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linux-stable-rt/arch/sparc64/kernel/itlb_miss.S

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[SPARC64]: Move away from virtual page tables, part 1. We now use the TSB hardware assist features of the UltraSPARC MMUs. SMP is currently knowingly broken, we need to find another place to store the per-cpu base pointers. We hid them away in the TSB base register, and that obviously will not work any more :-) Another known broken case is non-8KB base page size. Also noticed that flush_tlb_all() is not referenced anywhere, only the internal __flush_tlb_all() (local cpu only) is used by the sparc64 port, so we can get rid of flush_tlb_all(). The kernel gets it's own 8KB TSB (swapper_tsb) and each address space gets it's own private 8K TSB. Later we can add code to dynamically increase the size of per-process TSB as the RSS grows. An 8KB TSB is good enough for up to about a 4MB RSS, after which the TSB starts to incur many capacity and conflict misses. We even accumulate OBP translations into the kernel TSB. Another area for refinement is large page size support. We could use a secondary address space TSB to handle those. Signed-off-by: David S. Miller <davem@davemloft.net>
2006-02-01 10:29:18 +08:00
/* ITLB ** ICACHE line 1: Context 0 check and TSB load */
ldxa [%g0] ASI_IMMU_TSB_8KB_PTR, %g1 ! Get TSB 8K pointer
ldxa [%g0] ASI_IMMU, %g6 ! Get TAG TARGET
srlx %g6, 48, %g5 ! Get context
brz,pn %g5, kvmap_itlb ! Context 0 processing
nop ! Delay slot (fill me)
[SPARC64]: Access TSB with physical addresses when possible. This way we don't need to lock the TSB into the TLB. The trick is that every TSB load/store is registered into a special instruction patch section. The default uses virtual addresses, and the patch instructions use physical address load/stores. We can't do this on all chips because only cheetah+ and later have the physical variant of the atomic quad load. Signed-off-by: David S. Miller <davem@davemloft.net>
2006-02-02 07:55:21 +08:00
TSB_LOAD_QUAD(%g1, %g4) ! Load TSB entry
[SPARC64]: Move away from virtual page tables, part 1. We now use the TSB hardware assist features of the UltraSPARC MMUs. SMP is currently knowingly broken, we need to find another place to store the per-cpu base pointers. We hid them away in the TSB base register, and that obviously will not work any more :-) Another known broken case is non-8KB base page size. Also noticed that flush_tlb_all() is not referenced anywhere, only the internal __flush_tlb_all() (local cpu only) is used by the sparc64 port, so we can get rid of flush_tlb_all(). The kernel gets it's own 8KB TSB (swapper_tsb) and each address space gets it's own private 8K TSB. Later we can add code to dynamically increase the size of per-process TSB as the RSS grows. An 8KB TSB is good enough for up to about a 4MB RSS, after which the TSB starts to incur many capacity and conflict misses. We even accumulate OBP translations into the kernel TSB. Another area for refinement is large page size support. We could use a secondary address space TSB to handle those. Signed-off-by: David S. Miller <davem@davemloft.net>
2006-02-01 10:29:18 +08:00
cmp %g4, %g6 ! Compare TAG
sethi %hi(_PAGE_EXEC), %g4 ! Setup exec check
/* ITLB ** ICACHE line 2: TSB compare and TLB load */
bne,pn %xcc, tsb_miss_itlb ! Miss
mov FAULT_CODE_ITLB, %g3
andcc %g5, %g4, %g0 ! Executable?
be,pn %xcc, tsb_do_fault
nop ! Delay slot, fill me
stxa %g5, [%g0] ASI_ITLB_DATA_IN ! Load TLB
retry ! Trap done
nop
/* ITLB ** ICACHE line 3: */
nop
nop
nop
nop
nop
nop
nop
nop
/* ITLB ** ICACHE line 4: */
nop
nop
nop
nop
nop
nop
nop
nop