linux-kernel - [PATCH] x86: Let AS_WRUSS depend on X86

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-next>] [day] [month] [year] [list]

Message-ID: <20231031102111.32142-1-jirislaby@kernel.org>
Date:   Tue, 31 Oct 2023 11:21:11 +0100
From:   "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To:     bp@...en8.de
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Mike Rapoport <rppt@...nel.org>,
        Pengfei Xu <pengfei.xu@...el.com>,
        John Allen <john.allen@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: [PATCH] x86: Let AS_WRUSS depend on X86_64

Since commit 18e66b695e78 ("x86/shstk: Add Kconfig option for shadow
stack"), AS_WRUSS is set even in 32-bit .configs. It is due to how
Kbuild works. .config is not considered during make oldconfig (and other
make *config), so standard (64-bit) gcc is invoked from 'as-instr'
Kbuild tests. And such gcc indeed reports that wruss is supported, so
AS_WRUSS=y is set.

Provided the wruss instruction is 64-bit only (and used in pure 64-bit
X86_USER_SHADOW_STACK), it has little sense to have AS_WRUSS=y set on
32-bit.

Therefore, make the whole test dependent on X86_64 to ensure it's set
only on 64-bit.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
Cc: Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Borislav Petkov (AMD) <bp@...en8.de>
Cc: Kees Cook <keescook@...omium.org>
Cc: Mike Rapoport (IBM) <rppt@...nel.org>
Cc: Pengfei Xu <pengfei.xu@...el.com>
Cc: John Allen <john.allen@....com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
---
 arch/x86/Kconfig.assembler | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
index 8ad41da301e5..a5b5241711e3 100644
--- a/arch/x86/Kconfig.assembler
+++ b/arch/x86/Kconfig.assembler
@@ -27,5 +27,6 @@ config AS_GFNI
 
 config AS_WRUSS
 	def_bool $(as-instr,wrussq %rax$(comma)(%rbx))
+	depends on X86_64
 	help
 	  Supported by binutils >= 2.31 and LLVM integrated assembler
-- 
2.42.0