path: root/arch/powerpc/mm/40x_mmu.c
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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-10-31 16:42:19 +1100
committerJosh Boyer <jwboyer@linux.vnet.ibm.com>2007-11-01 07:15:30 -0500
commitb98ac05d5e460301fbea24cceed0f2a601c82e22 (patch)
tree2e556ad28a007d13339300fbbd4942d0ec9f023c /arch/powerpc/mm/40x_mmu.c
parent[POWERPC] 4xx: Fix 4xx flush_tlb_page() (diff)
[POWERPC] 4xx: Deal with 44x virtually tagged icache
The 44x family has an interesting "feature" which is a virtually tagged instruction cache (yuck !). So far, we haven't dealt with it properly, which means we've been mostly lucky or people didn't report the problems, unless people have been running custom patches in their distro... This is an attempt at fixing it properly. I chose to do it by setting a global flag whenever we change a PTE that was previously marked executable, and flush the entire instruction cache upon return to user space when that happens. This is a bit heavy handed, but it's hard to do more fine grained flushes as the icbi instruction, on those processor, for some very strange reasons (since the cache is virtually mapped) still requires a valid TLB entry for reading in the target address space, which isn't something I want to deal with. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Diffstat (limited to 'arch/powerpc/mm/40x_mmu.c')
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