I'm investigating some 4k stack issues with our driver, and I noticed this ordering in do_IRQ:
asmlinkage unsigned int do_IRQ(struct pt_regs regs) { ...
#ifdef CONFIG_DEBUG_STACKOVERFLOW /* Debugging check for stack overflow: is there less than 1KB free? */ { ... } #endif
...
#ifdef CONFIG_4KSTACKS
for (;;) { ... switch to interrupt stack } #endif
Is the intention of this stack overflow check to catch a currently running kernel thread that's getting low on stack space, or is the intent to make sure there's enough stack space to handle the incoming interrupt? if the later, wouldn't you want to potentially switch to your interrupt stack to be more accurate? (I recognize that often you will have switched to an empty stack, unless you have nested interrupts)
It checks for both process context (system call or kernel thread) or interrupt context (nested irqs) stack overflows.
--
Brian Gerst
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