diff options
| -rw-r--r-- | arch/x86/entry/entry_64.S | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 0d4483ae6360..b56f7f23f21c 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -469,6 +469,7 @@ END(irq_entries_start) DEBUG_ENTRY_ASSERT_IRQS_OFF movq %rsp, \old_rsp incl PER_CPU_VAR(irq_count) + jnz .Lirq_stack_push_old_rsp_\@ /* * Right now, if we just incremented irq_count to zero, we've @@ -478,9 +479,30 @@ END(irq_entries_start) * it must be *extremely* careful to limit its stack usage. This * could include kprobes and a hypothetical future IST-less #DB * handler. + * + * The OOPS unwinder relies on the word at the top of the IRQ + * stack linking back to the previous RSP for the entire time we're + * on the IRQ stack. For this to work reliably, we need to write + * it before we actually move ourselves to the IRQ stack. + */ + + movq \old_rsp, PER_CPU_VAR(irq_stack_union + IRQ_STACK_SIZE - 8) + movq PER_CPU_VAR(irq_stack_ptr), %rsp + +#ifdef CONFIG_DEBUG_ENTRY + /* + * If the first movq above becomes wrong due to IRQ stack layout + * changes, the only way we'll notice is if we try to unwind right + * here. Assert that we set up the stack right to catch this type + * of bug quickly. */ + cmpq -8(%rsp), \old_rsp + je .Lirq_stack_okay\@ + ud2 + .Lirq_stack_okay\@: +#endif - cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp +.Lirq_stack_push_old_rsp_\@: pushq \old_rsp .endm |