linux-kernel - [tip: objtool/core] objtool: Add option to print section addresses

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Date:   Fri, 22 Apr 2022 10:35:06 -0000
From:   "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] objtool: Add option to print section addresses

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     99c0beb547a3e0ec3a63edeba0960c6ddf2226b0
Gitweb:        https://git.kernel.org/tip/99c0beb547a3e0ec3a63edeba0960c6ddf2226b0
Author:        Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate:    Mon, 18 Apr 2022 09:50:31 -07:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 22 Apr 2022 12:32:02 +02:00

objtool: Add option to print section addresses

To help prevent objtool users from having to do math to convert function
addresses to section addresses, and to help out with finding data
addresses reported by IBT validation, add an option to print the section
address in addition to the function address.

Normal:

  vmlinux.o: warning: objtool: fixup_exception()+0x2d1: unreachable instruction

With '--sec-address':

  vmlinux.o: warning: objtool: fixup_exception()+0x2d1 (.text+0x76c51): unreachable instruction

Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
Link: https://lkml.kernel.org/r/2cea4d5299d53d1a4c09212a6ad7820aa46fda7a.1650300597.git.jpoimboe@redhat.com
---
 tools/objtool/builtin-check.c           |  1 +-
 tools/objtool/include/objtool/builtin.h |  1 +-
 tools/objtool/include/objtool/warn.h    | 31 +++++++++++++-----------
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 8c3eed5..6acfebd 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -50,6 +50,7 @@ const struct option check_options[] = {
 	OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
 	OPT_BOOLEAN(0, "no-fp", &opts.no_fp, "skip frame pointer validation"),
 	OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
+	OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
 	OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
 	OPT_BOOLEAN(0, "vmlinux", &opts.vmlinux, "vmlinux.o validation"),
 
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 44548e2..e0972fb 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -28,6 +28,7 @@ struct opts {
 	bool module;
 	bool no_fp;
 	bool no_unreachable;
+	bool sec_address;
 	bool stats;
 	bool vmlinux;
 };
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index c4bde3e..a3e79ae 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -11,30 +11,33 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <objtool/builtin.h>
 #include <objtool/elf.h>
 
 extern const char *objname;
 
 static inline char *offstr(struct section *sec, unsigned long offset)
 {
-	struct symbol *func;
-	char *name, *str;
-	unsigned long name_off;
+	bool is_text = (sec->sh.sh_flags & SHF_EXECINSTR);
+	struct symbol *sym = NULL;
+	char *str;
+	int len;
 
-	func = find_func_containing(sec, offset);
-	if (!func)
-		func = find_symbol_containing(sec, offset);
-	if (func) {
-		name = func->name;
-		name_off = offset - func->offset;
+	if (is_text)
+		sym = find_func_containing(sec, offset);
+	if (!sym)
+		sym = find_symbol_containing(sec, offset);
+
+	if (sym) {
+		str = malloc(strlen(sym->name) + strlen(sec->name) + 40);
+		len = sprintf(str, "%s+0x%lx", sym->name, offset - sym->offset);
+		if (opts.sec_address)
+			sprintf(str+len, " (%s+0x%lx)", sec->name, offset);
 	} else {
-		name = sec->name;
-		name_off = offset;
+		str = malloc(strlen(sec->name) + 20);
+		sprintf(str, "%s+0x%lx", sec->name, offset);
 	}
 
-	str = malloc(strlen(name) + 20);
-	sprintf(str, "%s+0x%lx", name, name_off);
-
 	return str;
 }