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From: "Bae, Chang Seok" <chang.seok.bae@intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <ak@linux.intel.com>,
	"Metzger, Markus T" <markus.t.metzger@intel.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v5 08/13] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro
Date: Wed, 13 Feb 2019 18:46:59 +0000	[thread overview]
Message-ID: <5474F9B1-6E8F-4677-976B-C10103175B05@intel.com> (raw)
In-Reply-To: <CALCETrU0LD_sZOM2d6dSbnvEbs=zsVxEiy6dPp0w+AJO2JZf3A@mail.gmail.com>


> On Feb 2, 2019, at 09:17, Andy Lutomirski <luto@kernel.org> wrote:
> 
> On Fri, Feb 1, 2019 at 12:55 PM Chang S. Bae <chang.seok.bae@intel.com> wrote:
>> 
>> +
>> +/*
>> + * CPU/node NR is loaded from the limit (size) field of a special segment
>> + * descriptor entry in GDT.
>> + */
>> +.macro LOAD_CPU_AND_NODE_SEG_LIMIT reg:req
>> +       movq    $__CPUNODE_SEG, \reg
>> +       lsl     \reg, \reg
>> +.endm
>> +
> 
> Please put the alternative in here instead of in FIND_PERCPU_BASE.

I would like to apply your comment though, build errors will come up due to the
__CPUNODE_SEG. So, still hoping the alternative line below is straightforward enough.
Will send out a revision, that reflects all other comments, shortly.

Chang

> 
>> +/*
>> + * Fetch the per-CPU GSBASE value for this processor and put it in @reg.
>> + * We normally use %gs for accessing per-CPU data, but we are setting up
>> + * %gs here and obviously can not use %gs itself to access per-CPU data.
>> + */
>> +.macro FIND_PERCPU_BASE reg:req
>> 
>> +       ALTERNATIVE \
>> +               "LOAD_CPU_AND_NODE_SEG_LIMIT \reg", \
>> +               "RDPID  \reg", \
>> +               X86_FEATURE_RDPID
>> +       andq    $VDSO_CPUNODE_MASK, \reg
>> +       movq    __per_cpu_offset(, \reg, 8), \reg
>> +.endm

  reply	other threads:[~2019-02-13 18:47 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-01 20:53 [PATCH v5 00/13] x86: Enable FSGSBASE instructions Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 01/13] taint: Introduce a new taint flag (insecure) Chang S. Bae
2019-02-02  2:42   ` Andy Lutomirski
2019-02-05 21:21     ` Andrew Morton
2019-02-05 22:46       ` Randy Dunlap
2019-02-05 23:07         ` hpa
2019-02-01 20:53 ` [PATCH v5 02/13] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 03/13] kbuild: Raise the minimum required binutils version to 2.21 Chang S. Bae
2019-02-02  2:45   ` Andy Lutomirski
2019-02-05  0:08     ` Andrew Morton
2019-02-01 20:53 ` [PATCH v5 04/13] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-02-02  2:52   ` Andy Lutomirski
2019-02-01 20:53 ` [PATCH v5 04/13] x86/fsgsbase/64: Add intrinsics/macros " Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 05/13] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2019-02-02  2:57   ` Andy Lutomirski
2019-02-01 20:53 ` [PATCH v5 06/13] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 07/13] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions if available Chang S. Bae
2019-02-02 17:28   ` Andy Lutomirski
2019-02-01 20:53 ` [PATCH v5 08/13] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-02-02 17:17   ` Andy Lutomirski
2019-02-13 18:46     ` Bae, Chang Seok [this message]
2019-02-01 20:53 ` [PATCH v5 09/13] x86/fsgsbase/64: Use the per-CPU base as GSBASE at the paranoid_entry Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 10/13] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 11/13] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 12/13] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-02-01 20:53 ` [PATCH v5 13/13] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
2019-02-01 23:02 ` [PATCH v5 00/13] x86: Enable FSGSBASE instructions Andi Kleen
2019-02-02  2:43 ` Andy Lutomirski
2019-02-05  6:26   ` hpa

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