linux-kernel - [tip:x86/fpu] x86/fpu: Use unsigned long long shift in xfeature_uncompacted

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Message-ID: <tip-d08452390179710dc7989242605e3c1faa62b64f@git.kernel.org>
Date:   Mon, 3 Dec 2018 13:00:55 -0800
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rkrcmar@...hat.com, riel@...riel.com, x86@...nel.org,
        pbonzini@...hat.com, tglx@...utronix.de, Jason@...c4.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org, luto@...nel.org,
        dave.hansen@...ux.intel.com, bigeasy@...utronix.de,
        mingo@...nel.org, mingo@...hat.com, bp@...e.de, hpa@...or.com
Subject: [tip:x86/fpu] x86/fpu: Use unsigned long long shift in
 xfeature_uncompacted_offset()

Commit-ID:  d08452390179710dc7989242605e3c1faa62b64f
Gitweb:     https://git.kernel.org/tip/d08452390179710dc7989242605e3c1faa62b64f
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Wed, 28 Nov 2018 23:20:07 +0100
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Mon, 3 Dec 2018 18:40:28 +0100

x86/fpu: Use unsigned long long shift in xfeature_uncompacted_offset()

The xfeature mask is 64-bit so a shift from a number to its mask should
have ULL suffix or else bits above position 31 will be lost. This is not
a problem now but should XFEATURE_MASK_SUPERVISOR gain a bit >31 then
this check won't catch it.

Use BIT_ULL() to compute a mask from a number.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Rik van Riel <riel@...riel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: kvm ML <kvm@...r.kernel.org>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/20181128222035.2996-2-bigeasy@linutronix.de
---
 arch/x86/kernel/fpu/xstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 87a57b7642d3..69d5740ed254 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -444,7 +444,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr)
 	 * format. Checking a supervisor state's uncompacted offset is
 	 * an error.
 	 */
-	if (XFEATURE_MASK_SUPERVISOR & (1 << xfeature_nr)) {
+	if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) {
 		WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
 		return -1;
 	}