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Date:   Fri, 07 Oct 2022 13:03:12 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        "Li, Xin3" <xin3.li@intel.com>
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        "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: =?US-ASCII?Q?Re=3A_=5BPATCH_6/6=5D_x86/gsseg=3A_use_the_LKGS_in?= =?US-ASCII?Q?struction_if_available_for_load=5Fgs=5Findex=28=29?=
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On October 7, 2022 12:24:13 PM PDT, Peter Zijlstra <peterz@infradead=2Eorg>=
 wrote:
>On Fri, Oct 07, 2022 at 06:01:06PM +0000, Li, Xin3 wrote:
>> > > +	alternative_io("1: call asm_load_gs_index\n"
>> > > +		       "=2Epushsection \"=2Efixup\",\"ax\"\n"
>> > > +		       "2:	xorl %k[sel], %k[sel]\n"
>> > > +		       "	jmp 1b\n"
>> > > +		       "=2Epopsection\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));
>> > >  }
>> >=20
>> > I'm very sure none of this was tested=2E=2E=2E the =2Efixup section h=
asn't existed for
>> > almost a year now=2E
>>=20
>> Weird, did you ever check a kernel dump?
>
>$ readelf -WS defconfig-build/vmlinux | grep fixup
>[ 5] =2Epci_fixup        PROGBITS        ffffffff826a5350 18a5350 003570 =
00   A  0   0 16
>[ 6] =2Erela=2Epci_fixup   RELA            0000000000000000 360c388 00502=
8 18   I 60   5  8
>
>In fact, when I add one I get:
>
>ld: warning: orphan section `=2Efixup' from `arch/x86/kernel/traps=2Eo' b=
eing placed in section `=2Efixup'

Perhaps the two of you need to compare confugurations?