Commit ae8a8b95 authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

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: default avatarAlbin Tonnerre <Albin.Tonnerre@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent b0088480

arch/arm/include/asm/tlbflush.h

+1 −1
Original line number Diff line number Diff line
@@ -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 | \

arch/arm/mm/proc-v6.S

+0 −2
Original line number Diff line number Diff line
@@ -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



/*

arch/arm/mm/proc-v7-2level.S

+2 −1
Original line number Diff line number Diff line
@@ -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)

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

+2 −1
Original line number Diff line number Diff line
@@ -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)

arch/arm/mm/proc-v7.S

+2 −2
Original line number Diff line number Diff line
@@ -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)

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