-/*
- * | | /\ Higher addresses
- * | |
- * --------------- stack base (address of current_thread_info)
- * | thread info |
- * . .
- * | stack |
- * --------------- saved regs->ebp value if valid (frame_head address)
- * . .
- * --------------- saved regs->rsp value if x86_64
- * | |
- * --------------- struct pt_regs * stored on stack if 32-bit
- * | |
- * . .
- * | |
- * --------------- %esp
- * | |
- * | | \/ Lower addresses
- *
- * Thus, regs (or regs->rsp for x86_64) <-> stack base restricts the
- * valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
- * exceptions use special stacks, maintained by the interrupt stack table
- * (IST). These stacks are set up in trap_init() in
- * arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
- * to the kernel stack; instead, it points to some location on the NMI
- * stack. On the other hand, regs->rsp is the stack pointer saved when the
- * NMI occurred. (2) For 32-bit, regs->esp is not valid because the
- * processor does not save %esp on the kernel stack when interrupts occur
- * in the kernel mode.
- */
-#ifdef CONFIG_FRAME_POINTER
-static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
-{
- unsigned long headaddr = (unsigned long)head;
-#ifdef CONFIG_X86_64
- unsigned long stack = (unsigned long)regs->rsp;
-#else
- unsigned long stack = (unsigned long)regs;
-#endif
- unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
-
- return headaddr > stack && headaddr < stack_base;
-}
-#else
-/* without fp, it's just junk */
-static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
-{
- return 0;
-}
-#endif
-
-