forked from Minki/linux
x86/dumpstack: When OOPSing, rewind the stack before do_exit()
If we call do_exit() with a clean stack, we greatly reduce the risk of recursive oopses due to stack overflow in do_exit, and we allow do_exit to work even if we OOPS from an IST stack. The latter gives us a much better chance of surviving long enough after we detect a stack overflow to write out our logs. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/32f73ceb372ec61889598da5e5b145889b9f2e19.1468527351.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -1153,3 +1153,14 @@ ENTRY(async_page_fault)
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jmp error_code
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END(async_page_fault)
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#endif
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ENTRY(rewind_stack_do_exit)
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/* Prevent any naive code from trying to unwind to our caller. */
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xorl %ebp, %ebp
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movl PER_CPU_VAR(cpu_current_top_of_stack), %esi
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leal -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%esi), %esp
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call do_exit
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1: jmp 1b
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END(rewind_stack_do_exit)
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@ -1423,3 +1423,14 @@ ENTRY(ignore_sysret)
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mov $-ENOSYS, %eax
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sysret
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END(ignore_sysret)
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ENTRY(rewind_stack_do_exit)
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/* Prevent any naive code from trying to unwind to our caller. */
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xorl %ebp, %ebp
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movq PER_CPU_VAR(cpu_current_top_of_stack), %rax
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leaq -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%rax), %rsp
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call do_exit
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1: jmp 1b
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END(rewind_stack_do_exit)
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@ -234,6 +234,8 @@ unsigned long oops_begin(void)
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EXPORT_SYMBOL_GPL(oops_begin);
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NOKPROBE_SYMBOL(oops_begin);
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void __noreturn rewind_stack_do_exit(int signr);
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void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
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{
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if (regs && kexec_should_crash(current))
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@ -255,7 +257,13 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
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panic("Fatal exception in interrupt");
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if (panic_on_oops)
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panic("Fatal exception");
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do_exit(signr);
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/*
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* We're not going to return, but we might be on an IST stack or
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* have very little stack space left. Rewind the stack and kill
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* the task.
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*/
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rewind_stack_do_exit(signr);
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}
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NOKPROBE_SYMBOL(oops_end);
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