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>
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index bcaaa8d..a286d47 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -80,12 +80,10 @@
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
/*
diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S
index 78f520b..9704097 100644
--- a/arch/arm/mm/proc-v7-2level.S
+++ b/arch/arm/mm/proc-v7-2level.S
@@ -110,7 +110,8 @@
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)
diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index 6ffd78c..363027e 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S
@@ -73,7 +73,8 @@
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)
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 3a3c015..37716b0 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -75,14 +75,14 @@
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)