linux-kernel - [PATCH v5 11/33] objtool: arm64: Ignore replacement section for alternative callback

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: <20220622154920.95075-12-chenzhongjin@huawei.com>
Date:   Wed, 22 Jun 2022 23:48:58 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kbuild@...r.kernel.org>, <live-patching@...r.kernel.org>
CC:     <jpoimboe@...nel.org>, <peterz@...radead.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <masahiroy@...nel.org>, <michal.lkml@...kovi.net>,
        <ndesaulniers@...gle.com>, <mark.rutland@....com>,
        <pasha.tatashin@...een.com>, <broonie@...nel.org>,
        <chenzhongjin@...wei.com>, <rmk+kernel@...linux.org.uk>,
        <madvenka@...ux.microsoft.com>, <christophe.leroy@...roup.eu>
Subject: [PATCH v5 11/33] objtool: arm64: Ignore replacement section for alternative callback

ARM64_CB_PATCH doesn't have static replacement instructions. Skip
trying to validate the alternative section.

Signed-off-by: Julien Thierry <jthierry@...hat.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
---
 tools/objtool/arch/arm64/special.c | 11 +++++++++++
 tools/objtool/check.c              |  3 +++
 2 files changed, 14 insertions(+)

diff --git a/tools/objtool/arch/arm64/special.c b/tools/objtool/arch/arm64/special.c
index a70b91e8bd7d..8bb1ebd2132a 100644
--- a/tools/objtool/arch/arm64/special.c
+++ b/tools/objtool/arch/arm64/special.c
@@ -4,6 +4,17 @@
 
 void arch_handle_alternative(unsigned short feature, struct special_alt *alt)
 {
+	/*
+	 * ARM64_CB_PATCH has no alternative instruction.
+	 * a callback is called at alternative replacement time
+	 * to dynamically change the original instructions.
+	 *
+	 * ARM64_CB_PATCH is the last ARM64 feature, it's value changes
+	 * every time a new feature is added. So the orig/alt region
+	 * length are used to detect those alternatives
+	 */
+	if (alt->orig_len && !alt->new_len)
+		alt->skip_alt = true;
 }
 
 bool arch_support_alt_relocation(struct special_alt *special_alt,
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 77911ca9cfff..54b736e94ede 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1686,6 +1686,9 @@ static int add_special_section_alts(struct objtool_file *file)
 				continue;
 			}
 
+			if (special_alt->skip_alt && !special_alt->new_len)
+				continue;
+
 			ret = handle_group_alt(file, special_alt, orig_insn,
 					       &new_insn);
 			if (ret)
-- 
2.17.1