- /*
- * If IRET takes a fault on the espfix stack, then we
- * end up promoting it to a doublefault. In that case,
- * modify the stack to make it look like we just entered
- * the #GP handler from user space, similar to bad_iret.
- */
-#ifdef CONFIG_X86_ESPFIX64
- ALIGN
-__do_double_fault:
- XCPT_FRAME 1 RDI+8
- movq RSP(%rdi),%rax /* Trap on the espfix stack? */
- sarq $PGDIR_SHIFT,%rax
- cmpl $ESPFIX_PGD_ENTRY,%eax
- jne do_double_fault /* No, just deliver the fault */
- cmpl $__KERNEL_CS,CS(%rdi)
- jne do_double_fault
- movq RIP(%rdi),%rax
- cmpq $native_irq_return_iret,%rax
- jne do_double_fault /* This shouldn't happen... */
- movq PER_CPU_VAR(kernel_stack),%rax
- subq $(6*8-KERNEL_STACK_OFFSET),%rax /* Reset to original stack */
- movq %rax,RSP(%rdi)
- movq $0,(%rax) /* Missing (lost) #GP error code */
- movq $general_protection,RIP(%rdi)
- retq
- CFI_ENDPROC
-END(__do_double_fault)
-#else
-# define __do_double_fault do_double_fault
-#endif
-