enable interrupts in user path of page fault.
This is a minor fix, but what is currently there is essentially wrong. In do_page_fault, if the faulting address from user code happens to be in kernel address space (int *p = (int*)-1; p = 0xbed;) then the do_page_fault handler will jump over the local_irq_enable with the goto bad_area_nosemaphore; But the first line there sees this is user code and goes through the process of sending a signal to send SIGSEGV to the user task. This whole time interrupts are disabled and the task can not be preempted by a higher priority task. This patch always enables interrupts in the user path of the bad_area_nosemaphore. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -458,6 +458,11 @@ bad_area:
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bad_area_nosemaphore:
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/* User mode accesses just cause a SIGSEGV */
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if (error_code & 4) {
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/*
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* It's possible to have interrupts off here.
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*/
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local_irq_enable();
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/*
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* Valid to do another page fault here because this one came
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* from user space.
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@ -476,6 +476,12 @@ bad_area:
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bad_area_nosemaphore:
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/* User mode accesses just cause a SIGSEGV */
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if (error_code & PF_USER) {
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/*
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* It's possible to have interrupts off here.
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*/
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local_irq_enable();
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if (is_prefetch(regs, address, error_code))
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return;
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