• Nicholas Piggin's avatar
    powerpc/64s/hash: convert SLB miss handlers to C · 5e46e29e
    Nicholas Piggin authored
    This patch moves SLB miss handlers completely to C, using the standard
    exception handler macros to set up the stack and branch to C.
    
    This can be done because the segment containing the kernel stack is
    always bolted, so accessing it with relocation on will not cause an
    SLB exception.
    
    Arbitrary kernel memory may not be accessed when handling kernel space
    SLB misses, so care should be taken there. However user SLB misses can
    access any kernel memory, which can be used to move some fields out of
    the paca (in later patches).
    
    User SLB misses could quite easily reconcile IRQs and set up a first
    class kernel environment and exit via ret_from_except, however that
    doesn't seem to be necessary at the moment, so we only do that if a
    bad fault is encountered.
    
    [ Credit to Aneesh for bug fixes, error checks, and improvements to bad
      address handling, etc ]
    Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
    
    Since RFC:
    - Added MSR[RI] handling
    - Fixed up a register loss bug exposed by irq tracing (Aneesh)
    - Reject misses outside the defined kernel regions (Aneesh)
    - Added several more sanity checks and error handling (Aneesh), we may
      look at consolidating these tests and tightenig up the code but for
      a first pass we decided it's better to check carefully.
    
    Since v1:
    - Fixed SLB cache corruption (Aneesh)
    - Fixed untidy SLBE allocation "leak" in get_vsid error case
    - Now survives some stress testing on real hardware
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    5e46e29e
exceptions-64s.S 52 KB