| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667 |
- /*
- * thunks.S - assembly helpers for mixed-bitness code
- * Copyright (c) 2015 Andrew Lutomirski
- *
- * 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.
- *
- * 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
|
