- unsigned long stack_start, stack_end, flags;
- int i, cpu;
-
- /*
- * The most common case is that we are in the task stack:
- */
- stack_start = (unsigned long)task->thread_info;
- stack_end = stack_start + THREAD_SIZE;
-
- if (in_range(stack_start, stack, stack_end))
- return stack_end;
-
- /*
- * We are in an interrupt if irqstackptr is set:
- */
- raw_local_irq_save(flags);
- cpu = safe_smp_processor_id();
- stack_end = (unsigned long)cpu_pda(cpu)->irqstackptr;
-
- if (stack_end) {
- stack_start = stack_end & ~(IRQSTACKSIZE-1);
- if (in_range(stack_start, stack, stack_end))
- goto out_restore;
- /*
- * We get here if we are in an IRQ context but we
- * are also in an exception stack.
- */
- }
-
- /*
- * Iterate over all exception stacks, and figure out whether
- * 'stack' is in one of them:
- */
- for (i = 0; i < N_EXCEPTION_STACKS; i++) {
- /*
- * set 'end' to the end of the exception stack.
- */
- stack_end = per_cpu(init_tss, cpu).ist[i];
- stack_start = stack_end - EXCEPTION_STKSZ;
-
- /*
- * Is 'stack' above this exception frame's end?
- * If yes then skip to the next frame.
- */
- if (stack >= stack_end)
- continue;
- /*
- * Is 'stack' above this exception frame's start address?
- * If yes then we found the right frame.
- */
- if (stack >= stack_start)
- goto out_restore;
-
- /*
- * If this is a debug stack, and if it has a larger size than
- * the usual exception stacks, then 'stack' might still
- * be within the lower portion of the debug stack:
- */
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- if (i == DEBUG_STACK - 1 && stack >= stack_end - DEBUG_STKSZ) {
- /*
- * Black magic. A large debug stack is composed of
- * multiple exception stack entries, which we
- * iterate through now. Dont look:
- */
- do {
- stack_end -= EXCEPTION_STKSZ;
- stack_start -= EXCEPTION_STKSZ;
- } while (stack < stack_start);
-
- goto out_restore;
- }
-#endif
- }
- /*
- * Ok, 'stack' is not pointing to any of the system stacks.
- */
- stack_end = 0;
-
-out_restore:
- raw_local_irq_restore(flags);
-
- return stack_end;