arch/ia64/kernel/esi_stub.S

   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  */
  49 GLOBAL_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
  98 END(esi_call_phys)
  99 EXPORT_SYMBOL_GPL(esi_call_phys)