buf)
__checksum_update_object(sym, 0, "data",
sym->sec->data->d_buf + sym->offset,
sym->len);
sym_for_each_reloc(file->elf, sym, reloc) {
unsigned long sym_offset = reloc_offset(reloc) - sym->offset;
struct symbol *target = reloc->sym;
s64 offset;
offset = reloc_addend(reloc);
if (is_string_sec(target->sec)) {
char *str;
str = target->sec->data->d_buf + target->offset + offset;
__checksum_update_object(sym, sym_offset,
"reloc string", str, strlen(str));
continue;
}
if (is_sec_sym(target)) {
target = find_symbol_containing(reloc->sym->sec, offset);
if (!target)
continue;
offset -= target->offset;
}
__checksum_update_object(sym, sym_offset, "reloc name",
target->demangled_name,
strlen(target->demangled_name));
__checksum_update_object(sym, sym_offset, "reloc addend",
&offset, sizeof(offset));
}
}
int calculate_checksums(struct objtool_file *file)
{
struct instruction *insn;
struct symbol *func;
struct symbol *sym;
if (checksum_debug_init(file))
return -1;
for_each_sym(file->elf, func) {
for_each_sym(file->elf, sym) {
/*
* Skip cold subfunctions and aliases: they share the
* parent's checksum via func_for_each_insn() which
* follows func->cfunc into the cold subfunction.
*/
if (!is_func_sym(func) || is_cold_func(func) ||
is_alias_sym(func) || !func->len)
if (is_cold_func(sym) || is_alias_sym(sym) || !sym->len ||
!sym->sec || !sym->sec->data)
continue;
checksum_init(func);
if (is_func_sym(sym)) {
checksum_init(sym);
func_for_each_insn(file, sym, insn)
checksum_update_insn(file, sym, insn);
checksum_finish(sym);
func_for_each_insn(file, func, insn)
checksum_update_insn(file, func, insn);
} else if (is_object_sym(sym)) {
checksum_init(sym);
checksum_update_object(file, sym);
checksum_finish(sym);
}
checksum_finish(func);
}
return 0;
}
@ -213,7 +266,7 @@ int cmd_klp_checksum(int argc, const char **argv)
int ret;
const struct option options[] = {
OPT_STRING(0, "debug-checksum", &opts.debug_checksum, "funcs", "enable checksum debug output"),
OPT_STRING(0, "debug-checksum", &opts.debug_checksum, "syms", "enable checksum debug output"),
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
OPT_END(),
};

2
tools/objtool/klp-diff.c
View File

@ -201,7 +201,7 @@ static int read_sym_checksums(struct elf *elf)
return -1;
}
if (is_func_sym(sym))
if (is_func_sym(sym) || is_object_sym(sym))
sym->csum.checksum = sym_checksum->checksum;
}