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/*
Copyright Oliver Kowalke 2009.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
*/
/****************************************************************************************
* *
* ---------------------------------------------------------------------------------- *
* | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | *
* ---------------------------------------------------------------------------------- *
* | 0x0 | 0x4 | 0x8 | 0xc | 0x10 | 0x14 | 0x18 | 0x1c | *
* ---------------------------------------------------------------------------------- *
* | RBX | R12 | R13 | R14 | *
* ---------------------------------------------------------------------------------- *
* ---------------------------------------------------------------------------------- *
* | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | *
* ---------------------------------------------------------------------------------- *
* | 0x20 | 0x24 | 0x28 | 0x2c | 0x30 | 0x34 | 0x38 | 0x3c | *
* ---------------------------------------------------------------------------------- *
* | R15 | RBP | RSP | RIP | *
* ---------------------------------------------------------------------------------- *
* ---------------------------------------------------------------------------------- *
* | 16 | 17 | 18 | 19 | | *
* ---------------------------------------------------------------------------------- *
* | 0x40 | 0x44 | 0x48 | 0x4c | | *
* ---------------------------------------------------------------------------------- *
* | sbase | slimit | | *
* ---------------------------------------------------------------------------------- *
* ---------------------------------------------------------------------------------- *
* | 20 | 21 | | *
* ---------------------------------------------------------------------------------- *
* | 0x50 | 0x54 | | *
* ---------------------------------------------------------------------------------- *
* | fc_mxcsr|fc_x87_cw| | *
* ---------------------------------------------------------------------------------- *
* *
* **************************************************************************************/
.text
.globl _jump_fcontext
.align 8
_jump_fcontext:
movq %rbx, (%rdi) /* save RBX */
movq %r12, 0x8(%rdi) /* save R12 */
movq %r13, 0x10(%rdi) /* save R13 */
movq %r14, 0x18(%rdi) /* save R14 */
movq %r15, 0x20(%rdi) /* save R15 */
movq %rbp, 0x28(%rdi) /* save RBP */
cmp $0, %rcx
je 1f
stmxcsr 0x50(%rdi) /* save MMX control and status word */
fnstcw 0x54(%rdi) /* save x87 control word */
ldmxcsr 0x50(%rsi) /* restore MMX control and status word */
fldcw 0x54(%rsi) /* restore x87 control word */
1:
leaq 0x8(%rsp), %rax /* exclude the return address and save as stack pointer */
movq %rax, 0x30(%rdi) /* save as stack pointer */
movq (%rsp), %rax /* save return address */
movq %rax, 0x38(%rdi) /* save return address as RIP */
movq (%rsi), %rbx /* restore RBX */
movq 0x8(%rsi), %r12 /* restore R12 */
movq 0x10(%rsi), %r13 /* restore R13 */
movq 0x18(%rsi), %r14 /* restore R14 */
movq 0x20(%rsi), %r15 /* restore R15 */
movq 0x28(%rsi), %rbp /* restore RBP */
movq 0x30(%rsi), %rsp /* restore RSP */
movq 0x38(%rsi), %rcx /* fetch the address to return to */
movq %rdx, %rax /* use third arg as return value after jump */
movq %rdx, %rdi /* use third arg as first arg in context function */
jmp *%rcx /* indirect jump to context */
.text
.globl _make_fcontext
.align 8
_make_fcontext:
movq %rdi, (%rdi) /* save the address of current context */
movq %rsi, 0x38(%rdi) /* save the address of the function supposed to run */
movq 0x40(%rdi), %rdx /* load the stack base */
pushq %rdi /* save pointer to fcontext_t */
movq %rdx, %rdi /* stack pointer as arg for align_stack */
call _align_stack /* align stack */
movq %rax, %rdx /* begin of aligned stack */
popq %rdi /* restore pointer to fcontext_t */
leaq -0x8(%rdx), %rdx /* reserve space for the last frame on stack, (RSP + 8) % 16 == 0 */
movq %rdx, 0x30(%rdi) /* save the address */
stmxcsr 0x50(%rdi) /* save MMX control and status word */
fnstcw 0x54(%rdi) /* save x87 control word */
leaq finish(%rip), %rcx /* helper code executed after context function returns */
movq %rcx, (%rdx)
xorq %rax, %rax /* set RAX to zero */
ret
finish:
xorq %rdi, %rdi /* exit code is zero */
call _exit /* exit application */
hlt
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