.global ___chkstk
.global __alloca
.section .text
___chkstk:
__alloca:
pushl %ecx /* save temp */
leal 8(%esp), %ecx /* point past return addr */
subl %eax, %ecx
cmpl %fs:4, %ecx # check low stack limit
jb 1f
movl %esp, %eax /* save old stack pointer */
movl %ecx, %esp /* decrement stack */
movl (%eax), %ecx /* recover saved temp */
movl 4(%eax), %eax /* recover return address */
/* Push the return value back. Doing this instead of just
jumping to %eax preserves the cached call-return stack
used by most modern processors. */
pushl %eax
ret
1:
int3 #trap to debugger
.ascii "Stack overflow"