lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <7d6a7093e117e7678aee82fedfa6cfad094a46d8.1746821544.git.jpoimboe@kernel.org>
Date: Fri,  9 May 2025 13:17:15 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org,
	Song Liu <song@...nel.org>,
	laokz <laokz@...mail.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Weinan Liu <wnliu@...gle.com>,
	Fazla Mehrab <a.mehrab@...edance.com>,
	Chen Zhongjin <chenzhongjin@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>
Subject: [PATCH v2 51/62] objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums

Add a --debug-checksum=<funcs> option to the check subcommand to print
the calculated checksum of each instruction in the given functions.

This is useful for determining where two versions of a function begin to
diverge.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/builtin-check.c            |  6 ++++
 tools/objtool/check.c                    | 42 ++++++++++++++++++++++++
 tools/objtool/include/objtool/builtin.h  |  1 +
 tools/objtool/include/objtool/checksum.h |  1 +
 tools/objtool/include/objtool/elf.h      |  1 +
 tools/objtool/include/objtool/warn.h     | 19 +++++++++++
 6 files changed, 70 insertions(+)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 9bb26138bb56..84918593d935 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -92,6 +92,7 @@ static const struct option check_options[] = {
 
 	OPT_GROUP("Options:"),
 	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
+	OPT_STRING(0,		 "debug-checksum", &opts.debug_checksum,  "funcs", "enable checksum debug output"),
 	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
 	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),
 	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
@@ -167,6 +168,11 @@ static bool opts_valid(void)
 	}
 #endif
 
+	if (opts.debug_checksum && !opts.checksum) {
+		ERROR("--debug-checksum requires --checksum");
+		return false;
+	}
+
 	if (opts.checksum		||
 	    opts.hack_jump_label	||
 	    opts.hack_noinstr		||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4ca4d5190f35..30a5eb725931 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3622,6 +3622,44 @@ static bool skip_alt_group(struct instruction *insn)
 	return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
 }
 
+static int checksum_debug_init(struct objtool_file *file)
+{
+	char *dup, *s;
+
+	if (!opts.debug_checksum)
+		return 0;
+
+	dup = strdup(opts.debug_checksum);
+	if (!dup) {
+		ERROR_GLIBC("strdup");
+		return -1;
+	}
+
+	s = dup;
+	while (*s) {
+		struct symbol *func;
+		char *comma;
+
+		comma = strchr(s, ',');
+		if (comma)
+			*comma = '\0';
+
+		func = find_symbol_by_name(file->elf, s);
+		if (!func || !is_func_sym(func))
+			WARN("--debug-checksum: can't find '%s'", s);
+		else
+			func->debug_checksum = 1;
+
+		if (!comma)
+			break;
+
+		s = comma + 1;
+	}
+
+	free(dup);
+	return 0;
+}
+
 static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
 				 struct instruction *insn)
 {
@@ -4789,6 +4827,10 @@ int check(struct objtool_file *file)
 	cfi_hash_add(&init_cfi);
 	cfi_hash_add(&func_cfi);
 
+	ret = checksum_debug_init(file);
+	if (ret)
+		goto out;
+
 	ret = decode_sections(file);
 	if (ret)
 		goto out;
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 3ec233406cda..ceabafb43327 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -30,6 +30,7 @@ struct opts {
 
 	/* options: */
 	bool backtrace;
+	const char *debug_checksum;
 	bool dryrun;
 	bool link;
 	bool mnop;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
index 927ca74b5c39..7fe21608722a 100644
--- a/tools/objtool/include/objtool/checksum.h
+++ b/tools/objtool/include/objtool/checksum.h
@@ -19,6 +19,7 @@ static inline void checksum_update(struct symbol *func,
 				   const void *data, size_t size)
 {
 	XXH3_64bits_update(func->csum.state, data, size);
+	dbg_checksum(func, insn, XXH3_64bits_digest(func->csum.state));
 }
 
 static inline void checksum_finish(struct symbol *func)
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 4d1023fdb700..4cfd09e66cb5 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -78,6 +78,7 @@ struct symbol {
 	u8 ignore	     : 1;
 	u8 cold		     : 1;
 	u8 prefix	     : 1;
+	u8 debug_checksum    : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index cb8fe846d9dd..29173a1368d7 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -102,4 +102,23 @@ static inline char *offstr(struct section *sec, unsigned long offset)
 #define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
 #define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
 
+
+#define __dbg(format, ...)						\
+	fprintf(stderr,							\
+		"DEBUG: %s%s" format "\n",				\
+		objname ?: "",						\
+		objname ? ": " : "",					\
+		##__VA_ARGS__)
+
+#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 %016lx",				\
+		      func->name, insn_off, checksum);			\
+		free(insn_off);						\
+	}								\
+})
+
 #endif /* _WARN_H */
-- 
2.49.0


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ