arch/ia64/kernel/efi_stub.S

   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
  45 GLOBAL_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
  86 END(efi_call_phys)