linux-kernel - [PATCH 11/21] objtool: Move unsuffixed symbol conversion to a helper function

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Date:   Thu, 14 Jan 2021 13:40:07 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 11/21] objtool: Move unsuffixed symbol conversion to a helper function

This logic will also be needed for the CONFIG_CFI_CLANG support.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 tools/objtool/elf.c | 59 ++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index be89c741ba9a..292f015f7ec6 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -262,6 +262,38 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
 	return find_reloc_by_dest_range(elf, sec, offset, 1);
 }
 
+static int find_unsuffixed_func(const struct elf *elf, struct symbol *sym,
+				const char *suffix, struct symbol **func)
+{
+	char name[MAX_NAME_LEN + 1];
+	const char *loc;
+	size_t len;
+
+	*func = NULL;
+
+	loc = strstr(sym->name, suffix);
+	if (!loc)
+		return 0;
+
+	len = loc - sym->name;
+	if (len > MAX_NAME_LEN) {
+		WARN("%s(): unsuffixed function name exceeds maximum length of %d characters",
+		     sym->name, MAX_NAME_LEN);
+		return -1;
+	}
+
+	strncpy(name, sym->name, len);
+	name[len] = '\0';
+
+	*func = find_symbol_by_name(elf, name);
+	if (!*func || (*func)->type != STT_FUNC) {
+		WARN("%s(): can't find unsuffixed function", sym->name);
+		return -1;
+	}
+
+	return 0;
+}
+
 void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
 			      struct reloc *reloc)
 {
@@ -456,37 +488,20 @@ static int read_symbols(struct elf *elf)
 	/* Create parent/child links for any cold subfunctions */
 	list_for_each_entry(sec, &elf->sections, list) {
 		list_for_each_entry(sym, &sec->symbol_list, list) {
-			char pname[MAX_NAME_LEN + 1];
-			size_t pnamelen;
 			if (sym->type != STT_FUNC)
 				continue;
 
-			if (sym->pfunc == NULL)
+			if (!sym->pfunc)
 				sym->pfunc = sym;
 
-			if (sym->cfunc == NULL)
+			if (!sym->cfunc)
 				sym->cfunc = sym;
 
-			coldstr = strstr(sym->name, ".cold");
-			if (!coldstr)
-				continue;
-
-			pnamelen = coldstr - sym->name;
-			if (pnamelen > MAX_NAME_LEN) {
-				WARN("%s(): parent function name exceeds maximum length of %d characters",
-				     sym->name, MAX_NAME_LEN);
+			if (find_unsuffixed_func(elf, sym, ".cold", &pfunc))
 				return -1;
-			}
 
-			strncpy(pname, sym->name, pnamelen);
-			pname[pnamelen] = '\0';
-			pfunc = find_symbol_by_name(elf, pname);
-
-			if (!pfunc) {
-				WARN("%s(): can't find parent function",
-				     sym->name);
-				return -1;
-			}
+			if (!pfunc)
+				continue;
 
 			sym->pfunc = pfunc;
 			pfunc->cfunc = sym;
-- 
2.29.2