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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@linutronix.de>
AuthorDate: Wed, 28 Nov 2018 23:20:07 +0100
Committer: Borislav Petkov <bp@suse.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@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: x86-ml <x86@kernel.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;
}
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