efi_stub.S (2685B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * EFI call stub. 4 * 5 * Copyright (C) 1999-2001 Hewlett-Packard Co 6 * David Mosberger <davidm@hpl.hp.com> 7 * 8 * This stub allows us to make EFI calls in physical mode with interrupts 9 * turned off. We need this because we can't call SetVirtualMap() until 10 * the kernel has booted far enough to allow allocation of struct vm_area_struct 11 * entries (which we would need to map stuff with memory attributes other 12 * than uncached or writeback...). Since the GetTime() service gets called 13 * earlier than that, we need to be able to make physical mode EFI calls from 14 * the kernel. 15 */ 16 17/* 18 * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System 19 * Abstraction Layer Specification", revision 2.6e). Note that 20 * psr.dfl and psr.dfh MUST be cleared, despite what this manual says. 21 * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call 22 * (the br.ia instruction fails unless psr.dfl and psr.dfh are 23 * cleared). Fortunately, SAL promises not to touch the floating 24 * point regs, so at least we don't have to save f2-f127. 25 */ 26#define PSR_BITS_TO_CLEAR \ 27 (IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT | \ 28 IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED | \ 29 IA64_PSR_DFL | IA64_PSR_DFH) 30 31#define PSR_BITS_TO_SET \ 32 (IA64_PSR_BN) 33 34#include <asm/processor.h> 35#include <asm/asmmacro.h> 36 37/* 38 * Inputs: 39 * in0 = address of function descriptor of EFI routine to call 40 * in1..in7 = arguments to routine 41 * 42 * Outputs: 43 * r8 = EFI_STATUS returned by called function 44 */ 45 46GLOBAL_ENTRY(efi_call_phys) 47 .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8) 48 alloc loc1=ar.pfs,8,7,7,0 49 ld8 r2=[in0],8 // load EFI function's entry point 50 mov loc0=rp 51 .body 52 ;; 53 mov loc2=gp // save global pointer 54 mov loc4=ar.rsc // save RSE configuration 55 mov ar.rsc=0 // put RSE in enforced lazy, LE mode 56 ;; 57 ld8 gp=[in0] // load EFI function's global pointer 58 movl r16=PSR_BITS_TO_CLEAR 59 mov loc3=psr // save processor status word 60 movl r17=PSR_BITS_TO_SET 61 ;; 62 or loc3=loc3,r17 63 mov b6=r2 64 ;; 65 andcm r16=loc3,r16 // get psr with IT, DT, and RT bits cleared 66 br.call.sptk.many rp=ia64_switch_mode_phys 67.ret0: mov out4=in5 68 mov out0=in1 69 mov out1=in2 70 mov out2=in3 71 mov out3=in4 72 mov out5=in6 73 mov out6=in7 74 mov loc5=r19 75 mov loc6=r20 76 br.call.sptk.many rp=b6 // call the EFI function 77.ret1: mov ar.rsc=0 // put RSE in enforced lazy, LE mode 78 mov r16=loc3 79 mov r19=loc5 80 mov r20=loc6 81 br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode 82.ret2: mov ar.rsc=loc4 // restore RSE configuration 83 mov ar.pfs=loc1 84 mov rp=loc0 85 mov gp=loc2 86 br.ret.sptk.many rp 87END(efi_call_phys)