From: "H. Peter Anvin" <hpa@zytor.com>
To: "Li, Xin3" <xin3.li@intel.com>, Peter Zijlstra <peterz@infradead.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>
Subject: RE: [PATCH 6/6] x86/gsseg: use the LKGS instruction if available for load_gs_index()
Date: Fri, 07 Oct 2022 11:49:54 -0700 [thread overview]
Message-ID: <3F0DCCD0-2179-47E2-BC57-A948C0C91098@zytor.com> (raw)
In-Reply-To: <BN6PR1101MB216170B28962901E72C539BDA85F9@BN6PR1101MB2161.namprd11.prod.outlook.com>
On October 7, 2022 11:07:34 AM PDT, "Li, Xin3" <xin3.li@intel.com> wrote:
>> >> + alternative_io("1: call asm_load_gs_index\n"
>> >> + ".pushsection \".fixup\",\"ax\"\n"
>> >> + "2: xorl %k[sel], %k[sel]\n"
>> >> + " jmp 1b\n"
>> >> + ".popsection\n"
>> >> + _ASM_EXTABLE(1b, 2b),
>> >> + _ASM_BYTES(0x3e) LKGS_DI,
>> >> + X86_FEATURE_LKGS,
>> >> + ASM_OUTPUT2([sel] "+D" (sel), ASM_CALL_CONSTRAINT),
>> >> + ASM_NO_INPUT_CLOBBER(_ASM_AX));
>> >> }
>> >
>> >I'm very sure none of this was tested... the .fixup section hasn't
>> >existed for almost a year now.
>> >
>> > e5eefda5aa51 ("x86: Remove .fixup section")
>>
>> Xin, what did you use as the forward-porting baseline?
>
>6.0 release, and my kernel dump shows me a fixup section is there, and a fixup section is created anyway if we do "pushsection "\.fixup\"".
>
>
>
Yeah. .fixup is really Just Another Text Section ™, so it is probably not surprising if it has crept back in.
next prev parent reply other threads:[~2022-10-07 18:50 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-06 15:40 [PATCH 0/6] Enable LKGS instruction Xin Li
2022-10-06 15:40 ` [PATCH 1/6] x86/cpufeature: add cpu feature bit for LKGS Xin Li
2022-10-06 15:40 ` [PATCH 2/6] x86/opcode: add LKGS instruction to x86-opcode-map Xin Li
2022-10-06 15:40 ` [PATCH 3/6] x86/gsseg: make asm_load_gs_index() take an u16 Xin Li
2022-10-06 15:40 ` [PATCH 4/6] x86/gsseg: move local_irq_save/restore() into asm_load_gs_index() Xin Li
2022-10-07 14:50 ` Peter Zijlstra
2022-10-07 17:47 ` H. Peter Anvin
2022-10-06 15:40 ` [PATCH 5/6] x86/gsseg: move load_gs_index() to its own header file Xin Li
2022-10-07 15:40 ` Brian Gerst
2022-10-07 17:43 ` H. Peter Anvin
2022-10-07 22:41 ` Li, Xin3
2022-10-06 15:40 ` [PATCH 6/6] x86/gsseg: use the LKGS instruction if available for load_gs_index() Xin Li
2022-10-07 14:47 ` Peter Zijlstra
2022-10-07 17:45 ` H. Peter Anvin
2022-10-07 18:07 ` Li, Xin3
2022-10-07 18:49 ` H. Peter Anvin [this message]
2022-10-07 18:01 ` Li, Xin3
2022-10-07 19:24 ` Peter Zijlstra
2022-10-07 20:03 ` H. Peter Anvin
2022-10-07 20:23 ` Peter Zijlstra
2022-10-07 20:33 ` H. Peter Anvin
2022-10-08 5:32 ` Li, Xin3
2022-10-08 7:16 ` H. Peter Anvin
2022-10-10 4:21 ` Li, Xin3
2022-10-14 4:36 ` Li, Xin3
2022-10-07 14:52 ` Peter Zijlstra
2022-10-07 15:09 ` Peter Zijlstra
2022-10-08 5:31 ` Li, Xin3
2022-10-07 16:18 ` Brian Gerst
2022-10-08 5:40 ` Li, Xin3
2022-10-08 12:40 ` Brian Gerst
2022-10-10 4:32 ` Li, Xin3
2022-10-10 4:51 ` H. Peter Anvin
2022-10-10 7:53 ` Peter Zijlstra
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