linux/tools/testing/selftests/x86/thunks.S
Thomas Gleixner 2025cf9e19 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms and conditions of the gnu general public license
  version 2 as published by the free software foundation this program
  is distributed in the hope it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 263 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.208660670@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:37 +02:00

60 lines
877 B
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* thunks.S - assembly helpers for mixed-bitness code
* Copyright (c) 2015 Andrew Lutomirski
*
* These are little helpers that make it easier to switch bitness on
* the fly.
*/
.text
.global call32_from_64
.type call32_from_64, @function
call32_from_64:
// rdi: stack to use
// esi: function to call
// Save registers
pushq %rbx
pushq %rbp
pushq %r12
pushq %r13
pushq %r14
pushq %r15
pushfq
// Switch stacks
mov %rsp,(%rdi)
mov %rdi,%rsp
// Switch to compatibility mode
pushq $0x23 /* USER32_CS */
pushq $1f
lretq
1:
.code32
// Call the function
call *%esi
// Switch back to long mode
jmp $0x33,$1f
.code64
1:
// Restore the stack
mov (%rsp),%rsp
// Restore registers
popfq
popq %r15
popq %r14
popq %r13
popq %r12
popq %rbp
popq %rbx
ret
.size call32_from_64, .-call32_from_64