LXR linux/arch/ia64/kernel/efi

   1/*
   2 * EFI call stub.
   3 *
   4 * Copyright (C) 1999-2001 Hewlett-Packard Co
   5 *      David Mosberger <davidm@hpl.hp.com>
   6 *
   7 * This stub allows us to make EFI calls in physical mode with interrupts
   8 * turned off.  We need this because we can't call SetVirtualMap() until
   9 * the kernel has booted far enough to allow allocation of struct vma_struct
  10 * entries (which we would need to map stuff with memory attributes other
  11 * than uncached or writeback...).  Since the GetTime() service gets called
  12 * earlier than that, we need to be able to make physical mode EFI calls from
  13 * the kernel.
  14 */
  15
  16/*
  17 * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System
  18 * Abstraction Layer Specification", revision 2.6e).  Note that
  19 * psr.dfl and psr.dfh MUST be cleared, despite what this manual says.
  20 * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call
  21 * (the br.ia instruction fails unless psr.dfl and psr.dfh are
  22 * cleared).  Fortunately, SAL promises not to touch the floating
  23 * point regs, so at least we don't have to save f2-f127.
  24 */
  25#define PSR_BITS_TO_CLEAR                                               \
  26        (IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT |         \
  27         IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED |        \
  28         IA64_PSR_DFL | IA64_PSR_DFH)
  29
  30#define PSR_BITS_TO_SET                                                 \
  31        (IA64_PSR_BN)
  32
  33#include <asm/processor.h>
  34#include <asm/asmmacro.h>
  35
  36/*
  37 * Inputs:
  38 *      in0 = address of function descriptor of EFI routine to call
  39 *      in1..in7 = arguments to routine
  40 *
  41 * Outputs:
  42 *      r8 = EFI_STATUS returned by called function
  43 */
  44
  45GLOBAL_ENTRY(efi_call_phys)
  46        .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8)
  47        alloc loc1=ar.pfs,8,7,7,0
  48        ld8 r2=[in0],8                  // load EFI function's entry point
  49        mov loc0=rp
  50        .body
  51        ;;
  52        mov loc2=gp                     // save global pointer
  53        mov loc4=ar.rsc                 // save RSE configuration
  54        mov ar.rsc=0                    // put RSE in enforced lazy, LE mode
  55        ;;
  56        ld8 gp=[in0]                    // load EFI function's global pointer
  57        movl r16=PSR_BITS_TO_CLEAR
  58        mov loc3=psr                    // save processor status word
  59        movl r17=PSR_BITS_TO_SET
  60        ;;
  61        or loc3=loc3,r17
  62        mov b6=r2
  63        ;;
  64        andcm r16=loc3,r16      // get psr with IT, DT, and RT bits cleared
  65        br.call.sptk.many rp=ia64_switch_mode_phys
  66.ret0:  mov out4=in5
  67        mov out0=in1
  68        mov out1=in2
  69        mov out2=in3
  70        mov out3=in4
  71        mov out5=in6
  72        mov out6=in7
  73        mov loc5=r19
  74        mov loc6=r20
  75        br.call.sptk.many rp=b6         // call the EFI function
  76.ret1:  mov ar.rsc=0                    // put RSE in enforced lazy, LE mode
  77        mov r16=loc3
  78        mov r19=loc5
  79        mov r20=loc6
  80        br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode
  81.ret2:  mov ar.rsc=loc4                 // restore RSE configuration
  82        mov ar.pfs=loc1
  83        mov rp=loc0
  84        mov gp=loc2
  85        br.ret.sptk.many rp
  86END(efi_call_phys)
  87