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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/ia64/kernel/efi_stub.S
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/*

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 * EFI call stub.

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 *

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 * Copyright (C) 1999-2001 Hewlett-Packard Co

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 *	David Mosberger <[email protected]>

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 *

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 * This stub allows us to make EFI calls in physical mode with interrupts

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 * turned off.  We need this because we can't call SetVirtualMap() until

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 * the kernel has booted far enough to allow allocation of struct vma_struct

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 * entries (which we would need to map stuff with memory attributes other

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 * than uncached or writeback...).  Since the GetTime() service gets called

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 * earlier than that, we need to be able to make physical mode EFI calls from

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 * the kernel.

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 */

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/*

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 * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System

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 * Abstraction Layer Specification", revision 2.6e).  Note that

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 * psr.dfl and psr.dfh MUST be cleared, despite what this manual says.

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 * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call

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 * (the br.ia instruction fails unless psr.dfl and psr.dfh are

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 * cleared).  Fortunately, SAL promises not to touch the floating

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 * point regs, so at least we don't have to save f2-f127.

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 */

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#define PSR_BITS_TO_CLEAR						\

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	(IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT |		\

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	 IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED |	\

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	 IA64_PSR_DFL | IA64_PSR_DFH)

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#define PSR_BITS_TO_SET							\

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	(IA64_PSR_BN)

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#include <asm/processor.h>

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#include <asm/asmmacro.h>

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/*

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 * Inputs:

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 *	in0 = address of function descriptor of EFI routine to call

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 *	in1..in7 = arguments to routine

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 *

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 * Outputs:

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 *	r8 = EFI_STATUS returned by called function

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 */

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GLOBAL_ENTRY(efi_call_phys)

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	.prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8)

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	alloc loc1=ar.pfs,8,7,7,0

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	ld8 r2=[in0],8			// load EFI function's entry point

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	mov loc0=rp

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	.body

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	;;

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	mov loc2=gp			// save global pointer

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	mov loc4=ar.rsc			// save RSE configuration

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	mov ar.rsc=0			// put RSE in enforced lazy, LE mode

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	;;

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	ld8 gp=[in0]			// load EFI function's global pointer

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	movl r16=PSR_BITS_TO_CLEAR

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	mov loc3=psr			// save processor status word

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	movl r17=PSR_BITS_TO_SET

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	;;

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	or loc3=loc3,r17

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	mov b6=r2

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	;;

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	andcm r16=loc3,r16	// get psr with IT, DT, and RT bits cleared

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	br.call.sptk.many rp=ia64_switch_mode_phys

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.ret0:	mov out4=in5

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	mov out0=in1

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	mov out1=in2

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	mov out2=in3

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	mov out3=in4

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	mov out5=in6

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	mov out6=in7

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	mov loc5=r19

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	mov loc6=r20

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	br.call.sptk.many rp=b6		// call the EFI function

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.ret1:	mov ar.rsc=0			// put RSE in enforced lazy, LE mode

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	mov r16=loc3

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	mov r19=loc5

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	mov r20=loc6

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	br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode

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.ret2:	mov ar.rsc=loc4			// restore RSE configuration

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	mov ar.pfs=loc1

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	mov rp=loc0

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	mov gp=loc2

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	br.ret.sptk.many rp

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END(efi_call_phys)

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