xref: /openbmc/linux/arch/ia64/kernel/esi_stub.S (revision 20e2fc42)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * ESI call stub.
4 *
5 * Copyright (C) 2005 Hewlett-Packard Co
6 *	Alex Williamson <alex.williamson@hp.com>
7 *
8 * Based on EFI call stub by David Mosberger.  The stub is virtually
9 * identical to the one for EFI phys-mode calls, except that ESI
10 * calls may have up to 8 arguments, so they get passed to this routine
11 * through memory.
12 *
13 * This stub allows us to make ESI calls in physical mode with interrupts
14 * turned off.  ESI calls may not support calling from virtual mode.
15 *
16 * Google for "Extensible SAL specification" for a document describing the
17 * ESI standard.
18 */
19
20/*
21 * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System
22 * Abstraction Layer Specification", revision 2.6e).  Note that
23 * psr.dfl and psr.dfh MUST be cleared, despite what this manual says.
24 * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call
25 * (the br.ia instruction fails unless psr.dfl and psr.dfh are
26 * cleared).  Fortunately, SAL promises not to touch the floating
27 * point regs, so at least we don't have to save f2-f127.
28 */
29#define PSR_BITS_TO_CLEAR						\
30	(IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT |		\
31	 IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED |	\
32	 IA64_PSR_DFL | IA64_PSR_DFH)
33
34#define PSR_BITS_TO_SET							\
35	(IA64_PSR_BN)
36
37#include <asm/processor.h>
38#include <asm/asmmacro.h>
39#include <asm/export.h>
40
41/*
42 * Inputs:
43 *	in0 = address of function descriptor of ESI routine to call
44 *	in1 = address of array of ESI parameters
45 *
46 * Outputs:
47 *	r8 = result returned by called function
48 */
49GLOBAL_ENTRY(esi_call_phys)
50	.prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(2)
51	alloc loc1=ar.pfs,2,7,8,0
52	ld8 r2=[in0],8			// load ESI function's entry point
53	mov loc0=rp
54	.body
55	;;
56	ld8 out0=[in1],8		// ESI params loaded from array
57	;;				// passing all as inputs doesn't work
58	ld8 out1=[in1],8
59	;;
60	ld8 out2=[in1],8
61	;;
62	ld8 out3=[in1],8
63	;;
64	ld8 out4=[in1],8
65	;;
66	ld8 out5=[in1],8
67	;;
68	ld8 out6=[in1],8
69	;;
70	ld8 out7=[in1]
71	mov loc2=gp			// save global pointer
72	mov loc4=ar.rsc			// save RSE configuration
73	mov ar.rsc=0			// put RSE in enforced lazy, LE mode
74	;;
75	ld8 gp=[in0]			// load ESI function's global pointer
76	movl r16=PSR_BITS_TO_CLEAR
77	mov loc3=psr			// save processor status word
78	movl r17=PSR_BITS_TO_SET
79	;;
80	or loc3=loc3,r17
81	mov b6=r2
82	;;
83	andcm r16=loc3,r16	// get psr with IT, DT, and RT bits cleared
84	br.call.sptk.many rp=ia64_switch_mode_phys
85.ret0:	mov loc5=r19			// old ar.bsp
86	mov loc6=r20			// old sp
87	br.call.sptk.many rp=b6		// call the ESI function
88.ret1:	mov ar.rsc=0			// put RSE in enforced lazy, LE mode
89	mov r16=loc3			// save virtual mode psr
90	mov r19=loc5			// save virtual mode bspstore
91	mov r20=loc6			// save virtual mode sp
92	br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode
93.ret2:	mov ar.rsc=loc4			// restore RSE configuration
94	mov ar.pfs=loc1
95	mov rp=loc0
96	mov gp=loc2
97	br.ret.sptk.many rp
98END(esi_call_phys)
99EXPORT_SYMBOL_GPL(esi_call_phys)
100