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From:   "Li, Xin3" <xin3.li@intel.com>
To:     Peter Zijlstra <peterz@infradead.org>
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Subject: RE: [PATCH 6/6] x86/gsseg: use the LKGS instruction if available for
 load_gs_index()
Thread-Topic: [PATCH 6/6] x86/gsseg: use the LKGS instruction if available for
 load_gs_index()
Thread-Index: AQHY2Z1YsyE3enznIkOfLcepaehVE64DCmMAgADvxtA=
Date:   Sat, 8 Oct 2022 05:31:20 +0000
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References: <20221006154041.13001-1-xin3.li@intel.com>
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> Something like so perhaps?
>=20
> 	asm_inline volatile("1:\n"
> 			    ALTERNATIVE("call asm_load_gs_index\n",
> 					LKGS_DI,
> 					X86_FEATURE_LKGS)
> 			    _ASM_EXTABLE_TYPE_REG(1b, 1b,
> EX_TYPE_ZERO_REG, %k[sel])
> 			    : ASM_CALL_CONSTRAINT
> 			    : [sel] "D" (sel)
> 			    : "memory", _ASM_AX);
>=20
>=20
> (completely untested, not even seen a compiler upclose)

It compiles (after adding "0x3e" to make it 5 bytes to match the size of "c=
all asm_load_gs_index") and passes my fixup test, thanks!