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ee4f2ea486
On hash table based 32 bits powerpc's, the hash management code runs with a big spinlock. It's thus important that it never causes itself a hash fault. That code is generally safe (it does memory accesses in real mode among other things) with the exception of the actual access to the code itself. That is, the kernel text needs to be accessible without taking a hash miss exceptions. This is currently guaranteed by having a BAT register mapping part of the linear mapping permanently, which includes the kernel text. But this is not true if using the "nobats" kernel command line option (which can be useful for debugging) and will not be true when using DEBUG_PAGEALLOC implemented in a subsequent patch. This patch fixes this by pre-faulting in the hash table pages that hit the kernel text, and making sure we never evict such a page under hash pressure. Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org> arch/powerpc/mm/hash_low_32.S | 22 ++++++++++++++++++++-- arch/powerpc/mm/mem.c | 3 --- arch/powerpc/mm/mmu_decl.h | 4 ++++ arch/powerpc/mm/pgtable_32.c | 11 +++++++---- 4 files changed, 31 insertions(+), 9 deletions(-) Signed-off-by: Paul Mackerras <paulus@samba.org> |
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