linux-kernel - [PATCH] x86-64/entry: add instruction suffix to SYSRET

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Date:   Tue, 10 Dec 2019 11:48:33 +0100
From:   Jan Beulich <jbeulich@...e.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     the arch/x86 maintainers <x86@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86-64/entry: add instruction suffix to SYSRET

Omitting suffixes from instructions in AT&T mode is bad practice when
operand size cannot be determined by the assembler from register
operands, and is likely going to be warned about by upstream gas in the
future. Add the missing suffix here.

Signed-off-by: Jan Beulich <jbeulich@...e.com>

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1728,7 +1728,7 @@ END(nmi)
 SYM_CODE_START(ignore_sysret)
 	UNWIND_HINT_EMPTY
 	mov	$-ENOSYS, %eax
-	sysret
+	sysretl
 SYM_CODE_END(ignore_sysret)
 #endif