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    powerpc: Remove ksp_limit on ppc64 · cbc9565e
    Benjamin Herrenschmidt 提交于
    We've been keeping that field in thread_struct for a while, it contains
    the "limit" of the current stack pointer and is meant to be used for
    detecting stack overflows.
    
    It has a few problems however:
    
     - First, it was never actually *used* on 64-bit. Set and updated but
    not actually exploited
    
     - When switching stack to/from irq and softirq stacks, it's update
    is racy unless we hard disable interrupts, which is costly. This
    is fine on 32-bit as we don't soft-disable there but not on 64-bit.
    
    Thus rather than fixing 2 in order to implement 1 in some hypothetical
    future, let's remove the code completely from 64-bit. In order to avoid
    a clutter of ifdef's, we remove the updates from C code completely
    during interrupt stack switching, and instead maintain it from the
    asm helper that is used to do the stack switching in the first place.
    Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
    cbc9565e
process.c 36.7 KB