David Daney c8f3cc0b65 MIPS: Don't vmap things at address zero. ... In the 64-bit kernel we use swapper_pg_dir for three different things. 1) xuseg mappings for kernel threads. 2) vmap mappings for all kernel-space accesses in xkseg. 3) vmap mappings for kernel modules in ksseg (kseg2). Due to how the TLB refill handlers work, any mapping established in xkseg or ksseg will also establish a xuseg mapping that should never be used by the kernel. In order to be able to use exceptions to trap NULL pointer dereferences, we need to ensure that nothing is mapped at address zero. Since vmap mappings in xkseg are reflected in xuseg, this means we need to ensure that there are no vmap mappings established at the start of xkseg. So we move back VMALLOC_START to avoid establishing vmap mappings at the start of xkseg. Signed-off-by: David Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/1129/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>		2010-04-30 20:52:41 +01:00
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asm	MIPS: Don't vmap things at address zero.	2010-04-30 20:52:41 +01:00