x86/irq/64: Remap the IRQ stack with guard pages
The IRQ stack lives in percpu space, so an IRQ handler that overflows it will overwrite other data structures. Use vmap() to remap the IRQ stack so that it will have the usual guard pages that vmap()/vmalloc() allocations have. With this, the kernel will panic immediately on an IRQ stack overflow. [ tglx: Move the map code to a proper place and invoke it only when a CPU is about to be brought online. No point in installing the map at early boot for all possible CPUs. Fail the CPU bringup if the vmap() fails as done for all other preparatory stages in CPU hotplug. ] Signed-off-by: NAndy Lutomirski <luto@kernel.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NBorislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190414160146.363733568@linutronix.de
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