J. Kain, licensed under standard MIT license */ setjmp: mov %rbx,(%rdi) /* rdi is jmp_buf, move registers onto it */ mov %rbp,8(%rdi) mov %r12,16(%rdi) mov %r13,24(%rdi) mov %r14,32(%rdi) mov %r15,40(%rdi) lea 8(%rsp),%rdx /* this is our rsp WITHOUT current ret addr */ mov %rdx,48(%rdi) mov (%rsp),%rdx /* save return addr ptr for new rip */ mov %rdx,56(%rdi) xor %eax,%eax /* always return 0 */ ret longjmp: xor %eax,%eax cmp $1,%esi /* CF = val ? 0 : 1 */ adc %esi,%eax /* eax = val + !val */ mov (%rdi),%rbx /* rdi is the jmp_buf, restore regs from it */ mov 8(%rdi),%rbp mov 16(%rdi),%r12 mov 24(%rdi),%r13 mov 32(%rdi),%r14 mov 40(%rdi),%r15 mov 48(%rdi),%rsp jmp *56(%rdi) /* goto saved address without altering rsp */ longjmp: jmp *56(%rdi) /* goto saved address without altering rsp */ /* Copyright 2011-2012 Nicholas J. Kain, licensed under standard MIT license */ setjmp: mov (%rsp),%rdx /* save return addr ptr for new rip */ Save and Restore • Machine stack position • Machine registers • Program counter
(Return address) 33