diff options
Diffstat (limited to 'arch/ia64/kernel/efi_stub.S')
| -rw-r--r-- | arch/ia64/kernel/efi_stub.S | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/ia64/kernel/efi_stub.S b/arch/ia64/kernel/efi_stub.S new file mode 100644 index 0000000000..1fd61b78fb --- /dev/null +++ b/arch/ia64/kernel/efi_stub.S @@ -0,0 +1,87 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * EFI call stub. + * + * Copyright (C) 1999-2001 Hewlett-Packard Co + * David Mosberger <davidm@hpl.hp.com> + * + * This stub allows us to make EFI calls in physical mode with interrupts + * turned off. We need this because we can't call SetVirtualMap() until + * the kernel has booted far enough to allow allocation of struct vm_area_struct + * entries (which we would need to map stuff with memory attributes other + * than uncached or writeback...). Since the GetTime() service gets called + * earlier than that, we need to be able to make physical mode EFI calls from + * the kernel. + */ + +/* + * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System + * Abstraction Layer Specification", revision 2.6e). Note that + * psr.dfl and psr.dfh MUST be cleared, despite what this manual says. + * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call + * (the br.ia instruction fails unless psr.dfl and psr.dfh are + * cleared). Fortunately, SAL promises not to touch the floating + * point regs, so at least we don't have to save f2-f127. + */ +#define PSR_BITS_TO_CLEAR \ + (IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT | \ + IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED | \ + IA64_PSR_DFL | IA64_PSR_DFH) + +#define PSR_BITS_TO_SET \ + (IA64_PSR_BN) + +#include <asm/processor.h> +#include <asm/asmmacro.h> + +/* + * Inputs: + * in0 = address of function descriptor of EFI routine to call + * in1..in7 = arguments to routine + * + * Outputs: + * r8 = EFI_STATUS returned by called function + */ + +GLOBAL_ENTRY(efi_call_phys) + .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8) + alloc loc1=ar.pfs,8,7,7,0 + ld8 r2=[in0],8 // load EFI function's entry point + mov loc0=rp + .body + ;; + mov loc2=gp // save global pointer + mov loc4=ar.rsc // save RSE configuration + mov ar.rsc=0 // put RSE in enforced lazy, LE mode + ;; + ld8 gp=[in0] // load EFI function's global pointer + movl r16=PSR_BITS_TO_CLEAR + mov loc3=psr // save processor status word + movl r17=PSR_BITS_TO_SET + ;; + or loc3=loc3,r17 + mov b6=r2 + ;; + andcm r16=loc3,r16 // get psr with IT, DT, and RT bits cleared + br.call.sptk.many rp=ia64_switch_mode_phys +.ret0: mov out4=in5 + mov out0=in1 + mov out1=in2 + mov out2=in3 + mov out3=in4 + mov out5=in6 + mov out6=in7 + mov loc5=r19 + mov loc6=r20 + br.call.sptk.many rp=b6 // call the EFI function +.ret1: mov ar.rsc=0 // put RSE in enforced lazy, LE mode + mov r16=loc3 + mov r19=loc5 + mov r20=loc6 + br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode +.ret2: mov ar.rsc=loc4 // restore RSE configuration + mov ar.pfs=loc1 + mov rp=loc0 + mov gp=loc2 + br.ret.sptk.many rp +END(efi_call_phys) |