From: "H. Peter Anvin" <hpa@zytor.com>
To: Peter Zijlstra <peterz@infradead.org>, "Li, Xin3" <xin3.li@intel.com>
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 13:03:12 -0700 [thread overview]
Message-ID: <80AC2E90-D842-4EA2-A413-3CC5CFF088BC@zytor.com> (raw)
In-Reply-To: <Y0B83cSSwJnRtGAn@hirez.programming.kicks-ass.net>
On October 7, 2022 12:24:13 PM PDT, Peter Zijlstra <peterz@infradead.org> wrote:
>On Fri, Oct 07, 2022 at 06:01:06PM +0000, Li, Xin3 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.
>>
>> Weird, did you ever check a kernel dump?
>
>$ readelf -WS defconfig-build/vmlinux | grep fixup
>[ 5] .pci_fixup PROGBITS ffffffff826a5350 18a5350 003570 00 A 0 0 16
>[ 6] .rela.pci_fixup RELA 0000000000000000 360c388 005028 18 I 60 5 8
>
>In fact, when I add one I get:
>
>ld: warning: orphan section `.fixup' from `arch/x86/kernel/traps.o' being placed in section `.fixup'
Perhaps the two of you need to compare confugurations?
next prev parent reply other threads:[~2022-10-07 20:03 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
2022-10-07 18:01 ` Li, Xin3
2022-10-07 19:24 ` Peter Zijlstra
2022-10-07 20:03 ` H. Peter Anvin [this message]
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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