linux-kernel - [RFC PATCH 14/17] objtool: arm64: Cache section with switch table information

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 20 Jan 2021 18:37:57 +0100
From:   Julien Thierry <jthierry@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     catalin.marinas@....com, will@...nel.org, ardb@...nel.org,
        masahiroy@...nel.org, keescook@...omium.org,
        michal.lkml@...kovi.net, jpoimboe@...hat.com, peterz@...radead.org,
        mark.rutland@....com, broonie@...nel.org,
        linux-efi@...r.kernel.org, linux-hardening@...r.kernel.org,
        Julien Thierry <jthierry@...hat.com>
Subject: [RFC PATCH 14/17] objtool: arm64: Cache section with switch table information

Section ".discard.switch_table_info", created by the gcc plugin will
be looked up for every dynamic jump in the object file while the section
might not even exist.

Cache the result of the first lookup.

Signed-off-by: Julien Thierry <jthierry@...hat.com>
---
 tools/objtool/arch/arm64/special.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/arch/arm64/special.c b/tools/objtool/arch/arm64/special.c
index 396b9c5feebd..c9c3e0bfd581 100644
--- a/tools/objtool/arch/arm64/special.c
+++ b/tools/objtool/arch/arm64/special.c
@@ -33,6 +33,19 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 	return false;
 }
 
+static struct section *get_switch_table_info_section(struct objtool_file *file)
+{
+	static bool first = true;
+	static struct section *info_section = NULL;
+
+	if (first) {
+		first = false;
+		info_section = find_section_by_name(file->elf,
+						    ".discard.switch_table_info");
+	}
+
+	return info_section;
+}
 
 /*
  * Aarch64 jump tables are just arrays of offsets (of varying size/signess)
@@ -64,8 +77,7 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
 	void *sti_sec_start;
 	struct reloc *text_reloc;
 
-	table_info_sec = find_section_by_name(file->elf,
-					      ".discard.switch_table_info");
+	table_info_sec = get_switch_table_info_section(file);
 	if (!table_info_sec)
 		goto try_c_jmptbl;
 
-- 
2.25.4