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| /* 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
|
|
