arch/ia64/kernel/esi_stub.S

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