forked from Minki/linux
f60fe78f13
We allocate our IRQ stacks using a percpu array. This allows us to generate our IRQ stack pointers with adr_this_cpu, but bloats the kernel Image with the boot CPU's IRQ stack. Additionally, these are packed with other percpu variables, and aren't guaranteed to have guard pages. When we enable VMAP_STACK we'll want to vmap our IRQ stacks also, in order to provide guard pages and to permit more stringent alignment requirements. Doing so will require that we use a percpu pointer to each IRQ stack, rather than allocating a percpu IRQ stack in the kernel image. This patch updates our IRQ stack code to use a percpu pointer to the base of each IRQ stack. This will allow us to change the way the stack is allocated with minimal changes elsewhere. In some cases we may try to backtrace before the IRQ stack pointers are initialised, so on_irq_stack() is updated to account for this. In testing with cyclictest, there was no measureable difference between using adr_this_cpu (for irq_stack) and ldr_this_cpu (for irq_stack_ptr) in the IRQ entry path. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> |
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