linux-kernel - [PATCH 2/3] x86-32: Remove SEP test for SYSEXIT

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Date:   Sat, 18 Jul 2020 10:38:38 -0400
From:   Brian Gerst <brgerst@...il.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Brian Gerst <brgerst@...il.com>
Subject: [PATCH 2/3] x86-32: Remove SEP test for SYSEXIT

SEP must be present in order for do_fast_syscall_32() to be called on native
32-bit.  Therefore the check here is redundant.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/entry/common.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 9e01445f6679c..bdb4c15b8610e 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -587,8 +587,7 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs)
 	 * We don't allow syscalls at all from VM86 mode, but we still
 	 * need to check VM, because we might be returning from sys_vm86.
 	 */
-	return static_cpu_has(X86_FEATURE_SEP) &&
-		regs->cs == __USER_CS && regs->ss == __USER_DS &&
+	return regs->cs == __USER_CS && regs->ss == __USER_DS &&
 		regs->ip == landing_pad &&
 		(regs->flags & (X86_EFLAGS_RF | X86_EFLAGS_TF | X86_EFLAGS_VM)) == 0;
 #endif
-- 
2.26.2