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ARM: 7691/1: mm: kill unused TLB_CAN_READ_FROM_L1_CACHE and use ALT_SMP instead 

Many ARMv7 cores have hardware page table walkers that can read the L1
cache. This is discoverable from the ID_MMFR3 register, although this
can be expensive to access from the low-level set_pte functions and is a
pain to cache, particularly with multi-cluster systems.

A useful observation is that the multi-processing extensions for ARMv7
require coherent table walks, meaning that we can make use of ALT_SMP
patching in proc-v7-* to patch away the cache flush safely for these
cores.

Reported-by: Albin Tonnerre <Albin.Tonnerre@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
hifive-unleashed-5.1
Will Deacon 2013-04-03 17:16:57 +01:00 committed by Russell King
parent b008848020
commit ae8a8b9553
5 changed files with 7 additions and 7 deletions
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2
arch/arm/include/asm/tlbflush.h
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@ -169,7 +169,7 @@
# define v6wbi_always_flags (-1UL)
#endif
#define v7wbi_tlb_flags_smp (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \
#define v7wbi_tlb_flags_smp (TLB_WB | TLB_BARRIER | \
TLB_V7_UIS_FULL | TLB_V7_UIS_PAGE | \
TLB_V7_UIS_ASID | TLB_V7_UIS_BP)
#define v7wbi_tlb_flags_up (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \

2
arch/arm/mm/proc-v6.S
View File

@ -80,12 +80,10 @@ ENTRY(cpu_v6_do_idle)
mov pc, lr
ENTRY(cpu_v6_dcache_clean_area)
#ifndef TLB_CAN_READ_FROM_L1_CACHE
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
add r0, r0, #D_CACHE_LINE_SIZE
subs r1, r1, #D_CACHE_LINE_SIZE
bhi 1b
#endif
mov pc, lr
/*

3
arch/arm/mm/proc-v7-2level.S
View File

@ -110,7 +110,8 @@ ENTRY(cpu_v7_set_pte_ext)
ARM( str r3, [r0, #2048]! )
THUMB( add r0, r0, #2048 )
THUMB( str r3, [r0] )
mcr p15, 0, r0, c7, c10, 1 @ flush_pte
ALT_SMP(mov pc,lr)
ALT_UP (mcr p15, 0, r0, c7, c10, 1) @ flush_pte
#endif
mov pc, lr
ENDPROC(cpu_v7_set_pte_ext)

3
arch/arm/mm/proc-v7-3level.S
View File

@ -73,7 +73,8 @@ ENTRY(cpu_v7_set_pte_ext)
tst r3, #1 << (55 - 32) @ L_PTE_DIRTY
orreq r2, #L_PTE_RDONLY
1: strd r2, r3, [r0]
mcr p15, 0, r0, c7, c10, 1 @ flush_pte
ALT_SMP(mov pc, lr)
ALT_UP (mcr p15, 0, r0, c7, c10, 1) @ flush_pte
#endif
mov pc, lr
ENDPROC(cpu_v7_set_pte_ext)

4
arch/arm/mm/proc-v7.S
View File

@ -75,14 +75,14 @@ ENTRY(cpu_v7_do_idle)
ENDPROC(cpu_v7_do_idle)
ENTRY(cpu_v7_dcache_clean_area)
#ifndef TLB_CAN_READ_FROM_L1_CACHE
ALT_SMP(mov pc, lr) @ MP extensions imply L1 PTW
ALT_UP(W(nop))
dcache_line_size r2, r3
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
add r0, r0, r2
subs r1, r1, r2
bhi 1b
dsb
#endif
mov pc, lr
ENDPROC(cpu_v7_dcache_clean_area)