linux-kernel - [PATCH 3.18 20/52] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels

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Date:   Mon, 29 Jan 2018 13:56:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
        Andy Lutomirski <luto@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Brian Gerst <brgerst@...il.com>,
        Matthew Whitehead <tedheadster@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Henrique de Moraes Holschuh <hmh@....eng.br>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel <Xen-devel@...ts.xen.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 3.18 20/52] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@...nel.org>

commit 1c52d859cb2d417e7216d3e56bb7fea88444cec9 upstream.

We support various non-Intel CPUs that don't have the CPUID
instruction, so the M486 test was wrong.  For now, fix it with a big
hammer: handle missing CPUID on all 32-bit CPUs.

Reported-by: One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Juergen Gross <jgross@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Matthew Whitehead <tedheadster@...il.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Henrique de Moraes Holschuh <hmh@....eng.br>
Cc: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: xen-devel <Xen-devel@...ts.xen.org>
Link: http://lkml.kernel.org/r/685bd083a7c036f7769510b6846315b17d6ba71f.1481307769.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/include/asm/processor.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -669,7 +669,7 @@ static inline void sync_core(void)
 {
 	int tmp;
 
-#ifdef CONFIG_M486
+#ifdef CONFIG_X86_32
 	/*
 	 * Do a CPUID if available, otherwise do a jump.  The jump
 	 * can conveniently enough be the jump around CPUID.